piston skirt to crank counterweight and crank counterweight to cam clearance

Grumpy

Grumpy

The Grumpy Grease Monkey mechanical engineer.
Staff member
here are some excellent links to info you should know about and understand,
about the forces and clearances that result from building any performance v8 engine combo
AS WITH EVERYTHING ELSE IN LIFE,
THINK IT THROUGH,
LOOK AT YOUR OPTIONS,
DO THE REQUIRED RESEARCH
before YOU MAKE EXPENSIVE CHOICES :like:

now consider a few factors that must be present in a recent engine build thread

PROJECT 900

Chris Cobb, The Dickey's, and myself wanted to build a TRUE 23º SBC that makes 900hp. The pieces were gathered and last week the Dickeys went to Paris TN to build and dyno the engine. The heads were a set of SRH v3.00 that I reworked to accommodate the 462cid. It peaked at 8300 rpm. The test...
garage.grumpysperformance.com

a SBC, has a bore centerline spacing of 4.4 inches center too center, thus even if the blocks cast without coolant flow clearance between the cylinder's and knowing theres a head gasket required to seal the heads between those adjacent cylinders your effectively limited to a max bore diameter of between about 4.125" (400 chevy) and maybe 4.2" on a custom made aftermarket block casting that still alows adequate room between the adjacent cylinders for the head gaskets to seal correctly

read the linked info carefully

Analysis of Forces on Reciprocating Engine Components by EPI Inc.

Analysis of Forces on Reciprocating Engine Components - Propulsion System Technology and Components for Aircraft, Automotive, Marine and Industrial Applications
www.epi-eng.com

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I'd point out that there's also the matter of the rotating assembly inevitably causing a potential clearance issue,
with the connecting rods clearing the cam lobes in most longer stroke configurations ,
especially if the connecting rods are not designed for maximum clearance.
with a 4.2" stroke engine spinning at 8500 rpm what's the piston speed?
https://www.omnicalculator.com/physics/piston-speed= 5950 fet per second:worried::relieved:
that is VERY impressive if it holds together

Your biggest stress in the bottom end with RPM's is the loading of the rods and rod bolts in tension,
resulting in a failure of the rod or the rod bolts.
CONSIDER WHAT YOULL HAVE LEFT,
IF A ROD BOLT COMES LOOSE AT LETS SAY 7500 RPM,
BECAUSE YOU SELECTED A CHEAPER ROD BOLT, CONNECTING ROD OR VALVE SPRING etc.

Piston And Rod Orientation & Clearance Issues Etc.

I got a new set of pistons (H423DCP/H640DCP) and a "new to me" set of OEM rods. The rods are numbered by cylinder, but the pistons aren't, and the dot is supposed to go toward the front of the block. I just put a rod on backward, so can it be interchanged with another cylinder on the opposite...
garage.grumpysperformance.com

sellecting valve springs, and setting up the valve train

How do you determine the spring pressure needed to keep the valves under control for a given lift, duration, and max rpm. It might take you several hours to read thru all the links and sub links but its time very well spent as it could save your engine from destruction and save you thousands of...
garage.grumpysperformance.com

Longer rod will help decrease max piston speed marginally
. Lighter piston and lighter small end will decrease the stress on everything.

the formula for engine displacement is bore x bore x stroke times 8(number of cylinders) times .7854 equals displacement

thus 4,185 x 4.185 times 4.2 times 8 x .7854= 462 CID. the quoted engine displacement

yes IM fully aware DART sells a raised cam shaft block (Raised .391" or Optional .434")
AND NO YOU CAN'T BUILD A SIMILAR ENGINE USING AN oem 400 SBC BLOCK
that helps reduce some issues in a larger displacement engine build
keep in mind some 383 builds have issues with the connecting rod clearance with cam lobes and a 383 SBC has about a 3.75" stroke
now if you take the max recommended bore diameter of that block which is 4.185 and a 4.2" stroke we get the 462 inch displacement value.
always think through your options realistically,
I can be sure that you are very unlikely to build and install a similar 463 CID SBC engine in your street/strip car and reasonably expect it to allow you to both race occasionally on weekends and use it for transportation for the next few years without major maintenance issues
provided its well maintained.
(something a well built 540-572 BBC with a centrifugal supercharger that might make only a little less hp might allow)

what has been built in a 23 degree SBC engines very impressive,
but its also surely very expensive to build and build with parts that can endure the stress levels for very long
, one of the major reasons I prefer building BIG BLOCK chevy engines is that reaching 750-900 hp is a good deal easier to accomplish with less expensive and more easily purchased parts, especially if you consider all your options. and without running nearly 6000 fpm in piston speeds
several guys have turbo charged LS engines they sourced from salvage yards and modified and exceeded 900 hp at a fairly low cost, especially if using E85 fuel

