Performance ideas stock 69 GMC 2500 396
 

I just picked up an all original 1969 GMC 2500 Custom Camper with matching 396 and turbo 400. I have been looking at what parts i might put on it to boost performance. It has factory A/C, P/S, and P/B. So far i have an offenhauser aluminum intake with a Barry grant 750CMF holly that I am going to put on it. I want to do a cam kit, headers and exhaust. It has an HEI distributor on it already. Please suggest any ideas for the cam, headers and mufflers or any other ideas. Also I have a 78 LWB that has front discs. will i be able to use the parts off the front end of the 78 to convert the 69 to front disc?

Re: Performance ideas stock 69 GMC 2500 396
 

For a cam suggestion, first we need to know what you are going to use the truck for.

Re: Performance ideas stock 69 GMC 2500 396
 

Gear ratio is 354. Just want it to be fast and sound tough. No towing or hauling.

Re: Performance ideas stock 69 GMC 2500 396
 

My suggestion would be to first do a compression and leak down test. There is no sense in putting in a lumpy cam if you have an engine that might be marginal. Has the motor ever been rebuilt? If it hasn't then I'm gonna go out on a limb and say I'd leave it alone.... JMO..

Re: Performance ideas stock 69 GMC 2500 396
 

Stay under 220 degrees at .050 lift on the cam (Something like a Comp 268 or even 260 or Crane 272 or 266)

Heads are limiting factor with the early closed chambers, but they should work with cam that size. Make life easier if you don't go big on cam so heads don't have to come off to be machined for studs.

Intake mods (not sure that Offenhauser intake is exactly the best choice anymore. I'd look into an Edelbrock Performer for this application). The Q-jet is a good choice for a mild driver too IMO.

I'd skip the headers and run 2 1/2" exhaust with Dynomax Turbo mufflers (Hemi Turbos if it were mine.)

Re: Performance ideas stock 69 GMC 2500 396
 

I had some luck with a cam in my 396 Impala that was 228/238 - and that's more than I would normally go, but the car had some gear and a converter. It also caused coil bind (didn't say it was all -good- luck) that wiped a lobe, so check that stuff...

Intake, cam, and headers. Once the health of the motor is established, of course.

Conversely I took a ZZ502 and dressed it as a 396 with stock iron itake, iron manifolds, the whole deal. Runs like a choked 396 now! I'm not a big fan of headers but the old iron manifolds are grim. I use the manifolds on my new LS3, but wouldn't do any kind of perf build with an old iron log manifold after seeing how it affected the 502.