piston to bore clearance

[grumpyvette]

ok first some facts
(1)cylinders will not be honed to true round as they will be in use with out the use of a deck plate to simulate and duplicate the bolt clamp stress on the cylinder walls, bores in blocks without a head or deck plate with the bolts or studs torqued to spec are not nearly the same shape before having the torqued studs bolts stress applied, theres almost no chance of getting a good ring seal without having the bores honed with a deck plate
always read, understand and follow the piston manufacturers guide for piston to bore clearance and how you measure that correctly
YOU NEED TO KNOW what is the piston to bore side clearance, where on the piston in relation to the pin,it will need to be accurately measured,in relation too the piston pin bore axis and piston top,surface, and how you measure it according to the manufacturer, and how did you measure both the piston and the bore and whats your ring gap supposed too be set at?
think carefully about both the initial cost and the structural strength of the engine block you select, the OEM blocks used in production car engines will RARELY accept a .030 plus over bore with out having one or more cylinders having marginally thin bore walls, this results in inadequate bore to ring sealing if its in the wrong area and promotes stress cracks. A .060 over bore in a SBC is rather commonly pushing that bore wall thickness up to or over a reasonable limit so you need to sonic and magnetically check the block for cracks and wall thickness.
you could easily dump $500-$1500 into machine work on a block that won't last more than a few months under high stress if its not carefully checked PRIOR to the machine work being done.

diagnosing a busted 632 BBC

there's a whole lot of info on the 632 CID BBC they go over, if you don't watch and listen carefully you'll miss important details the engine, disassembly can tell you a great deal, and look carefully at the components, listen carefully, and they point out a great many parts, strong points and...

garage.grumpysperformance.com

be sure you, measure EACH bore and EACH piston,
(CORRECTLY with the proper tools in the way the tool and piston manufacturers suggested)
and number them on an engine build sheet indicating the bore and piston diam.
from large to smallest on each and install them on each cylinder to get the most consistent piston to bore clearance's
yes the difference may only be a few ten thousands if the bores are machined correctly, but you'll get the best results , most consistent lubrication, best durability and less heat build up that might result in detonation issues that way. its the little things that add up to making a good durable engine assembly,
BTW check rod orientation, so the beveled sides don't fact the adjacent rods, and check the bearing clearances with plasti guage

btw
its standard practice to cc the combustion chambers, in the cylinder heads and the piston domes,(obviously check quenck and piston pin height, and clearances , mpisyton to head clearance, valve to piston cleances also,
(usually the piston domes volume is generally measured with the piston deck or quench surface rotated down the bore , exactly 1 inch) use your caliper or dial indicator and piston bridge)and the rings sealed temporarily with a bith of grease or paraffin to make sure you'll be dealing with as close as possible to the exact same compression ratio, in each cylinder, mark each piston with a indulable black magic marker A,B,C,D,E,F,G,H
and the bores 1-2-3-4-5-6-7-8 so you don't get measurements on the build sheet confused between bore diam and piston diam, and you can also not confuse dme volume on each piston

getting the correct piston to bore clearance, on your block

always think every step you take in any performance engine build through, logically and don't just jump off the dock head first, financially, without asking detailed questions , and documenting as much as you can in writing, and having a well thought through plan, parts list and time frame...

garage.grumpysperformance.com

http://www.sjdiscounttools.com/lis24000.html

measure carefully as the piston groove depth and back clearance must match the rings you use or youll have major problems
common sbc pin height info
Specs

• Comp Height 5.565" Rod - 1.561
• Comp Height 5.7" Rod - 1.433
• Comp Height 6.0" Rod - 1.13
• Pin Diameter - 0.9272

I've seen a great many machine shops who either just don,t give a rats A$$ or they are CLUELESS INCOMPETENTS
you can't assume anything you paid for was done correctly,
until
YOU VERIFY IT PERSONALLY (AND YES THAT REQUIRES PRECISION MEASURING AND EFFORT)

in either case this forces a decent engine builder to verify all the work was properly done

New
http://honingplates.com/index.php?main_page=product_info&products_id=28

http://honingplates.com/index.php?main_page=product_info&products_id=29


http://garage.grumpysperformance.co...-the-rabbit-hole-with-alice.10933/#post-66925


a day or so spent in careful research & reading can save you hundreds of dollars and months of wasted work

http://garage.grumpysperformance.com/index.php?threads/precision-measuring-tools.1390/

http://garage.grumpysperformance.com/index.php?threads/piston-to-bore-clearance.4630/

http://garage.grumpysperformance.co...tion-of-crank-durring-short-blk-assembly.852/

http://garage.grumpysperformance.co...g-and-installing-connecting-rods-pistons.247/

http://garage.grumpysperformance.com/index.php?threads/rotating-assembly-bearings.9527/

http://garage.grumpysperformance.co...oven-facts-if-your-in-doubt.13051/#post-69824

http://garage.grumpysperformance.com/index.php?threads/assembly-lube-summary.6352/

http://garage.grumpysperformance.com/index.php?threads/maximizing-piston-to-bore-ring-seal.3897/

http://garage.grumpysperformance.co...ng-and-basic-piston-ring-info-youll-need.509/[/quote]


read the links don,t skip them, youll likely save a great deal of cash and time knowing whats involved

http://garage.grumpysperformance.com/index.php?threads/block-prep.125/

http://garage.grumpysperformance.co...k-after-a-cam-lobe-rod-or-bearings-fail.2919/

http://garage.grumpysperformance.co...piston-to-bore-clearance-on-your-block.14251/

http://garage.grumpysperformance.com/index.php?threads/engine-block-cylinder-wall-thickness.976/

http://garage.grumpysperformance.com/index.php?threads/why-build-a-383-vs-a-350.715/

http://garage.grumpysperformance.com/index.php?threads/blocks-from-summitt-or-comp-products.10174/

http://garage.grumpysperformance.co...s-why-doesn-t-anyone-ever-ask-or-check.11532/


http://garage.grumpysperformance.com/index.php?threads/precision-measuring-tools.1390/

related threads with very useful info

assembling and installing connecting rods/pistons​

look closely at the connecting rods one edge of the main bearing are is beveled noticeably more than the other that beveled side faces away from the rod its paired with because it matches the slight radiased bevel of the crank journal many builder class pistons are designed to go in, in either...
garage.grumpysperformance.com

assembling and installing connecting rods/pistons​

look closely at the connecting rods one edge of the main bearing are is beveled noticeably more than the other that beveled side faces away from the rod its paired with because it matches the slight radiased bevel of the crank journal many builder class pistons are designed to go in, in either...
garage.grumpysperformance.com

