Total timing ? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Ron's68 · 11-27-2002, 01:34 AM

O.K. I just put my new proform HEI in and I'm not sure how to set the total timing. Can someone please help. Here's what I did, I set my inital timing to 12. Now do I leave the vacum line off to check total timing or put it back on? And what should total timing be set at? When I checked total timing with the vacum line on it was reading 45. It was 29 with the line off. Please help. Thanks.

stllookn · 11-27-2002, 01:40 AM

With the old standards you would check total timing at a certain rpm...like 3000 or so to ensure that both vacuum and mechanical advance are working properly. This is done with the vacuum on. I am sure HEI is the same.

bigjimzlll · 11-27-2002, 01:46 AM

sounds like you have the vacuum hooked up to the ported vac..try hooking it to the manifold vacuum

Ron's68 · 11-27-2002, 01:59 AM

Hay Jim, this might sound like a dumb question but which is the ported and which is the manifold vac? I have one at the base of the carb and one at the side of the carb.

bigjimzlll · 11-27-2002, 09:54 AM

the lower one will be full manifold vacuum.
on a side note..when I had the proform distributor I had a hard time dialing it in..had too much total advance..I bout the crane adjustable vacuum kit, it fixed it for a while, then the bushings went out. does yours have an adjustable vac. can?..it eill have a hexagon shape to it if it does

crazy longhorn · 11-27-2002, 10:06 AM

Ron, on your Holley the fitting on the side of the carb(on the metering block), is ported. The one at the base is full manifold. I havent run the Vortecs, but from what i have read on dyno testing ,they like a total @ 30-32 degrees with the vac can unhooked & plugged. I would try to limit the vac advance to 10-12 degrees, & hook it to manifold source for your combo. You may need to go to a Crane adjustable vac can to get those figures. I put a proform in my bro inlaws Olds, & it worked pretty well......going to an adjustable can was the only mod we did. The can will run you about $25 through Summit Racing. Good luck....crazy Al

11-27-2002, 01:34 AM	#1
Ron's68 Registered User Join Date: Mar 2001 Location: Modesto, ca Posts: 143	Total timing ? O.K. I just put my new proform HEI in and I'm not sure how to set the total timing. Can someone please help. Here's what I did, I set my inital timing to 12. Now do I leave the vacum line off to check total timing or put it back on? And what should total timing be set at? When I checked total timing with the vacum line on it was reading 45. It was 29 with the line off. Please help. Thanks. __________________ 68 LWB, .040 over 350 with 10:1 pistons, balanced, vortec heads,comp 270H cam, air gap RPM manifold, holley 750, 4.10 posi and gear drive to annoy the neighbors.

11-27-2002, 01:40 AM	#2
stllookn Saving 1 truck at a time! Join Date: Aug 2001 Location: Kent, WA Posts: 6,465	With the old standards you would check total timing at a certain rpm...like 3000 or so to ensure that both vacuum and mechanical advance are working properly. This is done with the vacuum on. I am sure HEI is the same. __________________ '68 C20 Longhorn 50th Anniversary 400/TH400 '68 C20 Longhorn 50th Anniversary 468/TH400w/buckets '72 C20 Halfhorn (Longhorn w/o cab and front clip) '69 Flxible Cruiser (look up ugly in the dictionary)

11-27-2002, 01:46 AM	#3
bigjimzlll Senior Member Join Date: Dec 2001 Location: Redding,CA...USA Posts: 4,736	sounds like you have the vacuum hooked up to the ported vac..try hooking it to the manifold vacuum __________________ It's called "drag racing" if they called it "tic..tic..WHAM!..BANG! F*&K!!!", they'd have to keep the magazines under the counter with the other men's publications click the clicky to join the site.... http://67-72chevytrucks.com/vboard/payments.php 67 lwb..first hotrod in 25 years..540 best ET is 9.45 @ 141.44 Anderson,CA

11-27-2002, 01:59 AM	#4
Ron's68 Registered User Join Date: Mar 2001 Location: Modesto, ca Posts: 143	Hay Jim, this might sound like a dumb question but which is the ported and which is the manifold vac? I have one at the base of the carb and one at the side of the carb. __________________ 68 LWB, .040 over 350 with 10:1 pistons, balanced, vortec heads,comp 270H cam, air gap RPM manifold, holley 750, 4.10 posi and gear drive to annoy the neighbors.

11-27-2002, 09:54 AM	#5
bigjimzlll Senior Member Join Date: Dec 2001 Location: Redding,CA...USA Posts: 4,736	the lower one will be full manifold vacuum. on a side note..when I had the proform distributor I had a hard time dialing it in..had too much total advance..I bout the crane adjustable vacuum kit, it fixed it for a while, then the bushings went out. does yours have an adjustable vac. can?..it eill have a hexagon shape to it if it does __________________ It's called "drag racing" if they called it "tic..tic..WHAM!..BANG! F*&K!!!", they'd have to keep the magazines under the counter with the other men's publications click the clicky to join the site.... http://67-72chevytrucks.com/vboard/payments.php 67 lwb..first hotrod in 25 years..540 best ET is 9.45 @ 141.44 Anderson,CA

11-27-2002, 10:06 AM	#6
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,402	Ron, on your Holley the fitting on the side of the carb(on the metering block), is ported. The one at the base is full manifold. I havent run the Vortecs, but from what i have read on dyno testing ,they like a total @ 30-32 degrees with the vac can unhooked & plugged. I would try to limit the vac advance to 10-12 degrees, & hook it to manifold source for your combo. You may need to go to a Crane adjustable vac can to get those figures. I put a proform in my bro inlaws Olds, & it worked pretty well......going to an adjustable can was the only mod we did. The can will run you about $25 through Summit Racing. Good luck....crazy Al __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....



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