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PostPosted: Mon Jul 02, 2007 1:14 pm 
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EFI Slant 6
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I've been having a real lack of power lately in my truck. The propane system is finally tuned, I think the tranny is OK, but from reading on this site I think it might be
The Distributor. :twisted:

The biggest clue, I think, is that it is only giving me an additional 15 degrees of advance at 3000 RPM (which is when I'd like it to be all in).
For instance, if I have 15 degrees of initial timing, at 3000 RPM I only get a total of 30 degrees.

I am getting 10" of ported vacuum at WOT

So, what do I do? Can you recommend a good place to get a new one? Rebuild w/ different springs?

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PostPosted: Mon Jul 02, 2007 2:37 pm 
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Normally the term "total" does not include the vacuum advance. If you are using the term correctly, then your distributor seems to be doing what it is supposed to. If you are including the vacuum advance in your "total" then you are right, you are not getting enough advance. All three should ad up closer to 40 with the initial you have indicated you have there. . What surprised me is that you are getting 10" of vacuum at WOT. That seems high to me. If that is the case, then the vacuum advance would never pull off to reduce the timing under WOT conditions, as they are usually set up to pull in around 8 inches. This means anything over 8" would have vacuum advanc added.

Sam

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PostPosted: Mon Jul 02, 2007 2:50 pm 
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Are you running a points or electronic type distributor?

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PostPosted: Mon Jul 02, 2007 7:59 pm 
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EFI Slant 6
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Thanks for the responses.

Electronic Distributor w/ blue box.

I'm including the vacuum advance for the total.

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71 D100 225 Super Six 727 AT 3:23 rear

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PostPosted: Tue Jul 03, 2007 4:23 am 
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You shouldn't have vacuum advance at WOT. With your throttle plate wide open to atmosphere there should be little, if any, vacuum to pull the diaphram.

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 Post subject: Unless...
PostPosted: Tue Jul 03, 2007 6:56 am 
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Quote:
You shouldn't have vacuum advance at WOT. With your throttle plate wide open to atmosphere there should be little, if any, vacuum to pull the diaphram.



Unless your carb is too small for the engine, then you can have vacc. still at WOT due to the restriction the under size carb makes (or your secondaries haven't opened adequately either)
.... but this shouldn't be his case.....

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PostPosted: Tue Jul 03, 2007 7:41 am 
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EFI Slant 6
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I'm confused about this vacuum thing. I understand that there isn't going to be any manifold vacuum at WOT. But the vacuum I'm using to pull the distributor diaphragm is ported and comes through holes in the throttle base that are in the throttle bores themselves.

I am using a mixer on top of the old BBD throttle body (base?) but I don't think that should make much difference, as it pulls air just the same.

If I were to get a new (or at least different) distributor, assuming there's something wrong with the mechanical advance, can anyone recommend a good source? O'Reilly and Advance here sell Cardone. NAPA has a distributor, too.

Thanks again for all your help,
Joe

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71 D100 225 Super Six 727 AT 3:23 rear

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 Post subject: Distributor
PostPosted: Tue Jul 03, 2007 11:25 am 
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I can build or rebuild a distributor for any use that you require. I have lots of parts and a couple of cores to work with, but they are getting pretty expensive to find (often $65 on ebay)

I agree with some of the others who question your vacuum advance. You should always resolve your mechanical advance before considering vacuum advance, it's just easier to do it that way. If you really are getting only 15 degrees of mechanical advance from your distributor, then you might need to make an internal adjustment such as lengthening the loop on the heavy spring. This involves removing the distributor from the engine and taking it apart.

A great deal has been written about how to rework the insides of a slant six distributor and I don't have time to type it again in this posting, but I will find you a link to some information and am willing to answer any questions you still have after reading it if you want to perform the modifications on your own.

Paul

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 Post subject: Here is that article
PostPosted: Tue Jul 03, 2007 11:31 am 
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Compiled this article a few years back while learning the ropes myself. I need to reread it and make some updates, but it should give you the basics and is slant six specific.

www.potentialtech.com/pmoran/dist-9-22-05.pdf


Here are some search terms for future searchers

Distributor
Recurve
Spring
Governor
Dist
degree

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 Post subject:
PostPosted: Tue Jul 03, 2007 12:53 pm 
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Ram--

I sent you a PM. Thanks for the advice.

Joe

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71 D100 225 Super Six 727 AT 3:23 rear

powered by Sweet Lady Propane


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