Rochester 2GC info

[Bench Racer]

Just doing a little bench racing and looking at the 350 Chevy 250/230 with the Rochester 2GC 1686/1375. I was checking to see if any other of the GM (Buick,Pontiac or Olds) cars ran the big 2 bbl. I didn't look at them all but it appeared only Chevy listed carb. measurements on the NHRA blueprint guide. Was the big 2bbl only used on the 350 Chevy? I would expect Billy Nees or Mark Yacavone, the gurus of the odd and obscure combos to chime in on this one. I have the highest respect for these guys because I love odd and obscure combos too.

[Mike Jones]

Originally Posted by Bench Racer

Just doing a little bench racing and looking at the 350 Chevy 250/230 with the Rochester 2GC 1686/1375. I was checking to see if any other of the GM (Buick,Pontiac or Olds) cars ran the big 2 bbl. I didn't look at them all but it appeared only Chevy listed carb. measurements on the NHRA blueprint guide. Was the big 2bbl only used on the 350 Chevy? I would expect Billy Nees or Mark Yacavone, the gurus of the odd and obscure combos to chime in on this one. I have the highest respect for these guys because I love odd and obscure combos too.

You can find them on Chevy 400`s as well. They are certainly getting harder to find with the 1.375 venturi. Not sure about BOP.
I agree, Billy and Mark would know.
Alan Peters too.


Mike A114
P/SA

[Dwight Southerland]

I believe that the 1969 and 1970 Chev 350 250 were the only engines to use this size carb. I queried the database for the ClassRacerInfo website and they were the only two engines that used a Rochester carb with 1.375" venturi.


There were some Oldsmobile engines from 1969 thru 1972 that used 2-Bbl carbs with 1.313" venturi.


There are no listed carb sizes for the Pontiac 2-Bbl carbs in the Tech Bulletins until 1974.

[Mike Jones]

Originally Posted by Dwight Southerland

I believe that the 1969 and 1970 Chev 350 250 were the only engines to use this size carb. I queried the database for the ClassRacerInfo website and they were the only two engines that used a Rochester carb with 1.375" venturi.

Learn something everyday.
Thought the 400 used the large 2GC.
Thanks Dwight.


Mike A114
P/SA

[Mark Yacavone]

Originally Posted by Dwight Southerland

I believe that the 1969 and 1970 Chev 350 250 were the only engines to use this size carb. I queried the database for the ClassRacerInfo website and they were the only two engines that used a Rochester carb with 1.375" venturi.


There were some Oldsmobile engines from 1969 thru 1972 that used 2-Bbl carbs with 1.313" venturi.


There are no listed carb sizes for the Pontiac 2-Bbl carbs in the Tech Bulletins until 1974.

Even the 69 Impala 396/265 used the 1.25 carb, strange as that sounds.

[Bench Racer]

Originally Posted by Mark Yacavone

Even the 69 Impala 396/265 used the 1.25 carb, strange as that sounds.

Yeah I noticed the early 400 Chevy and 396 used the smaller carb. From what I could find the 400 and 396 carb was around 12 or so CFM less than the 1969 and I think 1970 model 350's. Wonder how much the difference in CFM was worth?

[NORMAN BARNARD]

How many of the 1.375 venturi's do you need? I think i have a couple
in the shed. Also venturi clusters and baseplates left over from the local circle track racers who now are allowed to run holley 4412's.

Now is it true or false, nhra no longer is enforcing the carb. P/number but as long as it meet's dimensional configuration and " original visual design" it's good...... (notice i said original design ).
So with that being said and "untouched rochesters" being harder to find. Why can't the marine carb. (that meets the above specification) be used??? Easier to find (yes, even in the darn) desert and has all the good parts already installed (ok, maybe not all, but it has the "good booster cluster" and comes very darn close on the "fuel curve" needed.

Norm

[Mike Jones]

Originally Posted by Bench Racer

Yeah I noticed the early 400 Chevy and 396 used the smaller carb. From what I could find the 400 and 396 carb was around 12 or so CFM less than the 1969 and I think 1970 model 350's. Wonder how much the difference in CFM was worth?

I was told the difference between the big
and small carb is about .5



Mike A114
P/SA

[Mike Jones]

Originally Posted by NORMAN BARNARD

How many of the 1.375 venturi's do you need? I think i have a couple
in the shed. Also venturi clusters and baseplates left over from the local circle track racers who now are allowed to run holley 4412's.

Now is it true or false, nhra no longer is enforcing the carb. P/number but as long as it meet's dimensional configuration and " original visual design" it's good...... (notice i said original design ).
So with that being said and "untouched rochesters" being harder to find. Why can't the marine carb. (that meets the above specification) be used??? Easier to find (yes, even in the darn) desert and has all the good parts already installed (ok, maybe not all, but it has the "good booster cluster" and comes very darn close on the "fuel curve" needed.

Norm

You have a PM


Mike A114
P/SA

[Jeff Stout]

I may be interested in 2 of these carbs. New dirt track rules from imca and they are quoting the 1.375 carb as being the 1 to use. Price for 2 complete shipped to 85013 if interested in selling.

QUOTE=NORMAN BARNARD;482788]How many of the 1.375 venturi's do you need? I think i have a couple
in the shed. Also venturi clusters and baseplates left over from the local circle track racers who now are allowed to run holley 4412's.

Now is it true or false, nhra no longer is enforcing the carb. P/number but as long as it meet's dimensional configuration and " original visual design" it's good...... (notice i said original design ).
So with that being said and "untouched rochesters" being harder to find. Why can't the marine carb. (that meets the above specification) be used??? Easier to find (yes, even in the darn) desert and has all the good parts already installed (ok, maybe not all, but it has the "good booster cluster" and comes very darn close on the "fuel curve" needed.

Norm[/QUOTE]