71 351C 2V Carb Replacement

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patrickob17

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Howdy,

My dad and I got his 71 mach 1 firing again over Christmas break, but for some reason any time we shift from park to reverse or drive it automatically dies. At this point we think something's up with the Carb and it just needs to be replaced after 47 years. What's the best carb to replace a 2-barrel Autolite 2100, H-Code with? I've been reading a lot about what people are saying worked for them and Holley seems to be the way to go, whether it be a street demon or quick fuel or what; can I replace it with a 4-bbl carb with limited added modification? What have y'all done or heard that works best? 

Thank you! 

Also y'all will love this, the previous issues we were having where it would smell like gas and never run right before the oil pump jammed were due to the fact that the mechanics who worked on the electronics of it to get it going not only completely mistimed it but switched the 3 and 7 on the distributor so it was firing out of order this whole time.

 
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If you want to go from a 2bbl to a 4bbl carb you will need to replace the intake manifold as well. Are there any other mods to the engine such as Cam, head work, etc? Also what is the drivetrain? You said automatic with an H code so more than likely an FMX trans, what rear gear ratio? All of these should be taken into account when making any modifications so everything you have works together.

 
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I would rebuild the 2-barrel carburetor and get it running right before going the 4-barrel route. After sitting for a long time there may be other issues you'll need to take care of also.

If you press down the accelerator pedal a little or feather/pump it while shifting into gear can you keep it running?

It could be a number of things, other than carburetor, including vacuum leak(s), timing, spark plugs, points, torque converter, and transmission.

 

patrickob17

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@73Pony, there are no other mods or anything like that, I don't know the specifics on the rear gear ratio, but it should just be your standard factory conditions.

@Don C, rebuilding the carb is something we talked about doing but think that replacing it might just be the better route, are there any new 2-barrel carbs that would work well with what we have? If we power-brake it you can drive it, but you always have to at least have your foot on the accelerator to do so. Timing, point, and spark plugs were just reset and everything should be fine there. Don't know about torque converter or transmission, however we had it running and driving (not incredibly well, but we now know that's because the distributor firing order was off) this past summer and didn't have any real issues until the oil pump jammed when the sump screen failed to pick up a piece of hardened oil. So I would think the torque converter and transmission would be fine, but I can't say that I've thoroughly inspected them.

 
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Just a thought. Does the car still have the original door data plate (sticker) on it, drivers side? if it does, can you either take a picture or post what the codes are at the bottom. This will tell the experts, what exactly you have, trans, rear axle etc., unless of course somebody has changed things.

A picture speaks volumes.

 
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patrickob17

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Yeah absolutely, but I'm already back at school and my dad won't get home until later this afternoon so I'll post it once I can get the picture from him!

 
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Yeah absolutely, but I'm already back at school and my dad won't get home until later this afternoon so I'll post it once I can get the picture from him!
 Sounds good. We look forward to seeing it and hopefully giving you some better information.

Do you have a Marti Report for your car? If not, well worth getting one from martiautoworks It will tell you the whole story on your car.

www.martiauto.com

 
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patrickob17

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Alright, I've attached the picture that should have all of the information that was missing beforehand



 
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patrickob17,

It also could be the choke is worn out, Distributor vacuum canister could be bad. The vacuum canister on the distributor advances the timing during cold starts to help the engine warm up. Also, the stock factory setup had a stove pipe to the bottom of the air cleaner to help with warming the carb/air for cold starts. Check you vacuum hoses.

 

Bill73Ragtop

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former owner (25 yrs) of 1973 Convertible, 351c, A/C, RA
Stalling when you put a load on the engine is a sign of a vacuum leak. Might be carb base / gasket or other open source.

 
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We got the picture of the data plate and it's decoded for you. While this is going off the topic intended for engine and drive train, I'm putting it here so you can find it. There are a couple of other gems your car may still have on it that would offer a load of other information about the car.

Under the COIL hold down bolt, is there still a small aluminum tag? This is the engine tag. If it's there take care of it, but post a pic if you can.

On the front of the Radiator support, on the left side, looking at it from the front, is there a tag held by 1 screw? This is the BUCK tag. Again take a picture and post it.

One thing I meant to say when I first asked about the door data plate, was to obscure the vin #. While I don't think any of us members would be dishonest, there is no knowing where this information might end up. Sorry about that. We all need to be very careful about anything personal. Maybe I'm just getting paranoid in my old age, in an unfamiliar electronic era!

 
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We got the picture of the data plate and it's decoded for you. While this is going off the topic intended for engine and drive train, I'm putting it here so you can find it. There are a couple of other gems your car may still have on it that would offer a load of other information about the car.

Under the COIL hold down bolt, is there still a small aluminum tag? This is the engine tag. If it's there take care of it, but post a pic if you can.

On the front of the Radiator support, on the left side, looking at it from the front, is there a tag held by 1 screw? This is the BUCK tag. Again take a picture and post it.

One thing I meant to say when I first asked about the door data plate, was to obscure the vin #. While I don't think any of us members would be dishonest, there is no knowing where this information might end up. Sorry about that. We all need to be very careful about anything personal. Maybe I'm just getting paranoid in my old age, in an unfamiliar electronic era!
Thats answered a question before i asked it ::thumb::  Now i know where the engine tag goes. My carb tag is in the right place. I just need to know the exact positioning of the axle tag and buck tag

 
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The buck tag on all my 73 mustangs is on the drivers side front of the radiator support, partially behind the headlight bucket. Pics of the buck tag, axle tag and while we are at it the C6 transmission tag locations.







 
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Thats answered a question before i asked it ::thumb::  Now i know where the engine tag goes. My carb tag is in the right place. I just need to know the exact positioning of the axle tag and buck tag
 Steve, My reference was for a 71 Mach1. Yours may not be the same, can't remember the year of your car. Tags got put in different places apparently on other years.

 Do you have a copy of Kevin Marti's book "The Mustang and Cougar Tagbook" (1965-1973 models). It's a mine of information. It can be ordered off their website I'm sure. www.martiauto.com

They can reproduce tags for most applications if you prefer to do that and keep your delicate originals in a safe place.

Geoff.

 
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