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carb stumble

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badmav70 View Drop Down
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    Posted: 04-September-2013 at 1:55PM
nice too meet you all. im new and im having trouble with my 77 ltd ii. it has the 351m motor with the 2bbl that for the most part runs great. but i cant get rid of the carb stumble from a dead stop. the thig that has me really confused is my adjustment screw is out like 6-8 turns and it doesnt change. ive never had a carb like that. just had the carb rebuilt by my brother about 2 months ago, just swaped out the accel pump today and still no change....

cant seem too find any vacume leaks. dont want too tweek the timming cause otherwise the car rund great.... and seggestions? its keeping me from driving the car cause every now and then it will pop up threw the carb and/or stall


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Robbdtme View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Robbdtme Quote  Post ReplyReply Direct Link To This Post Posted: 05-September-2013 at 12:03PM
How bad was the accel pump diaphram? On the bottom is a power valve one that the rubber part gets really stiff too.
Johnny cash Special 74-75-76 freak. 77 XR7. 78 LTD II sport looks pretty but poop 302 in it.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote badmav70 Quote  Post ReplyReply Direct Link To This Post Posted: 05-September-2013 at 1:52PM
the acel pump was changed 3months ago when my brother rebuilt the carb. i did it again cause it was the cheapest start. i am unsure about the power valve he said he changed that too.. im guessing id have too pull the carb off too changed it again? or can it be done on the car?

another strange notei pulled out the one mixture screw i can see and shot some carb cleaner in it, put the screw back in and strangly it ran great no hesitation i took it for a ride and it scared the crap out of me the power it had. but after the next stop sign it was back too the stumble... a few people i talked too said the 351m is known for valve trouble but i have a hard time thinking that cause otherwise it runs great.
77 ltd II

78 monarch

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badmav70 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote badmav70 Quote  Post ReplyReply Direct Link To This Post Posted: 05-September-2013 at 1:56PM
this is my 77 LTD II

Edited by badmav70 - 05-September-2013 at 1:58PM
77 ltd II

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aquartlow View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote aquartlow Quote  Post ReplyReply Direct Link To This Post Posted: 05-September-2013 at 3:00PM
Badmav70, Nice ride you got there!
Dealing with the carb issues, it sounds like you have debris making it's way into the carburetor, possibly clogging the accelerator pump circuit and/or the mixture screw orifices. It has been a while since working on a 2100/2150 Motorcraft though.
www.supermotors.net/22468
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JoeKarasinski Quote  Post ReplyReply Direct Link To This Post Posted: 05-September-2013 at 4:43PM
Just a thought, Check the intake manifold gaskets. try to cover the top of the carb with your hands while its ideling and it should stall. if it doesn't you're sucking air from some where. probally arounf the intake.
 
My windsor only has 60,000 on it and we found this problem on it.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote n2fordwagons Quote  Post ReplyReply Direct Link To This Post Posted: 06-September-2013 at 12:34AM
Welcome!  Great looking LTD II.  I just sold a '77 LTD II Squire wagon, with the exact same problem.  I did replace the accel pump, but that's as far as I got, before I sold it.  When mine would stumble, I could hear a faint high pitched "whistling" from under the dash.  I was going to dig into troubleshooting vacuum next.  Good luck!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Robbdtme Quote  Post ReplyReply Direct Link To This Post Posted: 06-September-2013 at 4:40AM
Here is a stupid one I did myself..  The accel pumps 4 screws are different lengths, I didn't pay attention and had a longer one in a shorter ones position. It poked right through the carbs float bowl area and was hitting the float preventing it from working and filling properly. You can remove just the top of the carb while still installed and look at it. Hopefully this didn't happen.

