No Vacuum

  • Thread starter Thread starter Anonymous
  • Start date Start date
A

Anonymous

Guest
I went to time my car today and when I plugged the line to the distributer it felt as if there was no vacuum. Hooked up the vac gage and comfirmed that there is no vacuum going to the distributer.

Hooked up the vac gage to the line going to the C4 and have 16" Hg when idling at 600 RPM in park and fully warmed up. When I press on the gas vacuum drops to 12" Hg when I let off the gas vacuum goes up to 22" Hg.

Engine is a 200 with an autolite 1100 and standard distributer.

I am new to timing and vacuum stuff (this was the first time I used my new vacuum gage). So here are my questions.

1. Is this situation normal? and if yes then why plug the vacuum line to the distributer?

2. If this is not normal what do I do to fix it/test what is might be wrong?

Thanks in advance for the help.
 
well i was new to it too but ive got quite a lot of info already on it. just hook up the vac advance line from the distributer to the manifold, and if u need to, readjust your timing.
 
forgot to mention u can click on the www link at the bottom of this script cause i have a link on my site to a good vacuum advance tech.
 
Found the leak (sorta) by spraying WD40 where the vacuum line goes into carb. When at idle at 600 RPM fully warmed I only have 1" Hg vacuum to the distributer. If I rev the engine the vacuum goes up to 16" Hg. When I let off the gas it goes straight back to 1" Hg.

Is this normal if not then what does it mean and what can I do?
 
your carb port thing where the distributer hose is may not have enough oomph, and u might as well be running no hose. i have my hose hooked up to the manifold and the differences are quite nice. i accelerate the same and i get way better mileage and before when i had the hose to the carb my gas needle would go way down when i floord it and would slowly work its way up, now when i floor it the needle doesnt even move. try it out (maybe with a new hose if that ones got a leak) and drive it a bit.
 
Your idle should go up a bit when the ported source from the autolite is connected to the distributor. Timing of course is done with it disconnected.
It sounds like the ported source is partially blocked or something, granted for this carb the vacuum is not that great but 1 Hg is a bit too low. You may want to look at rebuilding your carb or getting a rebuilt. Personally, I would replace it with the stovebolt holley/weber 5200 for $65.00. You would also need the adaptor either from stovebolt or from clifford. I like the one from clifford very clean installation with it though the float bowl winds up on the side instead of in front. You can run the line from the manifold and it can give better advance for better mileage but the distributor was designed for the ported source on that carb only. You may experience problems with climbing hills and such when you may have too much advance for the road conditions. The carb and distributor come as a set, if you do change out the carb you will need to go to a different distributor, I think the electronic DS II from Ford is adequate.
 
Thanks for the fast replies. How much vacuum should I get from the carb normally?

The hose is actually a steel line. The fitting where it connects to the carb was loose and causing the leak.

Can't afford a new carb/distributer yet (but will keep it in mind) since my wifes car broke down over christmas while visiting her parents...and had to borrow money from them to get it fixed.

Thanks, Dan
 
You should be getting 19" hg @ idle
when you put your foot in the throttle it should drop to zero
then shoot up to 22-25" hg when you slap the throttle shut.
 
Dan - I believe you have the loadamatic distributor (I know very little about them and their operation), and forum regular MarkP has given some great tech info on these distributors in the past. Try a search for loadamatic or user MarkP and you should get the posts. Maybe Mark will respond to this post. 8)
 
It sounds like you are hooked up to a ported source. Besides the leaky fittings, you may want to check the vacuum can for a leak too. If you have a vacuum pump, hook it up and test the diaphram to see that it holds. With the distributor cap off, you should be able to see the mechanism advance when is vacuum is applied to the diaphram.
If you have the Loadamatic, check to see that the timing advances when you rev the engine. If it does not, you likely have a bad vacuum can, and you may have to replace the distributor, unless you can find a replacement vacuum can.
 
At idle there is going to be little or no vacuum on that line. That's because the carb is designed so that the throttle blade doesn't expose that port until the throttle is tipped in.

The reason to use this "ported" vacuum is because the engine does not require full advance at idle. The Load-o-Matic will add about 20-25 degrees of vacuum advance if you hook it to the manifold. Added to your initial settings, you might be running 30-35 degrees at idle. In fact, it may run poorly with that much advance at low speed. If you back it off so that the idle is good, you might not then have enough advance for higher cruising speeds. Hooking directly to the intake may not be a good idea.

The Load-o-Matic is a lousy performance distributor. It has no mechanical advance at all, so it has to rely on engine load to advance or retard the spark. It was developed on the same load sensing principle that Henry used on the original Flathead V8 in his vacuum brake distributor. And Flathead rodders usually tossed the distributor in the can as one of the first performance mods. The Load-o-matic continued in the Y-block. Again, the first performance mod on one of those engines is to toss the distributor.
 
Thanks Jack you explained it well. As soon as I can afford to I am going to swap in a DII.

Dan
 
You must log in or register to reply here.

Similar threads

A
All Small Six Duraspark conversion with some headache
Replies
19
Views
2K
adobejoe
A
A
All Small Six Chasing vacuum leaks.. solved ..but now overheating.
2
Replies
27
Views
1K
Frank
Frank
J
All Small Six High altitude jet size autolite 1101
2
Replies
22
Views
719
Frank
Frank
E
All Small Six 250 Warm start info?
Replies
7
Views
251
edcom
E
xavier296
All Small Six Ignition Timing Map
Replies
5
Views
389
xavier296
xavier296
Back
Top