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Re: timing/vacuum advance
[Re: bill8121]
#1662088
08/22/14 12:23 AM
08/22/14 12:23 AM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
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Circle Track
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Posts: 36,041
Lincoln Nebraska
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(1) rotor phasing (2) too much timing. with the can plugged in see what your timing is at at 3K (where it is acting up). Unplug the can & set it at 3K & crank the dist till the timing is back to where it was with the can plugged in so the RPM is the same & the timing is the same just that it ain't coming from the can. If it's OK now then it's rotor phasing. Only the can alters rotor phasing & since you need the can for street use there's several ways to reclock the rotor & the NAPA rotor may reduce the gap distance back to where it wont misfire. To rephase. easiest is to cut another rectangular notch in the top of the dist shaft where the rotor notch locates (carefull measureing required/measure twice (at least)/cut once. It's strong enough there to handle one more notch. NAPA offers a rotor (MO3000) for $8 & change out the door with a .060" longer metal blade that reduces the radial gap from rotor tip to cap terminal(s) & helps with circumferential phasing issues as it is the total gap that once it gets wider than the spark can jump then it misfires
live every 24 hour block of time like it's your last day on earth
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Re: timing/vacuum advance
[Re: bill8121]
#1662090
08/22/14 12:53 AM
08/22/14 12:53 AM
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Joined: Jul 2005
Posts: 1,044 minnesota
president61
super stock
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super stock
Joined: Jul 2005
Posts: 1,044
minnesota
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Quote:
I had it all the way up to 30 initial. Same outcome. Unplug the advance all the problems go away.
i had the same problem. take an old cap and drill a hole at the number 1 plug wire. shine a timing light in the hole so you can see the rotor spinning around. I guarentee when you bring up the rpm the rotor will be pointing between #1 and the next wire rather than at #1 the whole time. I sent my relutor away and had three more spots machined at different degrees to fix the problem
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Re: timing/vacuum advance
[Re: bill8121]
#1662091
08/22/14 12:59 AM
08/22/14 12:59 AM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
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Without a doubt rotor phasing. Another possibility is the other system the can alters which is pickup gap tho usually that change ain't enough to effect a misfire. It's handy to have a hand held vac pump available for dist work as you can see (& measure) the pickup gap change with more vac applied to the can on your bench. To check phasing cut a 1/2" hole in the top flat of a dist cap 2/3 of the way between the center cap terminal and the #1 cap terminal then shine a timing light straight down in the hole while idling & it will freeze the rotor like a strobe light will do to bodies on a dance floor & see how far around the circumference the tip clocking is from dead center on the cap #1 terminal. You can also make a mark on the top metal perimeter of the dist rim at the center of a cap bulge then take off the cap & see how far the rotor is from pointing dead on to it (rotor retracted & not into the springs & they likely will be retracted if free) & the can will shift rotor phasing CCW from that position on a SB and CW on a Big block. You have that circumferential distance and the radial distance from a too short of rotor blade. If you like math you can get the degrees of the can from the number on its arm and the diameter of the dist housing & C=Pi x dia & divide 360 into the circumference to figure the distance around the arc 1 degree is then multiply that number times the # of degrees the can will shift the rotor around the arc. EDIT the X factor is at what distance does the required voltage exceed the available voltage (that's when it startts to miss) & each ign system is different & required voltage is the greatest at WOT & that's when you want the pickup gap to be close to .008 and rotor phasing to be in the good range
Last edited by RapidRobert; 08/22/14 01:03 AM.
live every 24 hour block of time like it's your last day on earth
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Re: timing/vacuum advance
[Re: bill8121]
#1662098
08/24/14 12:45 PM
08/24/14 12:45 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
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I'd take off the cap & see what cap terminal the rotor blade is closest to then put the cap on & make a mark on the dist metal top rim in line with that particular cap bulge then take off the cap & with a 1&1/4" socket/breaker bar turn the crank slightly till the reluctor tooth is dead even with the magnet & at that point see how far the rotor blade is off from being dead on with the mark you made. The bold text is what I neglected to add to check phasing in my prior post. This ain't quite as accurate as the timing light method but it is very close & will tell you something significant regarding phasing in 5 minutes. Holler how it turns out for you
live every 24 hour block of time like it's your last day on earth
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Re: timing/vacuum advance
[Re: bboogieart]
#1662101
08/24/14 02:30 PM
08/24/14 02:30 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
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You might bump the crank CW till the tooth Boogie showed JUST moves past dead center on the magnet (& I'm talking a c hair past dead center) as it fires when the tooth just moves past being lined up dead on centered with the magnet. Im also thinking the NAPA 8 dollar Echlin MO3000 rotor may fix this WO you havein to mess with phasing but first see where it is. EDIT check the gap also (.008" with brass feeler gauge)
Last edited by RapidRobert; 08/24/14 02:43 PM.
live every 24 hour block of time like it's your last day on earth
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Re: timing/vacuum advance
[Re: bill8121]
#1662104
08/24/14 03:50 PM
08/24/14 03:50 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
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I would check the tooth/magnet gap first. Speaking of the gap not RP you set it at .008" at rest (eng off/no vac) & the can increases it but not to the point where it will misfire but if the gap is too much greater than .008 to start with at rest then when the can kicks in it will increase it past it's "limit" where it will then miss with the can activated. The can changes reluctor gap and RP. A stackup of tolerances in the wrong direction from poor machining can shift it (RP) past it's (functioning) limit.
live every 24 hour block of time like it's your last day on earth
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