Author Topic: 1111480 Looking for Collaborative Facts.  (Read 6429 times)

69znut

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1111480 Looking for Collaborative Facts.
« on: June 29, 2011, 04:37:45 AM »
I'm looking for photos of an unadulterated non-eBay 1111480 distributors in particular the;

1. 532 advance camplates
2. The number stamped on the rotor autocam

I know there were are two 532 advance camplates for the 1969 period however the one used on the 1111480 is different in that the advance plate limit stop slot is much longer for the Z28 in comparison to the 532 used in the 11111955 distributor.

L78 steve

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Re: 1111480 Looking for Collaborative Facts.
« Reply #1 on: June 29, 2011, 05:09:39 PM »
I thought a 532 was a 532 and there were no variations. Are you sure?
69 Z/28 Dover White. SOLD
67 SS/RS Mt. Green 1W,2LGSR,3SL,4K,5BY,07C. SOLD
70 Nova L78 Blk. Cherry,Sandalwood,M21,02B

69znut

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Re: 1111480 Looking for Collaborative Facts.
« Reply #2 on: June 29, 2011, 11:05:32 PM »
Hi L78 Steve,

Iím absolutely sure, I have several 532ís and an original 1111480. Iíve had the car since 1977 second owner.
I used body Bondo to cast and image of the Advance Plate Limit Stop Slot holes and colored them with a black marker and scanned them.
Not only is the 1111480 532 CCW slot longer and wider, but it is located in a different position in comparison to the 1111955 532CCW and many other Delco distributors.

L78 steve

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Re: 1111480 Looking for Collaborative Facts.
« Reply #3 on: June 30, 2011, 02:39:06 PM »
When I measure these slots with my calipers I do get a slightly larger measurement form the 480. Could it be that its just a different stamping procedure? Or is it intentionally longer? I would like to get these two variations on my Sun scope and see what the degree difference is.
69 Z/28 Dover White. SOLD
67 SS/RS Mt. Green 1W,2LGSR,3SL,4K,5BY,07C. SOLD
70 Nova L78 Blk. Cherry,Sandalwood,M21,02B

69znut

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Re: 1111480 Looking for Collaborative Facts.
« Reply #4 on: July 01, 2011, 02:14:11 PM »
Look at the top of the 480 advance plate where it is fused on to the points cam. The there should be 3 half moon notches equally spaced at 120 deg around the inner radius  of the plates stamped out hole. The plates from the 1111955 532"s just have a round hole, no notches.

I don't have a sun machine but was told the slot was intentionally manufactured wider because of the 3030 Camshaft needs this extra advance at idle to run smooth and allow a better transitional response from Vacuum to Mechanical advance which happens the micro-second the gas pedal is pressed and vacuum goes to zero your on mechanical advance.

Haven't found one to inspect but also heard the Corvettes with the 3030 cam and Delco Transistorized have the same sized slot.

Whats the stamped number on the bottom of the little cam (autocam) attached to the rotor shaft?




JohnZ

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Re: 1111480 Looking for Collaborative Facts.
« Reply #5 on: July 02, 2011, 03:36:35 PM »
I don't have a sun machine but was told the slot was intentionally manufactured wider because of the 3030 Camshaft needs this extra advance at idle to run smooth and allow a better transitional response from Vacuum to Mechanical advance which happens the micro-second the gas pedal is pressed and vacuum goes to zero your on mechanical advance.

The slot doesn't affect idle advance - that's a function of the vacuum advance can; the slot only defines the upper limit of the centrifugal advance system. Corvettes with the "30-30" cam (1964-65 L-76 and L-84) used the "236 -16" VAC (same as the current VC-1810/B28) and full manifold vacuum on the can, so the VAC was fully-deployed against the stop at 8" Hg. vacuum vs. the 9"-10" Hg. they produced at 900 rpm idle.

Not sure about the '67 Z/28, but the '68 and '69 with the 4053 carb used a "ported" vacuum source on the side of the carb baseplate for the vacuum advance, which provided ZERO vacuum to the distributor at idle; this was done intentionally to retard the timing at idle to increase the exhaust gas temperature to make the A.I.R. system afterburn more efficient with only 4* BTDC of initial timing and no vacuum advance until the throttle plate was opened.

