Carb Question CFM's

[Booker T]

Anyone know what CFM the original Carter 1 bbl was?

I have the Carter / Webber 2bbl setup from Langdons currently but have been thinking about running some other carbs. I have some Holly 1904's sitting around and also some 97 cores. I think the 97's run at 150 cfm and have no idea about the 1904's. The 1904's are the ones that sometimes came with the "visi-bowl" / glass bowl (the ones I have don't). I believe they were an IH truck carb...maybe some Fords too.

I used the calculator in the link below for suggested CFM. The formula seems to be affected quite a bit by the "Maximum Safe Engine RPM".

Based on 85% efficiency and 230 CI the suggested CFM jumps from around 200 to 250 when the RPM figure is changed from 3500 to 4500.

I have never run a tach on this car, but what do you think would be a good figure to use in this formula?

http://www.4secondsflat.com/Carb_CFM_Calculator.html

Edited January 10, 2011 by Booker T
forgot to put link in post

[Barabbas]

Booker,

The 230 has max HP at 3600 and "red line" of about 4000-4200; which calculates to 230 cfm

Mike (aka The MGs)

[Booker T]

Looks like a couple of 97's would be a case of "over-carbing"...since they would be around 300 CFM...

Thanks!

Brooks

[Barabbas]

Booker, if you read through some of the past threads on the forum you will probably find that the most popular carb set-up here is either two of the original Ball&Ball carbs or Dual webbers from Langdon. When it was time for me to decide I saw the same equation you did and finally decided on the dual B&B set-up--check out this post: http://www430.pair.com/p15d24/mopar_forum/showthread.php?t=20053

[bob westphal]

Dual 97s work well if you install a hot cam, go for a larger bore, do some porting, and up the compression. I had this set up using an Edmunds water heated manifold. It worked very well. If your going to stay stock, the dual singles work fine with maybe smaller jets.

Bob

[Booker T]

The 230 is at the machine shop now being rebuilt. I think they are going to take .50 off the head. I have a "mild" cam ready to go in it also. Right now I have the Langdons setup and the offy dual intake. I am also running the Langdon dual exhaust manifolds. I may just leave well enough alone...it was running relatively good before I took the engine out...well, relatively good considering it had 2 broken rings! The problem is that I always have trouble leaving well enough alone. My latest instance of this was to start polishing my intake...got just far enough along to realize what a pain it is...and to realize that I was far enough along that i have to finish it!

[Booker T]

Booker, if you read through some of the past threads on the forum you will probably find that the most popular carb set-up here is either two of the original Ball&Ball carbs or Dual webbers from Langdon. When it was time for me to decide I saw the same equation you did and finally decided on the dual B&B set-up--check out this post: http://www430.pair.com/p15d24/mopar_forum/showthread.php?t=20053

Hmmm...now I have something else to consider...the 3X1 Asche setup! Part of the reason I was considering changing out the Langdon setup I have now is to be a little different. My best bet is to get the thing running good with what I have and then move to something else if the bug is still there!

[Big_John]

Anyone know what CFM the original Carter 1 bbl was?

I have the Carter / Webber 2bbl setup from Langdons currently but have been thinking about running some other carbs. I have some Holly 1904's sitting around and also some 97 cores. I think the 97's run at 150 cfm and have no idea about the 1904's. The 1904's are the ones that sometimes came with the "visi-bowl" / glass bowl (the ones I have don't). I believe they were an IH truck carb...maybe some Fords too.

I used the calculator in the link below for suggested CFM. The formula seems to be affected quite a bit by the "Maximum Safe Engine RPM".

Based on 85% efficiency and 230 CI the suggested CFM jumps from around 200 to 250 when the RPM figure is changed from 3500 to 4500.

I have never run a tach on this car, but what do you think would be a good figure to use in this formula?

http://www.4secondsflat.com/Carb_CFM_Calculator.html

Keep in mind that 2 bbl carbs are rated using 3.0 inHg pressure drop and 4 bbl carbs are rated using 1.5 inHg pressure drop. I'll bet that forumula is for 4bbl carbs. There's a formula to convert, I had to look it up. Divide the 2bbl rating by 1.414 to equal 4bbl rating.