Ignition or Carb? - Team Camaro Tech
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post #1 of 11 (permalink) Old Jul 11th, 09, 03:12 PM Thread Starter
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Ignition or Carb?

New build 350 (50 miles), new Holley 670 Street Avenger, and stock distributor with electronic module. Timing at idle set around 20 degrees and 36 degrees at 2200 rpms (VA disconnected). Set engine to idle around 900 rpms (4 speed), it idles fine sometimes but rough and dies other times. Normal driving, come to a stop light gear down and push in the clutch and engine dies, throttle response is good though. Other issue I notice is when car is at crusing speed it seems to have a surge, not a miss. Car runs very good under increased throttle but has an issue at idle and cruising. Seems this began after installing the electron module for the points. Maybe I should reinstall the distributor with the points and see if it does the same thing. Maybe a sign to get an MSD. Any thoughts on whether it is ignition or carb?

1968 RSSS BB 396/325 AC TH-400 Black/Red (Sold)
1969 Nova SS 350 M-20 Red/Black (Original)
1967 Chevelle SS (Clone)(Project)
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post #2 of 11 (permalink) Old Jul 11th, 09, 03:19 PM
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Camarodude67
 
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Re: Ignition or Carb?

Hi Tim, you are in the right direction, I wonder if you can back down on the timing just a bit just for now and see if that helps. You put in a HEI correct, it requires for 12V at the
distributer did you do that?

Those are 2 things I would do , the carb/fuel delivery may be another issue but I don't know how radical your 350 is?

Jeff G.
69 Vert RS/SS 396.
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post #3 of 11 (permalink) Old Jul 11th, 09, 03:46 PM Thread Starter
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Re: Ignition or Carb?

Just one of those modules that takes place of the points. Is that considered HEI? Also, wondering if the distributor is wore out causing the surging at cruising speed? Just don't understand why the engine runs fine during acceleration, no skipping or surging. Why does it idle fine sometimes and bad other times? Looks like if something was wrong it would idle bad all the time.

1968 RSSS BB 396/325 AC TH-400 Black/Red (Sold)
1969 Nova SS 350 M-20 Red/Black (Original)
1967 Chevelle SS (Clone)(Project)

Last edited by tim68rsss; Jul 11th, 09 at 06:03 PM. Reason: spelling
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post #4 of 11 (permalink) Old Jul 11th, 09, 06:16 PM Thread Starter
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Re: Ignition or Carb?

Backing off on the timing at this point makes the enigne idle rough, about 20 is as low as I can get it right now. May install the points dist tomorrow and see if it still runs rough.

1968 RSSS BB 396/325 AC TH-400 Black/Red (Sold)
1969 Nova SS 350 M-20 Red/Black (Original)
1967 Chevelle SS (Clone)(Project)
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post #5 of 11 (permalink) Old Jul 11th, 09, 06:37 PM
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Scott
 
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Re: Ignition or Carb?

How much vacuum at idle? What VA can is in it? Ported or manifold vac?
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post #6 of 11 (permalink) Old Jul 11th, 09, 07:05 PM Thread Starter
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Re: Ignition or Carb?

Not sure vacuum at idle, can check tomorrow. Stock vacuum advance on distributor. If I understand your question, ported vacuum.

1968 RSSS BB 396/325 AC TH-400 Black/Red (Sold)
1969 Nova SS 350 M-20 Red/Black (Original)
1967 Chevelle SS (Clone)(Project)
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post #7 of 11 (permalink) Old Jul 11th, 09, 07:20 PM
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Scott
 
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Re: Ignition or Carb?

Read this to get you started: https://www.camaros.net/forums/showthread.php?t=160705 John Z's advice in his article is quite valuable. Lars' too.
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post #8 of 11 (permalink) Old Jul 11th, 09, 07:36 PM Thread Starter
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Re: Ignition or Carb?

Thanks! I'll check out the link.

Also, I read that the 670 Street Avenger comes out of the box lean. Wonder if this is my problem with surging at cruising speed? Pulled #1 plug and it was black, doesn't that mean it is running lean. How do you do the crayon test?

1968 RSSS BB 396/325 AC TH-400 Black/Red (Sold)
1969 Nova SS 350 M-20 Red/Black (Original)
1967 Chevelle SS (Clone)(Project)
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post #9 of 11 (permalink) Old Jul 12th, 09, 09:15 AM
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Charlie
 
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Re: Ignition or Carb?

Quote:
Originally Posted by tim68rsss View Post
Just one of those modules that takes place of the points. Is that considered HEI? Also, wondering if the distributor is wore out causing the surging at cruising speed? Just don't understand why the engine runs fine during acceleration, no skipping or surging. Why does it idle fine sometimes and bad other times? Looks like if something was wrong it would idle bad all the time.
If you are getting a surge at cruise speed, then more than likely you have too much timing. If you are running 36* total, how much advance is the vacuum advance unit pulling in? I ask because the ONLY time the VA is working is at cruise.

Charlie Knudsen 67 Camaro RS/SS 350 TKO 600, 4.10's, AFR 195 Street Heads, Comp 270H, Rhoads Lifters, Crane Ignition, Pertronix Dizzy, Performer RPM Q-Jet, Heavily Modified Q-Jet, Hooker Comp Headers, MagnaFlow 2 1/2", 144 Decibles(Alpine CDA-7998 Head Unit, RF X7 and RF 750X Amps, MB Quart Mid's & High's, Kicker L7 12" Solo Barics)
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post #10 of 11 (permalink) Old Jul 12th, 09, 09:17 AM
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Charlie
 
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Re: Ignition or Carb?

Quote:
Originally Posted by tim68rsss View Post
Thanks! I'll check out the link.

Also, I read that the 670 Street Avenger comes out of the box lean. Wonder if this is my problem with surging at cruising speed? Pulled #1 plug and it was black, doesn't that mean it is running lean. How do you do the crayon test?
If the plug is black, then that means it's rich. It would be white if it was running lean. I think your cruise surge is too much timing.

Charlie Knudsen 67 Camaro RS/SS 350 TKO 600, 4.10's, AFR 195 Street Heads, Comp 270H, Rhoads Lifters, Crane Ignition, Pertronix Dizzy, Performer RPM Q-Jet, Heavily Modified Q-Jet, Hooker Comp Headers, MagnaFlow 2 1/2", 144 Decibles(Alpine CDA-7998 Head Unit, RF X7 and RF 750X Amps, MB Quart Mid's & High's, Kicker L7 12" Solo Barics)
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post #11 of 11 (permalink) Old Jul 12th, 09, 03:26 PM Thread Starter
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Re: Ignition or Carb?

Ok, pulled the Holley Street Avenger and checked for zinc flaking and found some trash in the primary bowl. Cleaned carb and reinistalled, engine runs fine, even at cruising. I did go back through the timing and have 19 degrees at 950 rpms and 36 at 2000 rpms, no surging at cruising speed.

1968 RSSS BB 396/325 AC TH-400 Black/Red (Sold)
1969 Nova SS 350 M-20 Red/Black (Original)
1967 Chevelle SS (Clone)(Project)
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