Greets!
I've just had my engine rebuilt (Performance Pro). They did a great job but I now have a lot of noise (decibles) coming from the rear end. It sounds as though the mufflers (stock) are louder. Gear 1-4 islouder than normalbut 5 /6 are much like what I was use to. Is this part of the normal break in of the new engine? Any help is greatly appreciated. Thanks in advance!
Happy Motoring!

 

Sorry but in my haste I forgot to add that I drive a 91 L98 6 Speed. Thx!

 

Did you have a other than stock cam installed in the rebuild? Higher lift or different duration?

 

Thanks for the reply...all parts/specifications were stock/OEM specifications. Again, the sound is very beefy but goes away at 5th gear.

 

Every motor sounds different with the same muffler system.I had a built 400 in my 79 and replaced it with a mild 350 before selling and it was much LOUDER with the 350.I had hooker sidemounts with homemade mufflers that sounded awesome on the 400 but my uneducated guess is the 350 didn't move enough air to make them work.Probably mellows in 5/6 gear because motor is not working as hard.

 

Thanks. I agree but the sound is really thumping. The one thing that I also noted when the vehicle was returned is that the clutch is a little loose. Could it possibly be the pressure plate that is resonating this sound? Thanks again for the help!