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

**dtkarst** · 06-07-2012, 01:04 PM

On my 61 K10 it seems as if the 235 has an external vacuum advance on it which I have never seen before. i am used to working on V8s so I dont know how to get it set right or anything. It will almost fire up and run but it acts like the timing is off. Has new points and condenser as well. Would the vacuum parts need replaced? and can you even get that? Anyhelp you be appreciated

j.kirn · 06-07-2012, 02:10 PM

Opening up the throttle under the hood you can see if the vacuum advance is working and if not they are available

markeb01 · 06-07-2012, 02:52 PM

The correct way to set the timing is to disconnect the vacuum advance from the distributor and plug the line so it doesn’t affect the idle. Always make sure the points are set first, as this controls the dwell. Set the timing to specs, and reconnect the vacuum line to the distributor advance.

An easy way to see if the vacuum advance is working – with the timing light hooked up and the engine running, connect the vacuum hose from the distributor advance to a full manifold vacuum source. Don’t accelerate the engine, just leave it at idle. The timing should advance smartly. If it doesn’t move under full vacuum, the advance chamber needs to be replaced.

j.kirn · 06-07-2012, 05:23 PM

SEE answer above no tools required for vacuum advance to know if its working

**dtkarst** · 06-07-2012, 07:33 PM

Well I need to get it running first haha It wont quite run it gets real close then nothing. Points are set right and whatnot but I cant figure it out Ill try the suggestions

fleetsidelarry · 06-07-2012, 07:46 PM

how have you gone about setting the timing? did you determine #1 was on the compression stroke when the little timing ball on the flywheel lined up with the pointer? the ball and pointer will line up at two different occasions when #1 is at TDC. you may be 180° off.

**rideblue00** · 06-07-2012, 10:35 PM

I agree with what larry said.

Wrenchbender Ret · 06-07-2012, 11:17 PM

There is a screw under the dist that loosen s up to turn the dist in the vacuum advance clamp. Loosen the bolt holding the the dist down & set the scale on 0. This is called the octane selecter. Set the timing by turning the dist & tighten the clamp. A final adjustment can be made withe octane selecter.

06-07-2012, 02:10 PM	#2
j.kirn Registered User Join Date: Jun 2006 Location: MO. Posts: 970	Re: Timing question.. Opening up the throttle under the hood you can see if the vacuum advance is working and if not they are available

06-07-2012, 02:52 PM	#3
markeb01 Senior Enthusiast Join Date: Feb 2007 Location: Spokane Valley, WA Posts: 8,356	Re: Timing question.. The correct way to set the timing is to disconnect the vacuum advance from the distributor and plug the line so it doesn’t affect the idle. Always make sure the points are set first, as this controls the dwell. Set the timing to specs, and reconnect the vacuum line to the distributor advance. An easy way to see if the vacuum advance is working – with the timing light hooked up and the engine running, connect the vacuum hose from the distributor advance to a full manifold vacuum source. Don’t accelerate the engine, just leave it at idle. The timing should advance smartly. If it doesn’t move under full vacuum, the advance chamber needs to be replaced. __________________ My Build Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=444502

06-07-2012, 05:23 PM	#4
j.kirn Registered User Join Date: Jun 2006 Location: MO. Posts: 970	Re: Timing question.. SEE answer above no tools required for vacuum advance to know if its working

06-07-2012, 07:33 PM	#5
dtkarst Senior Member Join Date: Nov 2010 Location: Hays, KS Posts: 2,490	Re: Timing question.. Well I need to get it running first haha It wont quite run it gets real close then nothing. Points are set right and whatnot but I cant figure it out Ill try the suggestions

06-07-2012, 07:46 PM	#6
fleetsidelarry Senior Car Nut Join Date: Jan 2008 Location: shellman bluff, GA Posts: 1,411	Re: Timing question.. how have you gone about setting the timing? did you determine #1 was on the compression stroke when the little timing ball on the flywheel lined up with the pointer? the ball and pointer will line up at two different occasions when #1 is at TDC. you may be 180° off. __________________ Larry

06-07-2012, 01:04 PM	#1
dtkarst Senior Member Join Date: Nov 2010 Location: Hays, KS Posts: 2,490	Timing question.. On my 61 K10 it seems as if the 235 has an external vacuum advance on it which I have never seen before. i am used to working on V8s so I dont know how to get it set right or anything. It will almost fire up and run but it acts like the timing is off. Has new points and condenser as well. Would the vacuum parts need replaced? and can you even get that? Anyhelp you be appreciated

06-07-2012, 10:35 PM	#7
rideblue00 Senior Member Join Date: Feb 2010 Location: Lambertville, MI Posts: 1,859	Re: Timing question.. I agree with what larry said.

06-07-2012, 11:17 PM	#8
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,203	Re: Timing question.. There is a screw under the dist that loosen s up to turn the dist in the vacuum advance clamp. Loosen the bolt holding the the dist down & set the scale on 0. This is called the octane selecter. Set the timing by turning the dist & tighten the clamp. A final adjustment can be made withe octane selecter.



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