Hi everyone.....I have just bought a new melling MTP-1 cam and twin roller timing chain for my '66 389 , and was wondering if any one here has any input on running a cam advanced for better bottom end power ...my new cam chian can be set stock , advanced or retarded.....I have researched it on the net and see that advancing the cam can be good for bottom end power , which is what I want ....is this a good idea in a relatively stock 389.....thanks for any ideas......j
Pontiac engines by design have more bottom end torque than a Chevy. If it were my engine I wouldn't bother. That said, since getting at the timing chain is easier on a Pontiac vs the Chevy you can install it the 4degrees advanced. If you find the motor runs out of steam by 3500 rpm then pop the cover off and crank it back.
I can't tell you what the results are but on my 455 Tri Power with a RA IV cam I did the cam advance. I sold the car before it was completed and the new owner has put some miles on it. The little bit of feedback I did receive on how it ran was good though. I don't think he has put on enough miles, nor is he the type to beat on the car so can't say for sure.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars
Many cams have 4 degrees of advance ground into them right out of the box, so if you install them in the "straight up" position they're already advanced four degrees. The only way to know for sure what you've got is to check it with a degree wheel.
As a general rule most engines will make the best average power with the cam advanced about four degrees but it's as you mentioned,,, advancing the cam usually adds to the bottom end and midrange but usually gives up a little on the top end. But as dcneric mentioned, the Pontiac engine is already pretty torquey so you might just loose top end and not gain much on the bottom end.
Advancing the cam usually works great on a low compression motor but if the engine has fairly high compression, advancing the cam will make it more prone to detonation. Piston to valve clearance can also be a problem but probably not in your case with a relatively stock engine.
