[Chris-Austria]

Hi!

I searched a lot and could not find these information.. maybe someone can help me with this:

1. what is the intended rpm range of a 66 tri-power setup?
2. how "high" is the intake manifold of a tri-power compared to a stock 4bbl or the edelbrock performer?
3. will the tri-power in an performance engine sacrifice some power compared to a performer manifold? (not performer rpm)

I want to compare the operating range of the tri-power to the Edelbrock Performer (almost stock size) and later to the Performer RPM.
If I build an engine that has a power range from about 1700 to 5700 will the tri-power support the high rpm's or is a tri-power better at low to mid range rpms?

Thank you!

Chris

[Tom Vaught]

A few questions for you?

1) What are you trying to do?

2) Do you have these intake manifolds already?

3) What engine size do you want to make the comparison on?

4) What is the intended Vehicle, Transmission, Rear Gear ratio?

I am going to stop here vs play 20 questions about this topic (otherwise it is just wasting everyone's time). That is why no one has posted a reply so far.

Come back with some real info and many here can help you.

Tom Vaught

[Chris-Austria]

Hi!

Sorry!

1.trying to find a good setup for my engine that will see rpms up to 5600-5700
2. i have the Tri Power but dont want to use it because nobody here can adjust it properly.. i'll keep it for another engine! i want to buy a Performer manifold and holley carb for my 435cui and would like to compare performance of the tri-power and the new system! i dont know if the tripower is the best choice for my engine even if it was adjusted.. thats why i want to know the power range
3. its a 428 +0.04, 041 comps cam + 4deg, e-heads dport 72cc, 10.6:1 Cr, 4 Speed Manual, msd ignition..
4. 66 GTO, 3.55 gears, Manual, 3800lbs, Street use

Hope this helps

Chris

[Old Man Taylor]

With an engine similar to yours I shifted the engine at 6400 RPM. I now have a hydraulic roller cam, so I shift it at 6000 RPM. The bottom end (lower RPM) may be a bigger issue. The tri-power opens up too much venturi area below about 2500 RPM. From 3000 (depending on your cam) to 6000 it is great.

[Half-Inch Stud]

i have wondered about the Tri-Power with ganged linkage ( rather than progressive) being hyper-responsive to off-idle like my dual-quad was.

I HAD to switch to progressive to make it safe in the driveway. Then the dual-quad was just so so, like a single 4. High rpm seemed better by the pants seat.

[tom s]

There really is almost nothing to adjust!If the end carbs close completly then you are just running a normal 2 BBL.The usual problem is the end butterflys,not closed and pulling fuel.Tom

[Chris-Austria]

Do you think the Performer manifold with a 770 Holley will provide more power at lower rpm (under 3000) than the tri power?

[Tom Vaught]

Originally Posted by Chris-Austria

Do you think the Performer manifold with a 770 Holley will provide more power at lower rpm (under 3000) than the tri power?

Just based on the difference in the carburetors venturis, (Holley carb has 1.375" Primary Venturis and the 66 Tri-Power has a smaller Primary Venturi (even smaller than the 64 GTO Center Carb venturi), I would say that the Holley 770 (if calibrated properly) will make more power below 3000 rpm. The 66 Tri-power is basically an on-off switch.

Tom Vaught

[pfilean]

Chris
Can't say exactly how high the tripower manifolds are because it is hard to know where to measure from. But be aware that there were at least two different heights to the carb base. Early ones were fairly low but in 1964 (perhaps die to putting them on the GTO) the height was increased. Some refer to those as a "high rise" version. Attached are two photos. The one with the carb installed is a 1961 casting. The second without the carb is a 1964 and I have laid a straight edge across the front carb surface and have the tape measure from approximately the top of the mating surface to the head. The difference between the two manifolds is maybe 1 inch. But I don't want to take the time or effort to remove the cab from the 1961 to do a comparison. But maybe what you see will give you some chance to compare to what you are thinking of buying. How it compares to any 4 barrel manifold I can't say. I would expect that if your tri-power manifold is a 1966 the height is the same as the 1964 (there is always a question of how high can you go without hood interference) even though the casting has been changed to get to the 1965 and up bolt pattern to the head and also the 1966 choke stove for the divorced choke.

As to adjusting a tri-power setup you will find a lot of helpful hints in many threads on this forum. If your mechanic can't figure it out from that maybe you need another mechanic.

