86 250
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86 250
Hey guys, new on here and to the ford world, have an 86 f250 with a 460 I bought for dirt cheap and I think I'm finding out why. The guy put a 600 c.f. carb on it, it idles great revs good in park but driving down the road if you get into the secondaries it spits and sputtered and wants to die, I have 6 to 7 psi at the carb with fuel and there is no cat on it so I'm kinda at a loss
Laughing Gas
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What kind of carb?
If it’s an old Holley your secondary float bowl and passages may be full of varnish... if nobody ever got into the secondaries the gas just sat in the float bowl until it turned to varnish. Especially gas cut with ethanol.
If it’s an old Holley your secondary float bowl and passages may be full of varnish... if nobody ever got into the secondaries the gas just sat in the float bowl until it turned to varnish. Especially gas cut with ethanol.
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Just to let you know, holley's have small ports at the bottom of the throttle body in the rear to prevent this. These small ports in the rear contribute a very small amount of fuel at idle to to prevent the fuel from getting stale in the rear of the carb.
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Held the brake and put it in gear put the gas to the floor like I was trying to power brake, the truck would only get to about 1500 rpm but there was a bunch of black smoke coming out of the exhaust like it' running rich
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Hmm, I had something similar, it was because the old choke on my 2150 was stuck open.
Sadly, mine was a bit hard to fully diagnose because I had a couple of overlapping issues.
I had some leaky vacuum lines, that allowed the very rich truck to 'sound' like it was idling good even though it was running rich even at idle. I guess you could say that it was leaking so much air from the leaks that the it was evening out the choke being open.
I know my 2150 is only a 2 barrel.....I'm just sharing because the net effect was similar.
-LV
Sadly, mine was a bit hard to fully diagnose because I had a couple of overlapping issues.
I had some leaky vacuum lines, that allowed the very rich truck to 'sound' like it was idling good even though it was running rich even at idle. I guess you could say that it was leaking so much air from the leaks that the it was evening out the choke being open.
I know my 2150 is only a 2 barrel.....I'm just sharing because the net effect was similar.
-LV
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If you wanted to experiment, if you have a rubber hose to the carb, take some vise grips and pinch it off after you let the truck run a little while and warm up. Right after you pinch the line, go in there quickly and power brake it again. See if it is any different. Of course it will eventually run out of fuel, but in the beginning see if it's not pouring black smoke anymore.
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Okay, also looked at the choke to make sure it was open, closed it and it killed the motor, so seems like it' getting to much fuel and not enough air, so sounds like it could be a float issue, I have a line on a 750 holla, I might go that route. Thoughts?
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Old carbs sitting around are nothing but trouble. All the gaskets dry out and the old ethanol fuel evaporates and gums everything up. I would commit myself to one of those carbs and then rebuild it before I installed it.
You can stick it on there and roll the dice. I don't have much luck with that though.
You can stick it on there and roll the dice. I don't have much luck with that though.
Cargo Master
Joined: Oct 2005
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Vacuum advance is not very relevant in this case, you could plug it and it should still run fine. Verify base timing is ok (10* is good) and that mechanical advance is working.
Cargo Master
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