Another rings end gap question​

Hi, I'm rebuilding my 4.3L Vortec from 2003 Chevy Astro Cargo Van. When I bought it a year ago it had ~26.000 miles. The engine was knocking and I couldn't get rid of that annoying sound - tried to clean up lifters through the push roads and by "seafoaming". It didn't work out, so I just...
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resistance to rotation, of crank durring short blk assembly​

Ok youve just installed your crankshaft in the engine block, with new main bearings and everything's well coated with assembly lube,and oil, and youve torqued down the main caps to spec. in at least three stages, and then gone back and rechecked the studs or bolts per the manufacturers...
garage.grumpysperformance.com

Made a mistake filing rings, still good?​

First I want to thank Grumpy for his help on many forums and him maintaining this one. It's an absolute WEALTH of info. So.... I am assembling an essentially stock 350. For use in a daily driver 95 Tahoe with TBI. I'm using a .030 over eagle rotating kit and a hydraulic roller cam out of an...
garage.grumpysperformance.com

getting the correct piston to bore clearance, on your block​

always think every step you take in any performance engine build through, logically and don't just jump off the dock head first, financially, without asking detailed questions , and documenting as much as you can in writing, and having a well thought through plan, parts list and time frame...
garage.grumpysperformance.com

maximizing piston to bore ring seal​

From the February, 2009 issue of Circle Track By Jeff Huneycutt Piston Ring Prep It can be a hassle filing... read full caption Piston Ring Prep It can be a hassle filing three sets of rings per cylinder, but when done correctly the results can mean more power and less fall-off before the...
garage.grumpysperformance.com

installing rings in piston grooves​

obviously if you've been around engine rebuilds, long enough, your aware that you'll eventually see guys installing rings in piston grooves by spiral twisting them into place, like the picture below depicts, AND YES YOU MIGHT NOT EVEN REALIZE THAT THE RING HAS BEEN SLIGHTLY DISTORTED...
garage.grumpysperformance.com

cleaning piston ring grooves, and related info​

now if there's any job that's frequently ignored or avoided during an engine rebuild , its more than likely ,cleaning pistons and cleaning the grooves its high on the list! RELATED INFO (take advantage of millions of hours of previous engine builds, by skilled and experienced people, and the...
garage.grumpysperformance.com

crankshaft and connecting rod compatability​

POSTED BY, navygunner08; "Does it matter what length rod you use with a particular crank? So if a crank is listed for use with 5.7" rods, can you use a 6" rod without modifications? And vise versa? " one factor to keep in mind is that rods typically have a side that rides against its matched...
garage.grumpysperformance.com

piston ring gaps​

the general rule is that for normal use a pistons top ring should have a minimum of .004 thousandths end gap for each inch of bore diam. ie a 4" bore requires a minimum of a .016 end gap, to prevent the ring ends from bearing on each other after heat expansion,expanding them, so as to prevent...
garage.grumpysperformance.com

how piston ring groove depth & clearance effects ring seal​

the job of the rings is to provide a high pressure gas tight seal preventing pressure in the combustion chamber during the compression, exhaust and power strokes above the piston from leaking past the rings and piston, the combination of slight inertial loads friction and pressure above the...
garage.grumpysperformance.com

piston rings & related info​

step ONE if the bores not concentric, and bore walls parallel and the bore surface consistent in its surface Finish or if you had the bore honed without the use of torque plates simulating a cylinder heads bolted in place, the rings WILL NOT SEAL as effectively , as they would if you had...
garage.grumpysperformance.com

if you want a fast dependable car you will need to either do the research required to know exactly how and why things should work, or pay someone else to do the work that has taken that time and effort.

your going to need decent feeler gauges

if the ring gaps, or piston to bore clearances are not carefully checked, or not correct your engine could easily get screwed up
Due to machining tolerances on both pistons and bore sizes theres always some minor differences between components,
when your assembling any engine, youll file fit the ring gaps to individual cylinders,and youll,
generally you'll want to carefully measure each individual piston diameter and each individual bore diameter very carefully,
and match the larger pistons to the larger bore sizes to keep the average side clearance as consistent as possible

most applications would have a ring gap of about .004-.005 per inch of bore diam.
(2) if the cylinder walls are sonic checked at less than about .150 Id suggest looking for a different engine block or partly filling the coolant passages to increase cylinder wall strength

(3) pistons are NOT exactly ROUND so verify with the manufacturer as to the correct place to measure them and the correct bore size they are to be used in, pistons are not round or evenly dimensioned, in circumference as with the heat of running in an engine,different sections expand at different rates this varies a great deal between applications, piston design and piston materials.
typical side clearances range in the .002-.005 ranges but you need to verify and measure both the bore and piston per the piston manufacturers instructions Every piston manufacturer measures their pistons at different spots depending on the design but about the best place to measure those it perpendicular to the wrist pin even with the top of the balance pad - typically .500"-.750" down from the top of the piston quench, but as stated CHECK WITH THE MANUFACTURER., all forged,or cast, or hypereutectic pistons will not require the same clearances nor are they measured in the same place[/color]
On to clearance,,
.005 is fine with some forged pistons & not so fine with others depending on application & piston design.
All listed clearances are minimum.
There are some that run much tighter, down to .0015 & some that need more
Most pistons are measured at the pin center line or just below it & some come with a dimension from the pin or deck down for clearance measurement, some from the bottom up.
The older Speed Pro & TRW ones were measured at the pin center line
here is where you, or your machine shop can screw things up on ring to bore seal, you need to have the cylinders bored and honed to the correct size specified by the manufacturer of the pistons,after MEASURING THE PISTONS to verify their size per the piston manufacturers instructions, then gap the rings per the ring manufacturers instructions, when you hone the bores,get and use block deck hone plates, during the hone process , keep in kind you want to use the same (STUDS OR BOLTS) the machine shop used and the same torque settings they used when the cylinders were honed with deck plates or the distortion of the bore and ring seal won,t be identical (exactly round)or ideal, keep in mind the piston side clearance must match what the piston manufacturer states.
Read more: http://forums.hotrod.com/70/6661552/pit ... z1ZRP7N7a0
HONE WITH HONE PLATES to duplicate the stress the head bolts place on the cylinder walls to get a true round bore wall surface

http://www.mscdirect.com/browse/Measuri ... eler+gauge

(4) rings need both back clearance and the correct end gaps plus some vertical clearance to function correctly and lubricate and cool efficiently

(5) ring must be installed with the correct side facing upward and in the intended groove

(6) the cylinder wall finish is mostly dictated by the rings to be used, so verify that with the ring manufacturer, and each alloy and piston design may require a slightly different bore clearance.