while is not fair to compare the two ,
you can build a turbo or supercharged 454-598 cid BBC or LS engine and exceed the 900 hp for a bit lower total cost ,
than you can building a N/A 23 degree SBC build to reach 900 hp and do so with much easier to access & purchase parts
you always have options (SOME OPTIONS WILL BE BETTER THAN OTHERS OBVIOUSLY)

www.enginebuildermag.com

Weiand Supercharged 454 Big Block Chevy Engine - Engine Builder Magazine

For people like Jason Schaefer, making horsepower and enjoying performance is more about being the right mechanic than having the right billfold. He showcases that mentality in his 1929 Ford hot rod, which is equipped with a supercharged 454 big block Chevy engine. Find out what helps this thing...
www.enginebuildermag.com www.enginebuildermag.com


www.shafiroff.com

Shafiroff Big Block Chevy - Complete Engines and Short Blocks

Shafiroff Big Block Chevy - Complete Engines and Short Blocks
www.shafiroff.com www.shafiroff.com
 
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block prep.

you really should read these links for a lot more USEFUL info, on block pre prep use the best block you can afford, the better aftermarket blocks are faR STRONGER THAN THE oem BLOCKS IN ALMOST ALL CASES one of the least discussed & acknowledged, and yet more common reasons engines fail , is...
garage.grumpysperformance.com

types of crankshaft steel

I POSTED THIS BEFORE, when shopping for a rotating assembly , it pays too carefully compare features, read the fine print carefully ,and do some careful pre-purchase research. price is NOT the most important consideration, value per dollar spent, quality and durability would be far higher on my...
garage.grumpysperformance.com
 
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TIP, IT HELPS TO HAVE A SHOP VACUUM TO TRY TO CATCH ALL THE FINE METALLIC TRASH,
but you must pressure clean the block , and use high pressure air nozzles to remove all the trash
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block prep.

you really should read these links for a lot more USEFUL info, on block pre prep use the best block you can afford, the better aftermarket blocks are faR STRONGER THAN THE oem BLOCKS IN ALMOST ALL CASES one of the least discussed & acknowledged, and yet more common reasons engines fail , is...
garage.grumpysperformance.com
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harbor freight sells a very inexpensive air die grinder Ive used them for decades in clearancing blocks
at $20 each if they fail, you simply pitch it in the dumpster and grab a replacement
obviously buy quality cutting burrs designed for cutting what ever metal the blocks made of,
and keep a cup of diesel/wd40 handy to frequently dip the burr in ,
to both keep in cool and make it much less likely to pick up debris and clog.
don't be in a big hurry measure accurately and only take off enough metal to clear the connecting rod bolts clearance to the block walls by .060-.080 thousands
use a feeler gauge or large plastic straw as a test shim gauge , cut the lower end of the straw length wise and remove about 2" of 1 side, so your dealing with only one or two thickness of plastic (depends on if you have to double the plastic and use super glue to get the correct gauge thickness,) (measure with calipers to be sure its the correct thickness as the straw materials vary wildly) you can feel the straw squish as the rod bolt compresses it against the block
metal feeler gauges work but they can get damaged, its better to pitch a cheap plastic straw you modified if that was required in the trash
but if clearance is correct the bolt rotates through the block clearance notch easily after slightly compressing the straw easily.
if the plastic straw you bought is extra thin you might want to super glue a second or third thickness to the area you use to test clearance
big thick plastic straws are about 20-50 thousands thick (obviously measure before you use as a gauge)(some guys simply put a bit of super glue inside the lower 2" of the straw and compress it in a vise for 5 minutes to get the end to stay flat, then test the thickness.
obviously if your dealing with very thin plastic straws you could glue a short section of plastic cable tye inside the lower 2" before placing it in a vise for 5 minutes
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having a few accurate measuring tools helps
www.ebay.com

USA 500X 10mm Extra Wide Fat Jumbo Boba Bubble Tea Smoothie Drinking Straws Set | eBay

1: Our team is engaged in the collection of research, production, sales and service. We must provide you with a satisfactory solution. Material: PP. Color: Colorful.
www.ebay.com


www.harborfreight.com

Pneumatic 1/4 in. Die Grinder with 3 in. Extension

Amazing deals on this 1/4In Air Die Grinder With 3In Extension at Harbor Freight. Quality tools & low prices.
www.harborfreight.com www.harborfreight.com

air/die grinders

there's few tools in a decent mechanics tool chest, that come in as handy at times as a selection of carbide burrs carbide cut off wheels and a couple DIE GRINDERS cleaning up less than ideal welds, pocket porting heads, cutting off various components , are all well within the tools reach...
garage.grumpysperformance.com
 
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