Rochester 2bbl help

[Cglrcng]

Originally Posted by DanBar

There are a few 1.375 venturi Roch. 2 bbl carbs out there but I have only found 1.. I do know that the carb NHRA list for that combo 7029113 is a holy grail 1.375 venturi 1.6875 throttle blade set up. This is the same venturi throttle bore sizing of a holley 500 cfm carb. I have one, and I have not given up hopes of building a 1970 version of the 350 250 hp combo. That 69 and 70 350/250 combo are the only ones NHRA lists with that venturi size. As someone stated a 1/2" open end wrench will just fit over the dividing wall between the 2 throttle bores. it is a quick way to check if the carb truly is a 1.375 venturi without disassembly to measure. the two small orifices under the baffle held in place by the front booster cluster screws are the hi speed air bleed. they allow more or less air into the fuel well. the drops tubes in the fuel wells can have different size and number of holes. this is the emulsification circuit. the accel pump discharge are the 2 hole on the face of the cluster between the booster they are drill at an angle to shoot into the throttle bores. That is most of my knowledge of the Rochester 2VG other then a lot of builder drill and re tap the main jet holes to take Holley main jets and start in the mid 60's for jets. Ask any question Iwill pass the knowledge if I have it.

Oh boy...my throttle body by tech was in 1995 (long ago yes, and rules do change), to a carbed edition and the fact that my injector choices were the same as carbed combos jet choices, but the prohibited act of machining or otherwise changing, or altering in any way the seat area in either body or top where it is sandwiched was made very clear...incl. the comparisons to a carbed combo.

So, unless those rules have changed, be very careful. Rochester carbs did not come with Holley jet seats..

You alone will be there to answer to the alteration during a thorough teardown and nothing like the feeling of congrats and a handshake and encouragement of go win it all now, if you can. Vs the you have been DQ'd pack it up, see ya, wouldn't wanna be ya, ck the website on Tuesday cause we gonna make you a star...and not in a good way.

If it is allowed by the rules now...good for you guys. If not...fix it sooner rather than later folks. Too big a hidden thing to miss by a trained eye....I just successfully made it through a very deep dive. Happy man here, but it was built to pass.

[Cglrcng]

You can always find a builder that can make it faster. The secret is sit down with the good book (the rulebook), maybe even a tech that will discuss the prohibited items you cannot touch...then find a builder that will follow the required steps to make it faster and not touch those prohibited areas with a ten ft. pole.

Good luck finding that builder and the hopeful passing of future measurements, etc.

[SS/AM]

PSA - What tech doesn't notice, isn't there 😉

[Billy Nees]

Originally Posted by SS/AM

PSA - What tech doesn't notice, isn't there 😉

Good Luck with that!

[SS/AM]

Originally Posted by Billy Nees

Good Luck with that!

Let's see non-approved billet crankshafts in SS/GT winning class at INDY, non approved aftermarket aluminum heads on a combo that only allows the OE head winning class at INDY.

Billy for NHRA Tech Director!

Billy, Billy, Billy!!

[Billy Nees]

Originally Posted by SS/AM

Billy for NHRA Tech Director!

No thanks! I can think of plenty of other thankless jobs that I'd rather have before that one.

[Frank Castros]

Originally Posted by SS/AM

PSA - What tech doesn't notice, isn't there 😉

It apparently may be a surprise to you, but some of the members of the Tech Dept. also read this stuff.

[Mark Yacavone]

I don't see why you couldn't use Holley jets. Fuel metering modifications have always been legal...But why ? Rochester jets are available online, several places.
You know, the ones that have the actual orifice size on the sides :-)

[Cglrcng]

Originally Posted by Mark Yacavone

I don't see why you couldn't use Holley jets. Fuel metering modifications have always been legal...But why ? Rochester jets are available online, several places.
You know, the ones that have the actual orifice size on the sides :-)

Just reiterating the convo that he had with me and he said it 3 times...If the injector fits you can use it, but don't you dare modify that seat or the hat where that injector sits (and all the while comparing it to carb jets which he said can be modified for flow, and carb jet seats. (He stated those cannot be modified at all)....but it was a long time ago in May 1995 at Englishtown, NJ..

My knowledge beyond that warning as far as carbs in S/SS you can fit in a thimble. And disregard, since my combo has a Bosch upright T.B. currently. If (when...just not right now as the A is getting better every race), I attempt Billy's suggestion B, I'll have to learn if successful with convincing the powers that be.

[SS/AM]

Originally Posted by Frank Castros

It apparently may be a surprise to you, but some of the members of the Tech Dept. also read this stuff.

Of course they do, I provided no detail at all.
What I'd do they'd never catch, because they don't look, and again I care nothing about Stock.