GET THE RING END GAP TOO TIGHT ,OR PISTON SIDE CLEARANCE TOO TIGHT,OR NOT PAY ATTENTION TO THE LUBE SYSTEM DETAILS,AND WHEN THE RINGS EXPAND WITH ENGINE HEAT THE ENDS TOUCH THE RINGS LOCK IN THE BORE AND THE PISTON LANDS SHEAR OFF, it RESULTS IN EXPENSIVE FAILURES GET THE GAP A BIT TOO LARGE AND YOU MIGHT BURN A BIT MORE OIL OR LOOSE SOME COMPRESSION, YOU'LL SEE A CHART LATER IN THE THREAD, BUT GENERALLY YOU'LL WANT .0045-.0065 PER INCH OF BORE DIAM. FOR A RING END GAP
http://garage.grumpysperformance.co...ng-piston-pin-height-compression-height.5064/

http://garage.grumpysperformance.co...n-wrist-pins-one-really-over-looked-part.978/

http://garage.grumpysperformance.com/index.php?threads/maximizing-piston-to-bore-ring-seal.3897/

if you find the rotating assembly is more difficult to rotate than you expected, you may want to verify some clearance issues that get over looked at times,
theres also some, other potential issues,
theres a slight potential for the piston wrist pins too not rotate effortlessly in the piston pin bores ,

that may add to the difficulty in rotating the assembly in the block.
the piston rings must have vertical and back clearance in the piston ring grooves

Piston Ring Groove Clearance
Pistons are grooved to fit rings that seal the cylinder’s compression and allow for lubrication of the cylinder walls. Piston rings come in a set. There are two compression rings. The top ring is affected by the most cylinder compression pressures. The second compression ring reinforces the top ring. The third ring down is the oil ring. It controls lubrication between the piston and cylinder bore.

Place the new ring into the top piston groove, and then place a feeler gauge into the gap between the new ring and the upper land. Move around the pistons groove and obtain a few measurements. Compare this reading to specifications. If this reading is too much and the gap is too large, the piston must be replaced. The top ring takes the most compression. This causes the ring to slap against and wear the lands in the piston groove.

be sure you, measure EACH bore and EACH piston,
(CORRECTLY with the proper tools in the way the tool and piston manufacturers suggested)
and number them on an engine build sheet indicating the bore and piston diam.
from large to smallest on each and install them on each cylinder to get the most consistent piston to bore clearance's
yes the difference may only be a few ten thousands if the bores are machined correctly, but you'll get the best results , most consistent lubrication, best durability and less heat build up that might result in detonation issues that way. its the little things that add up to making a good durable engine assembly,
BTW check rod orientation, so the beveled sides don't fact the adjacent rods, and check the bearing clearances with plasti guage

don,t guess on clearances and journal surface

So I decided to buy a couple of worthless old 283s to learn how to build engines. If I acquire the appropriate skills, I'm going to build a torquey 383 out of the anemic '77 350 in my C30. It tows cars, but it doesn't exactly set the road on fire, if you know what I mean. Anyway, I bought two...

garage.grumpysperformance.com

ring gapping and basic piston ring info YOULL NEED

YES YOU NEED TO READ THRU THE LINKS THAT'S WHAT THEY ARE THERE FOR...AND THERE'S A GREAT DEAL OF USEFUL INFO IN THOSE LINKS, don,t get over whelmed, make a list and test adjust correct or replace each problem, and check it off the list then move to the next issue, its a finite list and theres...

garage.grumpysperformance.com

assembling and installing connecting rods/pistons

look closely at the connecting rods one edge of the main bearing are is beveled noticeably more than the other that beveled side faces away from the rod its paired with because it matches the slight radiased bevel of the crank journal many builder class pistons are designed to go in, in either...

garage.grumpysperformance.com

and of course the pistons must have the correct piston too bore clearance. and connecting rod can only be installed facing one direction

RELATED THREADS & INFO YOU SHOULD READ or look AT

viewtopic.php?f=53&t=110&p=1672&hilit=2618#p1672

http://www.youtube.com/watch?v=QtJAuDZX ... re=related

http://www.youtube.com/watch?v=HQfh6AZx ... re=related

http://racingarticles.com/article_racing-10.html

http://garage.grumpysperformance.co...in-height-compression-height.5064/#post-66240

 

[grumpyvette]

Hypereutectic -vs- Forged Pistons


Hypereutectic pistons are used in some original equipment engines. They are favored because of reduced scuffing, improved power, fuel economy and emissions.

Hypereutectic 390 refers to a unique aluminum piston alloy that contains dissolved and free silicon. The material can be T6 heat treated to high strength and stiffness. Non-heat treated 390 hypereutectic alloy aluminum has slightly less strength than conventionally cast F-132 aluminum.

With this in mind, we caution the reader about the use of non-T6 heat treated O.E. design hypereutectic pistons for high performance. Silvolite and others do make replacement-type hypereutectic pistons that are worthwhile for stock replacement applications. Original equipment design is almost never suitable for performance applications.

The KB line of hypereutectic pistons were designed around the 390 alloy. The result is a high performance part intended to give the performance engine builder access to the latest in piston technology.

Forgings have long been the mainstay of the performance business and did well in the big cubic inch engines of the 60’s. Now, with focus on peak cylinder pressure timing, ring sealing dynamics, cylinder air tumble and swirl, combustion chamber science, and extended RPM ranges, we need to consider some new piston options.

The KB T6 hypereutectics are considerably different than the forgings. The KB pistons have shown improvement in power, fuel economy, cylinder sealing, service life, and cost effectiveness. The reduced thermal expansion rate allows the piston to be run with reduced clearance. A tight piston is less likely to rock, make noise, and burn oil. A rocking piston wears rings and increases blow-bye. The close fit of the KB piston allows the piston rings to truly seal, minimizing blow-by.

The design flexibility enjoyed by the KB series of pistons has an advantage over present day forging practices. The die for a forged piston must be designed so it can be easily removed. This limitation makes it difficult to make a light weight piston without sacrificing strength.

