Flathead engine vacume

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Mar 25, 2017 | 08:05 PM

cowdog86

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From: Miles City, Mt

Flathead engine vacume

I wanted to check the condition of my engine and get my carb set correctly. At idle my 239 pulls 18 to 20 vacume at idle. The needle wiggles back and forth real qwik.
When I give it the trottle it. Drops at first then goes way up above 20 and is steady. What's this telling me about my engine.. That vacume guage is sure they way to go for setting carb adjustments I know that much.

Mar 25, 2017 | 08:31 PM

ALBUQ F-1

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From: NM

Is it jiggly at idle, or just jumping when you gas it? At idle usually means sticking valve(s). If just when gassing it, that's normal behavior. 18 - 20 is a good engine.

Mar 25, 2017 | 08:53 PM

cowdog86

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From: Miles City, Mt

It's jiggly at idle. Vacume improved after I adusted the carb about 2 " and after it warmed up the jiggle range went from 4 to only 2. The engine sat for 15 years before I resurrected it in my F3.. Perhaps it just needs to be run. I am running straight SAE 40 if that makes any differance.

Mar 25, 2017 | 09:41 PM

ALBUQ F-1

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From: NM

40 wt won't help, you want 20 or 30 wt this time of year, or quality 10w30. You aren't running non-detergent are you? It might help to dump a bottle of Sea Foam in the oil and run it for 100 miles, then drain. Or slowly drip some Sea Foam or Marvel Mystery Oil down the carb while rev'ing the engine. (It will smoke pretty bad!)

It might be worth pulling the intake manifold to get a look inside the valve chest. If it's full of sludge, no miracle chemical will help. Have you dropped the oil pan?

Mar 26, 2017 | 12:38 AM

Mixer man

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From: Bothell & Silverdale, WA

18 to 20 inches of vacuum is good. Try using a dampened vacuum gauge such as a Motor Minder or a regular vacuum gauge like you would install under a dashboard.

Mar 26, 2017 | 06:50 AM

cowdog86

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From: Miles City, Mt

The 40 w is a straight weight , diesel oil. Plenty of detertgent. I use it because I have the opportunity to buy slow moving inventory from c stores/ farm stores. I buy oil for 1.oo/ gallon. Yes , that's 25 cents a quart, and this straight weight diesel oil don't sell anymore, so I grab al i can get for my old tractors and pickups. I do manage to snag an 5 gallon pale of 90w every now and then. Sometimes i have to take some odd stuff like 20w 20 to get what i want. The truck sits in a heated shop when not in use, so starting isn't an issue. It is a quality name brand for my area. Anyway, the guage is dampened and I did oull the cleanout plug on the pan and clean the screen. It had some crud in it but all in all not too bad for a 60-70 year old motor. I think I will try the seafoam / 100 mile thing first. Right now I have too much other stuff in the shop. My 51 ford 8n is getting rebuilt and. 51 chevy 3100 is on deck after that. Thanks for you advise and suggestion guys.

Mar 26, 2017 | 07:34 AM

cowdog86

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From: Miles City, Mt

One question I need answered is this. If I installed an in cab vacume gauge, what would be a good reading on it for highway speed? I have the super low rear end and 50 mph seems ok. I read somewhere on line and I can't find it.