Need help with engine idle? - Team Camaro Tech
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post #1 of 15 (permalink) Old Mar 10th, 10, 06:26 PM Thread Starter
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Need help with engine idle?

383 SB with TH350 and 2400 stall. In drive it idles @ 850 rpm, any lower and it dies. But in park it idles at about 1250 rpm and seems high to me? Is this normal, if not what could cause it? The car drives great otherwise just wondering about the idle? Thanks

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post #2 of 15 (permalink) Old Mar 10th, 10, 06:30 PM
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Re: Need help with engine idle?

What carb are you running,and also what is the timing set at,is the carb 4 corner idle ?


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post #3 of 15 (permalink) Old Mar 10th, 10, 06:33 PM Thread Starter
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Re: Need help with engine idle?

Holley 770 street avenger vacuum secondaries, 13 initial, 34 total all in by 3000 rpm.



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Originally Posted by Bad67355 View Post
What carb are you running,and also what is the timing set at,is the carb 4 corner idle ?

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post #4 of 15 (permalink) Old Mar 10th, 10, 06:35 PM
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Re: Need help with engine idle?

Are you running vacuum advance?

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post #5 of 15 (permalink) Old Mar 10th, 10, 06:36 PM Thread Starter
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Re: Need help with engine idle?

Yes, initial 13 deg timing was set without vacuum advance.


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Are you running vacuum advance?

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post #6 of 15 (permalink) Old Mar 10th, 10, 07:26 PM
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Re: Need help with engine idle?

Do you have an adjustable vacuum advance can?
the engine vacuum could be too low for the vacuum it's trying to pull from the distributor.

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post #7 of 15 (permalink) Old Mar 10th, 10, 08:02 PM Thread Starter
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Re: Need help with engine idle?

Its a Pertonix flame thrower dizzy but I do not know if the advance is adjustable. When the advance is unhooked the rpm does not vary by much so I do not think that is the problem, but am not sure.

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post #8 of 15 (permalink) Old Mar 10th, 10, 08:25 PM
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Re: Need help with engine idle?

Quote:
Originally Posted by Black Z View Post
Its a Pertonix flame thrower dizzy but I do not know if the advance is adjustable. When the advance is unhooked the rpm does not vary by much so I do not think that is the problem, but am not sure.
i had the same problem, but once i advanced the timing a bit more and turned down the idle on the carb it worked fine

my engine only pulled about 12" of vacuum at idle if that helps at all
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post #9 of 15 (permalink) Old Mar 10th, 10, 08:29 PM Thread Starter
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Re: Need help with engine idle?

I do not think that that will have any change. I played around with the timing and idle for a awhile when dialing it in and it is was still about 500 rpm more in park then in drive no matter what the timing was at.


Quote:
Originally Posted by victimizati0n View Post
i had the same problem, but once i advanced the timing a bit more and turned down the idle on the carb it worked fine

my engine only pulled about 12" of vacuum at idle if that helps at all

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post #10 of 15 (permalink) Old Mar 10th, 10, 08:43 PM
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Re: Need help with engine idle?

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Originally Posted by Black Z View Post
I do not think that that will have any change. I played around with the timing and idle for a awhile when dialing it in and it is was still about 500 rpm more in park then in drive no matter what the timing was at.
did you check the secondaries and make sure they are not open too far?
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post #11 of 15 (permalink) Old Mar 10th, 10, 08:44 PM Thread Starter
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Re: Need help with engine idle?

I have not checked that but could that even cause this condition?


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Originally Posted by victimizati0n View Post
did you check the secondaries and make sure they are not open too far?

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post #12 of 15 (permalink) Old Mar 11th, 10, 12:30 AM
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Re: Need help with engine idle?

Quote:
Originally Posted by Black Z View Post
Its a Pertonix flame thrower dizzy but I do not know if the advance is adjustable. When the advance is unhooked the rpm does not vary by much so I do not think that is the problem, but am not sure.
Make sure your connected to manifold vacuum, not ported vacuum.
When you unhook the line and plug it there should be a noticable change.

Here is a link that gives good info.
https://www.camaros.net/forums/showth...ported+advance
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post #13 of 15 (permalink) Old Mar 11th, 10, 12:35 AM Thread Starter
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Re: Need help with engine idle?

I am on full vacuum, but the change is only maybe 200-300 rpm.


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Originally Posted by BrewHog55 View Post
Make sure your connected to manifold vacuum, not ported vacuum.
When you unhook the line and plug it there should be a noticable change.

Here is a link that gives good info.
https://www.camaros.net/forums/showth...ported+advance

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post #14 of 15 (permalink) Old Mar 11th, 10, 02:04 AM
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Re: Need help with engine idle?

I have the same distributor if it's the coil in cap version. Yes, the vacuum advance can is adjustable, you need a small allen wrench.
My motor would die out under 1,200 rpm or so when I installed a big cam and big runner heads, no velocity, and very little vacuum. I band aid fixed it for a while by running mechanical advance only, try that, if it idles steady, you have eliminated the carb problem.

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post #15 of 15 (permalink) Old Mar 11th, 10, 04:18 AM
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Re: Need help with engine idle?

X2 on BrewHog's suggestion. Once rpm is up due to full vacuum, you should be able to turn down curb idle, unless secondaries are open a smiggin', or another minute leak.

With a loose convertor, low rpm in neutral, selecting a gear should only drop rpm by about 100-200 rpm.

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