Fuel System: Carburetor size calculation chart

[Mike Van Veghten]

For you big carburetor guys, or folks looking to buy new and haven't seen the many size calculators on the web, ponder this.
Yes, it's old. BUT, math is math, and nothing's really changed, nor will it. "Some" newer calculators have another parameter in the mix, "engine efficiency" (in %). Interestingly, if you put in a realistic...efficiency value, the carburetor size normally goes "down" for this list..!

Also read the info below the chart. It describes to go "up" in size if your cfm number is between a carburetor size that's available vs. one that is not made by anyone.
E.G. - 485cfm recommended... Buy a 500cfm carburetor.

https://offenhauser.co/wp-content/up...talog-1987.pdf

See listed page 13.

Mike

[StudeRich]

I think maybe a PDF has to be "Hosted" somewhere to be on the Internet. I might be wrong but, I tried pasting the Link in the Address Window after clicking it didn't work, and neither worked.

[brngarage]

Worked for me, Rich.

[64Avanti]

Works fine.

[Mike Van Veghten]

Double checked, works for me also.

try this...
Go to Offenhauser - https://offenhauser.co/

Put your cursor on "Products" (do not click) at the top of the page, go down to "catalogue", click on "catalogue", down to page 13.

Mike

[StudeRich]

OK I finally remembered that my Computer and Windows 10, -Firefox do not hit me on the head and remind me that Files like this do not go in an Obvious place like the toolbar or desktop, they go in the "Downloads File".
I was expecting a HTTPS:// Website, -wrong!

So I had about 9 Copies there! . . .. ..
Thanks.

[showbizkid]

Mike Van Veghten , thanks! I made it a sticky and changed the title. Good stuff!

[rockne10]

Memo to Mark Wheeler, SDC web Master;

Should probably be part of the Tech Tips page of the SDC web site as well.

[Rafe Hollister]

I bought a 56 Commander 259 3sp auto a few months ago. It has an Edelbrock 600cfm. I get 14 - 15 mpg combined. It drives and accelerates fine, but when the secondaries open, I can barely tell any difference. Anyone wanna trade me their 500?

[tsenecal]

Yes, some good info, and some interesting items. I looked for a date, but couldn't find one. The latest vehicle that I saw listed was a 1981. Wouldn't it be nice if we could still order some of the items?

[PackardV8]

I bought a 56 Commander 259 3sp auto a few months ago. It has an Edelbrock 600cfm. I get 14 - 15 mpg combined. It drives and accelerates fine, but when the secondaries open, I can barely tell any difference. Anyone wanna trade me their 500?

The 500 is not the solution to your complaint. The secondaries will open a bit sooner and a bit wider than a 600, but the problem is your 259" just isn't sucking hard enough to need full secondary air flow on either.

jack vines

[Mike Van Veghten]

Yes, some good info, and some interesting items. I looked for a date, but couldn't find one. The latest vehicle that I saw listed was a 1981. Wouldn't it be nice if we could still order some of the items?

What items ? You mean from Offenhauser ?
You can. Many items are still available. 4 or 5 months back two oddball, angled carburetor spacers for a project. Yep, they had them in stock.

Rafe -

I mostly agree with Jack. Your engine just doesn't appear to have the "poop" that it should have.
Although, because the primary side of the 500 is much smaller than on the 600, the 500's secondaries may actually open a bit more. Though, they will open slowly and not necessarily be "feelable".

Mike

[t walgamuth]

The secondaries aren't needed until the engine gets to some higher rpm.

[jeds55]

[Mike Van Veghten]

I get better MPG with the dual quad set up than I did with the single quad I started with....

WAY...too many circumstances to deal with on this one !!!

Mike