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351C .060" overbore?
#1
saw this CL ad and it mentioned 351 Cleveland block more thick for '72?

http://kansascity.craigslist.org/pts/3127991926.html

I always heard that about .030" bore was all they could handle???

THX

Ray

1971 Boss 351  
1972 Q code 4 speed convertible 
1971 Mustang Sportsroof  351-2V FMX 
1973 Mach 1 (parts car)
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#2
mine is .040" but I had it checked out by a competent machine shop. So far so good. .060 seems a little high.

'Mike'
73 Convertible - 351C/4V CC heads/4bolt/forged flat tops/comp 270/rhodes/mallory unilite/tri-power/hookers/glasspacks/c6/3.50 limited slip/Gear Vendors/Global West sub frames, strut rods and shelby style traction bars/ Rear sway bar/tilt steering (not original)

Pics of modifications included in:
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#3
I belive 71 - 73 blocks are all the same thickness when it comes to the cylinder walls. Would have to see proof to show me otherwise. I have a 60 over 4 bolt main block but decided against uding it. Prob would be ok for racing with hard bock in it.
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#4
I call bullshit on the ad.

Cleveland blocks are a thin wall casting. while may will handle an .040 overbore, few will handle .060 to the point that most people simply say don't do it.

When walls get thin, bores distort at higher rpm's causing increased friction and heat and at the minimum reducing life and power.

at .040 I would not build a high performance engine in a cleveland block, though standard performance would likely be fine. In my opinion a Cleveland engine at .060 would be suitable for a show car that is trailered and just driven around gently on occasion.

[Image: 1_01_07_15_8_53_18.png]

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!
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#5
Guys,
My engine builder, Danbury Competition Engines did not recommend anything over a 30 over bore on a cleveland motor. Cylinder walls get too thin and could cause heating up issues. He has built a lot of these motors and I believe he would be an authority, in my opinion.
If anyone is looking, I have a complete 351 cleveland that is 20 over with forged flat top pistons that was completed by Danbury a few years ago for sale and also 4v closed chamber heads.
Let me know.
Thanks, Jay
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#6
.40 seems to be handling my build (see my sig). I probably poop out around 350 to 400hp. No overheating.

'Mike'
73 Convertible - 351C/4V CC heads/4bolt/forged flat tops/comp 270/rhodes/mallory unilite/tri-power/hookers/glasspacks/c6/3.50 limited slip/Gear Vendors/Global West sub frames, strut rods and shelby style traction bars/ Rear sway bar/tilt steering (not original)

Pics of modifications included in:
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#7
Boss 351 probably made 375-385 horsepower at the crank in reality- therefore, your engine is still a stock to very mild build, in my book, at 400 HP

We have improved cooling systems as well. Some blocks are better than others in terms of consistent cylinder wall thickness and bore alignment, so as I have said before each one has to be assessed as an individual.

Yours at .040 over sounds fine for the application, but I doubt you would want to build a stroker with an .060 overbore

[Image: 1_01_07_15_8_53_18.png]

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!
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#8
I guess we'll find out how well suited .060" works. Mine is bored out that far, and I had no problems finding pistons, rings, etc., for it. I honestly believe that with proper cooling, oil pressures, and tuning, that engine will be fine under 'normal' daily driving conditions. I'd be more worried about racing it, because you know for sure there will definitely be a failure at some point.

And if it blows up - so be it... the thing was seized up solid when I bought the car after all. I'll simply score another 351C block and start all over again. Catastrophic engine failure rarely tears up things like headers, intake manifolds, carbs, etc. - and after spending all that money on things of that nature, it only makes sense to stuff another 351C-2V back in there if it were to go south.

Eric

[Image: mach1sig2.gif]
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#9
As far as know all Cleveland blocks are the same, and they are rare in block form.
The Cleveland book mentioned in this forum says never over 030.
I bought a car that had a rebuilt Cleveland supposedly worked on by a good
machine shop. The block ended up with a crack and when we pulled the heads
the cracked cylinder wall was 040 over. Only two cylinders were bored 040 over
but that is the one that cracked. Why only two cylinders; got me.

Guess which cylinder was 040 over...

mike

   

[Image: 1_11_11_13_11_50_27.png]
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#10
Boss1Ray;79147 Wrote:saw this CL ad and it mentioned 351 Cleveland block more thick for '72?

http://kansascity.craigslist.org/pts/3127991926.html

I always heard that about .030" bore was all they could handle???

THX

Ray
Look up SK and XE blocks on the cleveland forum. They are the only blocks I know of that are supposed to have thicker walls. I think the SK had siamese cylinders. I actually saw a XE block not long ago in OKC. The only way to really know how much core shift the block has is to have a sonic test map done for every cylinder. Mine wouldn't clean up at .020. If it would have I'd have spent the money for quasi-custom Diamond Pistons. As it was I used Mahle power pak pistons for 408C. Chuck
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