The KB pistons' utilization of the permanent mold with multiple die parts allows undercut areas above the pin hole and material distribution in the skirt area that stiffen the entire piston unit. The forged piston requires thick skirts to achieve comparable piston rigidity. A rigid piston rocks less in the cylinder and improves ring seal.

The forged pistons' thick skirts add weight. The design of KB pistons gives us the option to build the lightest pistons on the market.

Some current KB pistons are not super light for several reasons. If the piston is to be used as a stock replacement, more than a 10% weight reduction will mandate that the engine be re-balanced.

Common sense suggests that the introduction of a new product be extra strong at the initial release. As the product becomes accepted, weight reductions are scheduled as regular product upgrades, as justified with actual race testing.

There will always be a market for custom forged pistons. Small runs of forgings are more economical than small runs of permanent mold pistons because of the complexity of permanent mold tooling. Where quantities justify, expect to see future KB pistons developed that are lighter and stronger than anything else on the market. Machined head profiles are easily changed with our CNC equipment so we will stay current with new cylinder head developments. Volume production is expected to keep the price reasonable.

Our pricing policy has given the impression to some that we are building an economy, or in between, piston. The truth is, we are striving to build the "State of the Art" piston that is best, regardless of price. Reasonable pricing is just an added benefit.

AUTO APPLICATIONS
APPLICATION Hypereutectic Forging
Ring End Gap Factor Suggested Piston To Wall Clearance Ring End Gap Factor Suggested Piston To Wall Clearance
Bore To 4.100" 4.100" & up Bore To 4.100" 4.100" & up
Street - Normally Aspirated .0065" .0015" - .0020" .0020" - .0025" .0040" .0035" - .0045" .0045" - .0055"
Street - Towing .0080" .0015" - .0020" .0020" - .0025" .0045" .0040" - .0050" .0050" - .0060"
Street - Nitrous or Supercharged .0080" .0020" - .0025" .0025" - .0035" .0050" .0045" - .0055" .0055" - .0065"
Circle Track - 2 BBL or Restrictor/Gas .0070" .0015" - .0045" .0020" - .0050" .0040" .0040" - .0050" .0055" - .0065"
Circle Track - Unrestricted .0080" .0025" - .0045" .0030" - .0045" .0040" .0045" - .0065" .0055" - .0075"
Circle Track - Alcohol Injection .0060" .0025" - .0045" .0025" - .0050" .0040" .0045" - .0065" .0055" - .0075"
Circle Track - Alcohol Carbureted .0080" .0030" - .0045" .0030" - .0050" .0045" .0050" - .0070" .0060" - .0080"
Drag - Gasoline .0075" .0015" - .0045" .0020" - .0045" .0040" .0050" - .0070" .0060" - .0080"
Drag - Alcohol .0065" .0015" - .0045" .0020" - .0045" .0040" .0040" - .0070" .0050" - .0080"
Drag - Supercharged or Nitrous Gas .0095" .0020" - .0045" .0025" - .0050" .0050" .0060" - .0090" .0070" - .0100"
Drag - Supercharged Alcohol .0085" .0015" - .0045" .0025" - .0045" .0050" .0050" - .0070" .0060" - .0080"
Drag - Supercharged Fuel .0115" .0030" - .0050" .0035" - .0055" .0060" .0070" - .0100" .0080" - .0110"
Marine - Normally Aspirated .0080" .0030" - .0045" .0035" - .0050" .0040" .0045" - .0060" .0055" - .0070"
Marine - Supercharged .0090" .0030" - .0045" .0035" - .0050" .0045" .0055" - .0070" .0065" - .0080"
Air Cooled Baja .0075" .0030" - .0045" .0035" - .0050" .0040" .0050" - .0070" .0060" - .0080"
Propane .0065" .0015" - .0045" .0020" - .0045" .0040" .0035" - .0070" .0045" - .0080"
Supercharged Monster Truck / Mudbog .0090" .0025" - .0045" .0030" - .0050" .0060" .0080" - .0100" .0090" - .0110"


https://garage.grumpysperformance.com/index.php?threads/measuring-piston-dome-volume.17255/

 

[grumpyvette]

" grumpy, Ive got to ask, if you purchased pistons to build an engine and after getting the block honed, by your selected machine shop, you find out the manufacturers suggested piston, side clearance is a bit larger than they, suggested do you need to buy larger pistons?"

As in most things there are several routes you can take here, and a certain tolerance or range of clearance that will work, and the obvious first step is to call the manufacturer tech engineering guys and discuss your options after CAREFULLY measuring the pistons EXACTLY AS THE MANUFACTURER SPECIFY with accurate measuring tools and ACCURATELY measuring each of the engine cylinder bore diameters, you can,t make intelligent choices without facts.talk to a local machine shop you trust, KNURLING THE PISTON SKIRT may be an option here

MOST MACHINE SHOPS WILL INSIST ON HAVING THE PISTONS YOULL USE IN THE ENGINE ,BEFORE THEY BORE AND HONE THE BLOCK FOR PROPER SIDE CLEARANCE
now there are thermal coatings that can be used or added to the surface of a piston,these can be used to slightly increase the piston heat resistance and its ability to hold, more oil or reduce the tendency of oil to stick on, a piston skirt,or hold oil on its surface, and they will in many cases slightly add to the piston physical size but were talking only a thousandth or so,, Id also point out that theres several aluminum alloys 4032.2016 and several hyper-eutectic alloys so you need to know what your dealing with, again you need FACTS and accurate measurements and info to make decisions
most piston manufacturer measures their pistons at different spots depending on the design and aluminum alloy ,but about the usual place to measure those pistons perpendicular to the wrist pin center line even with the top of the balance pad - typically .250 down from the bottom oil groove
but check for precise info from your manufacturer.
a loose piston will wear faster and cause a noise when cool commonly referred to as piston slap,until heat causes it to expand, it will also tend to wear rings faster, in some cases using the thicker or higher viscosity oil helps slightly, but in an ideal world you get the clearances as close to the manufacturers suggested specs as you can.
Id point out that measuring the combustion chamber seal at TDC , during a leak-down test, has the obvious advantage of easily duplicating the test results giving you a base line to compare the cylinders from, yet I'd also point out that you'll occasionally find the rings and valves do function correctly at TDC but the bore walls are not consistent in size and shape thus as the piston descends down the bore the rings tend to loose seal. cracks in the lower cylinder and out of round bores can in theory pass a leak down test done at TDC. Id also point out that an operating engine has combustion chamber pressure and heat levels that far exceed the test pressure and the dynamic movement of the piston and ring to bore seal in an operational engine can be happening repeatedly ,from 450 to 4000 times a minute, and thats 8- 66 times a second at a peak pressure frequently exceeding 600 psi,and temps easily approaching 450F or more clearances are far tighter than on a cold engine, which means the very reduced time factor, and far tighter clearance significantly reduce the volume of trapped compressed gasses getting out of the combustion chamber so a static test at 80psi-120 psi while helpful won,t tell the full story.

