I'm getting ready to build a motor for my 95 K2500. I would like to build the 400 that is sitting in my garage, but I need to keep my truck drivable while I iron out the chip and fuel settings, etc. I have also kicked around the idea of rebuilding the 350 that is in the truck. Either way, the motor is going to run the same basic components:
somewhere around 9:1 comp hyper pistons
Pro-topline heads, 76cc / 167cc runners
Comp 256H-12 TBI/TPI cam or similar
Edel Performer or Perfomer EPS manifold, no EGR

I know that either engine will require a 454 or Holley TBI and some chip changes, but will they run with the stock chip and TBI unit already in the truck while I work out all of the bugs? Will I risk engine damage if I do so? Or, should I consider a new TBI absolutely necessary and include that with the rebuild?

Thanks...

 

The car will run on the stock 350 prom but it will not run near it's potential. I see that you don't want EGR. That is okay if you tune it out but if you run the stock prom for awhile you will have problems. An aftermarket TBI will be a must with any setup larger than the stock 350 set-up now. I do not know the specs on the cam you listed but as long as it has a high enough LSA you should be okay to tune it. Also, what pistons will you run to get 9.0:1 or so compression with 76cc heads. I do not know what it takes to get that on a 350. You should look into some machined vortecs. They can handle some serious cams and can make huge power on either combo you mentioned.

 

If going with the 400 block you'd probably want like 18 psi to make the stock 350 chp run. You'll get codes but it should run ok. Try like 8deg timiing advance too. Then get into burning a nice chip for it.

 

I've thought about the vortecs, but the toplines flow quite a bit better, and are available with 64 or 76cc chambers and either style intake face (pre 87 or 87-up). I've found pistons that will give me the CR i'm looking for, although on a 350 I may go with a 64cc chamber. The cam has a CL of 112, it's the cam that Comp recommended for this application. Other than throwing a code, what other problems will removing the EGR cause? I realize that a new chip and TB will be required to run at anywhere near full potential, but I'd like to keep costs down for the time being so that I can get the motor in the truck.