Hi all, for anyone who has good 2nd gen knowledge or exhaust knowledge. I just started to enjoy my 70 Z28. It is an original/restored 4spd with its original motor and i think gardner exhaust. I will know today when i get it up on a lift.
Here is my question, I get a lot of back cracks when i de accelerate in this car. If i hold a gear and accelerate and than back of I get some solid exhaust pops.
Is this normal for the LT1? Is something not adjusted correctly?
I am running on 100 oct. race gas, (unleaded I think)

Thanks
Zgusto

To me, it sounds like your idle may be too lean. Back in 70, backfiring under de-acceleration hardly existed because carbs were tuned for power, not emissions. By the late 70s, backfiring in the exhaust was commonplace because of the too-lean idle circuits needed for emissions.

Hi all, for anyone who has good 2nd gen knowledge or exhaust knowledge. I just started to enjoy my 70 Z28. It is an original/restored 4spd with its original motor and i think gardner exhaust. I will know today when i get it up on a lift.
Here is my question, I get a lot of back cracks when i de accelerate in this car. If i hold a gear and accelerate and than back of I get some solid exhaust pops.
Is this normal for the LT1? Is something not adjusted correctly?
I am running on 100 oct. race gas, (unleaded I think)

Thanks
Zgusto

Just a delayed update. The cracking was caused by a the AIR pump. we are guessing a bad diverter valve. Put freeze plugs in and the problem was solved.(a while ago)

just in case that helps anyone.

John