Engine Performance problem
1991 Chevy S-10 V8 Two Wheel Drive Automatic 0
I have a 283 CI board.030 over engine. It has 10:1 forged pistons with a 480 lift cam. I am not sure of the duration. When I bought the short block, the guy said something about the cam having a 6% grind. It has aluminum heads with 2.02 intake valves with 190 intake runner. The brand name of the intake is Edelbrock torker. The roller rockers are 1.5 stock with a 650cfm double pumper Holley carb. It has an after market fluid balancer and Flowmaster shorty headers with 2.25 exhaust all the way out and Thrush ultra flow mufflers. This is all in an S-10 pickup.
I am getting an occasional backfire through the carb on acceleration. First, I had set my valve lash the standard way with engine running half turns after rattle stops. I backed off the half turn to only quarter turns to see if this would help. It did not.
Next, I started out with a Edelbrock 500 CFM carb on the engine. I thought it was too lean thus causing the backfire so replaced it with the 650 Holley. I came to this conclusion to change to the Holley after trying numerous timing settings. Now that the Holley is installed, I have set my initial timing to 16 degrees. The mechanical advance is 10 degrees and the vaccum advance is 10 degrees. This is a combined total of 36 degrees and still am having backfiring issues. I have tried setting the timing to 23 degrees intial and mechanical 10 degrees and no vaccum advance to no avail.
As a last resort, I have increased the exhaust valves to a half turn while leaving the intake valves at a quarter turn for valve lash. I did this thinking the exhaust was not staying open long enough to let the exhaust completely out before the intake opened thus allowing the backfire. However this doesn't appear to help my problem either.
Another issue is the passenger side of the engine, which I call the left bank, has a cylinder that only starts to fire as I accelerate. The collector of the header on that side gets to extreme temperatures, resulting in a cherry red glow because it is so hot. This bank and collector problem have been occuring throughout all changes to the engine.
Is it possible that the cam shaft might be my issue, possibly the root cause of my toubles? I am looking for any suggestions you may have to remedy my issues. It would be greatly appreciated.
Thanks in advance!
have the same problem?
Saturday, May 9th, 2009 AT 8:00 PM