[Chris-Austria]

@Tom
I had the carbs rebuild but nothing works like it should.. before the rebuild and with the same engine (also before rebuild) they worked better! Now I might need to get new throttle plates, new rebuild kits, enlarge the idle tubes.. and no expert who will do this.. its much easier and cheaper to use the Performer manifold with the Holley and keep the tripower stored for now..
I wanted to know the difference in Performance between both on my engine.. I guess the Performer manifold will be "enough" because I dont go past 5700rpm

[tom s]

Too bad the rebuilt are not right.Maybe send them to Mike and get them sorted out.I have never had to touch mine when he did them.Tom

[Old Man Taylor]

I ran an early Edelbrock manifold with a Holley 780 manyh years ago. With no other changes I picked up 0.2 seconds in the quarter when I installed the '66 tri-power. I had done a lot of work to the Holley, and no work to the tri-power.

[lust4speed]

Originally Posted by tom s

There really is almost nothing to adjust!If the end carbs close completly then you are just running a normal 2 BBL.The usual problem is the end butterflys,not closed and pulling fuel.Tom

Tom beat me to it. The rebuild could have been great, but if the butterflies are not seating properly the engine won't idle decent (or at all). Only other thing to watch out for is the Rochester carbs do not like very much fuel pressure, and a little too much will overpower the needle and seat and have fuel dripping in the carb which also screws up the idle.

Somewhere you have to allow for the cool factor, and the tri-power always wins that. Actually a standard Performer manifold and a Holley carb gives you negative cool points -. When you ask about power under 3,000 - are you actually referring to driveability? If you stay out of the end carbs, that center 2-barrel is going to have perfect street manners.

[android 211]

Jim Taylor did a back to back swap test on a 68 GTO with a 428 and Rochester/cast iron intake vs. a '66 tripower. With the tripower it picked up about .2 or .22 second and a few mph. Plus it sounds really cool at full throttle. A Performer/Holley combo is fine if your starting out with nothing and don't want to hunt parts but it isn't faster than the the alternatives.

[Cliff R]

The Performer intake has small runners and pretty restrictive compared to a stock intake. Probably OK for "mild" set-ups, but they don't fair well for big power.

I tested one a few years ago, and my 455 at 500hp wouldn't run correctly with it in place. It didn't even pull well at low rpm's, acted like a restrictor plate compared to my ported stock intake.

The Tri-Power would be a much better choice, IMHO, IF it were working correctly and dialed in for what you are doing.....Cliff

[tripwr1964]

my 2cents.
search on this forum and you'll find several guys running well into the 11's with 3x2.
so yes, they'll do it with correct porting on intake and jetting (and little idle circuit work).
i'd look at it more from a $$$ perspective and what do you want it to look like.
i have a '64, and to me, a '64 should have a tripower. so i go to much effort and spend more to get this look.
here is a pic of my 472ci w/ '66 setup (that i am currently installing). while it doesn't look stock, it does look like it belongs in a '64 gto.
bottomline if you're not on a strict budget and you want a classic pontiac look.... TRIPOWER.
cheers

[Tom Vaught]

Originally Posted by Chris-Austria

Hi! Sorry!

2. i have the Tri Power but dont want to use it because nobody here can adjust it properly.. i'll keep it for another engine! i want to buy a Performer manifold and holley carb for my 435cui and would like to compare performance of the tri-power and the new system! i dont know if the tripower is the best choice for my engine even if it was adjusted.. thats why i want to know the power range
Hope this helps

Chris

My Opinion,

1) A 1966 GTO really needs to have a 66 Tri-Power on it. IMAGE, HISTORY, FUN, CAN RELATE TO THE OLD SCHOOL HOT ROD DAYS.

2) There are people out there who ACTUALLY DO know how to calibrate a Tri-Power set-up correctly. Especially a complete system that was not cobbled together by some hacks. I have driven a Tri-Power on the street since the 1964-65 time frame.

You said: "i want to buy a Performer manifold and holley carb for my 435cui and would like to compare performance of the tri-power and the new system!"

You also asked about a Holley 770 carb to go with the intake and engine manners below
3000 rpm.

I mentioned a "switch" feeling on the 66 Tri-Power.

You see the 66 Tri-Power has a really small center carb compared to Holley stuff. The drivability WILL be GREAT until the carb runs out of steam (air flow) going down the highway with a 435 cid engine. So then you have to push the pedal a bit farther to gain more speed. Now you are into all three carbs and the Fuel Mileage goes to Chit. Fuel is not $.28 per gallon anymore (like in 1966). It is $4.00 per gallon and with your 3.55 gears you will be using a lot of it to keep up with the Trucks and the Buses who will be going 70+ mph on the normal roads. Ask me how I know this stuff.

So in my opinion you need to have the engine look like a 66 Tri-Power engine but drive like a 2013 engine. That means that you need to get more airflow thru the center carb venturis/ throttle blades during most of your driving and leave the end carbs off until you are impressing the locals.

