3x2 Tri-Power anyone?

[masterlock]

Is it worth it/possible to run a 3x2 setup on our trucks with a stock 350. Im just looking for a project to work on while my truck in in a thousand pieces getting body work done.

[79k30dually]

I don't have much experience with 3x2 set ups, but I have set up a couple 2x4 set ups. The 2x4 set ups needed a larger cam and carb rejetting. I've also see on a dyno a 454 with 2 4's make more torque than 2 other 502's, in 2 seperate cars. I have a 2x4 set up I need to find some thing to do with, but thats another topic=. Good luck, Ron.

[tucsonjwt]

Didn't old Pontiacs have 3X2s on their V8s? Seems like you need the appropriate intake manifold at a minimum. Maybe this is a question for GTO/Grand Prix Keith

[masterlock]

Edelbrock makes a 3x2 intake manifold and speedway motors makes a kit that takes care of the rest. Im just wondering if anyone has done it on a 73-87 c10. Im wondering about hood clearance, vacuum hoses, etc.

[79k30dually]

Yes pontiac ran 3x2 on the gto 389 motors. Chevy also ran 3x2 on the 67 427 corvette. There are after market intakes that run 2x4 and 3x2. It would definitely give the WOW factor. Like this.

[masterlock]

Do you have problems tuning it? In my research that is what I hear most, that 2x4s and 3x2s are beasts to tune.

[78 Chevyrado]

The way they work is that you use only the center carb at light throttle, and at a piont past half throttle on the center carb, the front and rear carbs start to open up.

The only thing to play with is that the front and rear carbs are setup the same, and that the throttle linkage is set to open them up at the right time and the right amount.

What 3x2 doesnt have that a 4bbl carb has is the upper air valve in the secondaries.
What they do is make sure you dont get too much air through the secondaries. when you floor it at low speed, all four throttle valves open to the max, but at that low engine spees, it doesnt need that much air so the upper air valve blocks the air flow to the secondary throttle bores until its actually needed, then as RPM goes up the air valves open more to allow enough air to pass the secondary valves.

I think thats mainly what makes them tricky, as you can have those same problems with a single 4bbl that has no upper air valve.

If you find some old car sites, a lot of cars came with 3x2 as stock from about 1958 to the late 60's. those restoration sites will have info on this somewhere.

[masterlock]

I would really like to see someone who has a 3x2 setup in their truck. Aside from the carbs and linkage and such I would like to see how everything else fits. Supposedly the distributor wont fit (from what Im reading).

[79k30dually]

I've had distributor clearance issues with 4x2 carb setups. One the one I have now I covered a points distributor to electronic using a pertronics kit. Good luck, Ron

[makman1297]

Check these guys out.
http://www.parts123.com/parts123/yb.dll?parta~partsort

[masterlock]

79k30dually can you explain the actual clearance issue and how using the conversion kit has solved the problem. I figure I should know all the problems before I jump into this project.

[BigBlocksRule]

3x2's are notoriously tough to tune. Center carb is used for idle and lower rpm driving, the outers come in with more pedal.
They're also a good bit more expensive than a single.
Parts for old ones are much tougher to find.
I just don't think they'll have the "sex appeal" on a truck that they did on a Corvette or GTO.
Why don't you find a good intake and polish it while you wait? Or untangle the phone cords at the house. Or sort out a big box of hangers...anything that can be completed and won't be something you'll have to mess with pretty much all the time.

[68longhorn]

Have not seen it on a square but think it would look sweet! Why not go with 4x2 or 6x2, for looks I say the more carbs the better!

[79k30dually]

The clearance issues start when you try to use a large diameter cap ie: HEI and some after market distributors. Small cap HEI or old school point type with an electronic conversion is best for looks and reliability. Some intake and carb combinations will allow you to use what ever style you want. My Offenhauser and edelbrock combination will only let me use a small cap. The proper jetting will save you alot of trouble, the 4x2 set up will need larger jets in the primaries and smaller in the secondaries. Thats the wonderful thing about progressive linkage. Ron

[masterlock]

Ron, I like your can do attitude! And what fun would it be having a truck if there was nothing under the hood to mess with.

[makman1297]

Sorry my link did not work, its for a place called vintage speed out of FL, they have a bunch of 2bbl stuff and intakes.