250 timing question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Chevy nutcase · 02-12-2023, 10:38 AM

Recently on my 66 I ditched the old points distributor for an HEI from summit. I put the timing mark on 0 so the rotor would be pointing at #1 before removing the old one. Installed the new one and had it pointing at #1. Got a new set of plugs and cut to fit Accel wires and it started right up. Yes I had the vac advance pulled and capped. When I put a timing light to it the mark on the crank was completely vertical which is 2" away from the indicator on the timing cover but it ran fine. If I twist the distributor so the mark is on or near 0 the idle slows, surges a bit and threatens to stall. Any ideas why this might be?

**bhap** · 02-12-2023, 12:50 PM

I'd pull #1 plug, find TDC (confirm with either valve cover off - both valves closed or finger in #1 spark plug hole to feel puff of air on compression), reset the distributor and wires and see where your timing light falls. The way you are doing it obviously worked, but assumes it was setup correctly the last time..

Chevy nutcase · 02-12-2023, 05:32 PM

Quote:

Originally Posted by bhap

I'd pull #1 plug, find TDC (confirm with either valve cover off - both valves closed or finger in #1 spark plug hole to feel puff of air on compression), reset the distributor and wires and see where your timing light falls. The way you are doing it obviously worked, but assumes it was setup correctly the last time..

I did as you said. Physically turned the motor to #1 tdc, confirmed through spark plug hole and the mark was on zero but now the rotor was well past #1 on the cap and was a third of the way to #5. I dont know how that happened but I pulled the distributor and moved it back 2 or 3 teeth to #1 and it runs beautifully. The timing mark on the crank is high on the stationary indicator which I think is a few degrees advanced but I hear that's where these motors like to run. I did get a tiny carb pop but that may have been it clearing its throat as I had all the bolt on accessories off so I could clean and paint the block. I'll give it a test run tonight or tomorrow and see how it likes the new electrical system. Thank you

02-12-2023, 12:50 PM	#2
bhap Senior Member Join Date: Mar 2006 Location: Pittsburgh, PA Posts: 246	Re: 250 timing question I'd pull #1 plug, find TDC (confirm with either valve cover off - both valves closed or finger in #1 spark plug hole to feel puff of air on compression), reset the distributor and wires and see where your timing light falls. The way you are doing it obviously worked, but assumes it was setup correctly the last time..

02-12-2023, 10:38 AM	#1
Chevy nutcase Registered User Join Date: Mar 2021 Location: Hershey Pennsylvania Posts: 330	250 timing question Recently on my 66 I ditched the old points distributor for an HEI from summit. I put the timing mark on 0 so the rotor would be pointing at #1 before removing the old one. Installed the new one and had it pointing at #1. Got a new set of plugs and cut to fit Accel wires and it started right up. Yes I had the vac advance pulled and capped. When I put a timing light to it the mark on the crank was completely vertical which is 2" away from the indicator on the timing cover but it ran fine. If I twist the distributor so the mark is on or near 0 the idle slows, surges a bit and threatens to stall. Any ideas why this might be?



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