I came across some great information while going over my carb this past weekend. I've made some minor changes and had a big bog on off-idle that I had previously fixed by putting in bigger shooters.

Well, turns out I had put the accelerator pump cam in the #2 position instead of #1. I had always discounted the difference these cams could make unless you were REALLY fine-tuning, because quite frankly the position of the cam screw holes are so dang close to each other that I just didn't think it would make that big of a difference. Well, it does, depending on what color cam you have in there.

Anyway, I came across the following information which should be quite helpful for anyone with an off-idle hesitation, big or small (This is for Holley models 2300, 4150, 4165, and 4175):

Cam Color / Pump Shot Position 1 / Pump Shot Position 2
Black...... / ......... 19cc ......... / .......... 18cc this is the only one with less shot in position 2.
White...... / ......... 17cc ......... / .......... 19.5cc
Red........ / ......... 18.5cc ....... / .......... 20cc
Blue....... / ......... 18cc ......... / .......... 20cc
Orange... / .......... 19cc ......... / .......... 24.5cc
Green..... / .......... 24cc ......... / .......... 30cc
Pink....... / .......... 30cc ......... / .......... 37.5cc

My cam is the orange one, I was amazed at the difference in shot size. But now that I know my shot size is 19cc, I can easily make minor changes by swapping to a different color cam & know where I sit. Hope this helps others playing with an off-idle hesitation but not getting there by just changing shooter sizes.

Thanks for posting this. It looks like some very useful information.

You need to divide those numbers by 10 to get the actual volume of the single squirt. Holley rates the pumps and cams by volume per 10 strokes.

Was playing around with a 750 dp this weekend and was woundering what the difference was. Thanks for the info.

FWIW my 454 likes a vacuum secondary but have been playing with a DP for the track.
No times yet this year :(

Oneovakind67, you are correct. However, I'm going to use these as reference points, I don't really care what the exact amount is. For example, I went from a huge bog with my orange cam in position #2 to a very minor bog in position #1. So my next step will be to go down from 19cc to one of the cams with 18 or 18.5cc and see how much it improves. If I get to the bottom of the scale and still have a the bog I'll lower my shooter size and start over.

Normally these bogs are caused by a lean condition, but I think mine is still a rich bog. If it gets worse at 18cc, it means I'm back to a lean bog and I'll just jump up to a 20cc shot without any guesswork.

BLT4FN, let us know how the switch to a DP goes. The DP's are supposed to provide better torque and HP, it will be interesting to see the change.

Another thing on accelerator pump cams, the different cams not only change the volume of the shot but also timing. If you change the cams and watch the pump you'll notice different durations and rates.