91hatchgt

Hey all, I would appreciate it if you would take the time to read this and give a comment on it as it is a serious problem, and I need it fixed!

I just installed AFR 165cc Heads (stud mount), Longer Hardened Mallory Push Rods, Stud mount 1.6 Scorpion Roller Rockers, and an E303 Cam. After the install, I got it to top dead center on the compression stroke, and poped in the disty. I double checked everything and decided it was time to fire it up. It started up on the first crank of the engine, and sounded awesome with the new cam! I drove it carefully down to the local speed shop and had the valves properly adjusted because I didn't think that I had done it 100% correct because the car was back firing under a load.

I got the car back, and layed into it leaving the shop, and once again it backfired, and it only made power to about 5k RPM, whereas my brothers 88 with the same mods can easily make power through 6k! I know that the valves are correctly adjusted because I followed the instructions when I did them, and the mechanic said that all the valves were close, except one exhaust valve was 3 turns too tight!

My question is, what could my problem be? The valves are correctly adjusted, I have went over the timing a million times trying to run from 10-16* with no changes, it still backfires every time. I am thinking that when my dad put the cam in, he didn't install it straight up, but I could have sworn that I watched him line up the dots.. What could my problem be!?? HELP!

stanglx2002

what injectors do you have and do you have an AFPR? it also sounds like a vaccum leak in the upper intake somewhere or the timing is still messup

Tims 88GT

can you hear it out of the exhaust or dose it sound like its in the engine compartment?

91hatchgt

It sounds like it is coming from the passenger side header, it could be considered either engine compartment or exhaust.

The main reason I am so puzzled is because I put in a much bigger cam, and AFR HEADS! and I can't really notice any power increase! I am going back to the shop in the morning to ask what they think it could be.. My bro's car droped a second, and picked up 10MPH in the 1/4 mile with the stock fuel system and ignition system in his 88, which kind of rules out those things being the culprit.

What can it be!

Quik

could be your pushrods are too long and hanging open so then youre getting back feed thru the chambers. or the timing is off, or youre tps isnt adjusted to the timing the car is set to

91hatchgt

I was also thinking that the pushrods may be too long, they are just a little longer than the stock one's.. The only reason I dont think so is because the shop that I got them from primarily deals with 5.0's and ONLY stocks Stud Mounted AFR's for the 5.0 Mustang, so how could they have got it wrong?

It sounds like I have a BAD exhaust leak on the right side head, Im thinking it is because I used pep-boys header gaskets because all the other shops were closed and I couldn't get anything else, so I am going to change those.. Could that cause a POP or backfire?? Sometimes when im driving, it is like I lose a cylinder, and the car starts to sound funny like I have a bad miss.. Could this be caused by an exhaust leak?

I'm still trying to figure this out, and it's been almost a week!

stanglx2002

still sounds like timing to me

Quik

yea that shop can be wrong. with different setups things are different. check your pushrod lenght