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Scott Hamilton

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Offline striper

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vaccum
« on: October 29, 2011, 11:24:51 AM »
hope someone knows this! I have 72' wagon, a 2.0 with a daul vac dist.and an autolite 5200 carb.what is the vaccum suppose to be at the small port of the intake //( mine is 6-10 and shakey) and the base of carb for the dist //( mine is like 2).fuel mixter is turned out 2+turns and still no power and rough idle..all vac ports blocked off at this tme to try to isolate problem .carb rebuild ?

Offline dave1987

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Re: vaccum
« Reply #1 on: October 29, 2011, 08:40:45 PM »
Sound like a leak somewhere. Do you have A/C controls inside the car? They are controlled by engine vacuum and the hoses can become dry and rot (haven't seen in pintos but have in other cars), or disconnected easily.

When I read mine on mh 73 wagon it's around 15-17. A little shaky but not much, idles real nice actually. Better than my 78's 2.3 does.
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Offline ToniJ1960

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Re: vaccum
« Reply #2 on: October 29, 2011, 11:04:56 PM »
 A vacuum test can sometimes tell you a lot. If the vacuum is low it could be a vacuum leak, or the timing is off. If its shaky like you said, then see if it drops regularly. It could be a misfire, bad plug or whatever. It could be a problem with the vales. If it steadys out as soon as you raise the rpms alittle supposedly that means the valve guides are worn. Mine does it some but not real bad,and smokes a little when I first start it sometimes. so I know my valve guides arent great but maybe not real bad.

 I think my vacuum runs around 17 or 18 if I advance the timing a little it should be between 18 and 20 (it used to stay around 20). But I have problems with pinging even with 89 now, suddenly (Im suspecting the gas)

 The vacuum youre reading on the carb base is probably venturi vacuum,and it should increase with your engine rpms.

Offline striper

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Re: vaccum
« Reply #3 on: October 30, 2011, 08:48:17 AM »
supposedly the engine was rebuilt when I got it but Ithink it just put together with a rebuild kit.top end was justput back on with no work on it.thanks.

Offline ToniJ1960

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Re: vaccum
« Reply #4 on: October 30, 2011, 11:21:39 AM »
 It still sounds like a vacuum leak with it that low. You could do a compression test anyway, and if it is low you should probably have a leak down test done or do one yourself if youre set up for it. Its where compressed air is injected into each cylinder and the pressure observed to see if it `leaks down`. Its possible to tell by where the air leaks out, exhaust, the radiator etc, whats leaking in that cylinder. Intake or exhaust valves for example.

 But if the compression was so low to cause that low of a vacuum, or the timing was far enough off to account for it, Im pretty sure it would present more obvious issues along with the low vacuum. Look real real close to be sure all the vacuum sources, manifold vacuum ones, are accounted for and block off as many things as you can. Check the manifold vacuum again. Maybe spray some carb cleaner or wd 40 around the base of the carb, carefully. See if you hear any difference in t he idle. The bolts that hold the carb on do get loose sometimes.

Offline nnn0wqk

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Re: vaccum
« Reply #5 on: November 04, 2011, 02:00:24 AM »
Think I would check your cam timing. Betcha you have jumped a tooth. My 2.3 did that many years ago and it drove me nuts for about a week until I figured out what was going on. It jumped at the cam so timing was still correct but it would hardly idle and vac was in the basement. Good luck and let us know what you find.

Offline striper

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Re: vaccum
« Reply #6 on: November 07, 2011, 12:39:01 PM »
How would I check to see If I'm one tooth off; all said marks line up.

Offline Pinto5.0

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Re: vaccum
« Reply #7 on: November 07, 2011, 07:41:29 PM »
Worn throttle shaft can cause rough idle as well as leaking carb or manifold to block gasket.
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Offline mrskydog

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Re: vaccum
« Reply #8 on: November 07, 2011, 08:28:24 PM »
Just went thru a 5200 for my 78 carb , acid tanked rebuilt ,blew out set up same thing low idle rough ,miss ,stall in gear ...Got a differant carb set it up runs like Ten! Old carb acted like there was a Vac leak somewhere just couldnt find it, internal?
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Offline striper

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Re: vaccum
« Reply #9 on: November 15, 2011, 01:54:15 PM »
 thanks ,that was  my thought to replace the carb yet after the rebuild I'm gonna try a jet size or two /up I think I'm running too lean.

Offline ToniJ1960

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Re: vaccum
« Reply #10 on: November 16, 2011, 03:35:02 AM »
 The only things I can think of where manifold vacuum could be lost inside the carb, would be the power valve diaphram leaking, or there might be a passage to the choke pull off. If the choke pull off diaphragm isnt ruptured and the housing is on good, I wouldnt worry about that. I did have one choke pulloff diaphragm I got somewhere get distorted, and cause a vacuum leak. It wasnt a ford one it was just rubber with no threads or whatever ford uses in theirs.

 You can check the power valve diaphragm by removing the top of the carb, pres the power valve down and hold your finger over the hole near the edge. The valve should stay pulled in until you remove your finger and let air in. I can try to take a picture of my spare carb top and show you where the hole is you need to cover after you push it in. If you dont understand what Im saying just let me know. But except for hose things unless the throttle plates were stuck I dont see it causing that low of vacuum. If your carb is running very lean it should be running hot too. But still that vacuum reading you said you had, is really low. I dont think mine was that low when my power valve leaked.