Head Warpage
Thread Starter
Burning Brakes
Joined: Mar 2005
Posts: 1,231
Likes: 34
From: Ontario
Head Warpage
Goodmorning. I am rebuilding a 71 small block with origonal cast heads. Can anyone tell me how much warpage is acceptable with fel-pro .040 composition head gaskets . The block deck is good.
Thanks Bill
Thanks Bill
Burning Brakes
Joined: Jan 2007
Posts: 1,057
Likes: 4
From: Concord Calif
NONE!! Let me say that yea that gasket will take up some warpage for sure. But think about this, the head was hot enough to warp so what do you think your valve seat run-out might be? Yea people who don't understand metal will say pour solvent in the port or chamber and see it they seal! Wrong, with enough seat spring pressure most out of round seats will seal ok at rest. Ever see a valve seat wider on one side than the other and the valve clearance was not that bad? And trying to lap a valve to seal is just bull also. You'll just trying to correct poor run-out with this procedure. If all is correct the valve will seal just right even with no valve springs installed. Your heads are in question here other wise you would not ask this question. I didn't even say anything about cracks here even. Get your heads checked out by a competent Machine Shop!! Good Luck!!
Racer
Joined: Feb 2008
Posts: 497
Likes: 0
From: Streator Illinois
I also say have the heads checked out at a shop. No sense going through all the expense and work of rebuilding an engine and then installing questionable heads which could come back to haunt you.
Terry
Terry
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
so long as seats&guides are OK ... then 0.005" warp will be too. Dunno how much if any your decks been cut? ... GM markets a nice composition gasket for sbc 350 ... 0.028" / 5.8cc ... p/n 10105117
Drifting
Joined: Jun 2010
Posts: 1,781
Likes: 15
From: Oxford Ohio
It's not that expensive to flatten them. How did you determine the .005 number? A machinist straight edge or a depth gage on a mill to be accurate in that regard. At .005 I'd be inclined to take care of them.
What shape are your valve guide in? While they are off do as much as you can to get them up to correct condition.
Check the guides, valve seals, check for flat surface and most of all have then magnafluxed or pressure tested.
I understand that the cash outlay begins to add up, but if you put the heads on without proper attention, as soon as an issue pops up you'll suspect the things that you didn't attend to while the heads are off.
If your .005 is between the cylinder area you don't have that much surface area for a gasket to maintain seal. That is often the area that has the warp. If the gasses begin to travel between two cylinders, they can cut a passage in the block deck surface that will require the block to be decked. There is a high temp. high pressure gas traveling between the cylinders and it can remove deck surface.
What shape are your valve guide in? While they are off do as much as you can to get them up to correct condition.
Check the guides, valve seals, check for flat surface and most of all have then magnafluxed or pressure tested.
I understand that the cash outlay begins to add up, but if you put the heads on without proper attention, as soon as an issue pops up you'll suspect the things that you didn't attend to while the heads are off.
If your .005 is between the cylinder area you don't have that much surface area for a gasket to maintain seal. That is often the area that has the warp. If the gasses begin to travel between two cylinders, they can cut a passage in the block deck surface that will require the block to be decked. There is a high temp. high pressure gas traveling between the cylinders and it can remove deck surface.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