if your serious about building engines as a hobby or even as a part time side business,
you'll be forced to either buy or borrow some decent quality precision measuring micrometers,
simply due to the need to check clearances accurately

http://www.globalindustrial.com/p/t...mpaignId=T9F&gclid=CL3al-3ZqNECFVU6gQodqAQF-g (ABOUT $250 a set)

http://www.mscdirect.com/product/details/06400865
(ABOUT $415 a set)

http://www.mscdirect.com/product/details/57480832?cid=ppc-google-Returning+-+Measuring+&+Inspecting+-+PLA_s2ymmR5OE&cid=PLA-Google-PLA+-+Test___164124957330_c_S&mkwid=s2ymmR5OE&cid=PLA-Google-PLA+-+Test|dc&pcrid=164124957330&gclid=CLPzkdLaqNECFYw8gQodiR0LNg
(ABOUT $877 a set)

dial bore gauges are about useless without a set of accurate mics, in the sizes of the bore diameter your checking as you use a dial bore gauge to measure consistency in a given bore size and basically how consistent or "ROUND" a bearing is but you use the mics to verify dimensions.
in my opinion you,ll also be smart to cross check ,bearing clearances with plasti-guage

http://www.tooltopia.com/fowler-72-646-300.aspx

Engine cylinder hone

Demo Block being used on the new honing machine.

www.youtube.com

viewtopic.php?f=53&t=2610&p=6737#p6737

http://www.beckracing.com/page05.htm

http://garage.grumpysperformance.co...d-what-goes-in-the-dumpster.13135/#post-68515

http://www.rosspistons.com/information/ ... lation.pdf

http://www.mscdirect.com/browse/Measuri ... eler+gauge

 

[grumpyvette]

I had a discussion today with a guy i know who seemed to have a good deal of difficulty understanding the reason his recent attempt to reduce an engines tendency to burn a bit of oil was rather self defeating, he had a failure to understand the cause vs result of engine oil burning issue.
his engine has valve covers with the rather typical PVC vacuum connection on one valve cover and a breather on the opposite side valve cover.
he decided to replace the valve covers with a new set that had no PVC or BREATHER hole locations and after the swap he found his exhaust pipes showed a bit of oil being burnt that had not been present before under hard acceleration,and his valve covers gaskets showed minor oil leakage that had not been an issue before the swap. I suggested he swap back to the old valve covers as a test and sure enough the result was the oil burn issue was greatly reduced, he just could not quite grasp the fact that cylinder pressure over the rings on the compression stroke forced the rings out against the cylinder bore walls, and sealing the engine allowed blow-by pressures to build up in the lower engine at higher rpms reducing the effect of that effective cylinder pressure on the rings too fully allow them to seat against the bore walls. having the lower engine crank case build pressure with no place to exit that pressure reduced the effective ring seal plus that same crank case pressure build-up at higher rpms allowed oil to seep out under the valve cover gaskets.
if theres any significant crank case pressure the second compression ring that normally acts in large part as an oil wiper ring as well as a secondary compression ring, tends to stutter or vibrate as the piston travels along the bore wall and not completely seal, resulting in a higher oil flow for the top ring to deal with.
this is a fairly well known problem, and one reason crank case vacuum pumps, and engines with dry sump oiling , can not only result in higher power being produced but lowering oil consumption and reducing an engines tendency to get into detonation as less oil enters the combustion chamber if the crank case is under a small negative pressure.

torque plate honing makes a differance

CNC BLOCKS N/E http://www.cncblocksnortheast.com/ posted much of this This is a pic of a 454 block that has come in for some work as it only has about 3200 miles on it since the rebuild and it was making some lower end noises. We line honed it and squared and decked it flat and bored it...

garage.grumpysperformance.com

#525 is a 220grit hard stone & pretty coarse.
It is what I consider a "production rebuilder finish" & not what I would finish any bore with especially a performance one but it will work with cast iron or chrome
#625 is a 280grit hard stone & mid range suited to moly rings

400-500 grit stones are sometimes used after a 280 grit hone to just prep the surface briefly before final clean-up and moly ring install

http://www.enginehones.com/lislehones.html

http://www.goodson.com/store/template/d ... 93a1b07466

http://www.wayfair.com/Lisle-Hone-Engin ... 49-IJO1028.

BTW when you go to buy a ring compressor....this type works far better than the others

http://store.summitracing.com/partdetail.asp?autofilter=1&part=PRO-66766&N=700+115&autoview=sku


related info, threads and sub-links, you should read carefully

http://garage.grumpysperformance.co...ng-and-basic-piston-ring-info-youll-need.509/

http://garage.grumpysperformance.co...ing-piston-to-bore-ring-seal.3897/#post-17109

http://garage.grumpysperformance.co...on-ring-info-youll-need.509/page-2#post-77252

http://garage.grumpysperformance.co...g-and-installing-connecting-rods-pistons.247/

http://garage.grumpysperformance.com/index.php?threads/flex-hone.9538/#post-72178

http://garage.grumpysperformance.co...ling-rings-in-piston-grooves.9490/#post-34908

http://garage.grumpysperformance.com/index.php?threads/piston-to-bore-clearance.4630/#post-30835

http://garage.grumpysperformance.co...ore-clearance-on-your-block.14251/#post-72471

related info

Performance Tool W80560 Performance Tool Cylinder Hones | Summit Racing

Free Shipping - Performance Tool Cylinder Hones with qualifying orders of $109. Shop Cylinder Hone Tools at Summit Racing.

www.summitracing.com

Powerbuilt Tools 648439 Powerbuilt Adjustable Cylinder Hone Deglazers | Summit Racing

Free Shipping - Powerbuilt Adjustable Cylinder Hone Deglazers with qualifying orders of $109. Shop Cylinder Hone Tools at Summit Racing.

www.summitracing.com

https://www.lowes.com/pd/GEARWRENCH-Engine-Cylinder-Hone-2-7-In-Diameter/5014118693?cm_mmc=shp-_-c-_-prd-_-tol-_-ggl-_-PLA_TOL_218_Mechanic-Automotive-Tools-_-5014118693-_-online-_-0-_-0&gclid=Cj0KCQjw5f2lBhCkARIsAHeTvljnDGRDjTxFzd7zZnlcy1WIfMRBIa4b6rW9ELIgmeVUHRwlei7tfPgaAs8tEALw_wcB&gclsrc=aw.ds

 

[Indycars]

Has anyone tried to quantify what value of crank case pressure where it becomes a problem ?

