#41  
Old 12-10-2021, 03:00 PM
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The 1966 Rochester center carb actually has a smaller carb venturi vs the 64-65 center carbs. But the center carb airhorn is the same size as the rear carbs so all the same air cleaners. Never really saw any real data that said a 66 center carb was better vs a 64-65 center carb. Now with Holley "500 cfm" Carbs #4412 they have a 1-3/8" venturi.
The Mopar mechanical secondary carbs #4783 carbs have a much larger venturi.


One of the good guys on Tri-Power stuff is Dick Boneske.

Do a search on his name and you will find lots of tri-power information.

Tom V.

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Last edited by Tom Vaught; 12-10-2021 at 03:10 PM.
  #42  
Old 12-10-2021, 03:34 PM
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Dick Boneske Dick Boneske is offline
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The stock “575” ‘66 center car has 1 3/16” Venturi’s. End carbs have 1 5/16” Venturi’s. The larger Rochester 2GC carbs with 1 1/4” Venturi’s are common.

I have enlarged a few of these carbs to 1.420”, a little larger than the end carbs, which are 1.410”. There is adequate material to at least 1.4375, or 1 7/16”.

Similarly, the end carbs can be enlarged, as I’ve described on previous posts.

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  #43  
Old 12-10-2021, 08:56 PM
keith646671 keith646671 is offline
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I have some more reading to do here on tri-power. Found reference info detailed in another thread. Obvious to me others here know far more than I about trips and can be helpful to me.. I did see ends have thicker throttle blades contoured differently and had sealing process to improve idle detailed on CD I bought.. Printed out some of Tom V details on 66 tripower and tried to get Dick B info but could not print legible copies from thumbnails. Think I have wrong version of Adobe for pdf or something. Trying to get to a point where I can select center carbs to try that will work in a final setup, debug and compare with blocked off ends. Thinking I have a good single 2GC, maybe just grab a rebuildable Holley core and adaptor, rebuild and compare to Rochester. This is my step one.

?? Will 2gc float bowl and air horn fit a 2g tripower throttle body? Would just as soon start with rebuilt correct throttle bodies. Did this when I could with good results doing Q-jets. The Holley Street Avenger carb is not much more than a rebuilt throttle body tho possibly not workable in setup. Research I guess.

?? Thinking for mainly street application might be better for smaller of cfm ends choices for more smoothness once engaged before WOT. Just a guess.

  #44  
Old 12-12-2021, 06:47 PM
keith646671 keith646671 is offline
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With a little more reading I find there was a vacuum operated linkage setup used on auto trans cars which mine will be. Did not find that detailed in CD I bought ... always had better luck de-bogging a q-jet with operating air valve, vacuum break adjusting spring tension on air valve. Can anybody detail what the performance difference is from experience on trips? Just wondering if I should chase as it appears most people dont.

  #45  
Old 12-07-2022, 08:55 PM
DaleW66GTO DaleW66GTO is offline
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Default My Barry Grant Tripower

Hey guys its been awhile since visiting this forum and thought I would post a cpl pics of how nice these tripowers can look. My 462 is disassembled at the moment and is getting rebuilt. I'm going to have kauffman D-port aluminum heads that will be cnc ported to 325 cfm. So I will probably need my intake ported to make use of the high flowing heads. I would also like to know what work will need to be done to the Demon 250 cfm carbs, or at least the center one. I already moved up 2 sizes on main jets and that seemed to work pretty good the last couple years. I would love to have these carbs be closer to 300cfm.
I'm right in the middle of this new engine build, so if anyone has suggestions or comments, I'll be checking back to this thread often.
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  #46  
Old 12-08-2022, 07:41 PM
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Two comments on the Post by DaleW66GTO, Nicest BG/Holley Tri-Power set-up I have ever seen, a real showpiece.

The Belt Drive for the Water Pump is very nice too. How many ribs is the belt??
Who made the pulleys?

Tom V.

