I had asked for your opinions on my last build, unfortunately it died so i picked up a new block and went at it.

The new build...





403 Olds engine cleaned and bored .024
Keith Black hypereutectic flat top pistons
Energy Camshaft Duration @ 0.050"224° / 230°
Ported Olds #5 Heads with larger valves
Edelbrock RPM Manifold
Q-jet 800 CFM carb (edited)
Blockers intake kit with open shaker scoop.
Comp Cams Roller Rockers
Hooker Headers
Moroso 7 quart oil pan
recurved stock HEI distributor
Stage two shift kit in Rebuilt TH350
2500-2800 rpm stall converter
Mondello Inertia Flexplate
Auburn Limited Slip
3:73 gears


No air conditioning on car,

Just built and in my 79 Trans Am

Any thoughts on anything I should do/overlooked. It seems to run strong,has 800 KM (500 miles) on engine,breaking it in a bit more before it sees 5500 RPM.

What amount of HP and torque do you think it would see on a dyno?
1/4 Et?

Cheers

Kanesdaddy

 

What work has been done to the heads? Larger valves? Looks like you are around 10.5 to 1 for compression. 13's or better should be easily possible depending on the heads. If it is the original 403 carb, it will be 800 cfm. Your tune better be right on to run pump gas.

 

Ya, hopefully you went with larger valves. The huge bores in those 403s are just the ticket for big valves. As for the build, from what I've heard, the siamese cylinder design requires head gaskets that can deal with the heat build up between the cylinders (this is said to be one of the biggest design hurdles on the 403). IIRC, a knowledgeable member said that he kept the revs down for a bit directly after short (10-15 minute) warm/hot engine shutdown periods. He did this to reduce the sudden shock of rapidly pumping cold(er) coolant from the radiator onto the hot siamese areas of the block. Meanwhile, please keep us posted on that sharp 403 build of yours. I'm considering a future '64/65 F85 403 build and could use any and all feedback on that engine.

 

Valves are oversized, and the head gaskets are some special kind ( Copper? I didn't build it) to handle the high compression of the new pistons and #5 heads. My engine builder also did a "grind" on the exhaust manifold side to get rid of the "shared" middle two exhaust ports and ground out the egr bumps while porting the heads. He figures with the extensive mods ( and there are lots ) that it's in the 350 to 360 HP range.

I agree with that advice, I NEVER start it and drive it until it is totally warmed up. It's also very cold here and its safe in my garage till spring. Once its broken in if I can it will see a dyno and I'll let you know where it sits RWP wise.

So far after a good warm up its only seen about 4500 rpm, but it just shreds the tires so my thoughts are it's making lots of torque.

I will pm you or post the dyno results in spring.

 

Probably Cometic or Mr Gasket MLS head gaskets. I never had head gasket issues on my 403, despite multiple, bad over heatings. It had Detroit head gaskets when I bought it, were still good when I redid the bottom end the first time. I put Corteco head gaskets on, lasted till I took out the bottom end again. I actually blew the same gaskets on a 350, go figure. Make sure your cooling system is top notch.

 

Thanks for the feedback 307/403

Have a big clean 3 row rad in the car and no air conditioning hopefully it keeps everything cool. My builder also blocked off some coolant ports to the intake manifold, and since the build it runs WAY cooler than before. I was more concerned about the higher compression than anything and as it is tuned there is no ping on premium pump gas and two cans of octane boost per tank.

FWIW this is the ONLY car I have ever owned that you could feel the difference from adding octane booster. Its pretty much sitting over winter with a full tank of gas. In the spring I am going to siphon it out, dump what's in it into my Wrangler and refill it with a 75% Premium/25% race gas mix and see how it runs.

I reused the 1 3/4" Hooker Long tube headers it came with when I bought it.Do you think I would realize a 25 HP gain using American Racing Headers over what now is in the car? Headers are cheap and easy to install on the T/A

(ps) good call on the carb cfm, when I checked with my engine builder he said it was an 800 CFM carb.

 

Sorry I misread, that you had manifolds. There is probably only a handful of HP and TQ to be gained over the Hooker, depending on the primary tube size. I need to do a cam swap, new exhaust and a custom tuned 800 cfm Qjet done in spring. A Trutrac and Moser axles are also on the list. Hopefully next year I will get the machine work done for my 403 stroker, already have the pistons, rods and crank.

 

You have almost exact build as my 403 thats in my 79 T/A and im running low 13s but i have stock 4a heads that i had shaved and i still have the 2.41 gears. my stall converter is a 2100. Did you get the main girdle??

 

No girdle, going to keep the revs below 5500 rpm so not expecting any issues.

 

well i imagine you will be putting out more horse's than mine, it helps with high revs but i mainly got it for safty reasons for adding alot more HP than stock and it isnt expensive for what it does. but your car is very nice i imagine you take it alot easeir on her than i do mine lol. also whats the paint code (shade)? i have yet to paint my rust bucket.

 

The color is Atlantis Blue