Rochester 2bbl help

[Tim Barrett]

Linda and I are working with a new combination,,69 Camaro 350 250hp NHRA Stock Eliminator rating 232hp. The 2bbl carburetor is new to me,,but I'm going to learn it. I've been told there's quite abit that can be done to them to make them run very good. We are doing great so far,but we will need a little extra to qualify for Indy. I know this will take time,,but I have lots of patience. Any help would be greatly appreciated!!

[Jeff Stout]

Any dirt track guys you may know? Out here Rochester 2 bbl is required. Only thing I learned is the barrels in main body are at different distances between each one. The closer they are is better. Then removable venturi also have different ID sizes. Bigger ID I think are on trucks. I don't what NHRA checks with go, no-go gauges. I did find once 56 Olds tri power that had carbs flowed more then others and they were Rochester.

[Stan Weiss]

Originally Posted by Jeff Stout

Any dirt track guys you may know? Out here Rochester 2 bbl is required. Only thing I learned is the barrels in main body are at different distances between each one. The closer they are is better. Then removable venturi also have different ID sizes. Bigger ID I think are on trucks. I don't what NHRA checks with go, no-go gauges. I did find once 56 Olds tri power that had carbs flowed more then others and they were Rochester.

Are you sure it was 56? Olds did have a tri power "J2" engine in 57.


Stan

[nickh]

Tim here are a couple of stout 2 bbl guys they can build you a 2bbl that will surprise you (in a good way)
1. Steve Taylor PRC Carbs
2. Dan Davinci Davinci Carbs

Both are in Houston area but and they do have quick turnarounds and both have facebook pages hope this helps.

[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.

[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.

[Jeff Stout]

[QUOTE=Stan Weiss;715381]Are you sure it was 56? Olds did have a tri power "J2" engine in 57.

Not sure, I went by the ad at swap meet and bought just the 1 with choke. An old old racer suggested they were better. I think it flowed 525 cfm and the best Rochester someone in our group was at 500 cfm.
The others were under 500.

[Mark Yacavone]

Tim, You want to be careful, going to Indy with that combo.
There's a fella out there that seems to think that some boosters are more okay than others on a 2 GC. He's not hard to find. In fact , he just might find you!

[SDT1DYI]

I have run the 2 barrel Combo in Camaro and Nova's. Call me if you want to discuss.

Steve Teeter 360 979 3126. PST.