Timing and Distributor help...advance? - Team Camaro Tech
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post #1 of 6 (permalink) Old Sep 9th, 04, 06:11 AM Thread Starter
Tech Team
 
Join Date: Jun 2004
Location: Minnesota
Posts: 97
Cool

I set my intial timing at around 800rpms to be 11 btdc. I get a slight hesitation off idle. I have the following:

350 .060 over, flat top pistons
492 heads 2.02/1.60, 64cc chambers
Comp 280H Magnum cam w 1.52 roller tip rockers
Edelbrock Performer RPM Air Gap
Edelbrock 750cfm mech sec Performer carb

Is my carb a bit big for my application and some additional tuning needed, or can I compensate with adjusting the timing up to 12 or 13 btdc initial at 800rpms? When I give it gas it seems like nothing happens for a second, then it catches itself and goes. That's the best way to describe it I guess.

Also, I have questions on my ignition set up:

I have an Accel distributor, which is electronic, there are no points. It has a small electronic module on the side that has two wires going in from the dist, and two going out to the Accel Super Coil. I'm not sure what this module does. There is no mechanical or vacuum advance mechanism that I am aware of. There is no electronic ignition box in the car such as an MSD either. How does this set-up work? It seems to work, but I haven't checked the advance to see where the total is. I'll do that tonight. How does this setup advance and what could keep it from going past 36 or so?
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post #2 of 6 (permalink) Old Sep 9th, 04, 07:13 AM
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Bruce
 
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Location: PA
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I don't know about Edelbrock carbs, but to me, it kind of sounds like a similar problem that can be solved by adjusted the accelerator pump on a Holley carb. Can the accelerator pump on an Edelbrock carb be adjusted? The carb size should be ok.

Bruce

69 Camaro, 496, 10.34 @ 134.77 mph.
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post #3 of 6 (permalink) Old Sep 9th, 04, 07:20 AM Thread Starter
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Duhoh...yeah, you're right. They can be adjusted. I remember adjusting it back when I had all my head problems....I'd better check that!
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post #4 of 6 (permalink) Old Sep 9th, 04, 11:45 AM
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Robert
 
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Location: Simpsonville, SC
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Josh,

Adjusting the pump may cure the hesitation but for what it's worth I had the same carb on my '69 and it would bog if I got on it from a low rpm. Normal driving was okay. I tried adjusting the pump but that had no affect on the bog. I never went any further trying to tune it because I thought the 750 mech sec. was just to much to throw at it off an idle. Sold it to a buddy with a big block Chevelle and it works great for him. I'm now running a Holley 750vs and it's working out better because the secondaries don't dump in all at once. Just 2 cents worth for you.

Robert

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355ci 10:1, 64cc Edelbrocks, Comp Mag 280H, Performer RPM, 700r4 (2000 stall), 3.55 posi A/C PS PDB Hotchkis

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369ci 10.3:1, 64cc Edelbrocks, Voodoo 276/284, Performer RPM, Holley 650DP ...T56 Magnum, 3.73 Moser 12 bolt
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post #5 of 6 (permalink) Old Sep 9th, 04, 12:25 PM
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Josh I have a mechanical secondary... a Speed Demon 850, but I have the secondary mechanical linkage in a hole on the throttle lever at the carb that does not bring the secondary into play until I'm about 2/3 rds. of the way depressing the throttle. I think this hesitation is absolutely related to carb size. Remember the old trick of drilling a hole in the butterflies? That was directly related to getting more airflow vice opening the butterfly by turning up the idle screw. Many Demon carbs now come standard with what is called an Idle-Eaze...
http://www.barrygrant.com/demon/default.aspx?page=10

So, you still keep the small transfer slot the proper size INSTEAD of turning up the idle, which changes how much slot is showing, and also CAUSES THE CARB TO GO LEAN AS SOON AS YOU STEP ON THE GAS.

ALSO... to save yourself a lot of grief and EXPENSE, this following item could easily eliminate the off idle bog...

http://www.jegs.com/cgi-bin/ncommerc...32&prmenbr=361

You want a four hole spacer, NOT the plenum or open type, and this company makes a "swirl" type for just such a problem of over carb, i.e. increasing velocity at idle through the carb and as it opens. Make sure and look at the package it comes in BEFORE removing it to see with side goes to the carb, and which side rests on the intake manifold. I believe it came with a gasket also. It was kind of rough with casting marks, but I buffed it up to a great shine, and it definitely works.

67 Camaro | 350 | 650 Speed Demon | Dual plane GMPP intake | MSD ignition | Secret Cam (I don't know what it IS!) | 2.02/1.60 Camel Humps ported | Thorley Tri-Y's | 8.5 10 bolt 3.73 | M22
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post #6 of 6 (permalink) Old Sep 12th, 04, 03:25 PM
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Jim
 
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I had that bog on my edelbrock 650, bought a tuning kit for $25, put the richest primary metering rods in, bog gone. Still wish I hada Holley.





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