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Tri Power


Does anyone have any info on converting the 2gc to a tripower setup. I know spudway sells a kit for the front and rear carbs. But i would like to research other options. I would like to gather up 3 rebuildable carbs and try it i really like the look. Don has a sweet setup with his adapter and strombergs. Are their any cons to this setup. Remember i have a stock 305er Thanks guys.

Ted Brown said:
I know several guys that have the end carbs blocked off under the base, also cut the bottom half off the butterflies, so all the linkage and all works, still runs great on just the center carb. :D

Gotta go with Ted....a stock'll look sharp and won't mess up that way.
I ran a 389 Pontiac with a 3X2 system.......out of a old GTO.......someone decided to play mechanic with it.....holycrap.....only took me about 6 months to get all the 'Elmore Fudd' crap off it and outta it.
If you like to steadily tweak on the carbs......its a great system......once you finally hit that magic note to make them scream.......don't tweak anymore!

Anyone thats run a 2x4 setup or a 3x2 setup for over 3 years has 'Paid their Dues!' Ha!:cool:
Thanks Don for the link . And thanks Ted and SM for the guidence Again.
The GTO setups used the large size 2G's. I agree with Metal. They're way to big for a small block. The smaller size carbs only flow about 200 CFM each and should be OK on a 305.

I'm running the small carbs on my 46 and my T. Both sets were put together with new bases on the end carbs, like Speedway sells. The set on my 46 has been in service for 10 years with no trouble. You can do it cheaper, but I don't have any experience with other setups.

Keep your fuel pressure under 5 PSI or you can have problems with flooding. I run 4 1/2 pounds on a regulated electric pump and have never had starvation problems.

No matter how you build your set, make sure the end carbs seal completely when they're closed. Trying to run idle circuits on the ends will cause a lot of frustration with tuning. They're not needed for a good street setup. The new end bases that Vintage Speed and Speedway sell have thicker butterflies than the center carb like a 4 barrel. This helps to seal off vacuum leaks when they're closed and helps keep them from sticking. They also have a springs to keep them closed.

It's lot easier to tune if you remove and block the end carbs while working on the center carb. Get the center carb running right before you go any further, since thats the one you'll be on 99% of the time. Then add the end carbs. If your tune goes away, you'll have a better idea where the problem is.

Good luck. If you get them set up right, they'll run at least as good as a 4 barrel and look a heck of a lot better IMO.

How do i identify the small 2GC . Is it a 2G. I also noticed some have side fuel feed and some front. I read a thread that the olds and pontiac are a better choice??? Anyone know any part numbers or id marks for the small carb. If i did what ted suggested do i want the large two barrel for the center ??and block off the front and rear?? would that make it a "FO-Power" get it . Thanks guys
Most of the aftermarket aluminum 3 x 2 intakes are set up for the small base Rochesters. That is what I am running on my 394 Olds. My Kid has an original 442 W30 tripower setup on his 30 rpu and they are huge compared to mine. The fuel pressure thing like Mike said seems very important to these 2 barrel Rochesters. I think that is the problem I am having with the 2 x 2 setup I installed. I have no regulator and the Holley electric pump may be overrunning the needles. I am going to add one soon.

Sorry Rooster. Didn't mean to cause confusion. All the Rochester 2 barrels are 2G's. Large and small versions. The "C" in 2GC just means that it has an attached choke actuator housing.

The small carbs have 1 3/32" cast into the upper part of the venturi. You can look through the top opening and will need bright sun or a flashlight to see the numbers. Once you see the difference between the large and small sizes, you will be able to recognize them easily.

If you can get them cheap or free, get all you can find, even the large ones. Some internal parts will interchange. Be careful with swap meet or EBAY carbs. Some will look good on the outside, but be corroded inside. I wouldn't bid or offer more than junk prices if I couldn't see the internals. Get the best carb you can for the center. The ends units just dump fuel.

The side fuel inlet carbs are easier to plumb the gas lines to. The tops will interchange if needed. Just be careful with the internal vacuum passages, since some aren't drilled on some carbs.

Don is right. The commonly available small block manifolds are for the small carbs. Offy used to make one for the large ones, but even they didn't recommend it. The rep I spoke with said it was pretty much a race only piece.

I'll try to get some pics of the numbers up if you want.

If you do decide to block the end carbs, the small center unit should be OK. They were used on single carb 327's. It'll just run out of breath on the top end pretty fast.
My other problem is i have a 92 305 and i think eldelbrock makes a tri-power manafold for my motor. It has the cantered center manafold bolts. i have seen several guys just redrill those center holes but i dont know about that.
I got my little 305 runnin so good i feal like i am cheating on her just talking to you about your 350. That is a great deal for some lucky person but i am in good shape thanks.
Rooster, 3 dueces might be a little much on that 305. My car has a 283 in it, running 2 of the small rochester 2g's on a modified tunnel ram, and it runs pretty good.

LKE said:
Rooster, 3 dueces might be a little much on that 305. My car has a 283 in it, running 2 of the small rochester 2g's on a modified tunnel ram, and it runs pretty good.

100_0390.jpg that is what I like......take a idea and adapt it to fit your own ride.......great work! I did that with a couple of downdraft webers on a 265 Chevy..................looked at your photos....really liked your frame jig there..............:cool:
one of the ratrod mags had an articl a while back on doing the mods. I have it "someware" and will try to find it. It sounds easy, but those mags are not pics with captions intensive.
Thanks Mike i am researching it as well. I think the center carb is easy its the front and rear that are the more difficult. The bigest problem is how the butterflies seal at an idle. Speedway makes a kit that is the base (thicker 5/16 instead of 3/16) with no idle mixture circuit and thicker butterflies. I think i can come up with the carbs and even redrill the center bolt holes in the center runners on the manifold. I dont think anyone makes a cantered bolt holes in a tripower manifold. 87-92 chevy. If anyone has any old carbs around they could part with i would be interrested. Winter project!!!!!
Does anyone have a comment on this setup.

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