AMC 258 carb question

fattypackard

fattypackard

Well-Known Member
Joined
Mar 20, 2005
Location
VA Beach
jeep would always crank up like a charm no problems.

then all of a sudden yesterday i went to crank her up and it wouldnt fire....just cranked and cranked and cranked.

so i figured maybe the engine was flooded, i let it sit all day and night and then all day today. tried it again this evening, same thing. so i checked out the carb and long story short, i can get it cranked and running fine if the air valve on the top of the carb is wide open. the jeep will cut off or run like crap if i close it half way or leave it closed like it use to be. any thoughts on why this all of a sudden happened?
 
MC2100

Hey Packard, If you still have A stock carb, it may be A Carter BBD. This carb is A big steaming pile of:poop: You need to go to jeepsunlimited.com/forums ,& search MC2100. This is A 2 barrel Motorcraft carb. You get one from A junkyard, & rebuild it. Look for one with 1.08 in raised letters on the drivers side of the fuel bowl. Super easy to rebuild, & then you'll know what to do out on the trail, if there's A problem. PM me if you still need any info on it. This mod along with the Nutter bypass, & the Team Rush (Duraspark ignition) up grade, are the best mods I have done to my 1990 YJ yet!!!:wheel:
 
^ its a carter carb...pile of crap i know but i try to not put any money at all into this thing. hah

i know about the MC2100 upgrade, i am sure i will do it at some point, just not right now. and i have seen post about the nutter bypass...havent read into it...could you send me some info on that and the ignition upgrade? thanks!
 
for the ignition Id go pertronix and leave all the dura fail boxes home.

Check the dizzy is it tight? Is it possible timing slipped at all?
Float hung?

BTW Im no pro, and less than average on AMC, but Im trying hard.
 
dizzy is tight, no slipped timing, floats ok.

just for some reason the air valve is the cause. some tiny spring probably flew off or something dumb.

^ i'll still give you a gold star for trying so hard
 
Isn't that the choke? I can't recall with the Carter BBD carb and that year if its an electric choke or uses a heat pipe to set it. If it has a round module off the side, check electric or mechanical connections off the side.

If you don't have a Haynes or Chilton manual, get one. You can't own a Jeep without one. I think I had both.
 
Teamrush upgrade, ( not T.F.I. )

Junkyard genius, is the man responsible for this mod. ( he invented it) Napa part numbers; distributor cap, FA136. Cap adapter, FA139. Rotor, FA159. 8mm wires, 700313. This mod gives you A larger cap. The idea is, you can increase coil output, & open plug gap from.035 to .045. The smaller stock cap, will allow crossfire. The new setup, has A two piece cap. You don't have to change out the distributor tower. (no need to disturb cam gear/ dizzy gear mesh (H.E.I. setup you have to swap the whole dizzy) This worked well for me ,W/Nutter bypass. If you decide to go this route, get back to me. There is also A coil upgrade to go along with it, ( E-core ). I have only done the cap, rotor, & wires ( I used the $50.00 Accel set from Advanced Auto. Couldn't pas up the red color option.) It seems to run A lot better, though maybe just needed A tune-up. So to recap, Mc2100 + Nutter + Teamrush = 4000 rpm. And plenty of seat of the pants performance improvement too, from A motor that almost got sent to the scrapyard.
 
fattypackard said:
^ its a carter carb...pile of crap

I don't know why I wrote Rochester, I meant Carter. 1st Post edited. Also Skyhik5 is right about replacement control modules, for the Ford Duraspark ignition. They will not last long, especially if you upgrade the coil, without using A ballast resistor wire 1.35 ohms. I bought A used, Real Duraspark control module from A junkyard. These units are supposed to be A lot tougher than the ones from the big box stores. They don't make 'em anymore. (new ones are all imported) So if my unit ever gives up the ghost,I'll put the real one in.
Click to expand...
 
For the cost drop $59 on the pertronix, it eliminates your points, gives true electronic ignition, with a hall effect pick up. Installs in 2 minutes and is warranted for life.

When I ran Nevaspark, I kept a spare in the glove box at all times.
 
what carb adapt. plate needs to be used to make the mc2100 carb bolt up to a 88 wrangler.
bryan
 
Mr. Gasket Adapter Plate, Pn. 1937

66bronco said:
what carb adapt. plate needs to be used to make the mc2100 carb bolt up to a 88 wrangler.
bryan
Click to expand...
Hey Bryan, Mr. Gasket makes the adapter plate, Part number 1937. Or you could use any made to adapt, 2bbl Rochester, to 2bbl Holley. They ordered A Mr. Gasket #1937 for me at Advanced auto, about $20.00+/-. I had to modify mine, using JB weld on one edge. My Mc2100 was from A 1974 Ford F-250. It depends on where you get/got your Mc2100, as to whether or not you'll need to do this. There is A gap, under the drivers side of carb that needs to be blocked off. FYI, there is also A particular passage in the carb, that needs to be blocked off too. It is the one that leads to the choke thermostat. There is A ton of info @ jeepsunlimited.com/forums about this swap. I could drop by sometime, & show you my setup, you,re only around the corner.
 
I've had real good success running a Chevy inline six HEI and the the Teamrush wiring upgrade. Swap a AMC V-8 gear onto the bottom of the HEI. I preferred the Weber 32/36 carb - but I had one before the MC2100 swap became popular. You can run a remote coil using whats called the low cap distrubuter. Then swap the springs in the distrubuter. All the parts for the coil and the cap are available at any parts store and spares are cheap and small if your so inclined to keep spares.
 
4wd.com has the ready to drop in GM HEI distributors for $99 on sale right now. I did this to my I-6 about 4 years ago and mine will start after about a half a revolution even after sitting for months at a time.
Super easy one wire hookup, parts available everywhere, and easy to repair and/or upgrade.
 
Pro's, & con's

uglyjeepoffroad said:
4wd.com has the ready to drop in GM HEI distributors for $99 on sale right now. I did this to my I-6 about 4 years ago and mine will start after about a half a revolution even after sitting for months at a time.
Super easy one wire hookup, parts available everywhere, and easy to repair and/or upgrade.
Click to expand...
The nice thing about the HEI. deal is that parts are easier to find. the nice thing about the Teamrush deal is that you don't have to disturb the distributer, or swap the cam gear. I figured, if I'm going somewhere, & want peace of mind I'll take A spare cap- rotor-adapter with me. From what I hear they both work well, & J/U has info on both. Also notable is the stealth HEI. An HEI module is rewired, & put into A gutted Duraspark box.
 
paul (buckshot500) please do stop by or next time i come by your house and you are out i will drop in. i bought a mc2100 from pull a part for $18.00. it still had good smelling gas in it. i know thatdoes not mean anything but most of the time the gas is very bad.
thanks,
bryan
 
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