Pelican Parts Forums - Weber Sync Help

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I followed the PP's Weber Carb sync details
Pelican Technical Article: "Carburetor Adjustment, Balance, and Tuning" - 911 (1965-73) -

All the throats are sync'd perfectly, the car idles fine and there's no lag on acceleration when I am on it.

The issue comes into play at 3200-4000rpm when just cruising, I can feel some hesitation and carb pop until I accelerate a bit. There's Rarely there is a exhaust backfire.

Any suggestions or is it just trial and error with the mixture?

BTW - The car ran great before I cleaned and and rebuilt the carbs. (a couple of the o-rings were leaking that's why I rebuilt them).

Thanks

Try this link....Paul is a master with these carbs.

Performance Oriented

Mid-RPM Carb Stumble

The link to Paul's page is some of the best info I found for helping me get my PMO's tuned.

I tuned my carbs with the help of a wideband sensor - which lets you know exactly what's happening with the mixture at various RPM's / loads. Highly recommend getting one to read & record your AFR for fine tuning and troubleshooting.

As a heads up - your issue may be challenging to resolve: its occurring in the RPM range where the carbs are transitioning from the idle circuit to main circuit.

From your description, it sounds as if your leaning out a bit as the idle slowly transitions to your mains. You probably don't notice the hesitation when accelerating hard because the accelerator pump/nozel dumps fuel into the carbs masking what could otherwise be a lean spot.

Recommend trying to adjust your mixture at 3k RPM's to get the engine running smoothest at that RPM - then give it drive. You may find this ends up quite a bit on the rich side at idle though.

Good luck, enjoy the carbs and the learning curve.

Gordo

Gordo2

That's a great idea, I will adjust my mixture at 3k and see what happens. I will also look into the wideband sensor.

Thanks

In addition to what's been mentioned already, the symptoms could be a result of your linkage being off. You may have to adjust the short arms or the mounts themselves so that the throttles are opening evenly.