 

[grumpyvette]

Has anyone tried to quantify what value of crank case pressure where it becomes a problem ?

I don,t think its a set back pressure number, factors like piston ring tension,piston ring design, piston groove design,engine rpms,the rate of piston acceleration, rod length, the block, and block web design, itself and oil control issues , plus the oil pan, oil temps, oil viscosity, bore surface finish,and if a windage tray is used all effect the results.

moroso tests about power with and without vacum pumps,eavc kit , bigger oil pan ,oil pressure ect , very interesting check it out!

Post 5pointslow on April 25th 2012, 6:54 am
Drag Racer Thrashes Parts on the Moroso Performance Dyno
July 7th, 2010 By Randy Fish

Check out our stats from 10 pulls in one day.

The original “Drag Special” front tire from Moroso Performance has been a “must-have” item for decades, thanks to its light weight construction and lower rolling resistance. And that’s not all the parts maker is famous for. Since 1968, Moroso has pioneered the development of deep-sump oil pans, pan evacuation systems, vacuum pumps, and countless other performance systems and accessories.

Recently, the Drag Racer team was pleased to spend a day at Moroso Performance, where its team of engineers soundly thrashed a host of parts on the company’s DTS dyno. This aggressive project showed us (in real time) how a host of products have increased horsepower over the years.

Mule Engine Basics

The mule engine selected for this exercise was a 582-inch big-block Chevy provided decent results from most of the products tested here. However, it’s difficult to baseline such a wide variety of power producing items using one mule, as different combinations respond differently when applied to engines that put out either less or more grunt.

Specs …


» 582-inch Big-Block Chevy
» 4.600-inch bore / 4.375-inch stroke
» 14:1 compression
» VP Racing Fuel (C-12 108-octane)
» DTS 4000 Dyno
» Water and Oil temperature (beginning of pull) 160 to 165 degrees
» Petroleum-Based 15W40 oil
» Dyno Pulls from 5,300 to 7,500 RPM
FIRST PULL

» Oil pan: #20401
» Oil pump: #22175
» Evacuation System: #68817 breathers w/ #68357 Valve Covers
» Peak H.P. 935
» Peak Torque 772
» Average H.P. 887
» Average TQ 732
» Average Oil Pressure 39.5
» Average Vacuum 0.00
» “Street Price” $819.86
RESULTS: This is the basic set-up that evolved from the early days of bracket racing engines. This initial test demonstrates what an engine with a street/strip pan and a standard volume oil pump will make for power. After 6,000 RPM the oil pressure dropped approximately 10 psi. Using six quarts with this set-up is suitable, but the stroke of the engine shows how it will affect the oil control in the oil pan. In most cases, this line of oil pans will produce restrictions on the performance of a 4.375-inch stroke (or higher) engine, as noted in our disclaimer at the end of the text.



SECOND PULL

CHANGE: #25900 Pan Evacuation Kit – Remove breathers, and install evacuation breathers and lines to pan evacuation bungs in collectors

Topic shown: The difference between the engine breathing versus a small amount of crankcase vacuum created. Many classes do not allow vacuum pumps, and many racers still use them.

» Peak H.P. 964 + 29
» Peak Torque 779 +7
» Average H.P. 904 +7
» Average TQ 745 +13
» Average Oil Pressure 38.1 psi (-1.4)
» Average Vacuum 5.04 in/hg +5.04
» “Street Price” increases $56.25
RESULTS: Releasing the crankcase pressure is essential to making power. Many classes of racing do not allow evacuation pumps or “vacuum pumps” by the rules, so making a “Pan-E-Vac” system work will gain power by creating some amount of vacuum. This type of system can be purchased for a minimal amount of money and effort to gain the numbers seen.

THIRD PULL

CHANGE: #22185 High-Volume Oil Pump and Pick-Up – drop oil pan, swap oil pump and pick-up, re-install #20401 pan.

TOPIC SHOWN: How the oil pressure and horsepower changes, based on increasing the oil pump size. Over the years, there has been endless discussions on how much power is used to turn a high-volume pump, and how much more oil pressure is created, along with volume.

» Peak H.P. 953 – 11
» Peak Torque 764 -15
» Average H.P. 890 -14
» Average TQ 733 -12
» Average Oil Pressure 45.0 psi +6.9
» Average Vacuum 5.14 in/hg +0.10
» “Street Price” increases $17.02
RESULTS: People always ask about needing a high-volume pump, which produces more oil pressure, thinking it’s going to be their savior. Well, it will give you more oil pressure, but a loss of nearly one-percent of the horsepower it takes to run your engine. This shows without a doubt that there is a cause and effect on making the decision to increase your oil pressure.

FOURTH PULL

CHANGE: Remove #20401 oil pan – Install #21047 oil pan

TOPIC SHOWN: Changing over from a Street/Strip oil pan to a full Drag Race oil pan with kick-out and solid-louvered tray. This oil pan also has a 5-inch deep front sump versus the 4.5-inch deep stock sump. How this works above 6,500 RPM will show the advantages between a “Street/Strip Pan” and a “Drag Race Pan.”

» Peak H.P. 993 +40
» Peak Torque 780 +16
» Average H.P. 919 +29
» Average TQ 756 +23
» Average Oil Pressure 60.1 psi +15.1
» Average Vacuum 5.02 in/hg -0.12
» “Street Price” increases $203.50
RESULTS: This test clearly demonstrates how much better a Drag Race Pan performs over 6,500 RPM and makes a big difference in the horsepower. It will also make gains at lower RPM and increase the torque, thus improving the elapsed time of any car. This 582 cubic inch engine showed that the benefits are big. However, the gains will always be proportional to the size of the stroke in the engine. The oil pressure is more stable as the oil will return to the sump area far more efficiently, and gives a much smoother pressure trace.

