Cylinder Head Question

agro1 · #1 (**permalink**) 10-02-2002, 06:14 PM

If you blow a head gasket and everything looks fine, block deck, head flatness - no need to resurface. Should anything else be done to the heads before they are put back on using a new gasket ? Do the heads need to be taken apart and inspected ? Thanks in advance

Ron61 · #2 (**permalink**) 10-02-2002, 07:12 PM

Argo1,

The experts on this will let you know for sure, but if everything is ok you could have just had a weak gasket. I had one years ago on a 390 that blew for no known reason. I even had the head pressure tested and magnafluxed and they found nothing. Replaced the gasket and never had another problem for the next three years, then I sold the car.

Ron61
Ron Widener

Jack21 · #3 (**permalink**) 10-03-2002, 06:05 PM

The question is, why did the head gasket let go? You have to answer that question before you replace the gasket. If the head is in good shape, and the block deck is in good shape, then get them both squeaky clean, and bolt it back up. For a little added insurance, re-torque the head bolts after the engine has fully warmed up, and cooled back down.

agro1 · #4 (**permalink**) 10-03-2002, 06:25 PM

The engine builder said it blew cause it was running a bit lean and detonating and also because when the heads were retorqued at 500 miles it was not done properly - both are bu!!sh!t...I run 100 octane and it ain't running lean or detonating and House of Cobras retorqued the heads at 500miles, and they know what they are doing.
It blew because they used a crappy graphite OEM style replacement head gasket on a motor running 12:5.1 compression - which you don't do. THAT is why it blew, and upon inspection of the other side, it too was getting ready to blow in exactly the same manner the right side did. Luckily it didn't. So do I now have to retorque the heads after I run it another 500 miles ??

Rodney · #5 (**permalink**) 10-03-2002, 10:16 PM

I blew a head gasket on a 12 to 1 compression engine with crappy head gaskets designed for a stock compression engine! My engine builder tells me I need to lower this compression w/ new dished pistons, rings and all the assorted labour charges! The cylinder heads needed to be cut .008 thou and are now sitting at 61cc. Long story short, we need to come up with 14cc to bring this thing down to 9.5 to 1. The Cam is designed to work at 8.75 to 1 up to a max of 10 to 1. I'm really pissed seeing as this thing has been in dry dock since Aug 16th!! What to do now? Rod.

agro1 · #6 (**permalink**) 10-04-2002, 08:19 AM

Sounds like the answer to this is pretty much the same anwser to allot of other questions - Don't skimp on crappy gaskets and otherwise similar parts that can be had for cheap. Especially on a high compression motor. It amazes me that someone can build something like that and then not follow through and use a high quality part that only costs 20 bucks more than the crappy one. Makes me think, "Where else did they use crappy parts that are not compatable in a 12:5.1 motor?" UGHHHH....

Sorry to hear about your problem as well Rod. You should just be able to use a good Fel-Pro gasket (part 1011-1or2). That is, if all your internals will still support running that high of compression, but since I started this post and am looking for answers myself - I would rely on the experts to chime in here...

A Snake · #7 (**permalink**) 10-04-2002, 11:08 AM

Frequently, steel shim head gaskets are used on hi comp motors. They come in several thicknesses, but none are thick enough to lower your compression. In fact, many times they are used to raise compresion. They ARE the gasket of choice for high compression.

On the compression matter, I'm curious as to why that much was used. To run 12+:1 requires straight racing fuel which is not avialable at every gas pump.

In spite of cost, I would go with getting the pistons changed to lower it to 10:1 at most. Even that with a carbureted engine will still require 100 octane fuel and judicious timing of the engine.

Al

agro1 · #8 (**permalink**) 10-04-2002, 11:43 AM

A Snake - I had the motor built with that much compression because I got the thing as strictly a track car, where they pump 100 octane. It may be expensive - but so is horsepower...Also, here in Southern Ca., certain 76 stations pump 100 octane racing fuel. Plus, nothing sounds better than a motor running high compression.

Jack21 · #9 (**permalink**) 10-05-2002, 12:17 PM

Another option...

Most of the aftermarket heads offer an "O" ring grooved head for just this reason. Grooving a head for an "O" ring is not that big of a deal, and can be done by any performance cylinder head \service shop.

Have your heads grooved, then use an "O" ring gasket. Should keep your 12.5/1 CR under control.

A Snake · #10 (**permalink**) 10-05-2002, 07:17 PM

Right on Agro! Just keep it shiny side up!!

Agree 100% with Jack21. The o-rings will do it. If they work for blower motors, they'll work for yours. You're right about the bark of authority from high compression...it's music to the ears and it does make hp!

Al