Twin "H" Expansion Plugs,Tip..

SuperDave

For those of us that collect recent useable part numbers for our Hudsons..
Recently I refurbished another stepdown Twin"H" intake manifold. As usual, I removed the six expansion plugs and cleaned the exhaust heat cavity. Probably 1/2 pound of carbon in there..Also some of the expansion plugs were thin and one actually had a hole in it. This could be a source of a hard to find exhaust leak. Even if you are planning on blocking off the heat riser and not use the designed intake heat function, It's still a good idea to clean the manifold out and replace the plugs. Also it's a good idea to make sure there are no leaks between the intake runners and the exhaust heat passages.
The factory used 7/8" plugs, but I have seen some occasional useage of larger plugs , no doubt to clean up a poor casting. These 7/8" plugs are not as readily available as they used to be. Most parts stores don't carry the big assortment that we are used to. So.. You may have to order them. Here are the numbers that you will need.
Dorman brand 550-010, steel, 560-010,Brass(More expensive and not needed,since these are not exposed to water and coolant.)MAY BE Available at AutoQuest. My experience was that AutoQuest didn't have any more in the system after I bought the last four they had.
Also Sealed Power Brand,381-1006, steel,available from NAPA
Napa ordered the Sealed Power and got them the next day in a package of 12..for $8.28 plus tax. Enough to do 2 manifolds.

Live in the past... It's cheaper