Frustrated noobie (MC2100 conversion)

Plugging it EXTERNALLY will work, but you leave the possibility that there could be another vac leak from any other little gap between the carb body and the choke assembly. A few of those pics show other little spots by the choke that can "leak vacuum". By blocking that port, you prevent vacuum from being felt against the choke.

In short, vacuum is only needed at the choke if you are using the thermal port.

RET32, you stated the adapter plate completely covers the bottom of your carb. Which carb do you have, the one on the right or left?



If it is the one on the left, where did you get your adapter plate? This would mean that adapter companies have enabled us to use later model, non-computer controlled 2100s!!!!!

 

You sure the one on the left is not a 2150? That would be my guess. What does the top look like?

 

Is the 2150 better than the 2100 (for the 304, anyway)?

 

Uh, don't know if it's better - it's the later version. It was used on the 360 Wagoneer till the end of its run in 92-93, and likely on other cars. All (AFAIK) the SJ carbs have an altitude compensator prominent on the back side. If you look at the top, the 2150 has a booster venturi to the side of the main venturis that replaces the vacuum pulloff IIRC. I think the 2150s come with larger jets too - ca 52F-56F or so.

There's a picture here http://www.ponycarburetors.com/default.asp?page=identification but their 2150 picture is different from the SJ carbs I've seen. Plus, I don't think that the bowl vents shown are typical.

Oh - the 2150 has an external vacuum line to the power valve, the 2100 does not.

 

I think you have eliminated the fuel system, at least from my experiences. What is the timing set at? It sounds like it might be too far advanced.

 

Not sure, but it's a new fuel pump (replaced it a year ago, has about 3k miles on it). I'll test the pressure this weekend (wedding to go to tonight).

I guess I'm not sure. I'm pretty sure it's the one on the left. I'll have the carb off this weekend to plug the Choke vacuum port (didn't have time last night, won't tonight either). I'll take pictures of the carb and the adaptor.

It's set at whatever the factory service manual says (I think 4* BTDC). I painted the marks when I got it so I don't have to look it up anymore and I don't have to try and read the tiny numbers.

Here's my to do list for the weekend:

1- Plug the choke vacuum port on the bottom of the carb (I guess I'll just convert to manual, probably should have done that to begin with). I'm hopeful that is it, based on Mugzilla's links.
2- Take pictures of the carb and the adaptor for additional identification.
3- Retest for additional vacuum leaks using starting fluid.
4- Test the fuel pressure.

 

There are 3 types of chokes available: Manual, thermal, and electric. Only the thermal requires the port to be open. You can use the electric choke w/ the port plugged.