I recently bought a 1973 Cutlass S where the prior owner put a 403 in there.

Everything works now, so the things I want to do are more for improving reliability with a tad more performance.


I am looking for brand/part number recommendations:


--Replace carb/intake
--Replace radiator
--Replace Water Pump
--Replace Timing Chain
--Headers??

 

I started out with an edelbrock performer with a edelbrock 600 cfm carb, then onto hedman shorty ceramic coated headers etc in my 76. Not much in gains with these upgrades just a few $$ spent. The guys here put me in the proper direction with getting me to look at rear gears. Best advice I ever took. I went with a 3:42 rear gear with an eaton posi, best upgarde $$ can buy you at this point. Others will chime in and give you alot more advice then I could.
Cheers
Eric.

 

The 403 is actually a small block but with "large" bores. To wake a 403 up one needs to do a combination upgrade. Better heads, upgrade the camshaft without going to large, an after market intake or possibility a factory A4, set of headers and as previous poster said better gear ratio. A small higher stall converter also. One can get real performance out of these engines. Breathing and exhaling is what it's all about and having the proper gears to utilize the torque. Build for torque and I always feel it's better to be under, such as under cammed/carb, than over. I am a fan of the 403's, love those large bores. I've not personally met anyone that's had one who didn't like them. Jmo, Ken

 

The 403 is externally identical to an Olds 350, so any bolt-on parts that fit the 350 will also fit the 403. The radiator and water pump aren't going to do anything for "performance". The A4 intake is designed for a 307 and will NOT be an upgrade for a 403. I'd suggest a Performer RPM and a 750 carb. Any headers for a 350 Olds in a 73 Cutlass will fit the 403.

 

A 600 cfm carb is too small for a 403.

 

Thanks for the correction M-14. As Joe posted the performer Rpm would also be a better upgrade as well .
I should have mentioned that I had a 350.
Thanks guys!

 

Then you never met me when the crank fell out of the bottom of the engine in my numbers matching #63, 77 Indy pacecar I used to own!
77 pacecar.jpg

 

What were you doing when it happened? Maybe it was just really bad luck and no actual fault with the 403 design.

For performance without tearing into the engine, I would go gears, exhaust, recurved HEI, and well tuned/setup Qjet.

 

Hey, all types/brands of engines have failures. Go to a Dick Miller meet at Norwalk. I've seen "scores" of Oldsmobile engines fail, it happens. I'm not talking about making a "national record" holder here. Just a fun street car with a little get up and go. I felt the poster was wanting more power without spending to much money. Jmo, Ken

 

Kept seeing an oil leak on the ground, and the block cracked on both sides from front to back, took the oil pan off and you could grab the crank and move the whole bottom end around by hand!
And as far as what was I doing, its a Delta 88 pacecar, what else but pacing Main Street! Anyway we took the "other" pace car without the sun roof and pulled the 403 out of it and put it in the real pace car.
We found a another 77 in a junk yard and pulled the engine and before we got it out we already could see the oil leak and the engine had the exact same problem!
We pulled several 403s looking for the imfamous "solid main web" block before we got smart and figured its a cruel myth!