The Stovebolt Site Forums The Shop Area Engine Shop Need some engine help.

Hey. Im brand new to the boards so go easy on me LOL. I have a restored 1978 GMC Sierra Classic shortbox pickup. I recently pulled the engine out and put on some upgrades. I put a new energizer cam in, new intake, and headers. I figured it would have a lot of power but it seemed to have lost some. I figured it was running way to lean with the intake and header combo. I changed the jets from .064's to .071's. This helped on the mid to high end but it was still doggy on the low. Then I put in some 44B metering rods. This helped low end but it still doesnt seem to have the "get-up-and-go" like it should.
It has true duals and glasspacks, with no H-pipe.
I was wondering what you guys would reccomend for me so I can achieve the power I know its cpable of. I've thought about acuall mufflers to increase backpressure?

any help would be appreciated.

Thanks, Dustin

Dustin Welcome: We need to know the engine size to make an educated guess. Sounds like not enough gas did you change carb size also. You add intake and cam w/headers it problay starving for fuel. popcorn The truth is Out There (your on the right track for HP)

Duh..sorry, my bad. Its a 350. The intake is an edelbrock S.P.2-P. My dad had it lying around in our shop that he had on an older car that he let me use. The cam is a crane cam energizer. The duration is 260. Oh, and I have the stock Q-jet still with the different jets and metering rods as i mentioned above.

that should help

Sounds like wrong gearing for low end launching. What rear ratio are you running?
Scott

What is the timing set at and how did you set it?
How well did you adjust the carb and what method did you use?
Did you use a new timing chain and gear set?
if you used a new set, did you allign the marks properly?
Just questions to help us help you

A cammed-up smallblock will benefit from increased initial ignition timing, BUT, you have to restrict the travel of the centrifugal advance weights in the distributor by an equal amount. This is a trick I use on the round track engines I build. I don't reccomend doing it unless you have access to a distributor tester to check your work, but generally, a 5 to 6 degree increase in initial timing, and the same drop in centrifugal advance gives a better launch.

Alternate suggestion- - - -drop to a lower ratio rear end gear for better low-end acceleration.
Jerry

There is a new timing chain and gear in the engine, I never messed with the timing, guess I never really thought of it :confused: With the carb I just put the different jets in and metering rods. Never really messed with the mixture screws. The timing gears are aligned properly. The gear ratio is 3:08. And my tire size are 235/70/15, I was thinking about going to a 235/60/15.

smaller tires would give me more grunt, but I would give up a little on my top end.

It seems to run alright with the 71s in the carb, I just need some help with finding more low end, Some trucks my year came with .074's stock. Would that help?

Thanks for all your help by the way.
-Dustin