FIFTH PULL

CHANGE: Install 22640 Vacuum Pump System – (Remove pan evacuation system and valve covers) – Install #68356, and vacuum pump system (#22640, #63910, #22649, #22630, #64888 #97172, #63849, #85465)

TOPIC SHOWN: The gain from a three-vane vacuum pump. This is the company’s best selling vacuum pump, and is also its original design. Oil pressure changes, horsepower and torque gains, and installation were the highlights with this change. The pump was run at 50 percent of engine speed.

» Peak H.P. 1018 +25
» Peak Torque 791 +11
» Average H.P. 934 +15
» Average TQ 768 +12
» Average Oil Pressure 58.1 psi -2.0
» Average Vacuum 13.25 in/hg +8.23
» “Street Price” increases $1095.00
RESULTS: Creating more crankcase vacuum is worth power, even though we already had a Pan-E-Vac” System on it. The belt-driven vacuum pump created more vacuum, more consistently, throughout the power range (and at idle). In some cases the oil pressure will drop when this much vacuum is applied, but having an oil pump that is larger than what the system needs will often make up for the vacuum that will typically create more oil flow, and less oil pressure to read on the oil pressure gauge.

SIXTH PULL

CHANGE: Install #22642 Vacuum Pump (remove #22640 pump and bracket)

TOPIC SHOWN: The difference between a three-vane and a four-vane pump on a wet-sump engine.

» Peak H.P. 1024 +6
» Peak Torque 797 +6
» Average H.P. 941 +7
» Average TQ 774 +6
» Average Oil Pressure 60.0 psi +1.9
» Average Vacuum 16.17 in/hg +2.92
» “Street Price” increases $140.29
RESULTS: The Moroso “Enhanced” vacuum pump works better in the area of vacuum than the “Original” design Moroso Vacuum Pump. This comparison shows the gain with a few inches of vacuum. On an engine this size, making and average of 16 inches of vacuum is about as much as you would want.

SEVENTH PULL

CHANGE: #21049 oil pan and #22187 oil pump combo (remove #21047)

TOPIC SHOWN: How well the new-style Steel Oil Pan and Shrouded Oil Pump work.

» Peak H.P. 1025 +1
» Peak Torque 802 +5
» Average H.P. 956 +15
» Average TQ 775 +1
» Average Oil Pressure 66.6 psi +6.6
» Average Vacuum 16.35 in/hg +0.17
» “Street Price” increases $31.89
RESULTS: While the peak numbers aren’t that different, the average horsepower number is much higher, and shows how oil pan tray design can increase power throughout the pull, and therefore, your run. Subtle changes can garner big results in oil pan design. Notice the better oil pressure throughout, as this pull was made with seven quarts of oil.



EIGHTH PULL

CHANGE: Install #22164 Billet Oil Pump (remove oil pan and swap oil pumps)

TOPIC SHOWN: The difference between a cast pump and a billet pump, in both horsepower and oil pressure.

» Peak H.P. 1025 0
» Peak Torque 803 +1
» Average H.P. 958 +2
» Average TQ 774 -1
» Average Oil Pressure 74.3 psi +7.7
» Average Vacuum 16.50 in/hg +0.15
» “Street Price” increases $290.28
RESULTS: The power didn’t change with the oil pump swap, even though it was a High Volume vs. Standard Volume change where we saw a gain in the previous pulls. But, you will notice how good the oil pressure was with a billet oil pump versus the cast iron pump housing. This will show that with all the power we are making, a standard-volume pump will keep up with (or exceed) what the end user would want for oil pressure.

NINTH PULL

Change: #20385 Aluminum Drag Race Oil Pan (remove #21047 steel oil pan), install race pattern gasket and stud kit #38361

TOPIC SHOWN: The difference in power and oil pressure with a larger sump and bigger kick-outs. Do these enhancements really make more power?

» Peak H.P. 1027 +2
» Peak Torque 805 +2
» Average H.P. 960 +2
» Average TQ 777 +3
» Average Oil Pressure 76.1 psi +1.8
» Average Vacuum 16.48 in/hg -0.02
» “Street Price” increases $168.60
RESULTS: The aluminum oil pan is lighter, easier to work with and has the full race bolt pattern and drain-back bungs. For this test, the 582’s stroke was not showing the gains that you would see on a 4.500-inch stroke (and up) combination. The aluminum pan holds the oil pressure and works very well over 8,000 RPM, a range which is commonly seen in today’s popular bracket racing engines.



TENTH PULL

CHANGE: #22843 Vacuum Pump (remove #22642 Vacuum Pump)

TOPIC SHOWN: Installing a large vacuum pump and making a bunch of vacuum. What does it do for power and oil pressure? How much is too much?

» Peak H.P. 1023 -4
» Peak Torque 799 -4
» Average H.P. 958 -2
» Average TQ 773 -4
» Average Oil Pressure 74.9 psi -1.2
» Average Vacuum 18.15 in/hg +1.67
» “Street Price” increases $213.73
RESULTS: Making “more” vacuum isn’t going to make you more power, as this pull shows. The #22843 Pro-Mod vacuum pump takes more power to drive, and will make more vacuum. But, as with anything, it will peak out. And on many engines this size, 16 inches of vacuum is typically the highest number you would want to see. Dry-sump engines will benefit from these vacuum numbers. Even with the high vacuum numbers, the standard-volume oil pump still maintained good oil pressure.

Moroso’s engineering guys went above and beyond the call of duty in order to complete 10 dyno pulls in one day. However, everything went off without a hitch and the end result came with a mountain of data that quantified each and every change that took place. We came away with new-found respect for the practice of research and development – something Moroso Performance used liberally while building its respected legacy. Of course, on-track testing (and winning) has always been another cornerstone of this company’s overall plan. Rest assured the same degree of engineering, research and development goes into the entire product line available from the Moroso Performance Products family, which includes Competition Engineering and Moroso Wire Technologies.

READ THESE LINKS
http://www.carcraft.com/techarticles/cc ... pump_test/

http://www.enginelabs.com/engine-tech/d ... cuum-pump/

http://www.strokerengine.com/vacuumpump.html

 

[Indycars]

From those test results, you certainly don't want a positive crank case pressure.

Are the only viable vacuum pump mechanical or are there some electric motor driven types that will work?

 

[87vette81big]

Just Mechanical Rick.
Have to be carefull using crankcase vacuum pumps. Sometimes they work to well.
More than a few cases of Piston pin Boss failures.
The vacuum pumps draw so hard that all crankshaft oil splash is nearly eliminated.
Starves Wrist pins of oil splash.
Driver gets on the gas hard. Boom.
Piston boss breaks locks up on wrist pin
No lubricating oil. Metal to metal galked locked up.

