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Author Topic: Distributor Questions..  (Read 706 times)
dutch
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« on: August 24, 2014, 02:34:26 PM »

There has been quite a bit of discussion regarding distributors lately - but the one thing I really haven't seen is many comments regarding the advance weights in them.
I have a '266 distributor in my '68 Zed and I recall taking out the original weights when I put in a kit and changed (lightened) up the springs and used the aftermarket weights in it, a few years back.
Question I have - since I can't right now locate the weights that are original to my distributor is.. are all GM distributor weights the same or were some specific to certain distributors like the high performance versions in L78 and Z 2/8's or solid lifter motors?
I'm sure the weights I took out are around somewhere (I recall seeing them a while back somewhere - but you know how you can never find stuff when you need to - only to have it show up later when you aren't looking anymore?) but in the meantime I have a couple of other old distributors from regular performance 283 and 327 small blocks, and I am wondering if they would likely exactly the same and be just as good to use.
I was going to trash the Accel or Mr. Gasket ones in it now and return it to 'as built' with slightly heavier springs than what I have in it right now, since the car occasionally has a wandering idle and I feel it is probably a case of the springs being a bit too light to settle it back down, along with possibly the aftermarket weights possibly being a bit different from the GM original types as well..
Any suggestions or comments are much appreciated - Thanks - Randy
 
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janobyte
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« Reply #1 on: August 24, 2014, 07:43:57 PM »

I had Jerry go through mine last year, as far as I know, never told otherwise, springs and weights are still born with in it. And he calibrates it on the Sun. Swamped this week, but I'll take a look at it and get back to you on any colors, numbers etc..in a few days. If any distinguishing marks are to be seen. It is dialed in for a 68 302.
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68camaroz28
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« Reply #2 on: August 24, 2014, 08:20:31 PM »

There has been quite a bit of discussion regarding distributors lately - but the one thing I really haven't seen is many comments regarding the advance weights in them.
I have a '266 distributor in my '68 Zed and I recall taking out the original weights when I put in a kit and changed (lightened) up the springs and used the aftermarket weights in it, a few years back.
Question I have - since I can't right now locate the weights that are original to my distributor is.. are all GM distributor weights the same or were some specific to certain distributors like the high performance versions in L78 and Z 2/8's or solid lifter motors?
I'm sure the weights I took out are around somewhere (I recall seeing them a while back somewhere - but you know how you can never find stuff when you need to - only to have it show up later when you aren't looking anymore?) but in the meantime I have a couple of other old distributors from regular performance 283 and 327 small blocks, and I am wondering if they would likely exactly the same and be just as good to use.
I was going to trash the Accel or Mr. Gasket ones in it now and return it to 'as built' with slightly heavier springs than what I have in it right now, since the car occasionally has a wandering idle and I feel it is probably a case of the springs being a bit too light to settle it back down, along with possibly the aftermarket weights possibly being a bit different from the GM original types as well..
Any suggestions or comments are much appreciated - Thanks - Randy
 
Hi Randy, our distributor was restored/rebuilt and we had issues as the weights were not correct as the pin diameter (inner diameter) was larger than the pin diameter they fit on. I'm not sure if GM used weights with different inner diameter holes but ours sure had issues along with too weak of springs. When we had the engine on the dyno for break-in the timing kept jumping around and would not stay stationary which we ultimately caused us to stop, review the distributor, and take out and repair.
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69 Z/28 NOR 07A Orig Block & GM Cross-ram/carbs
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67 L89 Corv Tribute
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dutch
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« Reply #3 on: August 26, 2014, 06:22:37 PM »

Thanks for the replies so far - guess I was hopeful of JohnZ or Jerry M or others who had vast knowledge of the Z 2/8 model and I'm sure that model's distributor, to assure me that I could use any SBC weights and feel secure (at least until my originals make a re-appearance) that all would be interchangeable and operate correctly as per original specs..
I swore I saw a post where someone had stated that the aftermarket ones weren't correct weight and profile-wise and that ANY SBC weights would work better than those sold with the spring kits, as all of the SBC ones were all the same - but for the life of me can't now find where I saw this stated or by whom.. 
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janobyte
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« Reply #4 on: August 26, 2014, 07:34:58 PM »

It has been a long time since I played with weights and springs in a stock GM distributor. Having a few personal replies, I actually did some review on this:

Moroso seems to have the kit we're looking for. 28 years ago I played with a Mr. Gasket set in a stout 327 I had, but this was 28 years ago.

