Distributor question
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Senior User
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Distributor question
I run a 351w that has a duraspark type distributor in it. I can't run the vacuum advance because it pulls more than 40 degrees of advance with it hooked up, and that's with initial set at 6 degrees! Also, the vacuum advance is adjustable, it's set to give the lowest amount of advance. I've verified that the timing marks are correct. I've done some research and know that these distributors are kind of screwy because they were designed for to work with all the emmissions crap that played with the timing. Is there any way to remedy this or should I start looking for a new distributor?
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Joined: Jun 1999
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From: Durham
Distributor question
Try hooking your vacuum advance to the timed port on your carb. This should keep your advance at whatever your initial setting is. The timed port won't open until you give the carb some throttle. Check the total advance by keeping the vacuum disconnected and plugged and run the engine to about 3000 rpm. Your total advance should have come in by then and it should be around 32-34 degrees.
'82 F150 2WD w/351W (orig 300 I6)
Slik
'82 F150 2WD w/351W (orig 300 I6)
Slik
Thread Starter
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Senior User
Joined: Jan 2000
Posts: 161
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Distributor question
Thanks for the advice, but I've tried using the timed port. I have around 24 degrees of mechanical advance, but with any vacuum hooked up I get much more. With 12 degrees initial, I end up with close to 50 degrees if I hook up any vacuum! Another guy suggested I use an earlier vacuum advance unit, I think I'll give that a try because they weren't set up for all the emmisions crap. My buddy has a '76 bronco with similar distributor and it does all kinds of funky advance/retard, it uses a a dual diaphragm distributor so that probably explains why mine is set up with so much vacuum advance.
Posting Guru
Joined: Jun 1999
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From: Durham
Distributor question
Your timed port should not give you any vacuum at idle. If it does, then there's something else wrong also. But... if you decide to get a new distributor, MSD makes some nice looking ones that give you a lot of control over the advance.
'82 F150 2WD w/351W (orig 300 I6)
Slik
'82 F150 2WD w/351W (orig 300 I6)
Slik
Elder User
Joined: Jan 2000
Posts: 656
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From: Gravel Switch, KY
Distributor question
Do you have a Crane adjustable vacuum advance can?
If so, I don't think the adjustment will affect the overall amount of advance, just the point at which you receive full advance. I got a reman. 77 Duraspark for my truck and it also had way too much vacuum advance so I made a little adjustable stop to limit the amount of advance it could deliver. This worked well, but I went ahead and ordered a Crane Adjustable and it didn't give as much advance as the stocker. I think you are right about the emission design of the can giving you too much advance. It's fine for a "decompressed and tuned for family use" emission engine, but for higher compression or performance applications, it's not good.
DannyP
If so, I don't think the adjustment will affect the overall amount of advance, just the point at which you receive full advance. I got a reman. 77 Duraspark for my truck and it also had way too much vacuum advance so I made a little adjustable stop to limit the amount of advance it could deliver. This worked well, but I went ahead and ordered a Crane Adjustable and it didn't give as much advance as the stocker. I think you are right about the emission design of the can giving you too much advance. It's fine for a "decompressed and tuned for family use" emission engine, but for higher compression or performance applications, it's not good.
DannyP
