Finally installed my Edelbrock carb today! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

MightyFine69 · 11-09-2002, 03:50 AM

Well, I finally did it. I decided to go with an Edelbrock 1405 on my '69 K20. I drove it up and down the road a few times tonight just to see how it would run. My question is which vacuum port do I hook my vacuum advance to? Right now I have it hooked up to the one that advances the timing at an idle with it hooked up. If I hook it up to the other port, the timing doesn't change until I rev the motor up. Which one is correct? It seems to run really well the way it is. It idles really smooth and drives good with no spark knock at high RPM. The initial timing is set a TDC, which is what the motor's manual I have says. My engine is a bone stock 350 (except for the new carb, that is). I am running regular unleaded with Lucas gas treatment every tank. Thanks in advance.

bigjimzlll · 11-09-2002, 09:51 AM

experiment experiment experiment...i would try bumping the timing to between 6-8 btdc..then try swapping the vacuum lines... form one to the other and back again ...if you have a vacuum gauge, advance the timing til you have the highest vacuum, then back of 1-2 inches of vacuum..check where your at with a timing light..and take it for a ride..up a hill under excelleration.. just make sure to right down each timing setup, with the results....have fun..

mikep · 11-09-2002, 11:36 AM

manifold vacuum ( the one that is on at idle ) will give you a smoother idle and allow you to increase the initial timing a good bit. Its the best vacuum to use for heavy vehicles as it decreases the spark advance as you push the gas so you dont detonate. Timed spark is better for emmisions controls and lighter vehicles or lower compression engines where detonation is not a problem.

You'll get better throttle response with more initial timing. Try to limit your vacuum advance to no more than 10 degrees if possible.

I run 14 degrees initial with manifold vacuum to the HEI but I cant run less than 90 octane gas with the 9.5:1 compression and rather small cam I use or I'll detonate.

Huck · 11-09-2002, 05:40 PM

Traditional ignition should run off regular manifold vacuum. HEI can run off either. Edlebrock suggests you run off timesd vacuum. I've tried both and honestly can't remember which one my Dist is hooked up to. ~~I guess this doesn't help~~~ I would set the initial timing to 6 degree advance as an initial starting point. Good luck and let us know how it works out for you. Huck

Bill72BB · 11-09-2002, 09:36 PM

Mine is hooked to the one on the right , which is supposed to be for non-emission controlled ,vacuum advance.
The one on the left is for emission controlled engines.

MightyFine69 · 11-11-2002, 04:09 AM

I was running my initial advance at about 4 degrees until I put the carb on. What will it do if I advance the timing up to about 6 degrees? How will it make the engine perform? Will I get better performance or better mileage? I never really noticed much difference when I had it at 4 degrees. What is the theory on timing advance? I don't really have any knowledge of this subject. I do know that if I advance it too far it will spark knock under load. Thanks again for all the advice.

bigjimzlll · 11-11-2002, 07:02 AM

you want to have as much timing as it wil take(b4 detonation),.but no more than 38 total...this will help gas milage and performance. the more retarded you have the timing the less power you will have and less effeicient the engine will be.
Jim

11-09-2002, 03:50 AM	#1
MightyFine69 Registered User Join Date: Jun 2001 Location: Traverse City, MI Posts: 97	Finally installed my Edelbrock carb today! Well, I finally did it. I decided to go with an Edelbrock 1405 on my '69 K20. I drove it up and down the road a few times tonight just to see how it would run. My question is which vacuum port do I hook my vacuum advance to? Right now I have it hooked up to the one that advances the timing at an idle with it hooked up. If I hook it up to the other port, the timing doesn't change until I rev the motor up. Which one is correct? It seems to run really well the way it is. It idles really smooth and drives good with no spark knock at high RPM. The initial timing is set a TDC, which is what the motor's manual I have says. My engine is a bone stock 350 (except for the new carb, that is). I am running regular unleaded with Lucas gas treatment every tank. Thanks in advance. __________________ 1969 3/4 ton 4x4 33's with no lift, gotta love it! A man and his truck, it's a beautiful thing.

