Vaccum advance?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bluex · 09-23-2004, 12:30 AM

Well after beating my head againts a wall for two weeks I finally broke down and pulled the distributor retimed it and it fired right up. Guess I had a plug wire out of order?

Anyways I was shooting for 12* before but wound up with 10. As soon as I hook the advance up AT IDLE it jumps straigt up to 28*. I know its good to have it come in as soon as possible, but at idle seems a little to quick to me and could be why its not performing the way I think it should.

Do I need a new canister or a new spring and weight set? I found the weight set in summit, but no canisters. Probably better off to do all of it right? I switched it to my ported hook up so it now has 12 at idle, but if you barley touch the throttle and give it vaccum it jumps to 28.

Now on to fixing the rear end.

**swervin ervin** · 09-23-2004, 01:19 AM

Yes, you need a new canister. A Crane adjustable vacuum advance canister. Stock cans usually provide 20 to 25 degrees of advance. A lot of folks will tell you to hook it up to a ported source. This will lower the advance at idle but IMO, is the wrong way to go about it.

Read this article.

http://www.73-87.com/7387garage/drivetrain/hei.htm

TIMSPEED · 09-23-2004, 07:13 AM

Quote:

Originally Posted by swervin ervin

A lot of folks will tell you to hook it up to a ported source. This will lower the advance at idle but IMO, is the wrong way to go about it.

I 100% agree with Mike on this one. I've been running with my advance on ported...I just now switched it over to full...MAN! I can't tell you how much of a difference it made. INSTANTLY! It was like NIGHT and DAY! Now, when I even TOUCH the throttle from a dead-stop, it will INCENERATE the rear tire. You just gotta make sure you're not running too much timing for your gas (ie: getting pinging/knocking/surging)

Blue Beard · 09-23-2004, 10:25 AM

Good article, lot there I never thought about.

09-23-2004, 12:30 AM	#1
bluex Registered User Join Date: Jun 2004 Location: Spartanburg, SC Posts: 1,963	Vaccum advance?? Well after beating my head againts a wall for two weeks I finally broke down and pulled the distributor retimed it and it fired right up. Guess I had a plug wire out of order? Anyways I was shooting for 12* before but wound up with 10. As soon as I hook the advance up AT IDLE it jumps straigt up to 28*. I know its good to have it come in as soon as possible, but at idle seems a little to quick to me and could be why its not performing the way I think it should. Do I need a new canister or a new spring and weight set? I found the weight set in summit, but no canisters. Probably better off to do all of it right? I switched it to my ported hook up so it now has 12 at idle, but if you barley touch the throttle and give it vaccum it jumps to 28. Now on to fixing the rear end. __________________ Paul '78 GMC Serria 15 Heavy Half. 361/NV3500/3.73. Former LWB NV3500 swap Trailing arm swap '98 ECSB Z71 daily driver -traded '03 burb. Family cruiser http://upstategmtrucks.com/

09-23-2004, 01:19 AM	#2
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	Yes, you need a new canister. A Crane adjustable vacuum advance canister. Stock cans usually provide 20 to 25 degrees of advance. A lot of folks will tell you to hook it up to a ported source. This will lower the advance at idle but IMO, is the wrong way to go about it. Read this article. http://www.73-87.com/7387garage/drivetrain/hei.htm __________________ Mike 1985 Chevy C-10

09-23-2004, 10:25 AM	#4
Blue Beard Registered User Join Date: Jan 2003 Location: Washington State Posts: 8,831	Good article, lot there I never thought about. __________________ 1970 Chev CST 2003 Harley Fatboy 1975 Chevrolet Step Van 1956 Chev Bel Air 1977 Blazer 2WD For Sale $3000.00 1978 Blazer 2WD For Sale $7000.00 1978 Silverado 2005 Monte Carlo



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