36 Ford truck on Ranger
- Thread starter MercuryMac
- Start date
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bob w
Still crazy after all these years!
One of my favorites.[cl
Torchie
Well-known member
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Torchie
Torchie
earthman
Fascinated by rolling objects!
Well? .... Be really good to see some pix of it out and about Mac.
MercuryMac
Builder Junky!
Thank You, Guys.
I think I have the gremlins out of the tune-up systems, but I had turned on both heater hose water valves, last winter, and the one hidden behind the heater will not shut off. I'll get'er beat into shape eventually.
The problem with the poor running engine was the power valve in the centre carb. I had blocked off the two secondary carb power valves but left the centre one stock. Well, a spring holds the valve open dumping in gas to the venturi, but if you have enough vacuum in the intake manifold, the vacuum will override the spring and shut the power valve. Then you will have the right amount of gas going into the venturi from other carb systems. If you have a racing cam, even a mild one, you might not have enough vacuum to shut the power valve, so your motor floods all of time.
I think I have the gremlins out of the tune-up systems, but I had turned on both heater hose water valves, last winter, and the one hidden behind the heater will not shut off. I'll get'er beat into shape eventually.
The problem with the poor running engine was the power valve in the centre carb. I had blocked off the two secondary carb power valves but left the centre one stock. Well, a spring holds the valve open dumping in gas to the venturi, but if you have enough vacuum in the intake manifold, the vacuum will override the spring and shut the power valve. Then you will have the right amount of gas going into the venturi from other carb systems. If you have a racing cam, even a mild one, you might not have enough vacuum to shut the power valve, so your motor floods all of time.
MercuryMac
Builder Junky!
Today I finally got the hidden water valve closed again and the heater back in its place and bolted down. What a horrible job! Who made this truck so 'user unfriendly', that rotten b ------- Oh wait----?
Old Iron
Well-known member
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MercuryMac
Builder Junky!
As I've said, my truck runs nicely, but it burns too much gas, I think. So, today I took apart an old power valve and cut two coils off of the spring so it should be weaker. Now, my lighter vacuum should be able to hold it shut. I haven't installed it yet.
earthman
Fascinated by rolling objects!
.....interesting [P
DozerII
Well-known member
I wouldn't worry about the gas MM, they make more every day.
Bamamav
Well-known member
Wouldn't cutting the coils make it stiffer, just like cutting the coils under a front end?
MercuryMac
Builder Junky!
I don't think so, Bama. In my way of thinking cutting a couple of coils off and stretching it a wee bit will make it weaker.
Dozer, you obviously don't know any Scottish people. Anyhow, I've made my living off the oil companies for forty-five years, so I should be a little bit bighearted towards them, I guess. I do want to figure this power valve thing out though.
Dozer, you obviously don't know any Scottish people. Anyhow, I've made my living off the oil companies for forty-five years, so I should be a little bit bighearted towards them, I guess. I do want to figure this power valve thing out though.
BlueNorther
Well-known member
think of a coil spring as a wound up torsion bar, for a given diameter, the longer the bar the softer it is.
every time you shorten a torsion there is less material to twist, thus making it stiffer.
the same holds for a coil spring, removing coils, will increase the lbs per inch rating.
and stretching it makes it even stiffer.
every time you shorten a torsion there is less material to twist, thus making it stiffer.
the same holds for a coil spring, removing coils, will increase the lbs per inch rating.
and stretching it makes it even stiffer.
MercuryMac
Builder Junky!
Luckily I tried that trick on an old valve that is too sticky so I've decided not to use it. I will have to order a new one that has a weaker spring.
My thinking was different than yours. The little spring is compressed a bit even at its longest so I thought cutting two coils off would release the tension, causing less pressure.
My thinking was different than yours. The little spring is compressed a bit even at its longest so I thought cutting two coils off would release the tension, causing less pressure.
MercuryMac
Builder Junky!
So, I went to town to order a new softer power valve. Surprise #1, there was a 3.5 inches of vacuum valve hanging on the rack in the auto store. I had a 4.5 inch one in the truck, so 3.5 should be good.
Today I took the centre carb apart and surprise #2, [see picture]. The little port in the base of the carb that the power valve sits in was full of gas, [the front round depression]. It is supposed to be a vacuum chamber. That gas was being sucked right into the intake all of the time the motor was running. The gasket on the 4.5 valve was not sealing right. I now, have put the 3.5 valve in with a different gasket and tightened the bejepers out of it with a big wrench. It is almost stopped leaking, now.
Today I took the centre carb apart and surprise #2, [see picture]. The little port in the base of the carb that the power valve sits in was full of gas, [the front round depression]. It is supposed to be a vacuum chamber. That gas was being sucked right into the intake all of the time the motor was running. The gasket on the 4.5 valve was not sealing right. I now, have put the 3.5 valve in with a different gasket and tightened the bejepers out of it with a big wrench. It is almost stopped leaking, now.
Attachments
Torchie
Well-known member
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Torchie
Torchie
DozerII
Well-known member
You might be able to get past the gas stations now.
MercuryMac
Builder Junky!
Hopefully, Dozer.
The more I thought about the bunch of gas in the vacuum chamber, the more I thought, that gas shouldn't be getting in there, and, gas shouldn't be staying in there. I better take more of this carb apart and see why gas wasn't escaping into the intake very quickly. [S[S[S
The more I thought about the bunch of gas in the vacuum chamber, the more I thought, that gas shouldn't be getting in there, and, gas shouldn't be staying in there. I better take more of this carb apart and see why gas wasn't escaping into the intake very quickly. [S[S[S
bob w
Still crazy after all these years!
The power valve calibration should be half the idle vacuum reading. Example: idle vacuum is 13.0, so power valve value should be 6.5.
MercuryMac
Builder Junky!
Bob, before I really dug into the carb, I thought the spring was too strong for the vacuum to overcome it, but now I see two other problems. The valve was probably all right, but the gasket seal was not sealing. I brushed the sealing surfaces with a file and found a different style of gasket, tightened the valve in there and tested it with gas in the bowl. Second problem, there was a chunk of crud in the vacuum channel in the carb base. The crud would let vacuum suck gas into the intake, but not let gas run [unhelped] in. I took the truck on a test drive, but there was two different kinds of construction on the mile and half of county road between my place and the pavement, so the test drive was short, but successful.
