403 Swap into Cutlass what Cam

[jpoole]

Hi, looking to swap a 403 into my car, currently 307 vin 9. Basic setup as below

1. 3.73 posi
2. 2004r with 22 to 2500 stall
3. Edelbrock Performer with EGR
4. Long tube headers running through 2 cats and duals
5. CCC carb from SMI stage 2
6. DUI distributor
7. Remove AIR system
8. 403 swap chip from COPO
9. High compression piston setup

Hoping for 350 + HP and 450 + torque

Looking for some help picking a cam for the setup.

Thanks, Jeff

 

[DoubleV]

Don't think you're going to get that much power out of a stock 403 with just bolt-ons and a cam. You most definately can upgrade the cam but with the stock garbage compression ratio ( not to mention restrictive heads ), you can only go so much. Put on some early 350 heads and your cam options open up alot. I'm not a cam expert but I would say you'd want to stock with a cam that will retain what little cylinder pressure you have and probably something on a tight LSA. In the end you will have a pretty fun ride but it won't be 350+ HP.... unless you cheat and rate it using the silly pre 72 gross HP method.

 

[jpoole]

Sorry forgot to add it has high compression pistons going in.

 

[L92 OLDS]

Sorry forgot to add it has high compression pistons going in.

If you're interested, I have a nice set of 4A heads from my 403 that would work well with high compression pistons. They only have about 5K on them and the large 455 valves, exhaust center divider welded for headers, etc. I went with #5 heads only because I have big dish forged TRW's and needed the smaller chamber. PM me if you want pics and more detail. I have a Comp cam and it works well but If I had to do it again I would look at Lunati. Your HP goal will be easy to hit if you get the CR where it needs to be.

 

[jpoole]

Sorry forgot to add it has high compression pistons going in.

If you're interested, I have a nice set of 4A heads from my 403 that would work well with high compression pistons. They only have about 5K on them and the large 455 valves, exhaust center divider welded for headers, etc. I went with #5 heads only because I have big dish forged TRW's and needed the smaller chamber. PM me if you want pics and more detail. I have a Comp cam and it works well but If I had to do it again I would look at Lunati. Your HP goal will be easy to hit if you get the CR where it needs to be.

Thanks for the offer Anubis, I am sure that would be a better setup, but I am purchasing a long block setup. he will allow me to choose cam though.

 

[jpoole]

Hey DoubleV, I noticed you have the American Racing headers, did you go 1 3/4 or 1 7/8? Also, do these go inside frame and how did they fit / install? Need mini starter etc? I like a ball and socket connector, what is used for the AR ones?

thanks, Jeff

 

[DoubleV]

High compression pistons are going to make a big difference in what cam to choose but you have to figure out exactly what your final CR is going to be.

I have 1 3/4" headers. They usually come with 3" collectors but mine are 2.5". The headers fit in the frame and fit perfectly. The headers were designed around using a particular mini starter ( Powermaster I think ). I don't even use anything to shield the starter or wires and have no hard hot start issues or burning wires. The collectors are slip fit. Since I have 2.5" collectors, my exhaust pipes just slips right on them and then you use a band clamp to keep it on tight. AR headers are one of the few aftermarket parts I wholeheartedly endorse.

 

[jpoole]

Not to turn this into header thread, but what did you need to hook Pypes exhaust up to the headers. I have contacted ARH and am going that way.

Thanks, Jeff

Also, I have asked for CR speck, but assuming 9.5 to 1 compression anyone have a cam recommendation to work with the car's computer?

 

[DoubleV]

The only thing needed to get the pipes onto my headers was 2 2.5" pipes of the proper length. These are the 2 pipes that connect to the X pipe. Since I have 2.5" collectors, the pipes just slip right over them and are held in place with typical band clamps. If you go with 3" collectors, you'll just need 3" pipes that merge down into 2.5". I don't remember the length of what these pipes need to be, but the ones included with the Pypes kit were too short.

You're really pushing running safely on the computer with 9.5 CR. I personally wouldn't want to risk that. Also, the timing curve for a swirl port 307 is not really well suited for 'normal' engines especially with higher CR ( assuming that's what you have ). Honestly I wouldn't even bother on picking out a cam until you know what your CR is really going to be and whether or not you're going to be able to even run on the computer.

If I were to have a 9.5 CR 403 built for the street and not having to deal with the computer, I would go with something like the 219/225 Voodoo cam or something with perhaps less extreme ramps. Somewhere in that dur range at least. You could certainly go bigger, but then you have to start to think about milage and how much lope you want. You also don't want to be making power at too high of an RPM with a weak block 403 with heavy pistons.

 

[jpoole]

Ok, talked builder and compression ratio can be set to my liking. He is going to call Comp and get their opinion on computer controlled cam with 9 - 9.2:1 ratio.

DoubleV talked me into AR headers and they are going to include a O2 bung on the passenger collector, how do I extent the O2 and do I need a heated O2, if so what part number. Also, will 403 balancer work with 307 Vin 9 accessory brackets?

Thanks, Jeff