Never heard of 351M valve problems
Johnny cash Special 74-75-76 freak. 77 XR7. 78 LTD II sport looks pretty but poop 302 in it.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote badmav70 Quote  Post ReplyReply Direct Link To This Post Posted: 06-September-2013 at 3:04PM
thanks for the compliments. its a little rough around the edges but i like it.. now that you mention it i tried the chokeing out the carb trick the other day and it didnt effect it as in would not stall. so i was figureing vac leak issue but for the life of me i couldnt find any. but thats what i will try too focus on. would that normally cause the popping threw the carb? i did notice that the accel pump screws were difernt sizes though
77 ltd II

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Post Options Post Options   Thanks (0) Thanks(0)   Quote badmav70 Quote  Post ReplyReply Direct Link To This Post Posted: 06-September-2013 at 3:08PM
any good tips for finding vaccume leaks? heard bout spraying carb cleaner and listening too the the motor rev.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Robbdtme Quote  Post ReplyReply Direct Link To This Post Posted: 06-September-2013 at 7:38PM
Popping back is running lean in your case. I think.
Nice LTD II BTW!
Johnny cash Special 74-75-76 freak. 77 XR7. 78 LTD II sport looks pretty but poop 302 in it.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Big Bird Quote  Post ReplyReply Direct Link To This Post Posted: 07-September-2013 at 6:51AM
Check your intake manifold. I'm not sure about cleveland/modified engines, but windsor motors need the intake retorqued every so often. the bolts lose torque and this can lead to vacuum leaks into the lifter valley.
The above post should be read in a "Grumpy Old Man" voice.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rockatansky Quote  Post ReplyReply Direct Link To This Post Posted: 07-September-2013 at 7:29AM
do you have about 7 miles of vacuum hose under the hood?
 
even if you only have 5 miles there can be a leak anywhere along any of them
 
as mentioned popping through the carb is a symptom of running lean, which is in turn a possible result of a vacuum leak. is there an EGR plate under the carb? they're known to either clog with carbon or burn through & leak, or both. they also present an extra carb base gasket that many people Never replace, or replace with a wrong type material. the gasket between the manifold & EGR plate needs to be exhaust rated, much more durable & temp resistant than a regular carb gasket
 
the carb clean into the mix screw hole does suggest that you may have a contaminated gas tank, you might want to place an easily serviceable / replaceable filter either before or after the pump. right before the pump in the rubber line is an easy spot & works well except for serious performance applications, after the pump you should have steel line & can be quite crowded.
 
sounds like it's time to flush that carb out on the bench again? have you used Berryman's carb dip?  
 
what happens is the jank in there somehow starts growing and separates the gasket, then it sucks air & runs lean. not saying for sure this is what you got goin on but something to check
 


Edited by Rockatansky - 07-September-2013 at 7:38AM
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Rockatansky View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rockatansky Quote  Post ReplyReply Direct Link To This Post Posted: 07-September-2013 at 7:40AM
another thing to check would be whether or not your vacuum & mechanical advance in the distributor are working properly
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 75GranMan Quote  Post ReplyReply Direct Link To This Post Posted: 07-September-2013 at 12:33PM
 check for a burned through EGR spacer plate.
John 75Gran Torino 4spd
Tighten it down until it snaps and then back it off a half turn!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ThunderOnTheRoad429 Quote  Post ReplyReply Direct Link To This Post Posted: 07-September-2013 at 2:34PM
I would disconnect the fuel line to the carb and run it into a soda bottle,  start the car and let it run untill it uses up all the gag in the bowls.  At this point the carb will open up and let and debris flow past.  Then reconnect the fuel line and check out it's performance.  This doesn't cost a thing and just might take care of the problem.
Waylon & Buddy
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Post Options Post Options   Thanks (0) Thanks(0)   Quote badmav70 Quote  Post ReplyReply Direct Link To This Post Posted: 07-September-2013 at 4:21PM
thank you all for the seggestions i will try messing with it again some tomorrow afternoon. and try a few of the segestions. will keep you all posted
77 ltd II

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Post Options Post Options   Thanks (0) Thanks(0)   Quote badmav70 Quote  Post ReplyReply Direct Link To This Post Posted: 08-September-2013 at 12:04PM
well i messed with it a little today found some vacume that was routed kinda messed up. egr was hooked too something with no vaccume and the vac advance was not getting any either. so its running much better so far, will know for sure when it cools down and i get more gas in the tank lol.
77 ltd II

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