There are some 455 2-bbl carbs that came with the 1.375" carb venturis that will swap on to your 1966 Tri-Power airhorn top and will also bolt up to your factory Tri-Power center carb base. So the carb will LOOK STOCK for the peanut gallery guys but will allow you to drive around on the center carb (with the 435 cid engine) without opening up the end carbs for 95% of the time. Course if you want to open up the end carbs they will open up just like normal. You just want to stay on the center carb as much as possible (in today's $4.00/gal gas world).

So a sharp Carb Guy like Mike Wasson could build you a very nice 66 tri-power set-up that would do everything that you want/need. Just you have to select the parts a little differently from 1966. You can keep the stock center carb Venturi/booster section from the 66 set-up for the purists who might buy the set-up down the road.

The deal is: You need to stay out of the tri-power end carbs at 65-70 mph to have any chance of decent gas mileage these days. A Larger venturi center carb section will allow more airflow out of the center carb (think the stock 455 engine probably with 3.08/3.23 gears from the old days.

Yes, you can play games with a Q-jet or a Holley Spread Bore carb with small primary venturis and keep the engine rpm fairly low but the velocity WILL be very high thru the small venturis with a 435 engine, a 355 gear, and a auto trans or manual transmission.

That is one reason who some engines like the 850 Holley carb better on the street vs the 750/780 type carb. The 850 Carb has larger Primary carb venturis and drives better on the primary only with bigger engines. You have to look at the whole system vs one or two components.

Tom Vaught

I see in your other post that you were asking about Double pumpers vs fuel economy. A Tri-power is actually a Triple Pumper so that is the main reason to not use them (If you DO care at all about fuel economy).

[Old Man Taylor]

I was able to cruise at 4000 RPM with my tri-power and still have more left on the center carb alone. I limited my cruise to 4000 due to the old rods I was using.

[Tom Vaught]

You have more money that I have Jim! I burned 21 gallons of gas in a 150 mile trip with a 4.33 gear at 4000 rpm cruise. That was a little over 70 mph to keep from being run over by the trucks and buses. Racing gas was ONLY 3.95 per gallon at the time and $82 was some cash for a 150 mile trip. Everyone has lots of money to spend these days. (;>)

Tom Vaught

[Chris-Austria]

Where I live the gallon is about $8.. fuel economy isn't my main concern but sure, if it uses less than before it would be nice! Most important is that it works efficient.. I'll give it all the fuel it needs to work good anyway.
I really searched a lot to find someone who has experience with the tri-power carbs.. the only one I found could get it running but not really well. I'm afraid to drive around with this setup because at idle there is much too less fuel and at 2000+ there is also not enough, even with the bigger jets we used. There has to be a problem with the rebuild and I guess all 3 carbs need to be worked on again. Idle tubes need to be enlarged, gaskets need replacement again, float level adjustments.. even if I know some things because of your great input in this and my other thread, I can't do it on my own because chances that nothing works after it are rather big

I want to keep the tri-power for later and now use another setup like the Performer manifold with the Holley carb. (easy to get, cheap, should run pretty good)
To rebuild my tri-power I'll maybe find a way to send it to the US and have a real expert do his work on them. But I'm sure that will cost me more than the all new 4bbl parts and I haven't driven my car for 5 months.. I don't want to wait at this time and will try to find a way to make the tri-power work on my engine next year.

I found a mechanic who has real good experience with Holley carbs and also worked on some Pontiac engines. He recommended the Holley Double Pumper over a Street Avenger and told me the only disadvantage of the DP is the worse fuel economy. So if I get such a carb with the matching manifold I can make sure that my engine will work fine for now and since it is completely rebuild I don't want to hurt the engine because of a bad adjustment on the carbs.

Back to the manifold question:

1. I guess because of the small runners it will deliver good throttle response at low-mid rpm's as well as good power and will run "out of breath" at high rpm's, did I get this right? So would it help a little to use a spacer between the carb and manifold? (0.5to1".. whatever fits)

2. Will the Performer RPM manifold be a big advantage over the std. Performer if I don't rev it up to more than 5700rpm? (my max hp is at 5550rpm).

3. Does someone know if the Performer RPM manifold with a Holley carb and a std. 3x14" filter will fit under my hood? I'm concerned about hood clearance if I decide to use a RPM instead of the std. manifold.. but I also don't think the RPM will be much better for my needs.. your opinion on that would be interesting as well.


@tripwr1964

Your setup looks great and I agree with your opinion on the tri-power!!

@pfilean

Thanks for the pics, didn't know that their height has changed over the years. I only know my 66 setup looks like there is not much space left under my hood

this is my engine: