indentifying a 308 Twin H intake

dave11

Found a fellow that has a 308 Thin H intake manifold for sale. Looking at the pictures it is a twin H intake, however, the seller is not absolutely positive which engine it is from.
 I would like to verify that it is indeed from a 308 and not a Jet. What is the best method to confirm which one it is ??

Dave Eddie

Courtesy Man

Also differences with 55 & 56 Twin H.

stevepet

Carb centres on a 308 inlet are 3 inch they are 2 3/4 inches for a 262 twin h not sure for a 202

50C8DAN

55s & 56s have an internal balance tube, where prior ones are external

railknight

I have a Twin H intake manifold on my '53 Super Wasp 262 engine.  It's embossed on the top, Hudson 307093.  

stevepet

Part numbers are the same for 262 and 308 inlets onley way to tell is to measure carb spacing

Glowplug

Doug Wildrick posted this in the past and allowed me to capture it and post it to my website... it answers most of the questions that most folks ask about Twin H and its applications.... Good Luck

Doug Wildrick explains the Hudson Twin H and other OEM 1948-54 Hudson carburetor configurations Provided by Ken Cates Hudson Stepdown Restoration Webpage https://hudsonrestoration1948-54.com/ Doug Wildrick wrote: Something Ken probably needs to add to his web page is the actual difference in the 2 Twin-H manifolds. I did just look at the page and might have missed the description. Even though the book gives 2 separate numbers for twin-H manifolds, BOTH manifolds, '51-'54 have Part# 307093 on them, and both use the same exact linkage from the linkage that is captured under the head bolts to each carb. Depending on what your transmission and wheelbase are, will depend on what you need for a bell crank coming from the stud on the side of the block and down from there. With that said, the 968S and 2113S carbs are for the 308 and 308 manifold, but the 990s carb number is only designed for the 262 manifold. The 990s carbs being for the 262, have a smaller base bore size, thus requiring a different manifold. If you compare the 2 side by side, you can see there isn't much difference, but there is enough base size difference it doesn't allow the 2 to interchange. Now with that said, I have personally installed the 308 Twin-H manifold on several 262 engines. I really think the larger bore 968/2113 gives the 262 a little more power, really only noticeable when using 1/2 or more throttle. To add to this, all the '48-'54, 232, 262, and 308 exhaust manifolds are all the same castings, with the only difference being the studs heights to mount the intake and exhaust together being the difference. For example, the 232,1bbl. stud lengths are different from the 2 bbl. 262/308 2 bbl., and a different length of studs for the Twin-H, both for the 262 and 308. I hope this doesn't confuse you too much, but hope it helps! '55-'56 intake and exhaust are different yet, and DO NOT interchange with anything prior, except the carbs and some of the linkage Ken, we should also add, when using the single carb manifold 1bbl. or the 2 bbl., the heat riser boss is there for the other hot air tube, just not drilled. That tube is actually made of stainless and is different in size on each end. It is designed to press into the exhaust manifold and seat tightly. We have a few of those tubes, but it is very unlikely there are very many left out there. With this said, we simply take and split the tubes going to either carb. The tubing size is 1/4, which can be found at most hardware stores and/or auto supplies. We use a Tee compression fitting, which is exactly what is used at the carb choke housing. I think the covering for the tubes needs to be there and Ken has something listed on his site to use, which ensures the heat will get to the designated choke thermostat housings efficiently. Originally posted to the HETCLUB.org Forum webpage

50C8DAN

Ken also note that the exhaust manifolds differ between the '51 - '54 intakes and the '55-'56 intakes.  You cannot swap the earlier intake with the latter unless you also swap the exhaust manifolds unless you are using tube headers.  The heat riser flanges are totally different.

stevepet

50C8DAN if using headers should the heat riser opening be blanked off?

50C8DAN

It is not necessary to block off the heat riser from the headers.  My '54 has headers and Twin H and has never had an issue with the opening not being blanked off.  In our upcoming 2x2 aluminum intake there will be no heat riser from the exhaust manifold and if you will be running the stock exhaust manifold we will have a block off plate for the exhaust opening, if you have headers none will be needed.

stevepet

Thanks for that

dave11

Thanks to all, all good stuff !