Saying it's all about the amount of air is over simplifying things. DEPENDING ON THE COMBINATION, a smaller carb can ET & MPH better than a larger carb when it has better shift recovery.

I bolted a BLP 3 circuit 1000 to my pump gas 505.....it was borrowed from a local dyno guy I know. So, I didn't want to monkey with it too much.

However, it fouled out my plugs in less than 1/2 of idling and one short drive.

I'm sure the 3 circuit can work on the street......but like Greg said.....plan on tuning time and prob a set of plugs

Mike

My BLP main body came with the third circuit plugged. I can't tell from the photos if the carb the OP is looking at has plugs or bleeds in it.

Why would a roundy round carb need the third circuit?

That I doubt.

I had a 950 on my 318, local friends told me car would ET better with a 750. It didn't. Wouldn't run within a tenth of the 950.
Brett and others on here said beforehand what happened is what would be the case. Me being hardheaded, I had to try it.

... a Gary Williams built 4150 1000 cfm carb that he ran once and will no longer use. I can get a good deal on it...

Doubt all you want, but I'm one of at least three people I know who switched from a Holley 850 w/ 1.56" v x 1.75" t to the Holley HP "950" (b.s. CFM #) w/ 1.38" v x 1.75" t and picked up.

I dynoed both carbs and they made virtually the same the same peak HP & torque #s, but on the track the smaller-venturi carb was over a tenth quicker in the 60, and .2 ET & 2 MPH faster in the 1/4. It was all in the smaller carb's ability to recover from the drop in shift RPM faster, plus it was more responsive off the launch. FWIW, w/ the 850 it ran 11.7s at 116 w/ 1.70 60-ft; with the "950" it went 11.5s at 118 with a 1.55 60.

Is it combination-dependent? Absolutely. And I'm sure the less RPM drop between the shift RPM and the converter RPM post-shift, the less of an improvement it would be. But it does go to show that just putting on a bigger carb is no guaranty of improved on-track performance.

A lot of people on here have trouble accepting that, since the same people keep saying "My car always ran faster with a bigger carb." Yep, "yours" did, others haven't. I know what my own results showed, along w/ some others who had similar improvements, in back-to-back testing. Bigger is no guaranty of better.

Thank you very much for all the replies!

So here is the rest of the story.........

The BLP body was not legal in his class so he had to send the carb back to Gary Williams to get a Holley main body put back on it (cost another $300 and Gary kept the BLP body - he has done those shenanigans to me too).

So below is a picture of how the carb sits today. Looks like its a 2 circuit but I am not familiar with those bleeds - look a lot different than my Dominator ones. What are these bleeds?

Would think it would still be a good carb - agree?

They used to run Dominators but found that the smaller 4150 carbs were more responsive during restarts.

I would make him send that body back...