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Post by 69Rebel on Sept 2, 2023 10:22:53 GMT -8
That's kind of a drag. I'm still running points on my Rebel and my blue Jeeptruck.
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Post by PHAT69AMX on Sept 2, 2023 12:21:11 GMT -8
Spud - MSD Distributor, it might have a Phasing problem, mis-alignment. Read some bs somewhere a few years back there was a bad batch, one of those stories. Easy way to check is a cap with a big hole drilled in inline with #1 plug post. Use a timing light with no advance, confirm rotor button tip aligns with cap post when unit fires. MSD does make and sale an adjustable Rotor Button to fix Phasing errors. Distributor Phasing is a separate animal from Timing or advance. Although when vacuum advance actuates, that does change the Phasing of the Distributor. Initial/Static Advance and Mechanical Advance do not affect Distributor Phasing. Only messed with AMC Delco points type units, and on those, when vac adv was fully advanced, was the only time they were exactly 100% In Phase, that is the Rotor Button Tip & Cap Post was directly aligned when the unit fired. With no vacuum advance pulled in they were slightly out of phase, about 8-10 distributor degrees out of phase since stock vac adv cans are about 16-20 crank degrees total max adv. That's why the Rotor Button tip is yay wide, for that 8-10 deg vac adv sweep. A Delco Points Distributor Rotor Button Tip is on a ~2-3/4" Diameter. 10 degrees on a ~2-3/4" diameter is ~1/4" length of Rotor Button width.
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Post by spud on Sept 2, 2023 13:02:43 GMT -8
Well, i considered that. I checked where the rotor was pointing at tdc, and it looks like its pointing at the post. Granted thats a static timing only, and it may be your right. I just dont have another cap to play with. I have a delco v8 cap with about a 3/4 hole in it, i sawed it out with a hole saw. I could be with a lot of advance the rotor is getting to far away from the terminal. It needs to be after the terminal ( when direction of rotation is considered) in static time. That way it gets closer to the terminal at mid to full advance. Now that i think about it the rotor might be a little before the terminal… which would go further out of phase as timing advances. But thats guesswork. A cap with a hole in it and a timing light is the way to check it. Msd caps aint cheap, i might figure out what kind of six culinder engine used a points delco distributer and get a cheap one to modify. But i think the only adjustable rotor does not work with the standard msd cap. It only works with a msd cap adapt. And the cap adapt kit is for v8. So… that would need a cap adapter, a adjustable rotor, and a hei delco six cylinder cap… and no tellin where the terminals index when its all put together. So here we go…
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Post by PHAT69AMX on Sept 2, 2023 13:11:18 GMT -8
probably best to pull it out, but might could see in-place in motor, try and look-see where trip and trigger are when rotor button is in cap post position using a sharpie mark on the housing from #1 Post centerline, since cap is keyed to housing. With cap removed and button centered on sharpie mark, are the trip and trigger lined up to fire? Vacuum Advance rotates the trigger. Mechanical Advance rotates the trip relative to the crank and doesn't change Phasing. Enough to make your head spin.
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Post by PHAT69AMX on Sept 2, 2023 13:22:29 GMT -8
If ya get a Chevy points Delco and and AMC side-by-side and the parts one can see the AMC has everything clocked and arranged different than the Chevy resulting from the desired installed vac adv can and point dwell window locations, the point plates are completely different shapes, arrangements. Buick uses the same different Point Plate as AMC afaik. Idea being Chevy Point Plate / angles / specs / geometry somehow whacked out some AMC MSD units.
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Post by spud on Sept 2, 2023 13:30:52 GMT -8
When centrifugal advance comes in, it rotates the rotor ( and reluctor) opposite rotor rotation to advance. This changes phasing. Vacuum advance moves the trigger and does not affect rotor phasing. This is more visible when one has a hole in the cap and checks the phasing with a light.
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Post by PHAT69AMX on Sept 2, 2023 15:06:07 GMT -8
Oh man I say it's the exact opposite oh boy
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Post by spud on Sept 2, 2023 15:46:29 GMT -8
The way i was imagining it, The distributer body is stationary, the gear and shaft are fixed to the cam gear, they dont change, the advance weights only move the rotor/ reluctor in relation to the terminal. If you have a hole in the top of the cap, you only see the rotor move from static to full mechanical advance. It cant move any more. The vacuum advance increases spark lead, it has to jump from the rotor to the terminal… somewhere in the rotation… I think thats where it gets stupid. So really, I think the vacuum does have effect on phasing actually, when i think about it. I’m thinking aloud, you may be correct.
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Post by spud on Sept 2, 2023 17:03:49 GMT -8
Well, after eyeballing the rotor position at tdc, ignition timing is 10 degrees advanced. Rotor is before the terminal, to about 30 degrees before tdc, rotor is much further before terminal, i would guess its pretty badly out of phase. It should be more like rotor tip after terminal, then sweeps past terminal as it advances, to a point somewhere before terminal, but not to far before. My rotor tip never gets to the terminal till after tdc. Now it might show something a little different if i had a hole in the cap and was strobing it with a light… and i might try that. I dont really wanna butcher up a good cap, but is it a good cap? The only way i can figure to fix it is grind out the indexing tab and rotate it? The only thing msd sells as a adjustable rotor is for a cap adapt v8 kit. So im kinda stuck. Unless i can call MSD and they have a fix. I might be able to screw on a cap adapt, but that all relys on getting a hei six terminal cap that indexes correctly.
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Post by 69Rebel on Sept 2, 2023 17:15:13 GMT -8
I know you're invested in the MSD, but I, and Joe, have both had pretty good results with the American Autowire electronic conversion kit for Delco distributors. Kinda pricey for what it is at $150, but at least the consumables are cheap and plentiful.
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Post by spud on Sept 2, 2023 17:21:23 GMT -8
Pricey? Lemme tell you pricey. The msd pro billit for the amc six is 500 bux. I bought mine several years ago and forget what it was then exactly, but it seems like it was 350. Given bidens assrape of america shit has really gone up. Ho hum. But anyways a quick trip to msd catalog and a little research and i find pn 84211, which is an adjustable version of the rotor pn 8467, which came in my distributer. It also has the same cap and rotor as the chevy 6 cylinder pro billit distributer. So here we go. Order up a msd 84211 from summit… lets see if they have one in stock… Probably should get a fresh cap too. Anywayd i invested in the msd because all i had were motorcrap distributers. And i hate them! If I woulda had a delco for the amc six, i would have put a FAST kit in it, i have some of those and they have been good as gold.
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Post by 69Rebel on Sept 2, 2023 17:33:50 GMT -8
Oh carp, I forgot you were running a sicks in your roadkill.
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Post by spud on Sept 2, 2023 17:35:33 GMT -8
Yep. Can you believe what an asswhipping this pile of shit is laying on me?🤣
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Post by 69Rebel on Sept 2, 2023 17:40:22 GMT -8
LOL!! I have a complete, unmolested 290. Wink, wink. Well, I did steal the oil filter bypass out of it for my 360.
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Post by PHAT69AMX on Sept 2, 2023 18:30:45 GMT -8
MSD # 8421 is the V8 Rotor Button needed that includes Phase Adjustment. And yeah, for the I-6 it's MSD Part No. 84211 apparently
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