Need vacuum advance with 8-9 degrees

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fishy68

fishy68

Tyr Fryr's Inc.
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Does anybody know of a reference to how many degrees advance factory vacuum advances for small blocks had? I need one that will give me 8-9 degrees at the dist. (16-18 at the crank) but don't know what they might have been used on. I checked into the Mopar Perf. vacuum advance can and even though it says it's adjustable it really isn't. Well it sort of is because you can adjust the time it comes in. But that doesn't adjust how many degrees of advance it produces.
 
If you take the cap off and pull the vacuum advance unit out, it will have a number stamped on one side it that says how many degrees it's worth. Seems like most of the distributors I've pulled apart are 22 at the crank.
 
Some info on vacuum advance pods here; looks like \6 and smallblock V8 cans are physically interchangeable. Remember also, if you have a pod that works the way you want in terms of when it comes in, but has too much total advance, you can limit the total advance by looping/crimping pieces of wire or slotted washers over the pull rod, against the shoulder that hits the can housing, so the rod can't pull as far.
 
slantsixdan said:
, but has too much total advance, you can limit the total advance by looping/crimping pieces of wire or slotted washers over the pull rod, against the shoulder that hits the can housing, so the rod can't pull as far.
Click to expand...

I've done this on 2 and it works good at limiting the vac advance.
 
wish4hemi said:
If you take the cap off and pull the vacuum advance unit out, it will have a number stamped on one side it that says how many degrees it's worth. Seems like most of the distributors I've pulled apart are 22 at the crank.
Click to expand...

Yeah I noticed the stamping. The problem is I didn't know what to order a vacuum advance for that would give me the amount of advance I need. I have only had 2 apart and they were both 26 at the crank which is way too much.

slantsixdan said:
Some info on vacuum advance pods here; looks like \6 and smallblock V8 cans are physically interchangeable. Remember also, if you have a pod that works the way you want in terms of when it comes in, but has too much total advance, you can limit the total advance by looping/crimping pieces of wire or slotted washers over the pull rod, against the shoulder that hits the can housing, so the rod can't pull as far.
Click to expand...

Thanks Dan. I'll check out that link and see what I see. I didn't realize there'd be enough room to limit it that way but if I don't find the right one I'll give it a try..

green1 said:
I just had a factory apart. 318 was 8.5, 340 was 9.5. They wouldn't interchange.
Click to expand...

Was that the stamp on the vacuum advance arm? If so you double that number at the crank so the 8.5 would actually be 17 degrees of advance and would be perfect. Do you know what year 318 that was and what it was out of? What was different that made them not interchange? Was one a point type dist. and the other electronic? That's the only reason I can think they wouldn't interchange.

Babyblue66 said:
I've done this on 2 and it works good at limiting the vac advance.
Click to expand...

Great, so that trick does work.

Thanks for all the replies.
 
It was a 70 318. 340 arm was different angle. Yes, was stamped on arm.
Got new one from Napa.
 
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