[davidgto]

I have a 65 Lemans/326. I was thinking of adding tripower to the 326. After looking closer, it appears the tripower water neck will probably hit the back of the timing plate cover. Your thoughts.

[tom s]

65 timing cover should have the dimple for the tripower?Tom

[steve25]

If your running a HEI that will need to get changed for a points type to get that Intake on.

[77 TRASHCAN]

That's a bunch CFM for 326cubes....*

[davidgto]

I wanted to put the tripwr on for appearance purposes only. I had planned to run off the center carb only. I appeciate comments and information.

[b-man]

You can always adjust the end carbs to open partially and use them as they were intended. A good running 326 could benefit from them opening up halfway or more. The ‘63 and earlier Tri-Powers were like that from the factory, the end carb throttle bodies were designed so as not to fully open.

The thermostat housing can be modified if you don’t have the timing cover with the half round dimple but as already mentioned it should.

[Sirrotica]

In 1969 I bought a 67 Firebird with a 326 HO 4 speed car, I traded the 4 bbl AFB, and intake for a tri power off of a 66 GTO, even up. If you stomped on it from a low engine speed, just off idle it would hesitate slightly, other than that it really helped on top end and mid range.

No one that owned a chevy 327 would say that an aftermarket tri power set up was too much induction for their engines.

BTW, my engine was completely stock, OEM cam, log exhaust manifolds, factory dual exhaust, with a transverse muffler. I wouldn't be afraid to run all 3 carbs on your 326, going from my past experience. As long as the engine is in reasonable shape, and in good tune, it may surprise you.

[tom s]

FYI,in 1963 GM showed a 326 HO tripower option at 290 HP.Farmer at NHRA would not buy it and put me in MP class.Tom

[Schurkey]

I ran 440 six-pack carbs on an Offy manifold on a 283 Chevy. "350" cfm center carb, "500" cfm end carbs (rated as 2-bbls) Rated as a 4-bbl, around 930-ish cfm.

'Course, they are vacuum-secondaries. Ran fine.

Those carbs are now on a 400 sbc, with HEI. The HEI took some "custom work" to fit.

[geeteeohguy]

In 1980, a friend had a '65 GTO with a 326 and the '65 tripower set-up on it. It ran strong. No issues at all. Car was a 4 speed with 3.55 gears.

[steve25]

Once Pontiac started using the bigger center carb on these Trip set up’s those small air cleaners they still used where a restriction and a likely reason why even on a 2 bbl Cam’ed 326 there was no issue with responce when running the 3 big carb 66 set up.

[Goatracer1]

I had a 1957 Tripower on my 287 engine and it ran well. Yes I know it has 3 small carbs but the engine is smaller also.

[BILL BOWMAN1]

Originally Posted by steve25

If you’re running a HEI that will need to get changed for a points type to get that Intake on.

I must respectfully disagree.

[misterp266]

Originally Posted by 77 TRASHCAN

That's a bunch CFM for 326cubes....*

Perhaps a Holley engineer could chime in here and explain how multiple carbs, especially three two barrels differ from one single four barrel carb or dual quads.
Carburation seems to be a mystery to most. More so than camshafts.
It’s assumed that a carburetor flows a certain CFM no matter what engine it’s on.
Tom?

[b-man]

Interesting to note that a ‘69 Z-28 302 came with a 780 Holley 4-barrel on a dual plane intake.

Pretty much the same cfm that a ‘59 - ‘66 Tri-Power has, which also uses a dual plane intake.

To work well having some decent rear end gears will help that, the Z-28 came standard with a 3.73 rear.

[Schurkey]

Originally Posted by misterp266

Perhaps a Holley engineer could chime in here and explain how multiple carbs, especially three two barrels differ from one single four barrel carb or dual quads...
...It’s assumed that a carburetor flows a certain CFM no matter what engine it’s on.

To over-simplify since I'm not a Holley engineer:

2-bbls are rated with 3 inches of vacuum sucking on them.

4-bbls are rated with only 1.5 inches of vacuum sucking on them.

More vacuum makes for higher numbers. Supposedly, when all this was established, a 2bbl on a V-8 engine might actually produce somewhere close to 3 inches of vacuum at WFO and max RPM. The bigger 4-bbls cut manifold vacuum to about 1.5 inches of vacuum at WFO and max RPM, depending of course on the engine and how high a person was willing to rev it. There's a conversion formula to go from one to the other. My "1350 cfm" as a 2-bbl tri-power is only "~950 cfm" as a 4-bbl. It's insane to use "2-bbl" ratings for a multi-2-bbl installation, since it's going to mimic a 4-bbl for airflow.

Reducing manifold vacuum at WFO and max RPM is why race cars get ginormous carburetors.

There's more to it than that--for example, wet flow (air plus a liquid gasoline substitute) vs. dry flow (air only). Dry flow gives bigger numbers.

[carbking]

Carburetors are tested for flow by engineers.

Carburetor flow ratings are published by marketing personnel.

At least as important, maybe more so, as the carburetor(s) flow rating is the efficiency of the intake manifold, both in maximum AND minimum cylinder flow!

Jon

[Tom Vaught]

Originally Posted by carbking

Carburetors are tested for flow by engineers.

Carburetor flow ratings are published by marketing personnel.

At least as important, maybe more so, as the carburetor(s) flow rating is the efficiency of the intake manifold, both in maximum AND minimum cylinder flow!

Jon

Proper Intake Manifold "design" has a extremely large effect on carburetor function.

Tom V.