Performance upgrade

G72Zed

Veteran Member
Sep 8, 2015
3,822
Canada
I fully plan on original motor overall good condition. Would really like to decrease the highway RPM. ABOUT 3000 @ 60 mph.

For the budget you mentioned around 10k, I would do the OD trans first, be it a good well built OD auto, or perhaps even a 5 or 6 spd manual, so much more fun and driving conectivity with the manual.....just saying.

Afterwards, either a good going through of the current original engine like fresh valve springs, carb and ignition rebuild and a pro tuneup to get everything out of it. If you want/need more, I would go with the Vortec styled Iron 64cc heads, mild cam/lifters/alum dual plane/Holley carb & upgraded ignition and full tune.

Save the smog topend for the next owner should you sell if they want to go back to boring/low power fun. There's a reason why higher power/efficient second gens with 5-6 spds and disc brakes & tires that are well done up sell for almost double the $$$ of the same model that's OEM/# match....I driven both styles many times....one drive and then it's like OK, I get it.

A 5spd or 6 spd manual with it's gear multiplications may just give you the extra punch you are looking for, and really lets you cruise at the rpm you want on the highway, don't like the gear your in, just grab the next one. Heck, you may even drive and enjoy it even more.

In the end, it's your car, do what you want with it.....don't restrict your joy by "saving it for the next owner" who cares about the next guy....
 

mallard

Veteran Member
Oct 3, 2013
1,804
SK, Canada
I fully plan on original motor overall good condition. Would really like to decrease the highway RPM. ABOUT 3000 @ 60 mph.

if Your automatic Z28 car has no factory AC , the turbo 400 could be ordered with a 3:73 axle ratio . I have seen a couple factory like that , and it will suck the gas down like crazy . You might find a 3:42 gear set to give you some relief from the RPM’s . The car was tuned , carb and trannie Shift point all from the factory set up to work together and delayed shift at high rpm s to get the max performance stock . If you put in the 3:42 gear set , I would have a professional retune the engine , dizzy, carb , after I put on a less restrictive exhaust pipes and use dual mufflers . A set of 1969 corvette 350-350hp heads or similar with higher compression will help things too. That’s too nice or car to mess it up .
As far as I can determine, 3:73 came with 4sp and 3:42 came with turbo 400 and there were no other combination gear ratio "options".

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