thx a lot for the detailed feedback....I might, after reading your questions get an idea what went wrong...
But first let me answer your questions.
- 302 out of 1972, HP no figures yet but should bee around 350 BHP, 11:1
- cast iron standard Ford Block
- block bored, honed first oversize, crank first undersize, decked
- open bottom holes
- ARP Bolts with hardened washers and assembled with arp moly.
- rechecked the torque readings after around 300km-500 and they have been fine
- I don't know the correct felpro number anymore because it is to long ago ( over two years)
BUT ..... !!!!!
I bought a set of brand new Edelbrock Heads, and I they didn't went to the machine shop....that was perhaps my failure, I just checked them at home and they looked O.K. ....
They only thing I could imagine is, that my failure was not to bring the head to the machine shop and let them straighten them....
Does that make any sense ...?
Originally Posted by GordsFord
As others have noted, in order to diagnose the problem and give best advice it is important to know all the details. Normally the Felpro gaskets are good but there are a number of Felpro gasket types and models. And the devil is in the details.
- Engine type and HP, compression ratio etc.
- Block material - iron or aluminum
- Block properly prepared, decked, deck smooth, threads chased and clean
- Blind holes/threads or open at bottom
- In Blind threads, no excess oil or thread lock to hydralic in the bottom when torquing and then relieve over time, lessening the clamping force
- Stock factory block or good aftermarket one? Manufacturer?
- Heads cast iron or aluminum, properly decked, straight, and with correct finish
- Bolts or studs?
- hardened washer under the bolt heads or stud nuts
- lubrication on threads. None, oil, or ARP moly type?
- Large built in washer type head bolts (such as the stock Ford ones, or even the ARP bolts and nuts) or nuts without a hardened washer between the head surface and the bolt head can be killers because half of the torque is used just turning the bolt against the head surface or a standard washer (even with it well oiled) and the result is low clamping force on the gasket. We learned this by testing.
Regarding copper head gaskets what has been said above and by others re the proper preparations is critical. We have used them for drag racing engines that are torn down frequently, after one, two or three weekends of use. Use an o-ringed block and receiver groove in the heads and sealer for the water passages and/or any oil passages. For long term use I would be less enthusiastic because of higher risk of galvanic corrosion.
The same approach can be used with composite gaskets - O-ring the block with or without a receiver groove in head depending on the specific gasket and all the other details. For moderate engines to 500hp +/_ the o-rings shouldn't be needed if everything is prepared correctly and good grade bolts or studs AND HARDENED WASHERS are used. Grade 9 bolts with small head and hard washer work very well because the friction level is very low thus the full clamping force is applied.
The modern trend is to use MLS (multi layer steel) shim type gaskets such as made by Cometic, Felpro and others. They are more expensive than composite gaskets but work very well to very high hp levels, without o-rings. Provided everything else is correct.
Re-torquing the head bolts is good after running for a bit, particularly with composite gaskets. If they are sealing right you should not have to take the heads off and check the gaskets!
Unless have a high compression high hp engine running with a lot of track time the Felpro gaskets should be good and my guess is that there is something wrong in the details. Just putting in new gaskets without determining and fixing the root cause of the problem is likely to have the same end result.
Feel free to provide further details and we will all try to help sort out your problem.
Good luck Carlos,