With the long duration cams some carbs won't idle as clean without four corner mixture screws. If you open the throttle plates far enough to get an idle you are into the off idle circuit. Four corner idle mixture is used on carbs that use the secondary throttle blades to smoth the idle mixture out.

The only advantage to a four corner idle mixture is at an idle. " I don't know of any S/SS cars that leave at an idle".

Bill Beebe

At the Chicago Allstar race I found several Holley carbs with 4 corner idle adjustment. I pointed this out to Danny Gracia. He said that 4 corner idle adjustment was not allowed in Stock/SS unless it came that way from the factory. It is allowed on Modified type cars in SS. The racers changed their carbs and the race went on.

The 2007 NHRA rulebook in Stock on page 54 under CARBURETOR states the following: "Drilling idle holes in primary throttle blades permitted."

This rule was written to help idle problems on engines with large duration camshafts.


Disclaimer: Opinions expressed by me on this forum are exactly that, my opinions.

Thank You Travis !

bp4133 Bob Pagano

It's okay to allow the Ford's to change the boosters so they flow more air but to do something to maake the car idle better is not. I thiught you could change the way fuel is metered as long as you didn't change the air flow.

Greg

Alan,
The cost of the "Right" part is sometimes crazy. Bob & I are building a 69 Vette & have been buying parts for about 3 or 4 years. (Bob is selling my excess inventory & old race parts to fund it) There are a couple of things that got to our pocket book. One was the "Right" hood & the other was the "Right" carb. We had the "right" heads, but they were worth so much we sold them and used the money for the 401 repalcement heads & a few other parts. Way back when we started the project Bob spent a lot of money for the "Right" manifold. Now since NHRA has allowed some more repacememt parts we can buy a cheaper manifold that works better. Bob actually did buy one on E-bay at about 1/4 the cost of the "Right" manifold.
This will probably be the last car I bulid so Bob & I have decided to take the high road & build it with the best parts we can or cannot afford. It is nice that NHRA has allowed all these replacement parts. I can only imagine what it would cost to build one of these "Rare"collector cars as a stocker. Maybe the new Sportsman series NHRA can move forward and address these & other cost issues. Well enough of the ramble. Still cooped up in the house, sick.. just need a racing fix or to talk about it....
Thanks, Travis for the real scoop!
:--)

Adger Smith

Adger,
Bob and I have spoken at length, several times, over the past year or so. Having hunted most of the same parts, we know EXACTLY where you're coming from. We hope to see both of you at the track soon.

Travis, thank you for the clarification. It is appreciated. We do not yet have a spare carb for this combination, so if we'd gone the wrong way, we'd not have been able to swap carbs and race, we'd have been trying to borrow one or going home.


Alan Roehrich


Bring "AA" classes to NHRA Stock Eliminator!

Alan & Adger -

At some point the realization comes that what is "Stock" in Stock Eliminator is what passes tech (NHRA's definition).

Anybody know for sure what was the year that Holley began making double pumper carbs?

Jim Cimarolli

Jim -

I bet that you could get an answer from my dad Jim Waibel.
His shop number is 863-666-5100.

If he does not know then Emory Pierpont would know I am sure. He is a Div 2 Super Stock guy, who helped me a lot in Orlando with our Carb.

Jeremy Waibel
K&N B/SA 69 camaro
2231

'68, IIRC. The '68 TransAm Camaro offerings in mid-year production included DP carbs. The '69 L88 may have been the earliest production use of DPs, and one of the only ones. (Definitley not on 428 Shelbys in 1967! Or the "hundreds" of single four-barrel Hemis in 1964 and 1965!) The center-squirter tunnel ram carburetors were the predecessors and they were available early '68. If I had time to look them up, I'm sure that the magazines of the era ran articles on them.