This is easily cured by capping the "ported" source nipple and teeing the distributor line into the rubber hose from the angled full manifold vacuum source nipple on the front of the baseplate to the choke pull--off diaphragm; then you have full manifold vacuum on the advance can at idle, adding 16* of advance to the initial idle setting.
'69 Z/28
Fathom Green
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L78 steve

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Re: 1111480 Looking for Collaborative Facts.
« Reply #6 on: July 08, 2011, 08:15:43 PM »
John. When I advance the weights on the 480 I have the weights don't allow the pin to travel the full length of the slot. Have you ever noticed this. I'm going to fire up the Sun machine this weekend and check how much centrifugal advance the 532 allows.
69 Z/28 Dover White. SOLD
67 SS/RS Mt. Green 1W,2LGSR,3SL,4K,5BY,07C. SOLD
70 Nova L78 Blk. Cherry,Sandalwood,M21,02B

JohnZ

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Re: 1111480 Looking for Collaborative Facts.
« Reply #7 on: July 09, 2011, 02:26:09 PM »
John. When I advance the weights on the 480 I have the weights don't allow the pin to travel the full length of the slot. Have you ever noticed this. I'm going to fire up the Sun machine this weekend and check how much centrifugal advance the 532 allows.

I sent my 480 to Jerry M. and had him restore it and set it up to start centrifugal at 900 rpm, with 20*-22* of centrifugal advance at 2800-3000 rpm; Jerry included several different size limit pin bushings if I wanted to tweak it futher, but I haven't touched it. I set initial at 10*-12*, and use a VC-1810 vacuum advance can, connected to full manifold vacuum (not the stock "ported" vacuum nipple). Mine's a cruiser, not a racer.
'69 Z/28
Fathom Green
CRG

fireZ

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Re: 1111480 Looking for Collaborative Facts.
« Reply #8 on: July 09, 2011, 06:21:14 PM »
If anyone questions  going with John Z tip of using full manifold vacuum it is the best thing I ever did to my 1968 Z. It runs so much better on the street. Likely the best tip I have ever done to make these 302 s run like they should .  Thanks John
1968 Z28 LA Built
LIC # RPO Z28

L78 steve

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Re: 1111480 Looking for Collaborative Facts.
« Reply #9 on: July 12, 2011, 05:40:26 PM »
John. When I advance the weights on the 480 I have the weights don't allow the pin to travel the full length of the slot. Have you ever noticed this. I'm going to fire up the Sun machine this weekend and check how much centrifugal advance the 532 allows.
[/q

I sent my 480 to Jerry M. and had him restore it and set it up to start centrifugal at 900 rpm, with 20*-22* of centrifugal advance at 2800-3000 rpm; Jerry included several different size limit pin bushings if I wanted to tweak it futher, but I haven't touched it. I set initial at 10*-12*, and use a VC-1810 vacuum advance can, connected to full manifold vacuum (not the stock "ported" vacuum nipple). Mine's a cruiser, not a racer.

Where can I obtain these limit bushings? Did GM use only one size and alter the slot for different tunes?
69 Z/28 Dover White. SOLD
67 SS/RS Mt. Green 1W,2LGSR,3SL,4K,5BY,07C. SOLD
70 Nova L78 Blk. Cherry,Sandalwood,M21,02B

JohnZ

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Re: 1111480 Looking for Collaborative Facts.
« Reply #10 on: July 12, 2011, 08:49:01 PM »
<<Where can I obtain these limit bushings? Did GM use only one size and alter the slot for different tunes?>>

As far as I know, GM used one bushing (many of which fell off as they aged); Jerry probably has his bushings made.
'69 Z/28
Fathom Green
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GaryL

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Re: 1111480 Looking for Collaborative Facts.
« Reply #11 on: July 14, 2011, 02:54:10 AM »
If anyone questions  going with John Z tip of using full manifold vacuum it is the best thing I ever did to my 1968 Z. It runs so much better on the street. Likely the best tip I have ever done to make these 302 s run like they should .  Thanks John

I second that, Stock 302s with good timing, good jetting and headers are great street engines. I use a scosh more initial and less centrifugal but the 30-30 loves it.
Gary

Lemans Blue X33. DZ, M20, manual steering. Only BU code rear end is original.