poor idling
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poor idling
I have a 81 f150 with a 351 cleveland in it and ive had some problems with it idling. It start up fine and will idle fine for about 10 minutes of driving and then it starts idling poorly. When im stopped at a light after a few seconds the rpm will drop a little and then go back up and it will keep doing this until its jumping up and down in rpm and it stalls. It will always start up fine after this. The guy I bought it from said the seal between the carb and manifold leaks and causes to do this, Do you guys think this is the problem, any other ideas?
thanks
thanks
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It could be that seal.... definitely a vacuum leak, take some ether and spray it near that carb (SPARINGLY you don't want to cause a fire!) if it idles up then theres your problem.
IF not spray near the base of the manifold it may be the manifold gasket. Look for cracked or torn hoses, and listen for vacuum leaks.
IF not spray near the base of the manifold it may be the manifold gasket. Look for cracked or torn hoses, and listen for vacuum leaks.
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Joined: Dec 2002
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From: chicago burbs
could be a bad hose coming from a thermovac switch, after the switch goes into "hot" mode the idle goes out the window.
could even be a marginal head gasket just starting to go, have you looked at the plugs lately? a sparkling clean plug is a sign of coolant in the chamber.
i hope it's just a hose for ya...
could even be a marginal head gasket just starting to go, have you looked at the plugs lately? a sparkling clean plug is a sign of coolant in the chamber.
i hope it's just a hose for ya...
Last edited by grclark351; Apr 20, 2007 at 11:25 AM.
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the carb gasket seems to be the problem. when i took the carb off, the gasket on the manifold was burnt up and completly wrecked. I will replace the gaskets get everything back together and see if it runs better on wednesday
thanks for all the help
thanks for all the help
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How do I know if the EGR is the problem? When I take off the carb spacer i can see the route for the exhaust gases, where is the valve. I don't know to much about this so the help is apreciated
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Lead Driver
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From: Albuquerque
I don't recall the last year for the 351M, you may have a Windsor 351 but not a 351C unless someone put it in there. On the 351m/400 there is a boss under the carb that the EGR mounts to, on the back.. It can burn out it's passages from the exhaust gasses. It doesn't take much to warp/erode the mounting surface.
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It is a 351c Im not sure what its out of (couger or mustang) I asked my mechanics teacher about the egr valve and he took a look at the manifold and says its been blocked off so I dont think its causing the vacuum leak. I didnt get to finish with the gaskets today so hopfully tommorow or friday it will be done
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I got everything back together and its running fine for now, The real problem i found was that the base on the carb is cracked so air was getting in the front right corner. Its running but i know that i wil have to deal with this pretty soon.