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Discussion Starter #1 (Edited)
recurving the remanufactured 1976 duraspark distributer i just got. I got the 925D mr gasket recurve springs. I tore the distributer apart to find i had the 13L and the 18L slots. But i noticed something on the "pin" that the spring attaches too. Its a BLACK PLASTIC bushing that fits over the pin to limit the travel of the slot thus decreasing the slot width. Are these bushings suppose to be plastic? that seems weak and i would think it would wear with use. From what im told u should weld the tabs to get the slot width u want but this bushing essentially makes my 13L slot a 10L slot which is perfect.

so if you guys say these bushings are suppose to be plastic and will not wear "fast" then i would put the mr gasket springs on and assemble it back together. Just want to know if the plastic bushing is good to go.

here are some measurements i took..
13L slot = .488"
10L slot = .410"
stock metal pin width (no bushing)= .149"
stock metal pin with bushing = .223"
so the plastic bushing thickness is = .074"

subtract the bushing thickness to the 13L slot width and i get a new slot width of .414" which is super close to the .410" slot width of the 10L.

im planning to run a 241/249 lunati cam with 10.5:1 compression. figure i would max mechanical centrifugal timing at 35degrees total and run 15 degrees static at idle which is why i wanted the 10L slot. the mr gasket recurve springs should allow max advance below 3000 rpms as well.
 

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Yup, it's supposed to be there and plastic is not a problem. The slot is actually made and marked with that "bushing" in mind. It only changes the amount, other than marked, if ya take it off or make one thicker.
 

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Discussion Starter #3
so your saying that the bushing thickness is already compensated for with the 13L?

so even with the bushing the 13L still is has the same slot width of .488"? or does the bushing decrease the slot width to .414"?
 

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I am saying that without the bushing it would give more degrees than what is marked on the plate. The amount was figured with bushing in place. A 13 marked slot will give 26 degrees with the bushing on. Take it off and ya get more, not less.
 

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Discussion Starter #5
oh ok gotcha. so basically if i want it to be like the 10L i need to modify the slot.
 

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Discussion Starter #6
so im gona weld the slot to the 10L size correct? and the bushing still stays on? or do i make the slot the .410" and not use the bushing?
 

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Discussion Starter #7
ok well i welded up the slot... made it .417" (painted the weld slightly to help with rust) and im trying to put it back together now. leave the little plastic bushing in? or no? need this done in a hr so please respond fast! thanks
 

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I don't have a 10 degree piece here right now so I don't know what it should measure. If ya aren't gonna use the plastic, then the slot should be shorter than stock. By how much I don't know. I always do a modification and the put it together and check it with a timing light. Never wrote anything down!
 

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Discussion Starter #9
ok so im gona use the bushing then i guess.

the stock 10L should be .410"... im assuming they account for the plastic bushing as well?

The stock 13L i measured was .483", on reacarnations website it states it should be .488". so I assume there are small fluctuations in the slots from peice to peice. so I got the slot within .007" of what the stock 10L should be. My thing is now if i should use the plastic sleeve thing bc i dnt plan on tearing this thing apart again lol.

so your telling me that the plastic sleeve thing should be used bc its already installed from the factory?
 

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Discussion Starter #11
ok, thanks. i left it in and got it all back together. doesnt seem to have much mechanical advance tho, bushing seems to take up a good bit. if i dnt get enough its gona be real annoying to have to tear this thing apart to get that lil bushing out lol
 

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A 10° slot is .410" and a 15° slot is .510" so each distributor degree would be .020" in the slot length.
 
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