timing marks 351m
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timing marks 351m
hello every one! my 79 4x4 150 has a 78-351m/400?auto trans,newer holley,electronic ignition headers but stock motor. real bad hesitation at idle when you hit gas. i think timing is way off.my balancer after being cleaned can only see little ,lines i guess but nonumbers-letters.dont know what timing should be or how to read them lines.i'm working on pict. of that and my 96-250
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Joined: Mar 2004
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From: Alabama
Timing could be the issue but be sure that all the vacuum ports are connected correctly. The two on the front are for the PCV valve and transmission... If you have the PCV plugged to the back port you have a vacuum leak. The top front little port is for the vacuum advance so if you’re not using it make sure it's plugged. If all that is correct take a closer look at your carb adjustments; accelerator pump, floats, idle air fuel mixture...
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Senior User
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will check that today, had prob. since changing carb and dist. tried standard dist. same prob so put elect back in. i no pcv is hooked to back of carb, will change that , other v/c has opening i think went 2 old air breather and is still open. vacum at idle is 16-18.
Lead Driver
Joined: Nov 2006
Posts: 5,217
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From: Pa.
The harmonic balancer is always suspect with regards to timing marks because the inner and outer parts are cushioned by a layer of rubber .. What happens after exposure to oils and natural road dirt the rubber breaks down and the outer ring which has the timing marks can spin on the inner throwing the marks off .. Replacing it with the new and improved version is the way to go eventually .. a replace the seal in timing cover while your there also ..
Learn to use a vacuum gauge it will be the best $25.00 you ever spent on your truck Carburetor Tune Up Guide - The Carburetor Doctor
Learn to use a vacuum gauge it will be the best $25.00 you ever spent on your truck Carburetor Tune Up Guide - The Carburetor Doctor
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Mista_Presley
1973 - 1979 F-100 & Larger F-Series Trucks
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Apr 15, 2002 01:35 PM
