need carb help...
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New User
Joined: Mar 2003
Posts: 1
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need carb help...
ok i got myself a 77 f250 2 wheel supercab witha 400 and a rebuilt motercraft carb..i got it last week the truck is in great shape body wise and the moter is a freash rebuild but it runs like crap i did all the new ignition parts plugs wires blah blah blah ...then i was looking at the carb and the messed up looking pate under it.. it just dont look right ,right under the carb its got the thick gasket and then a spacer plate that looks to small then under the spacer plate its got a small gasket with GASKET SEALER around it... i didnt like the looks of that..anyways can someone tell me how this is supposed to look and also if there is somewere with vaccum diagrams online thats a mess also.. well thats all for now. 
Posting Guru
Joined: Sep 1999
Posts: 2,297
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From: Indiana
need carb help...
The spacer plate you mention is the EGR valve spacer plate. That is if someone has not tried to make one of there own to block it off.
Is there a round looking vacuum diaphram sticking out from the back of the plate? If so, this is the EGR valve.
The thick gasket does go under the carb and a thinner one between the EGR plate and the intake manifold.
It could be sucking air under the EGR spacer plate. Spray some W-D 40 around the base of the carburetor and the intake and the spacer plate while its running. If the idle speed increases or the idle improves, you have found a vacuum leak. Spray along the intake manifold and the heads too, this will let you know if the intake is leaking.
Is there a round looking vacuum diaphram sticking out from the back of the plate? If so, this is the EGR valve.
The thick gasket does go under the carb and a thinner one between the EGR plate and the intake manifold.
It could be sucking air under the EGR spacer plate. Spray some W-D 40 around the base of the carburetor and the intake and the spacer plate while its running. If the idle speed increases or the idle improves, you have found a vacuum leak. Spray along the intake manifold and the heads too, this will let you know if the intake is leaking.