3 different stages of Accel points, heavy duty are not heavy duty(for a Z anyway) as point bounce will occur <6K on the tac. Actually about 700 off as advertised.(personal experience in the passenger seat Grin)
GET AN ADJUSTABLE TIMING LIGHT I've had mine for 25 years, and will never go back. Seeing as I basically play with race motors, set it to the total degrees I'm looking for--align timing mark to indicator--lock it down, done.   I've done lots more with it.


More duration in the cam= quicker you want the timing all in  305 on our race engine, advance is locked out, 38 degrees total. not a street motor Wink

There is a guide: spring (3 tensions)/weight combo to get you where you want to be.

Have fun playing with a few things with your car, tailor it to your liking. A few degrees this or that way is not crucial:find what your engine likesThese cars were mass produced, one size does not fit all, this is why there are adjustments.

All I had to do was pick up the phone and talk to my Dad vs. farming out my old single point ...it better be right.

 However his reply would have been go with a MSD. Wink (still is)

And no matter what, using the center line off my intake: #1 wire goes driver side,#8 passenger way. (centerline up the cap) May take a little more effort but with timing set #1 terminal is inline with #1 piston. Probably just a pet peeve, but this is the way I was brought up doing it. LOL!
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1971ls6
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« Reply #5 on: August 26, 2014, 08:43:36 PM »

Use any factory weight over the junk ones that come in the kit, use one gold and 1 silver for all in between 2,500-3,000 rpm.

I have a distributor machine and without it you cannot get it right without a lot of trials in the car.

I have learned that there are numerous shafts that had different profiles, plus the weights and the springs. The stock profiles are slow and lazy, if nothing else, order the mr gasket 247 distributor kit and use the springs listed above, the brass bushing limits the total advance by 6 degrees.

For bb cars I use 18 initial and 20 mechanical.
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TODD
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« Reply #6 on: August 26, 2014, 10:56:14 PM »

As 1971ls6 says; "I have a distributor machine and without it you cannot get it right without a lot of trials in the car."
It is a tall order with lots of trial and error to do one on the car, not impossible but my aching back would kill me with all those over the car adjustments.
Interesting though hardest time I had with my 480 distributor on my Sun machine was getting it to hold and come in at 1050 rpm These 302 cars like to idle at 900rpm plus and you can't have any curve come in at idle or it with dither like the dickens at idle. So if you can't set one up I'd say send one out for a curve. Mine is 1050~1100 to 2800 rpm 12 degrees or 24 total bushing restricting slot. Advance 12 degrees and distributor vac can with limiter for 10 degrees more.
Todd
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janobyte
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« Reply #7 on: August 27, 2014, 08:50:45 AM »

1111467  8A5
Centrifugal advance curve total 20 degrees
Total advance in at 2600 rpm     Sun #404,calibrated 2/3/2007

Back to your original question Dutch, pulled it of the bubble wrap:


Point cam 532CCW  stamped underneath, brass bushing, BLACK springs. Weights also original, same color/ finish as cam plate. Saw no distinguishing markings on them for certain, maybe a 1 on one, 4 on another, but my eyes have played tricks on me before trying to document  #'s.