Seen a few cases like that.
I think Dry sump better.
Best to purchase an engineered package Engine vacuum pump & pan, vacuum regulator, valvecovers, iil pump.

 

[Indycars]

Good to know Brian ...... Thanks!

 

[grumpyvette]

occasionally I'm asked a question that I find, a bit confusing, in that I thought the knowledge of the process or answer, too that question, was all too obvious ,forgetting that the experience Ive gained over the years is far from universal.
so heres a bit of info just so you are familiar with the concept, yeah old school but in some cases it works out fine
obviously talking things over with a skilled machinist and discussing your options then making an informed choice, THEN HAVING AN EXPERIENCED SHOP DO THE WORK, is the best route
Jacks rebuilding a basic transportation 307 SBC the bore walls were rather strait and barely worn after close to 100K miles, and there was no determinable upper bore ridge indicating bore wear issues, but the heads needed a valve guide replacement so he decided to have the heads replaced with heads the local machine shop supplied that were guaranteed to be in great shape as they were recently rebuilt and the previous owner never picked them up, they had been sitting on a shelf for over two years, and the machine shop sold then at the bargain price of $300 for the pair including a complete engine gasket set.
Jack was in the process of measuring the bores to buy rings and order gaskets when he found that the original pistons in the original bores (AFTER HE HAD HONED THEM WITH A DINGLE BRUSH)
now had a .006-.007 clearance which the local machine shop said is a bit too much, they gave him the option of boring the block to .010 over size and buying new pistons or knurling the current set and buying rings that were slightly over size and custom fitting the end gaps.
yes it sure helps to have the correct tools and know where to measure parts

READ THROUGH THIS LINKED THREAD
http://garage.grumpysperformance.com/index.php?threads/precision-measuring-tools.1390/#post-52469

now the machine shop stated the pistons were .005-.007 under size for the now re-honed bore diam. since this is an engine that rarely sees 4500rpm and hes desperately trying to keep the cost low I suggested he have the pistons knurled as this process expends the piston bore size and tends to add an area that collects and holds lubricant.(THIS KNURLING, THE PISTON SKIRT,PROCEDURE, TENDS TO BE A CHEAP, EFFECTIVE BUT NOT LONG TERM TACTIC, AS THE SURFACE HAVING BEEN RAISED TENDS TO WEAR AWAY , AT LEAST PARTIALLY IN 20k-30k)MILES)
pistons are NOT perfectly round, the skirts 90 degrees from the piston pin that holds them to the rods can be slightly expanded thru knurling, while this process is not as ideal as new pistons with a thermal and lubricant coating on the skirt is usually very cost effective (CHEAP) and the car took over 30 years to get 100K mileage so I'm reasonably sure the process should out last the cars life span in a rebuilt engine.
http://garage.grumpysperformance.co...breather-hole-in-valve-covers.2005/#post-5328

http://garage.grumpysperformance.com/index.php?threads/need-help-with-evac-system.15939/#post-95997

http://garage.grumpysperformance.com/index.php?threads/catch-can-related-info.4636/#post-12451

http://garage.grumpysperformance.com/index.php?threads/pcv-system-routing.10999/#post-48572

https://auto.howstuffworks.com/positive-crankcase-ventilation-system.htm

video

knurled...to restore the clearance.

What you are seeing is one of the pistons after it has been knurled on a K-line knurler. We are looking at the major thrust side of the piston. The minor thrust side looks exactly the same. The knurling is done to extend just beyond any scuffing mark. That way the raised surface area will be all of the surface area that comes into contact with the wall.

The purpose of knurling is to increase the diameter of the piston skirt: at the surfaces that come into contact with the cylinder wall. That diamond pattern raises the surface of the skirt about four thou [0.004in] on each side; resulting in a diameter increase of about eight thou [0.008in]. Eight thou is about the max you can go; but eight is plenty for this motor. The cylinders had about 2.5 thou [0.0025in] of belling. Honing the bores to get things cleaned up nicely ended up at about three thou [0.003in] larger than STD size.

That means that I had about five thou [0.005in] of knurled metal to carefully remove, using fine emery cloth, so as to end up with the piston to cylinder wall clearance that I want: right at one and a half thou [0.0015in]. That does not happen in five minutes. It does take time and patience.

Pistons have to be carefully examined before you knurl them: they have to be usable. The ringlands have to be in excellent condition. The wristpin bores through the piston have to be unworn and undamaged.

The first step is to clean the pistons and rods before dis-assembly: to facilitate the wrist-pin removal without damage. And only when clean can the piston be examined and measured, and closely checked for any cracks or other evidence of damage.

If everything passes muster, the pistons are knurled to the eight thou diameter increase: called "blowing them up" eight thou.

Then I get to REALLY clean them; especially the ring-lands. No carbon residue is allowable; and no ring scraper is allowable either. The pistons are soaked in carbon softening solvent, and the ring-lands are scrubbed with toothbrush size brass bristle or stainless steel bristle brushes. Sometimes I actually use an old toothbrush: the plastic bristles won't damage the aluminum alloy, especially in and around the wrist-pin bore.

When thoroughly cleaned, the fit of the new rings in the ring-lands are checked and verified.

milling stroker clearance on 350/383

Then I start the resizing to fit the bore procedure: sand a bit; clean; mike it; repeat. Once I get to about zero wall clearance, then it gets more intense, and the metal removal is done in smaller amounts...until I get to the right wall clearance.

Done carefully and done right, knurled pistons can perform as well as brand new pistons.

HERE BELOW IS SOME BIG BLOCK PISTONS ON A RACE ENGINE THAT WERE KNURLED TO INCREASE THE PISTON DIAM. SO ITS OBVIOUSLY NOT AN ECONOMY ISSUE IN ALL CASES

RELATED INFO


http://garage.grumpysperformance.co...block-cylinder-wall-thickness.976/#post-22976

 

[Indycars]

I've never seen someone knurl pistons, but valve guides are done all the time. I've
never had much luck with valve guides that were knurled lasting very long.

 

[Grumpy]

I just realized I was reading the wrong chart,........ I love it when I'm wrong.

 

[Grumpy]

I've never seen someone knurl pistons, but valve guides are done all the time. I've
never had much luck with valve guides that were knurled lasting very long.

knurled valve guides is a cheaper and vastly less effective or durable option,
its a cheap "FIX" that is never going to work nearly as well as the correct fix,
of replacing the worn valve guides with new properly fitted and clearanced valve guides