Engine Motorcraft 2100 1.23 carb

[FortyFive]

Does anyone have experience with a 1.23 Venturi size MC 2100 on a AMC 258 i6 / 4.2l (or smaller) engine? I see a lot of recommendations for the smaller 1.08 & 1.14, but also see people running 350 cfm Holleys (similar size as the 1.23) on 6 cylinders. Thanks

 

[Belizean]

Interesting question. I’m running a Holley Sniper, but considering going back to a good carburetor.

 

[Manic Mechanic]

I'm running a Holley sniper but when I was running my 2100 I had the 1.08 Venturi

 

[FortyFive]

I'm running a Holley sniper but when I was running my 2100 I had the 1.08 Venturi

Did the 1.08 seem like enough carb? Consensus seems to be that 356 cfm MC 2100s are too big, but 350 cfm Holleys aren’t. I’m just curious if anyone has that firsthand experience. Thanks.

 

[Manic Mechanic]

I never found it to be to much carb. It ran great. I just got tired of cold starts in the winter and snow. As well as off camber situations when wheeling. I love my sniper so I don't plan on switching back.

 

[FortyFive]

I never found it to be to much carb. It ran great. I just got tired of cold starts in the winter and snow. As well as off camber situations when wheeling. I love my sniper so I don't plan on switching back.

Did the additional cfm of the sniper seem to increase performance at all?

 

[Manic Mechanic]

Did the additional cfm of the sniper seem to increase performance at all?

Significant change in throttle response. As far as performance is concerned it's still a low compression inline 6. It runs great but it will never be a performance icon. The thing about the sniper is, if you have any engine issues (vacuum leaks, exhaust leaks etc) you may never notice them with the carburetor. But the EFI definitely will notice and may not run correctly until there fully fixed.

 

[Belizean]

Something also I have just learned about the sniper, you better have a good battery. I was getting some intermittent complete shut down where my engine would just die and the screen would go blank for several seconds then just power back up. My battery before starting was between 12.6 and 12.8 volts. I read somewhere that for optimal performance the battery needed to be 13 plus. Got a new battery and no problems now.

 

[Jeep Soup]

13 plus ??
That means it only works correctly if the Alternator is CHARGING. You will be in Deep Doodoo out on a trail ride and the Alternator goes south.
I have New never used SMALL Size Deep Draw 12v battery packs that are for Medical Units that reached their shelf life.
I have these for Ignition and ECU limp out situations if you loose all Battery/ Charging on your rig.

I would rethink that Sniper System.......

 

[CJ]

That's just how efi works.
It takes voltage. Don't discount the advantages of newer technology.

 

[Belizean]

Optimal is 13 +. I was running on less for a while. I only go out with others so I should be pretty good plus I usually take some spares so I might just toss an alternator in the box also.

 

[FortyFive]

Funny thing about forums in general. Lots of answers, but none to the original question…

 

[Belizean]

I have no experience with the 2100. And it seems like people only mention 1.08.

 

[Belizean]

Are you wanting the motorcraft over the Holley? I would be interested in what you go with and how well it works.

 

[FortyFive]

Are you wanting the motorcraft over the Holley? I would be interested in what you go with and how well it works.

Yes. Looking to go MC over the Holley. That’s why I was curious about the MC 1.23 that is similar in cfm to the Holley. I see a lot of people highly recommending the 1.08 and 1.14. I’m assuming they arrived at those sizes after someone experienced tuning/driveability issues going up to the 1.23 size. Searching through forums, I just haven’t found anyone talking about having that experience firsthand.

 

[Belizean]

I believe also, what I’ve heard some, is that the MC are getting pretty scarce and there are chinee knockoffs around now. Hopefully you can find a good original one.