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  #47  
Old 12-08-2022, 08:47 PM
DaleW66GTO DaleW66GTO is offline
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Thank you Tom for such a nice compliment. The serpentine setup is an 8 rib setup and its made by CVF Racing. I was taking your previous advice and did a search on BGTECH, and was reading some of the post when your comment popped up just now. Lots to read about. I noticed a lot were from way back when BG was still in business making the tripowers. Sounds like they weren't impressing anyone with their customer service. I'm hoping I run across some good info on the difference between a stock BG intake verses one that's been ported. Also by next summer my engine is going to be a monster (bored and stroked, forged pistons, radical hyd. roller cam, and approx. 12:1 compression running AV fuel (100 octane leaded). So obviously the tripower will be the choking point with the intake and a combined 750 cfm carb system. That's why I'm looking for info on enlarging the demon carbs and porting the intake.
My GTO goes to way more shows and cruises than it does to the drag strips, so I won't trade off the tripower coolness for more horsepower.

  #48  
Old 12-09-2022, 06:02 AM
3X24SPD 3X24SPD is offline
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When the TriPower becomes a choking point, you gotta give it a tracheotomy...
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  #49  
Old 12-09-2022, 08:53 AM
DaleW66GTO DaleW66GTO is offline
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3x24spd very nice setup with NOS plumbed straight into the intake runners. That should help the choking point problem. lol I'm planning on adding NOS hopefully next year, not a lot, just 100 or 150 shot. As much as I would like to plumb it straight into the intake ports like you did, I'm to nervous to drill holes in my BG intake because its so rare and would be hard to replace. So I will probably use a plate under the center carb for the NOS. I've never seen a NOS setup on a tripower until seeing yours now.
You have a very cool list of badass GTOs with tripowers. I will gladly accept any advice you have on getting the most out of my tripower setup.

  #50  
Old 12-09-2022, 04:39 PM
3X24SPD 3X24SPD is offline
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Thanks. I thought that setup was pretty slick back then. It was set up for a 250 shot.
But that pic is probably close to 20 years old.
That's a cast iron '65 intake.
I replaced it a long time ago with one of the limited first run 66 Aluminum Intakes that PY did.
You could just throw some plates under your carbs like OMT did if you needed & wanted a easier nitrous solution.
After I pulled that '65 Intake off I briefly considered putting it on another 455 & replacing the fogger nozzles with fuel injectors to do something different- but I had other project irons in the fire that took precedence.
It's now just a unique semi-exotic decorative piece sitting on a mock up engine with some 3D Printed carb bodies.

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  #51  
Old 12-14-2022, 07:24 PM
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Quote:
Originally Posted by DaleW66GTO View Post
Hey guys its been awhile since visiting this forum and thought I would post a cpl pics of how nice these tripowers can look. My 462 is disassembled at the moment and is getting rebuilt. I'm going to have kauffman D-port aluminum heads that will be cnc ported to 325 cfm. So I will probably need my intake ported to make use of the high flowing heads. I would also like to know what work will need to be done to the Demon 250 cfm carbs, or at least the center one. I already moved up 2 sizes on main jets and that seemed to work pretty good the last couple years. I would love to have these carbs be closer to 300cfm.
I'm right in the middle of this new engine build, so if anyone has suggestions or comments, I'll be checking back to this thread often.
Talk to Shaker455, he has done several investigations in enlarging the carb venturis to gain more flow.

Tom V.

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  #52  
Old 12-16-2022, 05:16 PM
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Dick Boneske Dick Boneske is offline
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I have modified the stock Rochester end carbs to enlarge the venturi from 1.310" to 1.437" (1 7/16"). This is the limit of enlarging the stock end carbs--anything larger would require epoxy or a replacement insert for the venturi area.

The same is true of the large center Rochester carb. There are 2G carbs that have venturi sizes up to 1 3/8", but they are not easy to find. But, they can be modified to enlarge the venturi area as I have done with end carbs.

Some of you may remember the '65 GTO Glory Days. In the 1980's, that car ran low 10's with a '66 Tri-Power that had STOCK VENTURI sizes.. The manifold was ported to match the 722 RAIV heads and the area below the carbs. The entire heat riser passage and the water crossover has been removed. I have this manifold in my shop if you need any photos.

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