My 90' vette

[grumpyvette]

I've fixed the suspension and drivetrain and got the vette back on the road but not for very long.

A few days ago my engine blew up. I was getting ready to do
a full rebuild anyway, but that doesn't make me feel much better.

Here are a few pics:

I still didn't open oil pan to check other damage, I'll do it in a next few
days. What worries me is the reason why this happened.
It looks like intake valve on cylinder #. 8 broke and destroyed the piston.
I revved the engine high when it happened (6500+) but I would expect
something to brake in the short block (it still stock) way sooner
than anything in the valve train. I have LPE valves springs with
titanium retainers, so 6500 rpm shouldn't be a problem.

6500 rpm should be and usually IS a problem with hydraulic roller cams, and stock or nearly stock valve trains especially those without a hydraulic rev kit installed,

http://www.airflowresearch.com/hydrauli ... s-c-9.html

and even then 6500rpm is pushing things to the edge of valve train stability, with a hydraulic rev kit installed,and heavy stock hydraulic roller lifters ...... 6200 rpm is far more likely to be the limit to valve train stability in your combo
getting away with a brief buzz to 6300rpm doesn,t mean that it was safe or could be sustained, or the valve train was under control, it only means that at THAT time you didn,t sustain damage,THAT TIME! but stress is cumulative, the more you push the edges the faster things fail
once a valve lofts or looses contact with a cam lobes surface,and as a result ,gets smacked with a piston it tends to bend and brake resulting in the damage you pictured, its the valve train not the lower end that usually fails first, but once a spinning crank and rod starts to slam pistons, into non- compressible objects it tight spaces like a broken valve in a combustion chamber its not un-common for rods to bend, pistons to shatter and rods to come loose, and rods get blamed for damage that resulted from valve train stability issues that caused the damage resulting in the rod failing[/color]
if you want to run that rpm range youll want a SOLID ROLLER CAM AND LIGHTER WEIGHT LIFTERS, HIGH SPRING PRESSURES, A BILLET CAM CORE,thats,DESIGNED FOR HIGHER RPMS AND SPRINGS DESIGNED FOR THOSE LOADS AND RPMS and balanced forged components with a well designed lubrication system, using a windage screen, a 7-8 quart baffled oil pan and probably roller rockers with a rocker stud girdle
its always a good idea to have a long and detailed discussion with both the cam manufacturer and the engine builder about your intended power range and operational rpm band,and clearances and lubrication needs, before you go buying components, installing parts or revving a chevy V8 engine to rpms approaching or exceeding 4000fpm in piston speeds

Read these links and their SUB LINKS

posting.php?mode=edit&f=52&p=215

viewtopic.php?f=52&t=1201&p=2511&hilit=girdle#p2511

viewtopic.php?f=52&t=663&p=911&hilit=+girdle#p911

viewtopic.php?f=52&t=181&p=1192&hilit=girdle#p1192

viewtopic.php?f=54&t=52

viewtopic.php?f=52&t=1716&p=4250&hilit=beehive#p4250

 

[bvlahov]

I've disassembled the heads and tested the valve springs.
I did it for two reasons:
1. to check if weak spring was a problem
2. to check if I could reuse springs with new cam.

However, I got some strange readings.

1.900" - 112 lbs
1.800" - 157
1.700" - 199
1.600" - 242
1.500" - 288
1.400" - 334
1.300" - 390
1.200" - 456

It's a little bit hard to be really precise with valve spring tester that I
used (see link below), but all springs were very similar.
The weakest one was 364@1.300" and stronest 392@1.300".

Link for the spring tester:
http://www.streetperformance.com/part/proform/valve-spring-compresser-tool/407760-66834.html

The scale is by 10 lbs, so my numbers could be 1-2 lbs off, but even
if they are 10l bs off, it still looks like those are a lot of
springs for small #219 cam.


I'm about to install XR-288HR cam that has alot more duration than
LPE #219 cam, similar lift and it needs less springs than what I've got.

This are springs that are recomended for XR-288 cam:

Comp Cams #249-986-16
Dual Valve Springs
Outer inside diameter: 1.070"
Inner inside diameter: .697"
Seat load: 132lbs @1.750''
Open load: 293lbs @1.250''
Coil bind: 1.150''
Rate: 322lbs/in


OR


Comp Cams #249-987-16
Dual Valve Springs
Outer inside diameter: 1.070"
Inner inside diameter: .697"
Seat load: 121lbs @1.800''
Open load: 343lbs @1.200''
Coil bind: 1.150''
Rate: 370lbs/in


What is your opinion on this? How is it possible that from 1.900" to 1.800" is 45 lbs and from 1.300" to 1.200" is 65+ difference? Is that valve tester any good at all, can it be that much off? Can it be that springs that came with from LPE are ~450lbs/inch rate???

 

[bvlahov]

I did some calculating today and I'd like to hear your opinions.

I plan to deck the block to 9.000" (mill down .025").
I'll use Felpro gasket with 0.039" comp. thickness.

According to my calculations that puts me to:

* 10.8:1 SCR
* 8.2 - 8.4 DCR (I'll do some work on chambers so I'm not 100% sure in final chamber cc)
* 0.039" piston to head clearance

I could go higher with CR because lowest octane fuel here is 95 and 100 is available almost anywhere. However, I'm limited with engine components that I've got.

Parameters that I've used for calculations are below, so if
anybody wants to doublecheck on me, please do.

- stroke 3.48"
- rod 5.7"
- adv. intake closing 70 deg (this is with xr-288hr cam)
- bore 4.020"
- chamber cc 58-60
- gasket thickness 0.039"
- gasket bore 4.080"
- piston dish 5cc

Any inputs and thoughts are welcome!

 

[grumpyvette]

http://en.wikipedia.org/wiki/Octane_rating

for everyone reading this lets drop back to basics a bit ,first , you'll want to read this link above carefully, as the octane number displayed on the gas pump varies a good deal, with the effective detonation resistance, of the fuel, between locations
example 100 octane rated fuel in western Europe is close to the same detonation resistance as 93 octane rated fuel in the USA, due to the difference in the methods used to rate the octane

re read this just to keep things fresh, in your memory

viewtopic.php?f=52&t=727&p=5480#p5480

you've always impressed me with your skill level, and your photography,and the care youve taken building your car, so I doubt you'll make any bad decisions

heres the cam , and its spec card your using
http://www.compcams.com/Cam_Specs/CamDe ... d=583&sb=2

at 10.8:1 cpr that cams a good choice if the other components match, but you might need to install it at a couple degrees retarded to lower the effective compression ratio.that will also move the whole torque curve about 150-200rpm higher and have the added benefit of reducing both the tendency to get into detonation and reduce low rpm torque slightly wile boosting the upper mid and high rpm power band,
on my vette I needed to index my cam in at 4 degrees retarded from split overlap for the best results, thats one reason degreeing in the cam rather than just installing it dot-to-dot is a smart move.

viewtopic.php?f=52&t=90

Im sure your aware that that cam is about the max duration, and rpm power range that the intake your using will efficiently support, with its flow rates and that your cams power and valve control start to fade before 6400rpm, so Id use an ignition with a rev limiter set to cut the ignition at 6500rpm as a safety measure to prevent problems with a hydraulic lifter valve train.

 

[bvlahov]

Thank you for your input. I wasn't aware about octane rating differences.

Also, the idea with regarding the cam sounds good. I actually have timing gear with
4 deg ret/adv possibility so it won't be a problem. 6500 rpm was exactlly the
rpm limit that I had in mind.

Thanks again, as allways, you're very helpful!

 

[bvlahov]

Update:

I did some work on cleaning and preparing the parts for
the machinist while waiting for the torque plate to be machined.

The torque plate that I had fabricated was finally done,
so I took the block to the machinist.

He will do next operations:
- boring/honing 0.020" over
- milling the decks to 9.000" deck height
- installing new cam bearings
- installing new freeze plugs
- polishing the crankshaft
- check the crank if it's in tolerances (I'll double check
that myself)

Here are a few pics:

While the block will be at the machinist, I will do some
work on the heads and intake. As you know, one of my heads
had some serious damage, so I gathered a new one. Only
difference is that this head is completelly stock. So now
I have one fully ported head (by myself) and one stock.

I've cleaned one of the ports just to take some pics for
comparison. I will do some more porting on both heads, as
there is still some room for improvement but I'll do that
later, after I'll have seats for new 2.02/1.60 valves
installed.

 

[grumpyvette]

looks like youve made some very worth while improvements, to the cylinder head ports.
just removing casting flash,and smoothing the port surface is usually worth several hp, reshaping the valve guides and smoothing the bowl can make flow improvements you can feel and see at the track. and the use of a hone/torque plate on the block during the cylinder hone process will be sure to increase the rings seal, increase effective compression and reduce blow-by

 

[bvlahov]

Finally I did some progress.

I was finished with rough porting so I took the heads to the machinist for new, larger valve seats to be installed.

Here are pics before:

While he installed new seats I also asked him to add some material on the
lower side of intake ports. I had some problems with leaks here bacause
gaskets didn't have to much material to seat on.


