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Old 03-06-2021, 06:53 AM
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The OP might want to try and find a build article in HPP mag where Jim Taylor put together a 421 with ported iron 389/ 421 heads that made 478 hp, and as I recall it put out 350 HP just running on the center 2 bbl carb only!

My hats off to that man for accomplishing that and sharing the details also!

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  #22  
Old 03-06-2021, 08:33 AM
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https://www.hotrod.com/articles/h-o-...-build-part-1/

https://www.hotrod.com/articles/h-o-...-build-part-2/
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  #23  
Old 03-06-2021, 08:54 AM
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i built a 467with ported eheads aluminum tripower intake we welded top of intake do ports would line up and seal a gasket

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Old 03-06-2021, 08:56 AM
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Hey Kenth, if you happen to read the second part of this Hot Rod article above in post 22, note the jetting changes that Jim had to make to that tripower carb set up!
Gee! I guess he just does not know enough to keep it stock does he?

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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs!
And he was not talking about 1/8 or 1/4 mile ETs!

1) 1940s 100% silver 4 cup tea server set.

Two dry rotted 14 x 10 Micky Thompson slicks.

1) un-mailed in gift coupon from a 1972 box of corn flakes.
Two pairs of brown leather flip flops, never seen more then 2 mph.

Education is what your left with once you forget things!
  #25  
Old 03-06-2021, 09:47 AM
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Im not sure what the difference are but we sure have never been able to run those little jets in our tri-powers in the end carbs.
Jet to what the engine wants.

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Old 03-06-2021, 09:50 AM
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Quote:
Originally Posted by steve25 View Post
They are 100% right on the porting work as any of the factory iron intakes even when ported can not really keep up with a out of the box round port E head or the speed master heads out of the box either!
Will such a set up not power you ask?
It will make power even with out of the box heads but amount of power and the power band will just not be what it could be and porting the heads only makes this issue worse!

The reason for the narrow power band that will result is the change in port area , and this change in area is happening the wrong way as the flow progressed from the intake Plenum on into the head , as the expansion rate that’s needed is the wrong way!

In my poorly drawn example number 1 is drawn as the expansion rate ideally should be, and number 2 is drawn to show what you will be having take place,

If your in need of the Eye candy of having a tripower under the hood that’s your decision and is perfectly fine , but you will be squandering away a good bit of power and a nice wide power band that you could otherwise be having!

I just realized how little I know. So as the engine heats up the intake tract dynamics change?



SO, should you flow test an intake head combo with the metal heated to temp?

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Old 03-06-2021, 09:52 AM
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What tri-power carbs would support 600 + hp?

  #28  
Old 03-06-2021, 10:05 AM
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I’ve been doing research on dropping a set of aluminum heads in with a hr. Figured I would shoot for porting at 290 or so. Plan was to continue to use the tripower and factory intake. I know not best way to make power but tripower just looks too cool. Talked with the butler guys today and they said I can’t do any porting on an ehead as the intake ports are too small and will be gobbled up the head ports. I have no reason to doubt them, but my question is- so this means their are no tripowers on the road with ported alu heads? Any options/ideas to retain tripower and have ported alu heads?
389 or 400?

Keep in mind that the later heads have larger valves and the valve angles are different than the #77 heads. You may have issues with valve clearance -to- cylinder wall and pistons depending on lift. Valve notches may have to also be added to the tops of the cylinders to unshroud the valves.

If rebuilding the engine, then replacement/matching parts will take care of the mismatches. Still may want to notch the tops of the cylinders.

Install the cast iron RA exhaust manifolds to save some frustration, but headers will work. I would also want a minimum of a 2 1/2 dia exhaust (prefer 3" dia myself) and high flowing mufflers so as not to choke the engine.

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Old 03-06-2021, 10:32 AM
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That is a great article from omt. I forgot about it. Super cool putting a value on the outer carbs in hp.

  #30  
Old 03-06-2021, 10:46 AM
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Hmm. Well I was not planning to open the bottom end. As it stands it has pretty deep dish forged pistons already, having no info on the build from po, I’d guess it’s at least .30 over on a 421. Enough side to side space for 2.11/1.66 valves?

  #31  
Old 03-06-2021, 11:36 AM
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If it where me, save the original heads and intake.
Use out of the box E-heads and aluminum intake. Enlarge intake runners all way up.
1/2" 2 hole spacers on all 3 carbs.
SFT cam around 240/250.
Easy 11's with 3.42-3.55 gears.

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  #32  
Old 03-06-2021, 11:59 AM
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Intake air flow in a NA motor goes down the runners in pluses in a on and off fashion.

These pulses will curtail the flow of air once the speed of these pulses reach 55 to 60% of the speed of sound.
This is because it takes energy to restart the air mass once it has stopped.

The speed of sound is stated as being at standard temperature and pressure at sea level.

This all means that as the intake air mass heats up on its way thru the complete intake tract that maximum velocity that it can attain before the cut off point is reached is taking place at a lower rpm.

Now this does not mean that super cold air will make the most power as the air temp and the fuels make up must be enough to turn the fuel into a nice burning vapor along with some fuel mist that will later be turned into a vapor when it’s cramped up at TDC.

Also interestingly enough if your thinking that having all the fuel turn into a vapor would be the way to go you would be wrong!

