403 camshaft selection

[SATURN5]

Time to decide what cam to run..

Usage, cruise, street, limited drag.

Trans 200R4 GN VB.

Gearing, 3.73

Intake Performer RPM

Carb rejetted Qjet for now. (Future plans are MPEFI, MSII ECM)

Looking at the W31 cam..

* RPM Range: 1800-5800
* ADV Duration: 329/329
* Duration @ .050: 232/232
* Valve Lift: .474/.474
* Lobe C/L: 113

Anyone running something close? Thoughts? Thanks, Bob

 

[megaladon6]

mine's pretty similar--it's all in the sig but the cam specs.
274/286 ADV, 230/236 @.050, .487/.490 lift
it has great power through the rpm range, almost too much low end torque--1/3 throttle and the tires spin 😀
it does not have that nice lope to it but oh well.

 

[beeterolds]

i ran a Comp Xtreme .475 .480 218 224 cam in my 9.0 403...i liked it..it had a rumpity idle...and pulled like hell to 5000

 

[85 Cutlass Brougham]

IF you plan on EFI in the future, keep the lobe separation angle as wide as possible. The 113 degree LSA you posted would work well with EFI as compared to the more common 110 or lower LSA of many cams. The other part of the equation to consider is the compression ratio, and more specifically dynamic cylinder pressure. Higher compression ratios allow you to run bigger cams without a degradation in idle quality, etc. What I would do before you make any purchases is to get a hold of a computer dyno simulation program and run your proposed engine on it, then make changes from there. This is how I picked my cam and it has turned out to be a good choice. The old "Dyno 2000" program I used (8 yrs old!!) predicted that a larger cam would actually reduce power in my engine. Without it, I would have been guessing. It may set you back $100 or so, but it is money well spent if it keeps you from making costly mistakes.

 

[megaladon6]

actually you can download the compcams program for free from their site. that's how i got it. actually i run yours now. ok i put in 9.5: compression, HP heads with no mods (1.94i, 1.50e valve--i guessed), dual-plane intake, small-tube headers w/muffler and no cats, and a roller cam(guessed again) it gave me 2 cams, the better one only has a 110* lobe sep but the other numbers are good--224/230 at 50, 276/282adv, and .505lift. it dynos at 373hp and 462tq. its an xr 276hr cam. if you want to PM me with more detailed specs (especially the head flow numbers) i can give you a better idea.

 

[SATURN5]

Thanks..

I think I'm going to go with this one..

Camshaft Specifications

Lobe Centerline Gross Intake Lift Gross Exhaust Lift
112 .496 .520

Intake Duration @.050" Exhaust Duration @.050" SAE Int Duration SAE Exh Duration
224 234 300 310

hydro flat tappet.

It's pretty close to what compcams software suggested.

Heads are stock 4A's until I find a set of 7a's. I'll clean them up and put the 4A intake valves in.

 

[beeterolds]

Thanks..

I think I'm going to go with this one..

Camshaft Specifications

Lobe Centerline Gross Intake Lift Gross Exhaust Lift
112 .496 .520

Intake Duration @.050" Exhaust Duration @.050" SAE Int Duration SAE Exh Duration
224 234 300 310

hydro flat tappet.

It's pretty close to what compcams software suggested.

Heads are stock 4A's until I find a set of 7a's. I'll clean them up and put the 4A intake valves in.

Dude...this is a very generic Chevy grind on an Olds cam blank... there are better choices out there...stick with Engle/Ultradyne or Lunati...with this cam you will have nothing but poor low end performance and lousy gas mileage.. the ramps on these cams are very lazy.... especially with a poor flowing set of 4a heads... go with the Jm 20-22 camshaft by Engle... 496 512 lift... 226 230 duration.... im telling you...this cam will idle more tamer..but its designed specifically for Oldsmobiles...use the 226/230 cam instead of the 224/234 cam...trust me..

whats your compression? tork converter stall speed...and vehicle weight..if your keeping the compression stock 7.9-1 unless u swap to early heads...dont use a cam with more that 210 212 duration in a 403... or say good bye to gas mileage..and it wont be fun on the street...

 

[KrisW]

By "swap to early heads," he means "C" casting big block heads. You can get them off eBay cheap.

That cam you have listed is the same as the Edelbrock performer RPM / Lunati bracket master 2 piece that I ran once. That one doesn't like fuel injection without LOTS of tuning. It pulled like a monster with a 795 Quadrajet...