Going back 30+ years ago, it was shelved. All honesty, performed very well in the car. About 20 years.  Somewhere around 34K was on the odometer(36K now)
Had it gone through just for piece of mind. Expecting no problemswhen it makes it's way back home in the 302.---steve
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jdv69z
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« Reply #8 on: August 27, 2014, 09:14:56 AM »


GET AN ADJUSTABLE TIMING LIGHT I've had mine for 25 years, and will never go back. Seeing as I basically play with race motors, set it to the total degrees I'm looking for--align timing mark to indicator--lock it down, done.   I've done lots more with it.


My timing light is from the 70's. Sounds like I need one of these. Whose light is good, and how does it work? It sounds like it knows where TDC is if it can tell total timing. Doesn't it have to be calibrated to the engine timing somehow to know what total timing is?

Sorry if I'm hijacking?
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Jimmy V.
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« Reply #9 on: August 27, 2014, 10:00:15 AM »

<< And no matter what, using the center line off my intake: #1 wire goes driver side,#8 passenger way. (centerline up the cap) May take a little more effort but with timing set #1 terminal is inline with #1 piston. Probably just a pet peeve, but this is the way I was brought up doing it. LOL! >>

That misprint in the shop manuals (and Chilton and Haynes) has confused many a mechanic over the years. It was supposed to read "...rotor pointing to the #1 wire tower in the cap..", not "..rotor pointing to the #1 cylinder..".  The correct distributor housing/vacuum advance orientation and plug wire indexing in the cap is shown below, with the point adjusting window on centerline; that's the way the car was designed.
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janobyte
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« Reply #10 on: August 27, 2014, 11:39:13 AM »

Hmph..learn something new every day! (or remembering) Even went out and checked the Anglia because of second guessing myself...this one built and ran on the dyno by the speed shop (Griff). No vacuum advance on the current MSD, or the Unilites I ran. Certainly prevents any future arguments at the local cruise in's ! LOL

JDV:
There is a dial on the back starting at 0,use as you would a normal light. Occasionally I do compare readings. These may have come about prior to markings being engraved on the performance balancers, alternative to timing tape or measuring/marking. Another toy in the box to help read timing advance.....all procedures still apply.
I have an old Craftsman ,some higher dollar ones floating around my father's garage, what I've seen, they perform the same.
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janobyte
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« Reply #11 on: August 27, 2014, 05:26:25 PM »

Ahh ,now I see why I've been doing it a certain way all these years, not going to elaborate. This is a 67-69 Camaro website.

This is why I post ,as much to help as fish for corrections. Would have taken me for a little loop in the months to come. Thanks John.---steve
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JoeC
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« Reply #12 on: August 28, 2014, 09:31:16 AM »

the GM weights are different and will give you a different curve since they work on centrifugal force

I have 1969  1111499 8M28 dist in unrestored condition, that has holes in the big end of the weights

someone did a comparison of the weights using same dist with same springs on a dist machine

they did a bunch of GM and aftermarket weights and mapped them out on a graph and you can see the different shapes of the curves RPM vs degrees



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dutch
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« Reply #13 on: August 28, 2014, 10:15:07 PM »

"they did a bunch of GM and aftermarket weights and mapped them out on a graph and you can see the different shapes of the curves RPM vs degrees"
Joe, do you mean from this that ALL the GM ones were the same in the test - but the aftermarket versions were the ones that differed..? I still trying to gauge if there are variances within the GM ones based on application - or if they are all basically the same and interchangeable between distributors.
I can understand and imagine the aftermarket versions being vastly different from the GM variants - but I am looking to see if there are differences within the ones GM used, to determine if any weight would replace the OEM ones that my '266 distributor was born with, and in fact if I need to keep looking for my original ones verses dropping in any old GM ones I presently have laying around..
Randy

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L78 steve
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« Reply #14 on: August 29, 2014, 11:49:43 AM »

I need to check my 499. Don't remember holes in the weights.
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69 Z/28 Dover White X33,ZL2,PS,M20,Std.int.04C
67 SS/RS Mt. Green 1W,2LGSR,3SL,4K,5BY,07C
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