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Discussion Starter · #1 ·
Ok I posted this a week or so back and after trying all the cheap fixes or in my case not so cheap (of coure the bolt broke while changing the thermostat and it broke the housing with it). My 304 resfuses to idle below 1500 until it is good and hot/wwwthreads_images/icons/crazy.gif. This only happens when the temp is near freezing/wwwthreads_images/icons/blush.gif. I have checked the choke and it is operating, I've checked all the vaccum lines and they all appear to be intact. The only thing I have noticed is a small exhaust leak on the pass side, from where the manifold meets the Y pipe. Any suggestions would be greatly appreciated. TIA
-Marky

80 CJ-7 Laredo 304v8 TF999 3.73's BFG M/T's
 

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I don't recall the other post........so I'll ask you.......have you checked the flapper (the thing that rattles on the end of one of your exhaust manifolds)? Is it moving freely and is the bi-metal coil sping intact? This is identical to the trouble I had when I first put headers on my SBC 25 years ago......I left the "heat riser" (as it is sometimes refered to) off of the installation. Since it was summer when I put the headers on ........no problem. I took my parents up to Mass. and encountered some 35-40 degree weather .....and the thing would not idle until it fully warmed up. I then realized that the flapper channeled hot exhaust gas through a port that passes through the manifold under the carb .........once the bi-metal spring heats up......it opens fully and the port goes dead since it's now "balanced"......since the flapper is "sprung" ...it opens when exhaust flow increases ..but still "inhibits" full flow until its warmed up. This would be where I'd look if all the "normal" remedies fail you.

(didn't CJDave ask you this ? .....maybe I do recall that post- I don't believe that you answered him)

GeeAea

 
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Discussion Starter · #3 ·
yeah CJDave answered, he suggested the theromstat was opening too soon or was the wrong temp. looking back at the post he also suggested the flapper, but I knew nothing of them so I figured I go with the easiest thing first, which turned out to be a whole lot of fun, and I forgot about the flapper/wwwthreads_images/icons/blush.gif.
-Mark

80 CJ-7 Laredo 304v8 TF999 3.73's BFG M/T's
 
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Discussion Starter · #4 ·
are you sure the fast idle cam on the carb isnt gummed up and sticking when its real cold? Or maybe the choke is just set to rich
keeping fast idle cam on? I know on my 258-BBD i have to set the choke just far enough for it to close and no more,any more tension than that
and it stays on fast idle a long time, and sometimes trys to choke itself out when its cold,not nearly as bad in warm temps.
Question,will it kick to idle if you tap the pedel to the floor ? yes-has to be the carb,no-still could be sticking carb parts.just another 0.2 cents

 
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Discussion Starter · #5 ·
the carb was professionally rebuilt in may, this guy is real good, he came highly recommended and he has done some incredible things on my buddies mustang. I keep my engine compartment very clean (when I have the time) also there is no problems when it is over 35 degrees. And it doesn't drop to idle if I unload the carb.
-Mark

80 CJ-7 Laredo 304v8 TF999 3.73's BFG M/T's
 
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Discussion Starter · #6 ·
Did you do a visual check of the fast idle cam position? not to keep barking up the same tree,but one thing ruled out at a time

 

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The exhaust leak is a bad "donut" gasket but I don't think it is the problem.
It might be that your throttle cable is sticking. Try spraying WD 40 on it. It might free it up. Good Luck!!

PS Mark, something like your thermostat adventure happenend to me too. We all live and learn....

 
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Discussion Starter · #8 ·
What model carb are you running? Do you have stock ex manifolds or headers? If manifolds, do you have the air tubes attached? Is the rest of the ign. stock? Not sure how likely it could be, but how long since you took off the rotor? Maybe you have a little too much thick grease in there messing up the vac advance that you don't notice until it is cold enough to make the grease a little thick. Seems like all the logical answers have been hit so I'm trying to come up with something a little more out of the ordinary since they havn't worked. I'm home in another 3 days, got a mechanic friend who is one of the best I know. I'll ask him about it if you still don't get it.

 
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Discussion Starter · #9 ·
It's bone stock with the motorcraft 2100 carb. It was raining today so I didn't get to check the flapper. I was looking for it (flapper) in the haynes manual and saw something about the CTO (coolant temp override) switch. it says
In reply to:

The symptom of a faulty CTO switch is sluggish operation when the engine is cold, becuase the vacuum is not reaching the distributor to actuate the advance mechanism
That is also a problem until the idle comes down. They're about $25. So if the flapper isn't it I think that is the next logical step/wwwthreads_images/icons/crazy.gif.
-Mark

80 CJ-7 Laredo 304v8 TF999 3.73's BFG M/T's
 
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