I purchased a 1985 camaro iroc z-28 that has a 396 bbc motor and a th475 trans. The question I have is it suppose to run high rpm’s when trying to run 65-70. Normal 55 mph she runs about 2500-2700 rpm and when I try to get to highway speeds she wants to run 3100-3200 rpm I’m going to assume it’s because the trans is only a 3 speed auto with no overdrive but I want to be sure and if that is the case what trans should I throw in it to be able to run highway? Any help would greatly be appreciated as the 3rd gen Camaros are my favorite and finally having one I’d like to be able to make it my own.

 

There are endless options it really comes down to price. A th700r4 is probably the least expensive 4 speed auto. There are more 4,5 and 6 speed autos that are stronger and more advanced. There are a number of manual transmissions as well. All modern transmissions will have overdrive and lower your rpm on the highway.

 

To answer your question... I have a 396 big block with a TH400 behind it... And I am at 3000 at 65 mph with a 3.08 rear end... So yes... That might be right... Depending on gearing...