I have had no luck getting my oringed gt40 heads to seal with the felpro 8548 gaskets. So I am looking into cometic gaskets, but I dont know what to do with the orings in the heads, they are ss. Should I pull them and spray the cometics with copper coat? Leave them in? This is a toss up because neither the block nor the heads have been surfaced. I dont want to spend too much more money getting a stock blocked setup up and running. I could go back to stock heads, but the gt40's have dual valvesprings, cobra rockers, and flow more and have bigger valves.

 

I think the general consensus is that the cause of your problems are the GT-40 heasd, not the gaskets. Many people have had problems sealing them up. Sell them and get some Alum. heads.

 

They cant be any worse then the stock heads? Or are they? I really cant afford to buy aluminum heads right now. I am in the process of buying a harley.

 

What is the thickness of the o rings and how far do they stick out of the heads? I ask because I had the same problem. The quick fix was to buy the cheap ass ( I think $10 each) Autozone gaskets. They looked orange and cheap. Take a mic with you and measure the thickness. If I remember right they were close to 70 thousanths thick (not compressed) The problem I had was the wire was too thick at 60 thousanths and they stuck out of the head about 10 thou. Eventually I had the wire milled down to about 6 thou. Hope this helps.

 

The wierd thing about mine is that it blows number 4 in the same spot every time, 3 times to be exact. Maybe I should replace the oring, but I am so sick and tired of replacing the head gaskets that if I replaced the wire and it blew again I would freak out and start my car on fire. Every time I have to replace the bastards it about 100 bucks. Maybe I should pull the wires and check to see if the heads are flat and the block. So I guess my options are

Replace the oring and try to reuse the gt40's

Throw the stock heads back on and hope the headgaskets dont blow

Sell the gt40's and try to get enough money together to buy some aftermarket heads

Put the gt40's on and run it n/a until I can save up to buy some aftermarket heads. Maybe hit it with a 125 shot? I have a nice lumpy cam that I could throw in it.

 

I thik people have found that the GT40 moves around a lot, and requires very flat surfaces, and a lot of head stud torque. I sold of set of GT40's last week for $350 plus hsipping. That's half way to a set of heads.....

 

if you keep blowing the same cylinder maybe you have an injector problem. I,ve had that problem before. Andrew

 

I think people have more of a problem with the *aluminum* GT40s rather than the iron GT40s.

Chris95svt, 19COBRA93, etc. used to use and still use GT40s (stock heads on pre-96 Cobras).

 

i am carbed so its not injectors, but it is weird that it keeps blowing the same cylinder.

 

Either your tuneup is bad, you have very bad distribution in #3, or the head or deck is warped around that cylinder.

If you just keep throwing gaskets at it without finding the problem, you're at risk of keeping the detonation (if that is the problem) from blowing the gasket and taking out the piston or rod bearings instead.

have you tried mic'ing the gasket around the remaining fire ring on that cylinder to see if it is the same?

 

My wideband was reading around 10-1 afr so I dont think it was bad tune. Could be a problem with flatness, the heads are pretty fresh so I dont really see them being the problem so its probally the block. I think I am going to straight edge the block and if its ok thow the heads on and run it na.

 

you can be pig rich and still get detonation if your fuel doesn't have enough octane. It will ignite itself from cylinder pressure before the plug fires. have you checked egt's in a few cylinders to see if that one reads differantly than the others?

 

BUYING A HARLEY!!! its one or the other bike people cant be muscle car people the two groups dont mix. my opinion... screw the harley buy car parts

 

The harley is going to be the pussy machine cause I dont think chicks will like my stang with the 12 point cage and no interior!!! That and the fuckers get 50+mpg so it will save me some money on gas this summer.

 

bikes,cars don't mix

forgive me for speeking on your post but.my brother rides a 600hp turbo bike on the street and still likes fast cars.it is just twice as much work to do both.the bike is not a harley though.i will find my place elsewhere now thanks for listening.
check out his web.he is 'THEMOTORHEAD'.
http://www.suzukihayabusa.org/phpbb/index.php

 

my vote, SELL the heads, I ran GT-40's tried the 1006 expensive oring gaskets etc. resurfaced heads flat etc, kept blowing gaskets anything over 10 psi...i'm tellin ya sell those suckers and pick up a good set of used aluminum heads, i put it off forever and now i'm running 17psi easily on pump gas hell forgot and put 87 in it once and no pinging...now i never worry about blowing head gaskets. bought the brodix st5.0 heads for $900 new from a guy that never used em. threw orings in the heads had TEA do the work, i would never go back to GT-40's.

IMO the gt40's suck for boost, some have had success who knows why..but i tried and tried with studs and everything else. if ur havin problems ditch em and come thank me later. lol