Horsepower

[cliff stillion]

Me again, the 400 that I just put together with the cam, compression, and intake you think would have enough butt to spin the tires in a Ventura body. With 3.73 rear gears you would think this motor would kick some butt. It idles great, seems to run fine as driving easy. When you rev the engine sitting in the shop it makes a strange vibration at around 1500/2000 rpm's. I hear no knocking when driving, both during acceleration and deceleration. Had the car out yesterday and it was just sluggish. It also began to overheat, glad I was close to home. Checked the radiator and it was full, new t-stat, new fluids. For my first Pontiac, thinking I should have stayed with the Chevy at this point. My 383 strokes made almost 500 horse and would push a 68 chevelle all over. Any suggestions? Going to pull the motor and check internals. Motor was built, heads and block, by a local performance shop and the assembled by myself. Never had this problem with any other motor. Sorry for rambling, just frustrated at this point...

 

[melsg5]

Lets start with the ignition system. What distributor are you running? Did you set total mechanical advance to 36 degress coming in at close to 3K RPM? Are you running vacuum advance. If so are you using ported vacuum or manifold vacuum. How many dergrees of advance does the vacuum advance provide by itself? What brand and number spark plug are you using?

 

[cliff stillion]

hosepower

R45 AC plug which is what the motor calls for stock. Accel distributor that was in the car when purchased. It has a vacuum advance but it was plugged off. I only set the timing as stated for a stock motor.

 

[melsg5]

Is the Accell distributor an HEI type or something else? Can you provide the part number? Do you have a dial back timing light? Is the harmonic balancer degreed? You cannt assume stock timing setting with an aftermarket distributor. The vacuum should be used not plugged.

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[cliff stillion]

I finally found out that the wrong specs came with the camshaft and lifter kit. The preload was way off. After getting the valves all set and replacing the carb, runs like it should. Now if I can just find time to get it out... Also, according to Accel, the vacuum does not need to be connected as with the engine timing and mechanical advance, it is around 32 degrees, the vacuum will add about 10 more if need be. They make a block off kit to just remove it. Thanks for the help.

 

[melsg5]

Unless you are running aluminum heads or very high compression you will get more power and economy by running the car with 36 degress total initial and mechanical advance. In addition the added 10 degrees from the vacuum will cause the engine to run cooler and get better economy.

 

[cliff stillion]

I am running the 670 heads with flat tops. The engine builder says with the head gasket we were a little over 10 to 1, which is supposedly below what the stock reference was. The vacuum advance is connected so we will see how it goes from here.