ATTN: Engine building Oppos

A new year comes with new challenges and projects! this year will be the year of the Oldsmobile 403: the best worst engine ever.

Before I get to the questions, my situation for those who arent familiar: My trans am is junk. the engine ran fine when it was in the car, but was leaking like a sieve. all of my surfaces are nice inside (minus the inch of oil goop in the intake valley) which isn’t strange for the 403, but indicates that it was definitely sitting for some time. My present circumstance means that I can’t really throw money at this thing, but I am willing to ballpark around $2k for the rebuild over what I have already spent on new oil pump, water pump, timing ect. Clearance issues also mean that I am stuck with stock heads and intake.


What does that leave me with? well, I can get high compression pistons that should remedy the 403's miserable stock 8:0:1 compression. combined with a cam and I would not have to go far into the serious expensive shit to get my engine in decent shape. The real question?

On stock heads, am I just pissing my power away? Concerned about flow mostly. This engine is seriously under-stressed for what it is designed for which will actually enable me to use stock everything for the most part, so I think I will be fine. but if the stock heads will bottleneck it I might as well not screw with things. I am not looking for racecar power here, just something that isn’t embarrassing for a 6.6l.


I know I can get my stock engine rebuilt just fine in my budget. If I start going into cylinder head porting, that is going out the window. I don’t love this engine. I don’t love my whole drivetrain for that matter. I could ls swap the thing and lose zero sleep. the problem is that I want to drive it, and that won’t happen unless I put this thing back together. I would be fine keeping it, but I want it put together properly, and I only want to do this once. I don’t want a $5k 403. I just want ~300hp which I know this thing can make.

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