big header issue

[670 of 4993]

so im going to try and make a long story short. I just installed head studs, got everything back together, and started the car up. It idled really well, but sounded like i had open headers even though the exhaust was fitted up perfectly. The passenger side collector flange was cracked so i decided to switch headers in hopes that this was the problem. I swapped for long tubes and a new midpipe, started the car up, and it made the same loud obnoxious sound. Does anybody know what this is? I dont think that this is caused from the head stud install though, i was very careful.

 

[670 of 4993]

i think i figured it out. I need to plug the air holes in the back of the heads. I'll test it out tomorrow and hopefully that will solve my problem

 

[fivestangs]

so, you put new heads on at the same time? what'd you get?

 

[cobra186]

Sounds like the egr holes on the back or front of the heads are open.

A friend of mine did the same thing when he rebuilt the engine on his 93 Cobra. He installed the heads backwards when putting the engine together... which is no big deal other than the threaded inserts that normally block the egr passages on the front are now at the back of the heads and now the front of the heads are open where the egr crossover tube at the back would normally go. His sounded just like a a super bad exhaust leak too.

 

[670 of 4993]

yea it was the egr holes on the back of the heads combined with timing.

I just put the stock heads back on, i lost a gasket not too long ago.

 

[fivestangs]

oh, so you ditched the crossover tube

 

[PRO50GT]

Well at least you found the problem.