Well, some people are having problems tuning their Holley. I just wanted to post my results with me street port 12a.

I have a RB Street Port Holley intake/carb setup. I pulled the primary bowls off, and checked the jet size. It is a 0.050" jet. The mix screw is 3/4 turn out from all the way in. It runs quite well, and idles nicely. Black smoke was noted in the upper RPM range. I think with 0.049" jets, and 1 turn out on the mix screw, that would be the best place to start with a SP 12a. It's a fairly stout port, but not too wild.

Just FYI for anyone wanted to switch to the Holley kit.

BTW, 600 CFM is WAAAAYYYY too big for a 12a. The 465 Holley is almost too much. Also, RB seems to modify this carb to run open jet holes on the secondary side. I wasn't too thrilled with this little "feature". I'd rather be able to lean out the higher RPM range a little bit. Also, the accelerator pump is a little too large, but it does the job. Just don't rap the accelerator pedal, or elese you flood it and foul the plugs.

Also running BR7EQ-14 Leading and BR8EQ-14 Trailing with stock coil/dist.

I will be switching to a 2nd Gen Coil setup in the near future.

 

That is because the RB carbs have a metering plate (not block) on the secondary side of the carb. Metering blocks conversion kits are available and are fairly inexpensive, you will be pleased with the increased tunability. You will definitely be able to tune out that black smoke in the uppers.

-Marques

 

oh.. and holley 600's are juuuust fine on an ol' 12a.