Excess Fuel vapor takes up room that could air at a certain point and this then makes for a reduction in power output just like having not enough fuel going into a good burnable vapor !

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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs!
And he was not talking about 1/8 or 1/4 mile ETs!

1) 1940s 100% silver 4 cup tea server set.

Two dry rotted 14 x 10 Micky Thompson slicks.

1) un-mailed in gift coupon from a 1972 box of corn flakes.
Two pairs of brown leather flip flops, never seen more then 2 mph.

Education is what your left with once you forget things!
  #33  
Old 03-06-2021, 12:07 PM
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^Way to complicated for me^

Not sure if way I built my engines over the years, but the hotter they get(200-210 degrees), the faster they run.

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  #34  
Old 03-06-2021, 12:51 PM
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Quote:
Originally Posted by steve25 View Post
Intake air flow in a NA motor goes down the runners in pluses in a on and off fashion.

These pulses will curtail the flow of air once the speed of these pulses reach 55 to 60% of the speed of sound.
This is because it takes energy to restart the air mass once it has stopped.

The speed of sound is stated as being at standard temperature and pressure at sea level.

This all means that as the intake air mass heats up on its way thru the complete intake tract that maximum velocity that it can attain before the cut off point is reached is taking place at a lower rpm.

Now this does not mean that super cold air will make the most power as the air temp and the fuels make up must be enough to turn the fuel into a nice burning vapor along with some fuel mist that will later be turned into a vapor when it’s cramped up at TDC.

Also interestingly enough if your thinking that having all the fuel turn into a vapor would be the way to go you would be wrong!

Excess Fuel vapor takes up room that could air at a certain point and this then makes for a reduction in power output just like having not enough fuel going into a good burnable vapor !
As temperature increases so does the speed of sound. In other words the speed of sounds is slower at 60 degrees then it is at 120 degree.

Stan

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  #35  
Old 03-06-2021, 01:04 PM
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Quote:
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As temperature increases so does the speed of sound. In other words the speed of sounds is slower at 60 degrees then it is at 120 degree.

Stan
Cooler air is more dense meaning there is more of it. Probably why the cold air intakes are so beneficial.

  #36  
Old 03-06-2021, 01:05 PM
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Quote:
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^Way to complicated for me^

Not sure if way I built my engines over the years, but the hotter they get(200-210 degrees), the faster they run.
Why would anyone ever build an engine without having a degree in mechanical engineering and fluid dynamics? I went to college for 20 years securing both degrees and a Phd in both subjects and a minor in thermodynamics and air flow resonance. Then I felt confident enough to build my first 326CI/516 stroker with twin turbos pushing through a double helix super charger with Hildebran fuel injection running alcohol and 95 percent nitro.

4,000 thrust HP and 4,785 ft pounds of torque - honest. You just gotta know all the scientific stuff because it matters, right? I can't believe anyone would just slap a 500HP engine together without knowing all the related scientific formulas and what is needed to make it all work and then take it to the track and run 11's only to have some other Pontiac guy want to know what your sound wave pulses ratio is between intake plenum and exhaust heat flange. How embarrassing in not being able to answer such a basic question - then everyone will know you are a rookie in the engine building skills.

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Old 03-06-2021, 01:09 PM
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Cooler air is more dense meaning there is more of it. Probably why the cold air intakes are so beneficial.
Don't forget AlTITUDE - dense air versus thin air, and of course don't forget about humidity. All basic knowledge found in the 1969 Chilton's handbook of the best 6-second Pontiac engine builds for street racers, and dummies. Book comes with a slide rule to generate all formula answers.

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  #38  
Old 03-06-2021, 01:14 PM
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^I'm still a rookie^
Nichols Engineering did machine work on ours.
I was running low 11's at age 20 back in 79. Course my father and brother had a lot to do with it.
68 FB 400ci 256/263 SFT iron intake w/a Q-JET. TH400 3.55 gears.
Got 16 mpg around street.

I've helped assemble 500 to 1000hp NA plus engines at my buddies shop since 85.
A lot of power adder engines too.
Learned a few things along the way...

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Last edited by Region Warrior; 03-06-2021 at 01:23 PM.
  #39  
Old 03-06-2021, 01:35 PM
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Originally Posted by PontiacJim1959 View Post
Why would anyone ever build an engine without having a degree in mechanical engineering and fluid dynamics? I went to college for 20 years securing both degrees and a Phd in both subjects and a minor in thermodynamics and air flow resonance. Then I felt confident enough to build my first 326CI/516 stroker with twin turbos pushing through a double helix super charger with Hildebran fuel injection running alcohol and 95 percent nitro.

4,000 thrust HP and 4,785 ft pounds of torque - honest. You just gotta know all the scientific stuff because it matters, right? I can't believe anyone would just slap a 500HP engine together without knowing all the related scientific formulas and what is needed to make it all work and then take it to the track and run 11's only to have some other Pontiac guy want to know what your sound wave pulses ratio is between intake plenum and exhaust heat flange. How embarrassing in not being able to answer such a basic question - then everyone will know you are a rookie in the engine building skills.
Great post Mr Jim.... Only way it could be better is to word it to Ole' McDonald's farm song or something.

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  #40  
Old 03-06-2021, 01:43 PM
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Great post Mr Jim.... Only way it could be better is to word it to Ole' McDonald's farm song or something.
Better not use Old McDonald....might offend someone

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