Timing problems - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Rons86 · 02-19-2009, 11:32 AM

A little history on my truck, 86 c10 with reman. stock 350 (about 6k miles), 400 trans, eledbrock performer intake and 1406 carb, stock hei distributor.

I have a problem after replacing the coil, pick-up coil, module, cap mechanical advance weithgs and springs (used the medium springs) and rotor, when i set timing with vacuum advance plugged it runs great. When I hook the vacuum advance up again (either on the timed vacuum port on the manifold vacuum port) it runs terrible and has a very bad hesitation just off idle. Was wanting to get your opinions. I think the vacuum advance is bad, but not sure.

85_prairieboy · 02-19-2009, 02:37 PM

What did you use to set the timing? Timing light, vacuum gauge, by ear?

Rons86 · 02-19-2009, 03:48 PM

Timed by ear and timing light. When I hook the vac advance up to the timed port it runs ok at idle and half to full throttle, but when hooked to the manifold port it really runs bad all thru the throttle position. If there is any other information you need to form an opion let me know.

piecesparts · 02-19-2009, 04:16 PM

Did you use the timing marks that are directly behind the water pump? There is a timing tab that you can see by looking down from the top of the engine. That is where these motors are timed at. Also check the dizzy weights to see if they are not stuck in one position and causing you to be too advanced or retarded. Finally check the rotor position---ensure #1 is at TDC and the lrotor is pointing at the #1 cylinder. To do the pickup coil, you had the dizzy out, so you could be off of the timing mark.

Rons86 · 02-19-2009, 05:23 PM

Did all that. Took to TDC exh. stroke #1, lined up #1 on dizzy ,started it up and now this problem. Is there something I am missing, have done this a few times and have never had these problems. Would the vacuum advance being bad cause this?

vtwinsport · 02-19-2009, 08:37 PM

Maybe this thread on vacuum and timing will help?
http://67-72chevytrucks.com/vboard/s...d.php?t=274806
best

Rons86 · 02-23-2009, 01:44 PM

Put a new dizzy in it and fired right up.

02-19-2009, 02:37 PM	#2
85_prairieboy Registered User Join Date: Jan 2009 Location: Glaslyn, Sask Posts: 131	Re: Timing problems What did you use to set the timing? Timing light, vacuum gauge, by ear? __________________ 85 GMC toy Lowered, newer box swap, 350 .060 over with AFR 195s, forged pistons, TCI TH350 1.83 60' 13.14 @ 100 on motor 1.49 60' 11.52 @ 116 w/150 shot 1952 Chevy truck project 1980 Z28 Camaro 1967 Camaro drag car 10.60@126

02-19-2009, 03:48 PM	#3
Rons86 Registered User Join Date: Sep 2008 Location: Holt, Missouri Posts: 94	Re: Timing problems Timed by ear and timing light. When I hook the vac advance up to the timed port it runs ok at idle and half to full throttle, but when hooked to the manifold port it really runs bad all thru the throttle position. If there is any other information you need to form an opion let me know.

02-19-2009, 04:16 PM	#4
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Re: Timing problems Did you use the timing marks that are directly behind the water pump? There is a timing tab that you can see by looking down from the top of the engine. That is where these motors are timed at. Also check the dizzy weights to see if they are not stuck in one position and causing you to be too advanced or retarded. Finally check the rotor position---ensure #1 is at TDC and the lrotor is pointing at the #1 cylinder. To do the pickup coil, you had the dizzy out, so you could be off of the timing mark.

02-19-2009, 05:23 PM	#5
Rons86 Registered User Join Date: Sep 2008 Location: Holt, Missouri Posts: 94	Re: Timing problems Did all that. Took to TDC exh. stroke #1, lined up #1 on dizzy ,started it up and now this problem. Is there something I am missing, have done this a few times and have never had these problems. Would the vacuum advance being bad cause this?

02-19-2009, 08:37 PM	#6
vtwinsport Registered User Join Date: Nov 2008 Location: edmonton, alberta Posts: 293	Re: Timing problems Maybe this thread on vacuum and timing will help? http://67-72chevytrucks.com/vboard/s...d.php?t=274806 best __________________ 76 Silverado, 2wd, long box, 350/th350, 3.42 posi, edelbrock performer 64cc heads, edelbrock 1405, 2101 intake, Hedman Headers, Comp Cam XE262 http://beerbreadbike.wordpress.com/ Last edited by vtwinsport; 02-19-2009 at 09:40 PM. Reason: better info found

02-19-2009, 11:32 AM	#1
Rons86 Registered User Join Date: Sep 2008 Location: Holt, Missouri Posts: 94	Timing problems A little history on my truck, 86 c10 with reman. stock 350 (about 6k miles), 400 trans, eledbrock performer intake and 1406 carb, stock hei distributor. I have a problem after replacing the coil, pick-up coil, module, cap mechanical advance weithgs and springs (used the medium springs) and rotor, when i set timing with vacuum advance plugged it runs great. When I hook the vacuum advance up again (either on the timed vacuum port on the manifold vacuum port) it runs terrible and has a very bad hesitation just off idle. Was wanting to get your opinions. I think the vacuum advance is bad, but not sure.

02-23-2009, 01:44 PM	#7
Rons86 Registered User Join Date: Sep 2008 Location: Holt, Missouri Posts: 94	Re: Timing problems Put a new dizzy in it and fired right up.



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