Edelbrock 650 AVS2 going super lean at part throttle

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Geoff2
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Re: Edelbrock 650 AVS2 going super lean at part throttle

Post by Geoff2 »

You can rig up a switch that grounds the p/up lead on the HEI. This still stop spark production. So, with the switch activated crank the engine & once cranking, flick the sw to remove the grd. You can also then run whatever amount of initial timing you want. If the sw is hidden, also makes a good theft deterrent....
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Re: Edelbrock 650 AVS2 going super lean at part throttle

Post by Tuner »

Geoff2 wrote: Wed Apr 21, 2021 4:17 am You can rig up a switch that grounds the p/up lead on the HEI. This still stop spark production. So, with the switch activated crank the engine & once cranking, flick the sw to remove the grd. You can also then run whatever amount of initial timing you want. If the sw is hidden, also makes a good theft deterrent....
If you mean to add a ground wire to the magnetic trigger, between the pickup coil and module, I don't think it is a good idea to put what amounts to an antenna on the trigger signal.

Have you not had the experience with MSD systems of the extension cord from magnetic trigger distributor to box being too close to the coil or coil high-voltage or low-voltage wiring and that condition causing a feedback that continuously triggers the spark box if the engine is not running and causes wild backfiring if it tries to run? That can be exciting sometimes.
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Re: Edelbrock 650 AVS2 going super lean at part throttle

Post by Tuner »

travis wrote: Tue Apr 20, 2021 4:10 pm I finally got to play with this a bit today, and made some positive improvements.

I slightly tightened up the secondary air valve, which helped a bit by itself. I also put a much more aggressive curve in the distributor...it’s still 8* initial, but now it’s 32* total all in by 2200, instead of 3000...plus another 15* vacuum advance on manifold vacuum. More tweaks of the idle mix screws and idle speed added another 1-1.5” vacuum at 700 rpm idle, so now it’s 18-18.5” vacuum at idle. Idle afr is 12.6:1 now...but with these timing settings this seems to be what it likes.

I tried 16* initial...it flat will not start with that much initial when at operating temps. Is there any way to do a start retard with an HEI?

Drivability is definitely better now, and it lights the right rear tire up easier than ever.
Good job on sorting this out. Continue to follow your nose. Your idle A/F is normal for best lowest idle RPM.

Crazy late '60s and early '70s emissions lean idle near 14.7/1 requires fast idle speed and actually made more NOx, again proving politicians and bureaucrats should keep their noses out of things they know nothing about.
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Re: Edelbrock 650 AVS2 going super lean at part throttle

Post by F-BIRD'88 »

Its better to simply put a on/off toggle switch on the 12v power wire (pink) to create a hot start interupt switch.
Use a 15A rated HD switch (RV accessory dept of auto parts store). The starter motor or starter solenoid may be cooked from header heat. Needs a heat shield.
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Re: Edelbrock 650 AVS2 going super lean at part throttle

Post by Geoff2 »

Tuner,
The set up I mentioned above has been on my car for over 20 years, zero problems.
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Re: Edelbrock 650 AVS2 going super lean at part throttle

Post by novadude »

Tuner wrote: Thu Apr 22, 2021 2:07 pm

Have you not had the experience with MSD systems of the extension cord from magnetic trigger distributor to box being too close to the coil or coil high-voltage or low-voltage wiring and that condition causing a feedback that continuously triggers the spark box if the engine is not running and causes wild backfiring if it tries to run? That can be exciting sometimes.
haha... I have a somewhat non-conventional ignition on my car. It's an old '63 327 iron distributor with a chrysler pick-up / reluctor, and a remote mounted 4-pin HEI module. Had the module mounted up near the front of the engine bay to hide it. Learned this lesson the hard way when the electirc fan kicked on during the first test drive and killed the engine. The module is mounted closer to the distributor now with EMF shielding on the pick-up wires. :D
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