#21  
Old 07-19-2021, 02:23 PM
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Quote:
Originally Posted by padgett View Post
Back when I was autocrossing the V8 Sunbird (thutty yar ago) I was limited to one Rochester 2G. Found there had been some large ones for big block trailer towing packages think 1 3/8 flange. Closing on 400 cfm. Good tripower could flow over 1,000 cfm with proper stacks - little factory AC93s were only about 200 cfm (big cars got a big air cleaner, think I have one in the attic). Was also a 500 cfm Holly 2bb but that was right out.

Also do not forget that for the '67 QJ vs Trips test, Milt was under strict instructions which would be faster
How did the 500 cfm Holley compare with a modified Rochester?

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  #22  
Old 02-11-2022, 07:07 PM
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Update here- Dick built me a new center carb - he opened to 1.42. Can’t wait to see how it runs when salt on street is no more. Sounds great, idles good, responsive. Added an electric choke too.

Dick was great about helping me dial in. Thank u!

Bring me warm weather…
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  #23  
Old 02-11-2022, 07:53 PM
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I did a 2 bbl Rochester for the local dirt track car I sponsored. This as a 2bbl class, 500 CFM Holley was legal, but the guys I sponsored were very low bucks. I built the 400 Pontiac for them, used a iron Q Jet manifold with adapter to the 2 bbl. Car was a 76 X body olds omega.

I used a hole saw in a drill press to open the venturi's on the main body, the size escapes me since it was 25 years ago, but I took it out as much as I could without breaking through. I used a brake cylinder hone to smooth, and blend the inside of the venturis.

Die ground the clusters to remove as much as possible. I tapered the throttle shafts round end upstream tapered to a thin point on the bottom. I also modified the cross piece that the air cleaner stud screws into, but you have to be mindful of how much you take off, so as not to make it weak. I rounded out the square edge on the top of the air horn to help out too. Used a GM air cleaner base with an open element stacked 2 air cleaner elements to keep the restriction down.

He won a bunch of heats and features over 3 years with the combo, against a lot of chevys that had a lot more money in them, and they had the 500 CFM Holley too. I feel for how much money was invested, he did very well.

It's entirely possible to upsize the Rochester 2 bbl at home with basic tools, just requires some work.

I probably wouldn't sacrifice good tri power carbs, find something else, and keep the real ones as is.


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Old 02-12-2022, 04:53 PM
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Quote:
Originally Posted by chrisp View Post
The 59 to 66 tripower end carbs have a 1 3/8" venturi = 1.375" from the link posted , Is this info. wrong ?
Sorry I posted incorrect info. The end carbs from 1959 through 1966 had venturi's sized 1.310".

As I've said in previous threads, I've enlarged some of them, similar to MidnightAuto's carb. Have no test data.

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Old 02-14-2022, 09:24 AM
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Originally Posted by chrisp View Post
Is this chart wrong on the end carb sizes ??????

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Old 02-14-2022, 03:31 PM
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Yes, the end carb venturis are 1.310" or 1 5/16". This is true of all'59-'66 end carbs, the "997" and "683" float bowl casting numbers. They too can be enlarged if you want to increase flow.

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Old 02-16-2022, 10:05 AM
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Quote:
Originally Posted by Dick Boneske View Post
Yes, the end carb venturis are 1.310" or 1 5/16". This is true of all'59-'66 end carbs, the "997" and "683" float bowl casting numbers. They too can be enlarged if you want to increase flow.
end carb venturis are 1.375" or 1 3/8"

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Old 02-16-2022, 03:05 PM
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1959-66 end carb venturi size is 1 5/16" from factory.
At least that´s what Rochester info says.

FWIW

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Old 02-19-2022, 09:09 AM
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Quote:
Originally Posted by Kenth View Post
1959-66 end carb venturi size is 1 5/16" from factory.
At least that´s what Rochester info says.

FWIW
Is this info incorrect ?
https://pontiactripower.com/pages/faq#8
The 59 to 66 tripower end carbs have a 1 3/8"

  #30  
Old 02-19-2022, 11:15 AM
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I measured a few end car venturis, both the 997 and 683 casting numbers. They are 1.310” or 1 5/16”. Attached pictures show detail.
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  #31  
Old 02-19-2022, 11:28 AM
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Quote:
Originally Posted by chrisp View Post
Is this info incorrect ?
https://pontiactripower.com/pages/faq#8
The 59 to 66 tripower end carbs have a 1 3/8"
The answer is yes.
Just made a 1 3/8" steel wire gauge and it did not get pass the venturi, were a 1 5/16" gage did.
Rochester info is correct.

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  #32  
Old 03-27-2022, 01:14 PM
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Quote:
Originally Posted by Kenth View Post
The answer is yes.
Just made a 1 3/8" steel wire gauge and it did not get pass the venturi, were a 1 5/16" gage did.
Rochester info is correct.
There is a lot of incorrect info out there on the Tri-Power Rochester Carbs.
The Rochester Carburetor Spec sheets I posted about years ago agree with Kenth's info.

Tom V.

So much BS out there.

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  #33  
Old 03-27-2022, 01:25 PM
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I recently saw a picture on either Roadkill, or Hot Rod, that one of the staff is using a 66 Tri Power intake, with three 2 bbl Rochester throttle body units for the induction units. These are the type of TBI that chevy used on 350 SBC in the early 90s before port injection was adapted.

If they get it worked out, it should be interesting to see how well it performs.


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