MC 2100 jet sizes

Not having any luck with the search function, but it's probably me.
I have a 2100 on a 1973 258 and am trying to find out what most of you are running for main jet sizes. Mine has #48 jets and it seems to be running rich. The engine has the 1982 intake/exhaust, TFI ignition and a Comp Cam #252H cam ( very mild). Was thinking maybe 46 or 45's would work. Any suggestions?:?
Rick

 

What do your plugs look like? Are you sure you don't have a blown power valve?

I recall I have 46s in my truck's carburetor. The change from a 48 to a 46 is not drastic though ... about a 9% difference. You can tweak the mixture by changing the float level too - lower float means less fuel.

 

Hi Tim, I just had the power valve out and checked it for bad diaphragm, no leak. The plug tips are a light brown, which I think shows the correct mixture, but I'm not too happy with the soot I can wipe out of the tailpipe. Maybe I'm looking for too much from the carb setup, as far as cleaner burning.
If your opinion is that this is in the ballpark, then I'll leave well enough alone. Might try the float level at a later date.
Rick

 

Yeah, I think you're ok if the plugs look good - light brown sounds excellent.

The tailpipe soot probably comes from warmup, when the choke is closed.

 

OK, I'll give it some miles and see how it goes. Just started using it after a three winter build.
Thanks,
Rick

 

Hey, you're welcome - glad I could help! :tea:

 

www.carburetorfactory.com.