Carbs
 

I heard a couple of racer iat the allstar race had some problems with there holley carbs . true or flase ?? Jim Hanig

Hey jim,
Travis had a problem with the holleys on a couple of the BBC cars that had the '4 corner idle circuits'. They don't come that way but it really doesn't affect performance down track, it only helps driveability around the pits and idle.
He's right, but, is it a down track performance issue?

Thanks Bernie Terry is the one that said he had heard it . JHanig

What was the outcome ??

bp4133 Bob Pagano

That better idle and transition circuit is included on Holley race carbs for a reason. And it is not for better in town driving. And if it wasn't an improvement to a race car, those racers would not have applied the technology. Would be a waste of money. A clean leaving stocker does have an advantage. Nice try.

I don't think any of the "FACTORY" carbs had 4 corner metering blocks, If so you also get them for the 428 "735" Carb.

I have a 3310-1 780 carb that David Cook did. It is the Vac carb that is legal as a 750 in some comp & SS classes. I have done some testing with it in my SS/DS car. Before I paid David & started testing I had Wesley check out the carb. He made no mention of the carb having 4 corner idle.
I really don't see that it is a big thing because I have cleaned up the idle circuits on non 4 corner carbs when I do dyno testing of the engine. It is no big deal to change air bleeds & fuel bleeds. It just isn't as adjustable as with a screwdriver. I agree the screws & outside of the metering block don't look stock. (like the original carb) I would like to know the out come because I was about to let Kevin Helms try this carb on his 396 combo. I would like to give David a pat on the back. This carb had a very nice fuel curve, right out of the box...

Adger Smith

I wonder if that falls under the "new" rule that the carburetor must be the same brand and model, as well as having the same venturi and throttle plate size? I wrote a letter, and sent an email, to Glendora a while back, with a list of Holley carburetors the same size and model as the one required for the car, and they said any of them could be used. A couple were newer carburetors with 4 corner idle circuits. I think one or two may have even had a different type of booster venturi. In any event, we bought a carburetor with the correct list number for the car and had that one built. Just to make tech easier and prevent questions. It does not have 4 corner idle circuits.

Alan Roehrich


Bring "AA" classes to NHRA Stock Eliminator!

Alan,
I think the booster issue is avalid one. There are flow advantages to some types as well as signal & fuel mixing. I have seen photos in an NHRA Tech's book about correct boosters. I know the Hemi guys are having to use the correct boosters, Non down leg & Down leg, where they were originally used. I just don't see the 4 corner idle being as big an issue as the boosters. As I have said before, a good tuner can clean up the idle & response without 4 corner idle. It is just easier to retune for atmospheric & other changes with the metering block screws. What was the out come of the concerns that Travis had?

Adger Smith

Adger, I'm not sure, maybe they simply didn't look to see if the boosters were different. I agree, there is a real difference in flow between the three different booster designs. We were looking at what carburetors we could run as replacements rather than spend big bucks for the original number. We were wanting to find an accepted replacement that matched the original, so we could go through tech with no worries. Turns out some of our great racer friends took care of us with a killer deal on the right carburetor.

Alan Roehrich


Bring "AA" classes to NHRA Stock Eliminator!

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.

Thanks Dwight,
I know that the present '69 Chevy 427 combo that is being run at 445 hp has an 830 cfm vacume operated secondary carb on it. I did not know of ANY combination in the stock eliminator classification guide pre-1970 that came from the factory with an 850 Holley Double Pumper Carburetor.

Jim Cimarolli

For the 69 ZL-1, NHRA lists the Holley R-4296A. Holley lists the R-4296 as an 850 double pumper. Shows a 0.025 primary squirter and a 0.035 secondary squirter, and a 4150 series, with metering blocks front and rear. Shows it to have 1.750 throttle blades and 1.562 venturis. Same carb is listed for the 69 L-88.

The ZL-1 is rated at 445HP by NHRA, and the L-88 at 440HP.

I will say I've seen several carbs for sale listed as L-88 and ZL-1 carbs that ARE vacuum secondary.

Supposedly at least some of the ZL-1 cars were delivered with the R-4346A carb that came of the L-72 427-425HP cars, and the carbs had to be swapped before they could race.

Alan Roehrich


Bring "AA" classes to NHRA Stock Eliminator!

Thanks Alan,
Will NHRA allow a double pumper carb on the ZL-1?

Jim Cimarolli

Jim,

Are you still on here?

Sherrie

Can anyone tell me where I can find some info on the race that's going on right now in Tulsa?

Sherrie

The FastNews guy probably won't be there until tomorrow.....

Thanks but I finally found out the results. I just thought they were posted somewhere and I thought Jim might know but I guess the 'ol man went to bed?!

Sherrie

JIM, Alan is correct, 69 L88 vette and the ZL-1 Camaros can run an 850 DP

bp4133 Bob Pagano

Having not carried ours to the track yet (it ain't even on the dyno yet) I can't tell you what tech is accepting at the track, only what the rulebook and the blueprint sheet call out, and what the Holley tech guide says. The only person I know successfully running a fast L-88 in NHRA is Steve Calabro, maybe Steve will drop by and say what is on his car.

Again, I have SEEN vacuum secondary 850 carbs CLAIMED as correct for the 1969 427-430HP engines, and been told they are legal. The new looser rules on carbs MAY mean you can run either or, provided it is the correct size and model. Maybe Travis will check in again and give us another clarification.

Alan Roehrich


Bring "AA" classes to NHRA Stock Eliminator!

The '69 L88 and ZL1 carb was an 850 DP. The R-4296 that is listed in the blueprint specs is described by Holley service manuals as a DP and if you have ever seen a restoration you know that it is. The '67 and '68 L88 engines (R-3418 and R-4555 Holleys) were 850 vacuum secondary carbs.

Thanks Dwight. Too bad the 67 L-88 is no longer a legal combination. I've seen a few restorations, and they do have the double pumper. I've also seen a couple of ZL-1 restorations with the "wrong" carb the factory shipped the cars with.

Alan Roehrich


Bring "AA" classes to NHRA Stock Eliminator!

Is there any truth to the 'rumor' that ZL-1 Camaros must run the aluminum block in stock eliminator? The iron block has been allowed in SS for years, but I just heard this 'rumor' and was wondering if anyone else has heard the same. Now, wouldn't that would be a great way to hold down the cost???!!!!!

Arnold, I was told by a couple of sources at NHRA that we could use an iron block in Stock for the ZL-1. We have a GM 2nd generation aluminum block, we're told it is legal. We're also told that GM is not selling or making them right now. Also, that block comes from the factory (in assembled crate engine form) with ARP head studs, which are not legal for NHRA Stock, according to what we've been told, and ARP doesn't make head bolts for it either, they require that you order a custom set. At least that's what GM and ARP told me.

Alan Roehrich


Bring "AA" classes to NHRA Stock Eliminator!

Alan, I hope your source is correct. Apparently, a higher up NHRA official told another racer, last week, that the iron block would not be legal for stock eliminator.

Word of mouth, has two Camaros being built with aluminum blocks, currently. I don't know either person, so I can't comment on the stud/bolt issue.

Good luck to everyone with this combination!

Arnold, Kevin Helms has run his big motor with steel block a few nhra national meets with no mention of Alum.

bp4133 Bob Pagano