Mechanical advance stuck
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From: Le Roy NY
Mechanical advance stuck
While getting my 1980 ready for another cruising season, I took a look under the rotor to see which springs I had installed 3 years ago. To my surprise, the mechanical advance mechanism was not turning. Winter storage and condensation must have corroded it. With a little PB blaster and WD-40, I got it back in shape. Here's the dilema: with the mechanical advance stuck the car ran great! The mechanism was frozen about half way. I have an Accel vacuum unit that I have not adjusted. I can't be sure when the mechanical advance stuck, but it ran great last year and so far this year too. After freeing the mechanism, I notice a lower idle and hesitation when I accelerate. Previously I had set the timing at 36 degrees at 3,600 RPM.
I plan to check the total advance again. I assume the vacuum canister should be attached for this. I'll bring the idle up a little also, and hope that helps the hesitation. Any advice on setting the Accel vacuum unit? The car is just a cruiser modified with a 290HP crate engine, RV cam, headers and a 5-speed manual tranny. Highway cruising is at 2,000 RPM. Thanks.
I plan to check the total advance again. I assume the vacuum canister should be attached for this. I'll bring the idle up a little also, and hope that helps the hesitation. Any advice on setting the Accel vacuum unit? The car is just a cruiser modified with a 290HP crate engine, RV cam, headers and a 5-speed manual tranny. Highway cruising is at 2,000 RPM. Thanks.
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From: At my Bar drinking and wrenching in Lafayette Colorado
Total advance at 36 degrees is not set with the vacuum hooked up - you need to pull off the hose and inactivate the vacuum to set the total timing.
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From: Le Roy NY
Thanks Lars. I re-read the sticky post on timing which I should have done prior to posting my question. I'm anxious to get the motor tuned again now that I have the mechanical advance operating. Is this a common problem on cars seeing limited use? Are there ant good ways of lubricating the parts to prevent it?
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From: At my Bar drinking and wrenching in Lafayette Colorado
This is a very common problem on the HEI distributors, whether the car is driven or not: About 50% of the HEI cars I tuned during my "Tuning for Beer Tour" seminar series had the mechanical advance seized. For some reason, the problem is much less common on the old points-type distributors.
Once you have the distributor disassembled, note that there are 2 circumferential grooves in the mainshaft just below the top of the shaft: These grooves are to retain grease to prevent the seizure of the advance parts. Fill those 2 grooves with assembly lube and wipe off any excess after assembly: The grease will stay where it belongs without getting flung out into the cap, and it will keep the advance working correctly for many years.
Lars
Once you have the distributor disassembled, note that there are 2 circumferential grooves in the mainshaft just below the top of the shaft: These grooves are to retain grease to prevent the seizure of the advance parts. Fill those 2 grooves with assembly lube and wipe off any excess after assembly: The grease will stay where it belongs without getting flung out into the cap, and it will keep the advance working correctly for many years.
Lars
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Joined: Aug 2008
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From: Le Roy NY
Tuning for beer... I like that! Thanks for letting me know that my problem is not unique. Are there any good links to HEI removal and disassembly instructions? I've had it out before, and it's not my favorite job. Sounds like it needs doing.
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Joined: Aug 1999
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From: At my Bar drinking and wrenching in Lafayette Colorado
Years ago, I had an HEI Curve Kit that I was selling. I no longer build and sell the kits, but I have the .pdf file with the complete instructions for disassembling and setting up the distributor and then getting it installed correctly - it has photos and diagrams. E-mail me for the "HEI Curve Kit Instructions" if you'd like a copy of the booklet:
V8FastCars@msn.com
Lars
V8FastCars@msn.com
Lars
