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08-10-2009, 02:37 PM
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#11
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I, Vettezuki
Join Date: Feb 2006
Posts: 14,754
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Quote:
Originally Posted by big2bird
His alternator is running too slow, and he is dropping ignition below 1,000 RPM.
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What's the cause? Does he have an underpulley?
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08-10-2009, 03:10 PM
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#12
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Fast & Filthy
Join Date: Jun 2008
Posts: 3,840
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Quote:
Originally Posted by big2bird
His alternator is running too slow, and he is dropping ignition below 1,000 RPM.
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With the cam he has and the fact that he is driving the supercharger I don't think it will idle below 1000rpms anyway. The cam in the Cobra has 220* at .050 on a 110 LSA and it idles at 1000. The Chevelle also idles at 1000 with 246* at .050 on a 110 LSA but it's not driving a supercharger. The supercharger take a lot to drive even at an idle.
What is the voltage output from the alternator at 1000 and below? |
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08-10-2009, 05:10 PM
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#13
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Power's off.
Join Date: Dec 2008
Posts: 673
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Quote:
Originally Posted by Vettezuki
What's the cause? Does he have an underpulley?
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Yes
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Chrome don't get you home.
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08-10-2009, 05:11 PM
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#14
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Power's off.
Join Date: Dec 2008
Posts: 673
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Quote:
Originally Posted by 94cobra69ss396
With the cam he has and the fact that he is driving the supercharger I don't think it will idle below 1000rpms anyway. The cam in the Cobra has 220* at .050 on a 110 LSA and it idles at 1000. The Chevelle also idles at 1000 with 246* at .050 on a 110 LSA but it's not driving a supercharger. The supercharger take a lot to drive even at an idle.
What is the voltage output from the alternator at 1000 and below?
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I haven't looked at the car. This is heresay from a casual conversation last night.
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Chrome don't get you home.
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08-11-2009, 04:44 AM
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#15
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Super Moderator
Join Date: Dec 2007
Posts: 6,850
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Motor will idle lower than 800, but below 1K (or 900, found out today) it will not charge and it will drain the battery in a few mintues of idling. The crank pulley and alt. pulley are custom offset units from ATI (Procharger), can't change them without giving up the blower.
CobraSS, as I'm sure you know comparing your Chevelle to your Mustang, different motors take different timing. I'm back 12 degrees from stock, what does a stock Cobra want to see?
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I <3 forced induction.
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08-11-2009, 04:50 AM
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#16
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Super Moderator
Join Date: Dec 2007
Posts: 6,850
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Bird, sorry I didn't get back to you. I was out... late. Earlier today I changed out the pump cam, turns out I had a green one installed already (totally forgot). Installed my blue one which is a little more aggressive. Helped the off idle lean spit, but not in the mid rpms. When the vacuum guage tips close to zero the carb still spits. Going to up the jet sizes from 67s to 69s tomorrow and see if I can correct the spit without going much below stoich at cruise.
If that doesn't work I'm busting out the drill and attacking my PCVRs.
The alternator works great. Helps it idle more consistently and at a lower rpm with the advanced base timing. Turned the motor off at 3K and fired it back up like you suggested, no problem.
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I <3 forced induction.
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08-11-2009, 03:24 PM
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#17
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Fast & Filthy
Join Date: Jun 2008
Posts: 3,840
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Quote:
Originally Posted by enkeivette
CobraSS, as I'm sure you know comparing your Chevelle to your Mustang, different motors take different timing. I'm back 12 degrees from stock, what does a stock Cobra want to see?
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36* just like a SBC or BBC. |
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08-11-2009, 03:26 PM
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#18
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Fast & Filthy
Join Date: Jun 2008
Posts: 3,840
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Quote:
Originally Posted by enkeivette
Bird, sorry I didn't get back to you. I was out... late. Earlier today I changed out the pump cam, turns out I had a green one installed already (totally forgot). Installed my blue one which is a little more aggressive. Helped the off idle lean spit, but not in the mid rpms. When the vacuum guage tips close to zero the carb still spits. Going to up the jet sizes from 67s to 69s tomorrow and see if I can correct the spit without going much below stoich at cruise.
If that doesn't work I'm busting out the drill and attacking my PCVRs.
The alternator works great. Helps it idle more consistently and at a lower rpm with the advanced base timing. Turned the motor off at 3K and fired it back up like you suggested, no problem.
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What did you do to the alternator? |
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08-11-2009, 11:57 PM
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#19
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Super Moderator
Join Date: Dec 2007
Posts: 6,850
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Haha, oops, typo. I meant to say the distributor works great.
Didn't get a chance to tune today. Worked on the gf's car. 1.6L of fury.
I did notice while I was driving that the lean stumble actually starts as soon as 5" of vacuum. I've been thinking about reinstalling the 6.5PV. If it opens sooner it might make up the difference to keep the AFR happy. What do you guys think? Now that I have more timing and a higher idle, vacuum is closer to 8".
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I <3 forced induction.
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08-12-2009, 09:37 AM
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#20
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Neanderthal
Join Date: Mar 2008
Posts: 5,320
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Quote:
Originally Posted by enkeivette
Haha, oops, typo. I meant to say the distributor works great.
Didn't get a chance to tune today. Worked on the gf's car. 1.6L of fury.
I did notice while I was driving that the lean stumble actually starts as soon as 5" of vacuum. I've been thinking about reinstalling the 6.5PV. If it opens sooner it might make up the difference to keep the AFR happy. What do you guys think? Now that I have more timing and a higher idle, vacuum is closer to 8".
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What's your vacuum at idle?
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1990 F150 351 ci SuperCharged
48 Harley Pan Head 76 ci
2016 Nissan Altma
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