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SoK66 07-10-2013 10:51 PM

Adapting Motorcraft 2100 to CJ?
Read an interesting old JP article the othern day about the 2100. How difficult is it to adapt to a 258?

leogetz 07-11-2013 02:21 AM

I have a pretty extensive PDF document describing the install I can send to you. Its not too difficult, you will need an adapter plate though.

scrapman 07-11-2013 10:54 AM

Done a ton.

There has been an ebay guy selling 2100's for cj's for years now.

Find an old MC2100 with 1.08 venturies, buy a rebuild kit and a carb adaptor, and figure out how to deal with the linkage. It is the best modification I did to my jeep, followed by Team Rush and Nuttering it.

Use the search function and there is lots of information about this switch. Heck, even Google it, and you find tons of info.

sgtbookie 07-11-2013 09:23 PM

Linkage isn't even all that bad. Got an accelerator cable from a 304 v8 and its a straight shot to the Motorcraft. I eventually Bought some Spector or the like throttle cable holder I bolted on. Works great. If you want to retain the factory air cleaner you will have to so some modifying of it.

wendell 07-12-2013 06:56 AM

The ebay guy includes every thing you need to hook it up and detailed instruction, plus he's only a phone call away.

Ken4444 07-12-2013 12:34 PM

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Originally Posted by SoK66 (Post 15664609)
Read an interesting old JP article the other day about the 2100. How difficult is it to adapt to a 258?

It's a well documented and fairly uncomplicated process. There are several articles and posts and documents floating around about it.

You need an adapter plate to connect the 2100 to the 258 intake manifold. These are low cost and easy to find. You need the correct gaskets which are also easy to find.

You need to buy or build an assembly to attach the throttle cable. You may need to install a bracket and throttle cable attachment stud on the throttle shaft on the 2100. One consideration is do you want the cable to pull down or pull toward the firewall.

You may need a grounding wire if the automatic choke on the 2100 has a grounding tab.

One tricky area is the air filter housing. The standard air filter housing may not fit right (I don't remember the standard size off the top of my head)... 11" or 12" maybe). It might bump into your brake booster, if you have one. I ended up using a Moroso 9" housing and filter that works well for my 85' although I am roped into using their air filter replacement part.

This is the guy on Ebay who sells complete 2100/2150 kits for the 258:

You will typically pay $300+ to him so for a complete kit with a rebuilt carb, adapter plate, bolts, throttle linkage parts, etc. If you can get a 2100 or 2150 for cheap and rebuild it yourself, you can do the whole project for less than what this guy charges.

The benefit of the Ebay guy is that you make one purchase and wait for the big box to show up. He is of course selling used/rebuilt carbs, so in my experience you can expect some variation about what specifically you will get since there are a lot of variants with the 2100 and 2150. Another issue is the problem of play in the throttle shaft. When you're dealing with used carbs, you always have the potential problem of a throttle shaft that is loose and allows a vacuum leak. I would pin him down on this issue and do all you can to ensure that you're not getting a carb that has this problem. His install documentation is OK but a bit unpolished.

SoK66 07-12-2013 07:33 PM

Thanks for the link, I have him in my watch list.

I'm just curious about this. My '76 232 has a 258 2bbl manifold and a Weber. The thing runs great, but if it ever craps out I may go to a 2100 conversion for simplicity's sake.

Skerr 07-12-2013 10:49 PM

The 2100 was manufactured as far back as the 60s. There's a zillion of them out there. Check out Ford cars, trucks, and vans through '85, I think. The venturi size is stamped on the side, driver's side, IIRC. It will say 1.08 or 1.21... there are others. The 1.08 is the preferred carb, although I have a both a 1.08 and a 1.21, and I like the 1.21 better. You will need to rejet to a smaller jet size, a 46 or 47 ($10 a pair). Expect to pay $30 for a carb from the JY. Get everything associated with it from the donor vehicle. The rebuild kit will rebuild a 2100 and a 2150, so you'll have extra parts ($25). It is very easy to rebuild. As Ken mentioned, check the throttle shaft and make sure it doesn't wobble in the body. Find another if it does. Adaptor plate will run you about $20 from any parts store (Mr. Gasket #1937). I used the factory throttle cable and built a bracket. It's not hard if you can fab stuff. I'm getting good economy with the 1.21 on my 258 with Teamrush and nuttered.

SoK66 07-14-2013 09:31 AM

In the early 70s while in college I worked on a big ranch in NM that had about 30 2wd F250 pickups, 390 2bbls. All of 'em had the 2100 and we never had any common carb problems. The trucks were beaten senseless by the cowboys, too. Always keep the 2100 in mind for a reliable trail rig. As I said, I haven't got much to complain about running the Weber 2bbl, but when the time comes I'll look into the 2100 as a replacement.

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