11-09-2002, 09:51 AM	#2
bigjimzlll Senior Member Join Date: Dec 2001 Location: Redding,CA...USA Posts: 4,736	experiment experiment experiment...i would try bumping the timing to between 6-8 btdc..then try swapping the vacuum lines... form one to the other and back again ...if you have a vacuum gauge, advance the timing til you have the highest vacuum, then back of 1-2 inches of vacuum..check where your at with a timing light..and take it for a ride..up a hill under excelleration.. just make sure to right down each timing setup, with the results....have fun.. __________________ 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

11-09-2002, 11:36 AM	#3
mikep Used to have a truck Join Date: May 2002 Location: port orchard WA Posts: 1,552	manifold vacuum ( the one that is on at idle ) will give you a smoother idle and allow you to increase the initial timing a good bit. Its the best vacuum to use for heavy vehicles as it decreases the spark advance as you push the gas so you dont detonate. Timed spark is better for emmisions controls and lighter vehicles or lower compression engines where detonation is not a problem. You'll get better throttle response with more initial timing. Try to limit your vacuum advance to no more than 10 degrees if possible. I run 14 degrees initial with manifold vacuum to the HEI but I cant run less than 90 octane gas with the 9.5:1 compression and rather small cam I use or I'll detonate. __________________ No truck :-(

11-09-2002, 09:36 PM	#5
Bill72BB Thats the Hillbilly way Join Date: Jul 2001 Location: Torrance,Ca Posts: 5,980	Mine is hooked to the one on the right , which is supposed to be for non-emission controlled ,vacuum advance. The one on the left is for emission controlled engines. __________________ BILL Torrance Calif 90504 Member DUF Club Member Old Farts Club 72 3/4ton Custom Camper BB402/400 trans Dynomax Cerama-coat headers , Hei distributor ,Edelbrock 1411 air,ps,pb,leafsprings ,98 chevy 60/40 seat,S10 shoulder belts tilt,3.54 Dana 60 rear. 16" Eagle wheels with LT265/75 16 tires,Gaylord Lid,H4 headlights with 100W relay conversion. " If I knew I was going to live this long I would have taken better care of myself " Marriage changes passion...suddenly you're in bed with a relative. A GUY'S PRAYER.... Lord, I pray for a nympho with huge boobs who owns a liquor store and likes to fish and hunt and has a Harley .Amen ,

11-11-2002, 04:09 AM	#6
MightyFine69 Registered User Join Date: Jun 2001 Location: Traverse City, MI Posts: 97	I was running my initial advance at about 4 degrees until I put the carb on. What will it do if I advance the timing up to about 6 degrees? How will it make the engine perform? Will I get better performance or better mileage? I never really noticed much difference when I had it at 4 degrees. What is the theory on timing advance? I don't really have any knowledge of this subject. I do know that if I advance it too far it will spark knock under load. Thanks again for all the advice. __________________ 1969 3/4 ton 4x4 33's with no lift, gotta love it! A man and his truck, it's a beautiful thing.

11-09-2002, 05:40 PM	#4
Huck Senior Member Join Date: Jun 2001 Location: Shelbyville, KY Posts: 3,269	Traditional ignition should run off regular manifold vacuum. HEI can run off either. Edlebrock suggests you run off timesd vacuum. I've tried both and honestly can't remember which one my Dist is hooked up to. ~~I guess this doesn't help~~~ I would set the initial timing to 6 degree advance as an initial starting point. Good luck and let us know how it works out for you. Huck

11-11-2002, 07:02 AM	#7
bigjimzlll Senior Member Join Date: Dec 2001 Location: Redding,CA...USA Posts: 4,736	you want to have as much timing as it wil take(b4 detonation),.but no more than 38 total...this will help gas milage and performance. the more retarded you have the timing the less power you will have and less effeicient the engine will be. Jim __________________ 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



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