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#21
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BONESTOCK GOATS '64 GTO Tripower Hardtop (Wife's Car) '64 GTO Tripower Post Coupe (My Car) '99 Bonneville SE Sedan |
#22
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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… |
#23
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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. |
#24
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As I've said in previous threads, I've enlarged some of them, similar to MidnightAuto's carb. Have no test data.
__________________
BONESTOCK GOATS '64 GTO Tripower Hardtop (Wife's Car) '64 GTO Tripower Post Coupe (My Car) '99 Bonneville SE Sedan |
#25
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#26
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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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BONESTOCK GOATS '64 GTO Tripower Hardtop (Wife's Car) '64 GTO Tripower Post Coupe (My Car) '99 Bonneville SE Sedan |
#27
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end carb venturis are 1.375" or 1 3/8"
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#28
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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 |
#29
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https://pontiactripower.com/pages/faq#8 The 59 to 66 tripower end carbs have a 1 3/8" |
#30
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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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BONESTOCK GOATS '64 GTO Tripower Hardtop (Wife's Car) '64 GTO Tripower Post Coupe (My Car) '99 Bonneville SE Sedan |
The Following User Says Thank You to Dick Boneske For This Useful Post: | ||
#31
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Quote:
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. |
The Following User Says Thank You to Kenth For This Useful Post: | ||
#32
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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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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
#33
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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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