The Stovebolt Site Forums The Shop Area Engine Shop Swap to dual carb setup

This May have been discussed before but I’m curious if anyone has converted from single to dual carbs on a 216. My question is it worth the expense? Does it really help the motor run cleaner, stronger, better? I have a 47 Chevy one ton panel. Thanks for any advice.

Eye candy- - - - -sold by a guy named Barnum!
Jerry

Dual carbs won't make it run cleaner, stronger or better but that is an interesting way to ask the question.

Unless you are prepared to spend time and a lot of money modifying the camshaft, doing a bunch of head work, valve work and improving the exhaust system, you probably will wind up with less horsepower, less efficiency and lower miles per gallon. You may also get flat spots, odd acceleration and your low and midrange use will suffer. If you do all the work and make all the changes, you'll be left with an engine that likes to run at wide open throttle. Maybe...or maybe not, depending on how much homework you do...maybe you could improve things a little bit if you had 2 very small carburetors (which in total were equal to the CFM your engine was designed for (roughly 190 CFM). But if you just go out and buy a manifold and put a couple of Rochesters on there I think you'll just make it worse. You might make it much worse.

In my opinion the best thing you can do is find a good (or better yet new old stock) Carter made for the 216 and use the stock manifold. YF 964s or 965s are good ones. If you have a Rochester on there now, either of these Carters will be an improvement. There should also be some W-1 models that would be good. Good luck. Search this topic and I think you'll find it has been pretty well beaten to a pulp here.

In theory, adding venturi area increases peak power slightly... if the new setup has the same or better fuel distribution as the original manifold (developed from decades of experience).
Dual carburetors are only useful in a siamese engine operating on both* (not progressive linkage), which means throttle response must be somewhat rich to be acceptable in traffic, and adjustments are... shall we say, critical vs. OEM.

* there's no way to use 1 carburetor each on the 1-2-3 and 4-5-6 cylinders because the 3 & 4 cylinders use the same port.

If I wanted a bit more power I would adapt a smog-era air cleaner assembly and duct cold air from the grill.

I have run dual carbs on my 235 and 261 motors for decades now. And over the years I have learned a few things. Can you put dual carbs on a stock 216, why yes you can. But if you think doing so will give a vast improvement over the single 1bbl, no, not really. It will look great, good conversation, but it will run fat no matter what you do, unless you are using some really really small carbs. To get a dual carb set up to run right requires some tinkering. A more aggressive camshaft, heat to the manifold, maybe slightly higher compression, maybe slightly larger valves, tinkering with the fuel circuits, timing. So as much as I love my dual carbs, they are not really for a bone stock motor, unless you are willing to put up with a few inconveniences. As for the carter YF carbs, they are a really good carb in both design and function. In fact, I have had the best luck in dual 1 bbl installs using the YF carbs with the small 216 base. They run way better.

On an otherwise perfectly stock 216:

Short answers:

"Does it really help the motor run cleaner, stronger, better?" Three questions - maybe, yes, yes (but how much cleaner, stronger, better? - read on)!

"My question is it worth the expense?" - Your call

Long answer:

Panic (2 posts above) said it well.

Longer answer:

IF - (A) you pick the correct size smaller carbs, (B) recalibrate these smaller carbs perfectly, (C) modify the intake for the smaller carbs (D) modify the intake (if needed) for heat, and (E) perfectly synchronize these carbs; well, expect 3 to 5 percent improvement. NO MORE!

If you don't do ALL of the above perfectly ........................you won't break even!

And, quoting Jerry (Hot Rod Lincoln) - "Eye candy- - - - -sold by a guy named Barnum!"

If you really want improvement from multiple carburetion only - go with triples (and again re-read the post by Panic). Do everything 4 sentences above perfectly and you might get 15 percent.

The stock Carter W-1 is very difficult to beat on an otherwise stock 216. Jon G. and Dragsix both mentioned the Carter YF, which I agree, IS a good carb; but I prefer the W-1.

Jon.

Thanks to everyone for responding. I definitely got my questions answered well. I’m going to drop the dual idea and go the single carter route. This one ton only goes about 45 mph without overreving the engine anyway. Putting something on that functions best at higher rpms is not wise. Thanks again. I needed a good talking to on this! David

If you don't plan on hauling heavy loads in your 1 ton, a T-5 transmission will amaze you on how much more you can get out of your 216. There are two extra gears which are closer together, eliminating the lugging right after the shift, followed by red-lining the engine before the next shift. On top of that, you have overdrive so you can go over 60 without red-lining in fifth gear.
Since you have an open drive shaft already, you can use your original rear end.

I agree, a transmission swap will be a far more rewarding project than adding a carburetor.