Best heads that can still use 65' tripower - Pontiac GTO Forum
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post #1 of 7 (permalink) Old 11-12-2017, 11:11 PM Thread Starter
 
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Best heads that can still use 65' tripower

I am interested in increasing my HP. I currently have a low compression (~8.5:1) 400 cu. in motor running at 65 ' tripower setup. I have looked at Butler, Kaufman, Edelbrock, and AFR options, but I believe all required a much larger carb setup. So my question is, what is the best head I can run with my 65' tripower setup and an what levels does the tripower max out ? (My goal is to have ~550 hp at the crank.) Thanks

1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie
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post #2 of 7 (permalink) Old 11-13-2017, 08:44 AM
 
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Going to take cubic inches & then good head flow to get anywhere near 550 hp.

Numbers like 550hp, 600hp seem to get thrown around quite a bit by new members to this site when first noting what they want out of a Pontiac V8 build. My first question for any of them, have you personally experienced seat time behind a 450+ hp, 530-500 ft/lbs of torque Pontiac V8 in LeMans, GTO, or Firebird street car? There is a point where bigger & bigger & more torque, just going to blow the tires away on the street, the real street. Its not that hard to find a "Boutique" Pontiac engine builder that will build a very expensive bullet that can make 550-600 or even more hp, if big hp numbers are what you are after. Would also agree, even with such a well thought out engine combo, a '65 or earlier Tripower is going to hold the numbers back.

Last questions, your new project, a Tripower 3spd '65 GTO convert, am assuming that is what PHS invoice showed as original options? From experience, that is a very expensive & desirable GTO convertible when properly restored, just trying to wrap around my brain, why the direction on such a such a factory optioned GTO, versus building off a more common early GTO, LeMans, or Tempest convertible.
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post #3 of 7 (permalink) Old 11-13-2017, 10:39 AM
 
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I totally agree with Pinion Head on this. With large HP/torque levels, you will also have to get a stronger rear axle (think Moser or others). modify and strengthen rear suspension, get a custom made, high strength driveshaft, and have a transmission built that is capable of handling these large amounts of power. And as Pinion Head said, the tri-power will only hold the power back. I would think more like the above quoted 450hp/500-550 lbs torque as a very strong engine that the tri-power would be maxed out on, but would really slam you back in the seat.
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post #4 of 7 (permalink) Old 11-13-2017, 12:17 PM Thread Starter
 
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Originally Posted by Pinion head View Post
Going to take cubic inches & then good head flow to get anywhere near 550 hp.

Numbers like 550hp, 600hp seem to get thrown around quite a bit by new members to this site when first noting what they want out of a Pontiac V8 build. My first question for any of them, have you personally experienced seat time behind a 450+ hp, 530-500 ft/lbs of torque Pontiac V8 in LeMans, GTO, or Firebird street car? There is a point where bigger & bigger & more torque, just going to blow the tires away on the street, the real street. Its not that hard to find a "Boutique" Pontiac engine builder that will build a very expensive bullet that can make 550-600 or even more hp, if big hp numbers are what you are after. Would also agree, even with such a well thought out engine combo, a '65 or earlier Tripower is going to hold the numbers back.

Last questions, your new project, a Tripower 3spd '65 GTO convert, am assuming that is what PHS invoice showed as original options? From experience, that is a very expensive & desirable GTO convertible when properly restored, just trying to wrap around my brain, why the direction on such a such a factory optioned GTO, versus building off a more common early GTO, LeMans, or Tempest convertible.
Pinion head - Thanks for your thoughts and help. Prior to owning this 65' GTO, I had never driven one, I just have always loved the lines of the car. As far as horsepower goes, I used to race in IMSA, I still drive / race a shifter kart, and my daily driver has over 700 hp (602 whp). I like to drive. That said, I do not want to hurt the value of my car. The car is PHS documented and was originally a 3 spd (I have it in the garage), tripower 389 convertible with 4 wheel drum brakes. Someone installed a 69+ 4 speed muncie along the way (I am guessing the previous owner as he had it for more than 18 years) along with a 400 motor with low compression heads. (So the car is not a numbers matching beauty.) Honestly, I'd probably be very happy with 400 + hp and a very broad power curve (nice torque).

For safety and performance standpoint, I really want to put on big brakes and wheels (I know many on here don't like that route, but I really do plan on driving and enjoying the car). I will save all of the original parts so that if a purist wants to go back to stock they can.

Thanks again for your help!!

Chris

1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie
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post #5 of 7 (permalink) Old 11-13-2017, 07:02 PM
 
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As PH pointed out, to get the HP you are looking for will take cubes. Get a stroker kit from Butler and bring the 400CI up to 461CI.

Head choice is based on HP levels as matched to CFM's of air flow & cam selection (roller cam for bigger HP levels as you are looking to have).

All the Pontiac builders can give you advice on how to go to reach your goal.

On the tripower, CFM's are needed to get bigger HP levels. The stock '65 tripower used the smaller carbs throughout while the '66 unit used the larger end carbs. I might purchase the aftermarket '66 aluminum intake, gasket match the intake runners to the heads you choose, and fit the larger Rochester 500CFM 2 Bbl end carbs to it. They also make carb adapters to mount the Holley SixPack type carbs to the Pontiac manifold if you want to go that route. Ebay has them for $40 each.

Might just take a little experimenting.
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post #6 of 7 (permalink) Old 11-13-2017, 11:13 PM Thread Starter
 
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Originally Posted by PontiacJim View Post
As PH pointed out, to get the HP you are looking for will take cubes. Get a stroker kit from Butler and bring the 400CI up to 461CI.

Head choice is based on HP levels as matched to CFM's of air flow & cam selection (roller cam for bigger HP levels as you are looking to have).

All the Pontiac builders can give you advice on how to go to reach your goal.

On the tripower, CFM's are needed to get bigger HP levels. The stock '65 tripower used the smaller carbs throughout while the '66 unit used the larger end carbs. I might purchase the aftermarket '66 aluminum intake, gasket match the intake runners to the heads you choose, and fit the larger Rochester 500CFM 2 Bbl end carbs to it. They also make carb adapters to mount the Holley SixPack type carbs to the Pontiac manifold if you want to go that route. Ebay has them for $40 each.

Might just take a little experimenting.
Thanks Jim! I've been talking to Butler, AFR, and Kaufman. General consensus is I can get north of 450hp pretty easily, which is probably more than I need for a beach cruiser (even though I'd like to have 500+ on tap)....

Again thanks for all of the help .

1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie
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post #7 of 7 (permalink) Old 12-29-2017, 06:48 AM
 
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There's a few articles that show factory sixpacks with 500HP. I read a couple in the Pontiac rebuild book. Personally I'd go aluminum if I could, don't think there's a set that can be used with the 64 sixpack intake.

1964 Convertible GTO
2004 PBM M6 GTO
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