I was looking at other carburetors for my 37 Hudson 212ci 6 cylinder splasher engine & in the calculations one must choose a percentage for volumetric efficiency. I have absolutely no idea as to a percentage for this old L-Head engine. Can anyone give me an idea? The engine is pretty stock except a bunch of porting, gasket matching, & 8.5:1 compression head. Stock cam & valve head size is stock too. Thanks Sent from my iPhone using H.A.M.B.
I was reading that most engines (modern) are 80-85% so I’d guess 70% max but maybe more like 60-65. Max RPM is 4,000 from all I’ve read. Sent from my iPhone using H.A.M.B.
Those 80% VE engines can generally make 1hp/cu in. An 85 hp 221" flathead makes .38 hp/cu in. Not very efficient. One sidevalve I was playing with lately was good for ~1/2 hp/cu in. I used a VE of 56% when I was doing math. Mike
You are starting with a 212 inch engine. It is basically stock except for a little port grinding and slightly raising the compression. The cam is stock and the valves are the stock size. Why do you think the current carb isn't sufficient for the engines needs with maybe just a jet change. You could work backwards mathmatically to see what result you get for the factory set up. If you need a carb because the old one isn't usable, I'd just look for something with a similar amount of flow and not worry about hypothetical VE using some unknown.
I realize this is a hot rod forum so bigger is always better however: The 1937 Hudson 212 CID 6 used a TWO-BARREL carb, not a single barrel. The main venturii were 1 1/16 inch (larger than the Stromberg EE-1 or the Holley AA-1 used on the Ford V-8). The Chevrolet 216 CID 6 used a SINGLE BARREL carb in 1950 with the same main venturi diameter. In fact the two-barrel used on your Hudson is about the same size as the two-barrel Ford used in 1955 on the 272 CID V-8. As far as your question about V.E., don't know, but would guess your guess of 60~70 percent would be in the ballpark. You COULD work backward as suggested to come up with a figure; but unless you have a factory Hudson dyno sheet on your engine, you are working with "advertised" horsepower. Advertised figures are those imagined by the advertising department, not necessarily accurate. Jon.
Had a chance to do a wee bit more research. Hudson continued to use various models of the Carter type WD-0 through the end of the 212 (1947). Someone called a couple of days ago on this, possibly you? Hudson used the newer type WGD on the 254 and 262 engines. The 1937 WD-0 was close to the beginning of the WD-0 development; and newer WD-0 versions were more sophisticated. While I doubt seriously if you would see any difference by replacing the 1937 carb with a 1947 WD-0 as far as WOT power, the mid-range and driveability would probably be significantly better. Unless you plan on significantly increasing maximum RPM or a bigger camshaft, I don't see any benefits (in fact, low RPM torque and idle quality might be worse) by using one of the WGD carbs from the 254/262 engine, even though the WGD is more sophisticated than even the latest WD-0.. Jon.
Hudson with its long stroke and splash lubrication is NOT a high RPM engine, and from what Carbking says, it came with a lot more carburetor than most engines of its size. I would take his advice and especially, not push the engine to higher RPMs or road speed. To do so invites rapid engine wear and possibly a blow up. Having said that, Hudsons were known as a fairly hot performer in their day. They were light weight, had efficient engines and good handling. English makers Railton and Brough Superior chose Hudson ch***is to build sports cars to rival Bentley at half the price. The Terraplane Eight sold in the Ford price range, and could outdo the Ford flathead V8. Even though your engine is smaller than a Ford or Chev it should not be too bad in traffic.
I am going to go out on a limb here and say that maybe we are way overthinking this. it is a flathead 6 and really even with an adapter a carb that bolts on is going to be pretty close to what it came from the factory with and probably be close enough for the girls I go out with. That said given that it is what it is VE is going to be real close in the 60-70 percent range.
Yes, I actually have a WGD carb from an 8 cylinder (254) and the bolt pattern is around a 1/4” bigger overall. I would have to make an adapter as nothing is available & I think there is going to be interference with those two bolt patterns. I see an adapter with two plates (one top & one bottom with a section of oval pipe in the middle. The original one on it has a goofy decelerator on the side of it used only one year, too many caught fire I’ve been told! You are right the WGD would certainly be plenty & I’d like to make mine work if at all possible. If I could adapt it, I could at least try it out & see how it runs. So are you saying this is a bad idea? I kept it under 3800 rpm.....
The WGD from the 254 will actually flow LESS than the WD-0 on your 212 UNLESS you machine the intake manifold to match the throttle bores on the WGD. An adapter for the flange is not as important as the air flow from the carburetor to the intake manifold. The "goofy decelerator" is actually a dashpot. It was not a one year only; Hudson used it through mid-1941. Dashpots were used by various manufacturers clear into the 1970's. And while I am not a member of the Hudson club, I have never had a customer say anything about this being a fire hazard. Jon.
Jon, interesting that you brought up the matching of throttle bores to the intake manifold. The intake manifold has much larger bores/ports than does the carb base plate. I would ***ume one would want the base plate to match the intake at the point which they join, in a perfect world. If this ***umption is correct should one open up the base where it attaches to the intake? Two pics attached in one photo the carb gasket is on top of the WDO base (photocopy) and the other is on the WGD base. Last pic is of the gasket on the intake. Sent from my iPhone using The H.A.M.B. mobile app
Interesting picture on the intake. Surprised that the ports would be that much larger. So this eliminates the problem with extra corners in the adapter. However, you still may experience idle/low RPM issues due to lack of air velocity. You may have to add an idle air byp*** circuit to the carburetor to improve idle. A suggestion: Before switching the carbs do some performance and driveability testing, write down the results; then do the same tests with the larger carb and compare results. You may be surprised. Jon.
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