1977 351M Carb Question, F150

cyoung

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Joined
Apr 7, 2005
Location
Gibsonville, NC
Thinking about going through the carb to try and get it running better. Called my local NAPA and they want a part # off the carb. The carb is still installed and I don't see anything that looks like a part # on it. Anybody know what kit to ask for?
 
Might be able to back in to a part number through rock auto website
 
If it's a 2V... will be a Motorcraft 2100 or possibly 2150 (same carb w/ "altitude compensation")

99.9% of all the rebuild kits I've used/seen had enough extra gaskets/giblets to work on any of them.
 
^^^This...should be something stamped on choke horn. If it's a swapped autolite from years ago, sometimes those just had a buck tag that are typically long gone. But if it's stock...Motorcraft 2150 rebuild kit will have what you need. Even if not stock 2bbl, should still be stamped on the choke tower.
 
X whatever all of the above. I picked up a carb kit for my 78 from advance it listed three different numbers but they had one on the shelf all for the 2150 motorcraft 2 barrel. I said give it to me, and it worked even had gaskets left over.

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When I did the 2150 on my '78 F-250, the kit had several extra gaskets, differing in size, for multiple versions.

Good luck!

Luckily, you can almost rebuilt these carbs with a butter knife.
 
Sorry guys, I should have said it is a Motorcraft carb and looks like the stock 2b. I'll look for the 2100/2150 kit.
Thanks for the responses!!


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Well the Bronco has been sitting for a while due to my frustration with it! I went through the carb, put it back together, fired it up and it sounded pretty good. Pulled out of the garage to take it for a spin and headed down the road pretty excited; until....... About a quarter of a mile down the road it went "bang" with what sounded like a big back fire. After that it would crank and barley run but wouldn't get above a few hundred RPM and it wouldn't stay running. Pulled it back to the house and have been messing with it off and on ever since, several months now. It is getting gas but seems like a very weak spark. So far I have replaced the ignition module (actually tried a couple different ones), the coil, the pick-up in the distributor, the wire to the coil from the dist cap and the dist cap and rotor but the problem persists. Also checked and cleaned the ground from the block to the fire wall and looked for loose connections all over. Since this motor was recently transplanted into the Bronco, I'm wondering if something has come loose somewhere but I cannot find it and am getting tired of not being able to get it to run!!
Bottom line is I could use some help. Any suggestions? Could any of you Ford experts come take a look at it with me? I'm not asking for free help. If you know these 70's Fords and aren't too far away, I'm willing to pay you for your time; cash, beer, maybe a real good deal on a 77 F150 I want to get rid of or some other stuff I may have around.....:)
Any input is appreciated!
 
Chances are if it's never been opened up the timing set is streched.

I've found most of my "carb" issues have been ignition. Verify tdc on number 1 cylinder and check your timing marks. Then put a timing light and check initial, mechanical all in, and then with the vacuum advance hooked up make sure the vac advance work.

Once your timing is good put a vacuum gauge on it and tune the air bleeds for max vac and rest the idle. You may have to go over all three, timing, vac, and idle a few times.

Then see how it does. I haven't played with a 2 barrel in a long time to know if it has a power valve that may have blown.

Hope this helps.
 
Might also pull the carb off and check to make sure there are no screws missing that could have gone down the intake and bent a valve or two.
 
Checked to be sure distributor isn't moving and it OK.
Used a screwdriver through the spark plug to confirm Top Dead Center on #1 piston. Not the most precise way to do that I guess but I have it pretty close and the timing mark lines up at about 5° ATC.


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So doesn't sound like a timing backfire...which means it has to be fuel. Shot in the dark but can you tell if there are any leaks/excessive fuel at the butterfly rods? That's all I got if the carb is tuned right and timing is good, a hidden dump of fuel after it warms up. Have you tried any known good carbs???
 
I haven't tried any other carbs and don't have one available. I guess I'll take another look at that and pull the carb off as suggested above.
You may not have seen my comment in post 8 about "weak spark" but I keep thinking that is at least part of the problem. I just don't know what else to look at. When I pulled #1 plug earlier today it had unburned gas on it, at least that is what it looked/smelled like.
I'm probably missing something really dumb.
 
cyoung said:
Checked to be sure distributor isn't moving and it OK.
Used a screwdriver through the spark plug to confirm Top Dead Center on #1 piston. Not the most precise way to do that I guess but I have it pretty close and the timing mark lines up at about 5° ATC.

So with number 1 at tdc your marks should be at 0. So look into that, then once tdc is confirmed re mark the pulley to have just a tdc mark.the balancer may have slipped but that's ok with the dial back timing light.

The use a dial back timing light and confirm inital, mechanical, and vacuum advance. Should be something around 10* initial and 36-38 all in mechanical. Once ignition is good then look at your carb.

All the timing stuff is free to do. Start with ignition 1st.


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Click to expand...
 
I don't think you are missing anything. Your observations lead me to believe it is an ignition problem from the way it quit running and the spark plug smelling of gas. I don't know anything about Ford ignition systems to help there. I would pursue ignition issues.
 
Thanks guys! Hopefully I can get back at it in a couple of days unfortunately my garage isn't heated so the weekend isn't looking so good...... it's gonna be cold!


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Check out this thread by ratlabguy: Testing distributor

Towards the end of it someone posted about test procedures for the duraspark system. Also Ive seen weak spark if the stator (the 8 arm octopuss thing) looses its magnetic field. It should be very weakly magnetized, you should barely feel a pocket screwdriver or paperclip attract. A weak coil or a coil with the primary wires hooked up backward will have a weak spark, also.

Just a few more things to check out.
 
Would it have the same Motocraft Ing. that Jeep ran? Mine got weak & then nearly died on my 79 CJ. A shop with the proper tester found that out. That's when I bought the MSD unit.
 
Back to the Bronco.....
Today I'm checking things out and see that when #1 cyl is at TDC, the distributor rotor is pointing close to #2 plug wire. I guess I'm looking at a timing chain at least. Hope something else didn't get screwed up!!
 
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