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Re: Why degree a camshaft? [Re: RapidRobert] #1444035
06/01/13 01:57 PM
06/01/13 01:57 PM
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S.W. Pennsylvania
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markrr Offline OP
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Quote:

The even/fairly decent comp readings tell you the long block is healthy, I dont like to shotgun parts to a car to diagnose so I wouldn't suggest buying an ECU just to guess & I'm thinking the ECU may be OK tho nowadays keeping a spare makes good sense with their track record for breakdowns. With the dist cap on make a mark on the top of the dist metal perimeter rim at the center of a cap terminal bulge & pick the bulge slightly to the left CCW of where the rotor is right now then turn the crank with a 1&1/4" socket/breaker bar clockwise slowly/carefully till the magnet is dead even with the next tooth then at that point see if rotor is pointing at the center of the mark you made on the dist metal perimeter or very close, which is rotor phasing & if it's very off post how far & which way (vac adv shifts it CW from it's at rest location on a big block). I'm assuming the plugs/wires are in good shape & routed 1-8-4-3-6-5-7-2 CCW. I keep coming back to a vacuum leak & it is less noticeable at higher rpm's since there's less time between each firing so that masks the problem. Myself I think I'd pull/replace the valley pan which on a BB ain't hard to do & use Permatex #1 in the toothpaste like tube lightly/evenly around each of the 8 port openings on the valley pan & check if bolt holes/ports are matching (on the slope). Maifold may not be dead flat. Good visual & go from there.




I just checked the rotor phasing as described above and the rotor seems to be in phase. One of the points of the star on the top of the distributor is pointing directly at the magnet when I aligned the rotor with the mark I made on the distributor rim. But...I may have discovered another problem. After turning the dampener with a socket I can move my dampener 10 degerees in the opposite direction before the rotor moves again. Is this too much play in a timing chain?

Re: Why degree a camshaft? [Re: markrr] #1444036
06/01/13 05:44 PM
06/01/13 05:44 PM
Joined: Nov 2003
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Lincoln Nebraska
RapidRobert Offline
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Quote:

After turning the dampener with a socket I can move my dampener 10 degerees in the opposite direction before the rotor moves again. Is this too much play in a timing chain?


Yes & alot of that is likely in the lower dist shaft tang clearance in the top of the intergear slot. Twist (rotate) the rotor/shaft lightly back & forth to see how much play you have there just dont twist hard enough to get into the springs which'll skew your reading. Might need to peen the end of the dist shaft (carefully) and or add one of the 1/2" ID collars that are available (McMasters/Carr). Yes whichever place the slop is originating from (& likely both) it needs to be reduced as 10 deg is way too much (ideally want zero or 1 max)


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Re: Why degree a camshaft? [Re: RapidRobert] #1444037
06/01/13 06:19 PM
06/01/13 06:19 PM
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markrr Offline OP
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Quote:

Yes & alot of that is likely in the lower dist shaft tang clearance in the top of the intergear slot.





Could you please explain what this is?

Re: Why degree a camshaft? [Re: markrr] #1444038
06/01/13 06:28 PM
06/01/13 06:28 PM
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Posts: 36,040
Lincoln Nebraska
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The tang on the end of the dist shaft is alot smaller than the slot groove in the top of the intergear that if fits into. You want it tight like a key in a lock. rotate the rotor back & forth & see what you have just from the dist & 10 deg total is too much to ignore but I would still suggest R&R the intake.

Last edited by RapidRobert; 06/01/13 06:30 PM.

live every 24 hour block of time like it's your last day on earth
Re: Why degree a camshaft? [Re: RapidRobert] #1444039
06/01/13 06:41 PM
06/01/13 06:41 PM
Joined: Apr 2004
Posts: 965
S.W. Pennsylvania
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markrr Offline OP
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markrr  Offline OP
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Joined: Apr 2004
Posts: 965
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Quote:

The tang on the end of the dist shaft is alot smaller than the slot groove in the top of the intergear that if fits into. You want it tight like a key in a lock. rotate the rotor back & forth & see what you have just from the dist & 10 deg total is too much to ignore but I would still suggest R&R the intake.




Thank You.
I will check this out.

Re: Why degree a camshaft? [Re: markrr] #1444040
06/01/13 06:43 PM
06/01/13 06:43 PM
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert Offline
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We'll stay with it till we fix it


live every 24 hour block of time like it's your last day on earth
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