How much power can the factory '98 short-block handle? If you can keep the engine out of knock, and don't spin it over 6,500 rpm, you should easily build 500 to 550 hp. The pistons, on the other hand, may be the first thing that I would think to replace. With most of the late castings thinner than their earlier brothers, I also wouldn't bore the engine beyond 0.030-inch over. However, you should be able to have many years of fun if you keep your head about you.
Hard StarterQI recently bought an '86 Chevy 4x4 with a 350 and TPI induction off of an '86 Firebird. The installation looks bad, with the harness spliced in from the donor and the mechanical fuel pump still hanging there. My problem is that it doesn't start right up. It takes about four to five seconds to fire. I have done a complete tune-up and was told that this type of start time was normal. Also, it idles rough from time to time. My mpg is currently at 12 and I think it should be around 15. I have the TPI swappers book and it states that if you have a weak alternator it can wreak havoc on a fuel-injected engine. What else should I check? I was told it has an RV cam, but also that it should be OK with the MAF setup.Dennis MartinMemphis, TN
A A crank time of four to five seconds isn't normal. Yes, system voltage is critical. A standard operating voltage of 13.8 to 14.2 is a nice range for the system to work with. While the computer has voltage compensation built into the software to adjust for lower or higher numbers, the EFI will run fine. Still, you should shoot for these numbers.
We would look to your fuel pressure for your hard-starting problem. You need to check if you have residual fuel pressure with the engine off. There is a check valve built into EFI fuel pumps to hold residual pressure for the next engine start-up. Also, the fuel pump should cycle when you turn the key to the run position for around three seconds to prime the fuel system. Install a fuel-pressure test gauge to the fuel rail of the EFI. If the system doesn't retain a pressure in the high-30-psi range, the fuel pump is the problem. With your TPI system being a swap, it's tough to say which pump they used. All the in-tank pumps used for your model of truck were TBI pumps that put out a max pressure of 18 psi. For a good universal inline EFI pump, check out ACCEL universal fuel pump, PN 74701, which produces 200 lb/hr fuel flow at 45 psi, supporting up to 400 hp. This is a perfect size pump for your application.
As you said, a small RV camshaft will work fine with an MAF sensor-controlled EFI system. As with any heavy 4x4 truck, it takes quite a bit to getter rolling. I would agree that you should be able to knock down 15 mpg out on the highway, although I doubt you will see that type of mileage around town. Work out your fuel pressure issue and clean up your connections from that badly spliced harness and you will have better reliability. Good luck with your truck and enjoy.
Stat SelectionQI recently put a new aluminum radiator in my '70 SS 454 Chevelle and was wondering if the choice of thermostat temperatures would make a difference in the car's performance. The choices are, of course, 160, 180, and 195 degrees. I put a 195-degree stat in the car and want to know if this will help or hurt the overall performance, or does it not really matter? Thanks.Bart PinsonVia e-mail
A The thermostat selection in some engines doesn't really matter because the engine operates above that temper-ature all the time. The only time the stat comes into play is during start-up and the period before the cooling system controls the engine temperature. Many big-block Chevelles couldn't run at 160 degrees if their lives depended on it. When you're running down the freeway at 70 mph and it's 50 degrees outside, maybe the cooling system could pull the temp down that low. But that would be rare.