Timing Vacuum
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Joined: Oct 2005
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From: Alamogordo, New Mexico
Timing Vacuum
Should have included this in the last one, but I bought me a fancy (not really) vacuum guage for the truck to check the timing with. Bro in law is a decent meckanick and said timing can be checked via vacuum. So I done bought me the guage. It has a nice green zone that says the engine is good, but the range is between 17 and 22Hg. I was hoping to tighten it up even closer but don't know where to go to with it. Any ideas on where I should shoot for when adjusting the timing using the vacuum? By the by, my timing light is ghetto and my balancer is hard to read...
Thanks again!
Rich
Thanks again!
Rich
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Joined: May 2006
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From: Kingsport, TN
I used to clean the timing marks off REAL GOOD and use a thin stripe of white finger nail polish on the wheel - where you want it to be. It usually stays and is visible for a couple years. Sometimes, it's easier to crawl under the truck to do this - it saves trying do reach around hoses, wiring and such - and it'll be right in front of your nose.
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From: Sonoma, CA
Vacuum guage will check vacuum not timing. An engine is a big air pump. Use the vacuum guage to adjust idle mixture once it's timed with your timing light. Adjust idle mixture to acheive the highest vacuum level you can get. It'll be a little rich at this point. Also adjust idle speed to the proper setting and check vacuum again. It gives a good reference on engine condition.
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From: Alamogordo, New Mexico
Maybe my brother in law ain't as smart as I thinks he is! I'll get under and clean off the balancer again and mark it with paint this time. Tried chalk before but was still hard to read. Next question, where do I set it at? My manual says to go by the truck specs. Sadly the sticker with timing info has departed this earth and is no longer with us...
i ain't rite
Joined: Mar 2005
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From: Marlboro Mental Hospital.
i normaly advance the timing till i get pinging on an at temp engine, then back it off a tad and try it again, backing off till the pinging goes away. then i shut it off and make sure it starts up with no problem, and leave the timing that way. most of my vehicles have not had timing marks in so long that there is no way to do it with a light anyway.
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Had you mentioned what year and model of truck
Engine, transmission, axle state of operation.
you would have known the specs on this post.
Engine, transmission, axle state of operation.
you would have known the specs on this post.
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From: Alamogordo, New Mexico
It's a '77 F150 351M 4WD shortbed, not sure what the axle ratios are, can't find the tag to read them. Haven't scraped off enough dirt and grease and mud yet to. Plus I'm afraid all that gunk is keeping it from leaking worse than it is. Engine's been rebuilt a little over a year ago, but I never got the timing right. It's dang close, but need to tweek it a smidge more. I did it by ear after I tried it with the cheap light I bought. Worked better even though my wife says I can't hear 
Gets horrid gas mileage but is a beast up in the mountains out here. Just may have to go again this weekend and uhh get firewood...
Gets horrid gas mileage but is a beast up in the mountains out here. Just may have to go again this weekend and uhh get firewood...
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From: Alamogordo, New Mexico
4 speed manuel. I would guess by California or 49 state, you're referencing emissions. Now that's funny! I imagine brand new it had emisions on it, but that old truck is more junk yard dog than anything now.
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quote:
"Next question, where do I set it at?"
I'd guess the stock setting was 6* btdc. Anyway, I'd start at 6*, then if it dosen't ping, go up to 8*, then maybe 10*.
A good starting point on the carb idle mixture screws is 2 1/4 turns out. Then set them for the best vacuum, and then turn back in 1/4 turn. This will lean the idle slightly; should be about right.....
"Next question, where do I set it at?"
I'd guess the stock setting was 6* btdc. Anyway, I'd start at 6*, then if it dosen't ping, go up to 8*, then maybe 10*.
A good starting point on the carb idle mixture screws is 2 1/4 turns out. Then set them for the best vacuum, and then turn back in 1/4 turn. This will lean the idle slightly; should be about right.....
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calibration code
7-71-R10
http://mil1ion.clubfte.com/78Calibra...e-upSpecs.html
choke 2 rich
curb idle - 650 rpm
Timing setting - 6* BTDC @ 650 rpm vacuum advance disconnected and hose plugged.
7-71-R10
http://mil1ion.clubfte.com/78Calibra...e-upSpecs.html
choke 2 rich
curb idle - 650 rpm
Timing setting - 6* BTDC @ 650 rpm vacuum advance disconnected and hose plugged.