AMC 258 I-6 carb question

[dbongo]

I have a '74 RHD Scout II that I use for mail delivery. It has an AMC 258 engine with a 727 auto transmission. I'm using a 1 barrel carburator, the stock unit (Holley 1940, IIRC.)

I've been having some problems with the engine dieseling, and we've tracked it down to the auto choke. It is supposed to have a heat pickup tube, but it's not there. And, where the tube connects to the choke has been damaged, so even if I had a tube, it wouldn't connect easily, if at all.

So, my question is can I get a replacement choke (preferably electric, but manual is OK) and what would the approx. cost be? It'll need to be bolt-on forme to do it. My mechanic ordered a kit, but was unable to connect it (not surewhat the problem was) but he was able to get it tuned up pretty good. This is the preferred solution money- and time-wise, but...

On the IHC mailing list somebody recommended the Weber progressive 2-barrel carb as a replacement. It's a bolt-in kit, with an adapter to connectt it to my existing 1 barrel intake manifold. I have two concerns. I called one vendor up on the phone and he initially thought that the 32/36 progressive would be too small for the 258. He later backed down after learning I use it for mail delivery. Anybody have it, and if so, any problems with it? Is it undersized for a 258? And, does it really lead to improved fuel economy?

Now, the real problem with going this route is kickdown linkage. My current setup has rods leading to a cable. I haven't traced the end of the cable (too busy this time of year at work) but based on this, what is the best (easiest) way to connect the Weber carb? Get a kit to use the rod linkage? Convert the whole span to cable?

FYI-I'm fairly ignorant when it comes to hands-on mechanical work. I'm not stupid (college degree in math...which I'm using to deliver mail...) but untrained mechanically. Any solution requiring fabrication is out. At this point, anything remotely "tricky" would be out as well. Just thought you should know my skill level before responding.

And Merry Christmas, everybody.

Dave

[Ben Segrest]

I've got a friend with a 32/36 on his cj7 and it is very driveable even with 35" tires. I have a 38/38 and it sucks, but that's cause it's not jetted right. There are 2-barrel manifolds off of some amc and jeep vehicles that will bolt up to your engine, you will still have to get the correct adapter to run a weber, though. Basically, I think you would just need to get the weber kit for whatever vehicle you pulled the carb from. As for the linkage, my scout came with the weber already in it, so I don't know what the factory setup looked like, so I can't be much help on that one. I hope this helps get you started. By the way, where are you located? There is probably somebody near you who could give you a hand.

[Brendan]

You need a very built 258 before you need to step up to the 38/38 from the 32/36.

For what you use it for, I don't get why you want to pour $4-500 into converting to the weber.

Find a better mechanic who can fix a choke.

[Geoff B]

The weber conversion seems pretty pricy to me. One my 232, I used a 2 barrel intake off of an '82 Jeep, a carb adapter for a Rochester to Holley two barrel, and a Motorcraft 2100 off of a 1979 Ford 302. Total price for all parts was around $60 including a new air filter. I got better mileage, power, and driveability than the 1 barrel ever thought about. If you want more details, let me know.

[dbongo]

Thanks for the replies. Let me take the replies in order in a single response.

Ben, I'm in Florida, and kinda of not near anything. I've got to drive 1/2 hour just to buy a TV. The Weber conversion is interesting, but I'm not fully sold on it, mainly due to cost.

Brendan, I figure the parts cost on the Weberconversion to be about $350. I put $1500-$2000 in gas per year into my Scout, so a small increase in fuel economy could pay it off inside of 3 years. (I currently get 7-8MPG.) As far as finding a better mechanic, I'm pretty happy with the guy I've been using. If they can't fix it, I don't get charged. And they're always honest about whether or not they can get it done. Unlike this other mechanic I tried...I ended up cleaning up the job he didn't do right.

Geoff, this is interesting. Please give me more information. Also, you have a manual tranny if I read your sig properly. Any idea on kickdown linkages with this setup?

Thanks,

Dave

[Brendan]

I believe that a competent professional mechanic ought to be able to rig up a choke. It's not that hard.

If he doesn't charge you for failing to complete the job, that's definately decent of him.

A new weber 32/36 is about $350 and a couple hours labor to install it puts you up above $400. Weber swap is not the most effective $/HP or $/reliability swap. Think MC2100!

7-8 mpg out of a 258 is ridiculous. You should get TWICE that. I get 13-17 out of mine in a fullsize truck. I run a motorcraft 2100 that doesn't work right. I really think that your expectations are TOO LOW.

This upgrade alone will get you a few MPG:

http://home.off-road.com/~tom85cj7/tfiupgrade.htm


Swapping to an aluminum intake and matching exhaust manifold will help, and make your two bbl swap more efficient.

Here's a writeup on MC2100 swap:

http://www.cjoffroad.com/writeup.asp?WU_ID=16&noAdd=1


If I think of it, this weekend I'll put together a complete 258/232 upgrade/modification post that we can link to from the sticky FAQ post.

[Geoff B]

That cj writeup was the inspiration for my swap. The only info that wasn't accurate was regarding power valves. There is another site that had GREAT tech info on these carbs including ford part#'s for all size powervalves. It was called Bubba's big block Fords or something like that, definitely had Bubba in the title and covered FE block ford engines, unfortunately I must have deleted it out of my favorites by accident or something. I used an aluminum water heated intake off of a '82 jeep cj, but I have a header. Definitely get a 2100 marked "1.08" on the float bowl, the smallest CFM made. You could find a 70's 2 barrel intake off of a jeep of amc product that would bolt to your exhaust manifold or combine the intake and exhaust off of the 80's engine. My combo runs #49 jets, 7.5" single stage pv, and the accel pump in the 2nd hole from top. Pulling the plugs has shown them to be burning perfect, mileage is 12-13 around town and 16-17 highway @ 70 mph with a definite increase in power. Throttle linkage I winged it, modifying the existing brackets and using a universal hotrod throttle cable. I don't know what you'd have to do about kickdown linkage, but it couldn't be too hard, and the carb I got had linkage on it for an auto trans. I made an EGR block off plate on the intake, used a 1/4" thick carb mounting gasket for pv clearance, and ported the intake to match the larger ports of the carb. There was a few other minor things, but it was a smooth swap and I'm pleased with the results. I'll try to post a pic.

[Geoff B]

Here's a link to that site I mentioned:
http://home.earthlink.net/~bubbaf250...rb/carb01.html

I haven't hooked the choke up yet, Texas is pretty warm in the winter, and I haven't had any trouble w/o it. It uses a combo electric, heat stove type choke and wouldn't be hard to do with a factory exhaust, my header creates complications with the heat stove.

I'll have to trim my picture down before I can post it, its too large for the forum.

Brendan, e-mail me if you want any more info on my swap, or I can e-mail anyone interested pictures.

[Brendan]

You can use holley power valves in the MC2100.

[Brendan]

If have any scout-specific tips on doing this swap, I'll throw them in my MC2100 post.