AnthonyH'79Delta88

Hey, I have a 403 oldsmobile engine that I'm about to build up. I'm going to be using some of the oldsmobile parts that I have laying around. I was wondering if anyone would know what my output would be around with this engine combo.

• 403 with .030 over bore
• milled 1979 350 heads about 70cc (some porting)
• cam lift: .450" in/ex duration: 274@.006" lift and 218@.050"
• edelbrock intake mailfold 3701
• 9.5:1-10:1 c/r
• 750cfm Q-jet carb

thanks

Warhead

I would not use the 350 heads, unless you put in some larger valves. The 403 come with a set of 1.995 intakes, and a too small exhaust, and it was undervalved to start with.
I would rather see you use a set of early heads (1967-1972, #4-7a), and have the head bolt holes opened up, but if you must use these castings, get some bigger valves in them.
1.995/2.07 intakes, and some 1.625 exhausts.
If you don't, you will cut off some 40 hp.
From your post, I would believe you are not in the states...posting your location can help with getting/obtaining parts, castings, and good work done locally.
Where you are at now, 250 hp, depending on tuning, cold air, exhaust, accesories, etc.
JMO
Jim

AnthonyH'79Delta88

thanks man

cutlassefi

I agree with Warhead, sounds like a good plan. Definitely do the 2.07/1.625 valve sizes. Should make over 300hp imo.

AnthonyH'79Delta88

How much do you think I could gain from a bigger cam and maybe a better flowing intake. I was thinking about getting the Edelbrock RPM Performer 7111 intake manifold and a cam with: lift in/ex .496"/.520" advised duration 290/300 @.050 224/234. What do you think?

cutlassefi

I like your intake choice but not the cam, you can do better than that imo.

AnthonyH'79Delta88

You mean, you think I so should go even bigger?

cutlassefi

Not necessarily bigger, just different.

AnthonyH'79Delta88

Should I get my crank balanced? I'm trying to get a good 400hp.

My crank is in the machine shop getting the journals polished.
My block is also in the machine shop; its getting it's overbore right now.
I am going to be using KB/Keith Black hypereutectic aluminum pistons which have a small "D" dish in them.

svnt442

It's always a good idea to get the reciprocating assembly balanced.
If you don't have the pistons yet you'll have to wait on the balancing.

AnthonyH'79Delta88

They are on there way.