On the pics below you can see how much is gained in intake and exhaust
ports with new seats installed. Also, you can see where material was added
for better gasket sealing.

After removing extra material that was gained with larger seats, I went to work
on chambers. Deshrouding valves is very important as new valves are
significantly larger than stock and are much closer to chamber walls.
First I roughly removed some material and then polished the chambers.

Here are a few pics of work and the final result:

Next, I have to take the heads back to machinist to have new guides installed
and valve job done.

 

[grumpyvette]

IM IMPRESSED with BOTH your port & combustion chamber clean up work and your photographic skills
your engine refurbish project looks like its coming along very nicely, and youve obviously put a great deal more time and effort into those components than the average guy does on his car, who will wonder why your car runs so much better, because most guys don,t fully grasp the fact that its all the small changes and attention to small details that add up to make a very noticeable difference.

can you post more info or details on both the tools you used to port the heads and any tips or problems youve run into as IM sure it will help most of the members



these threads might help, those guys who want to do something similar

viewtopic.php?f=52&t=462&st=0&sk=t&sd=a&hilit=porting

viewtopic.php?f=55&t=2773&p=7200&hilit=port+matching#p7200

viewtopic.php?f=52&t=2630&hilit=+porting


http://www.gofastnews.com/board/technic ... rting.html

http://www.gofastnews.com/board/technic ... tions.html

http://www.gofastnews.com/board/technic ... l#post5343

 

[bvlahov]

Thanks grumpy!

It's coming along well, just not as fast as I'd like to. But hopefully it will be done soon.

 

[bvlahov]

That orange color was too much for me, so I cleaned it all
off and repainted it.
So the block is bored/honed, zero decked, new cam bearings
and freeze plugs are installed.
Just one more final cleaning and it's ready for assembling.

 

[grumpyvette]

Ive always been impressed with your photography skills and its good to see progress, on your engine.
engine paint serves several functions, rust prevention obviously , but it also traps fine metallic crud and seals micro cracks that may hold grinding or abrasive particulates the engine picked up during machine work and tends to smooth the oil flow over the blocks inner surface.
colors not that important, silver or gray can be used.
bright blue, black , yellow or pale blue are popular if you don,t like orange, but obviously the brighter colors make tracking and locating oil leaks a bit easier

viewtopic.php?f=51&t=125

 

[bvlahov]

Did some work last few days

Here are "a few" pics

crank balanced and polished

new ARP main bolts

crank in place and all mains measured with plastigauge

all mains are cleaned of plastigauge and lubed

checking crank end play

rings file fitted and measured for correct gap

new SCAT forged rods and Clevite rod bearings

plastigauged all rod journals

rods, pistons, rings assemblies

rotating assembly done

new (CC HR288) vs old (LPE 219) cams

cam and timing set are in

new LS lifters

That's it for now!

 

[grumpyvette]

you could very obviously have a second career taking photos for tech manuals as its so darn rare to find some one with your photography skills.

Im glad to see your project progressing so smoothly

 

[bvlahov]

Thanks grumpy!

 

[bvlahov]

Update.............


I've finally found some time to finish the heads.


New bronze valve guides are in and cut for .530" seals

Valve spring seats are cut for larger springs and to exact
height

New seals, valves, springs, Ti retainers...

......................

 

[grumpyvette]

Ive got to say,your skill with a camera is always impressive!
and its nice to see your progress reports.
QUESTIONs?
what tools did you use to cut the valve guides, and valve spring seats, and were you happy with the tool and the results?
did you use a mill,? drill press?

why did you select THOSE heads?
was it because they came with the car or did you buy them separately?

 

[bvlahov]

Thanks grumpy!

The tools that I used (pic below) are Comp Cams guide cutter (check link below) and
custom made adjustable spring seat cutter. I'm very pleased with both. Very easy to use
either on press drill or even with electric hand drill. Both tools have pivot guides that go into
valve guide and are really easy to use.

http://www.compcams.com/catalog/313.html

I used #113 corvette heads for 2 reasons. First is obvious, I had them on my engine. But that's not the only reason.
I did some search and #113 heads have very good D-shaped exhaust ports, and with some work they can be made
to produce decent power. I know that there are aftermarket heads that are much better from the box, but for my goal,
which is 400 or maybe a few more HP, well prepared #113's should be enough.

Here is a pic of the tools:

 

[bvlahov]

Update......


I'm finished with intake manifold (superram) porting:

.......................

 

[grumpyvette]

Id like to see some dyno results and a list of all the engine mods, youve done, listed in one place when you get time,
as Im sure many other people would, as you've obviously taken some effort above the normal levels, usually seen,
to do the project correctly, and IM sure the mid rpm torque and power curve will be impressive