88 GMC timing Help
09-01-2008, 07:28 AM
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88 GMC timing Help
Hoping someone in the forum can help me out.
Im working on a co-workers 88 GMC 5.7L 4X4.
The previous owner blew the original 88 motor, so we put in an 85 motor, and swapped Heads to the 88 style and used all existing electronics and parts off the 88. The 85 motor came out of his tow vehicle, and ran perfect and could tow a car with no problem, but with a carb.
My co-worker is trying to use the 85 balancer, which has 2 timing marks on it.
My plan today when I go over there, is to compare the 88 balancer to the 85 and figure out what mark to use.
We do know, that the 85 balancer with 2 timing marks is different than the 1977 balancer he had laying around.
Either way, I thought the 85 balancer should work since TDC is....TDC. Each time we roll it to TDC, we can feel the compression.
It Idles OK, but has no power. I thought we were a tooth off on the distributor, but I've tried placing the distributor tooth advance and retard, and its the same way.
I did disconnect the timing wire after it was warmed up and running, set it to zero, and then shut the truck off, and re-connected the wire. The timing mark jumps off the tab and bounces around somewhere around 18-20 degrees advanced.
Any thoughts of what I might be doing wrong, or tips?
Im working on a co-workers 88 GMC 5.7L 4X4.
The previous owner blew the original 88 motor, so we put in an 85 motor, and swapped Heads to the 88 style and used all existing electronics and parts off the 88. The 85 motor came out of his tow vehicle, and ran perfect and could tow a car with no problem, but with a carb.
My co-worker is trying to use the 85 balancer, which has 2 timing marks on it.
My plan today when I go over there, is to compare the 88 balancer to the 85 and figure out what mark to use.
We do know, that the 85 balancer with 2 timing marks is different than the 1977 balancer he had laying around.
Either way, I thought the 85 balancer should work since TDC is....TDC. Each time we roll it to TDC, we can feel the compression.
It Idles OK, but has no power. I thought we were a tooth off on the distributor, but I've tried placing the distributor tooth advance and retard, and its the same way.
I did disconnect the timing wire after it was warmed up and running, set it to zero, and then shut the truck off, and re-connected the wire. The timing mark jumps off the tab and bounces around somewhere around 18-20 degrees advanced.
Any thoughts of what I might be doing wrong, or tips?
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