ClassicCar

duncan

What was done at the factory to a 308 engine to make it a 7X engine. Could you please tell me all the things that were done. Thanks Ray

oldhudsons

You might want to know first, that you could not order a 7X engine in a car, they were a dealer only installed option.
They could be bought as a "short block". 10 thousandths was taken off the crank so the engines would be "loose" & ready to race right "out of the box". They use 1/2" studs rather than cap screws (keep heads from blowing head gaskets). They had larger exh. valves & the heads were "ported & polished" as hot rodders would have said at the time. They had a high lift cam.
Now that said they changed cams several times. They used a "262" head but with 1/2" holes rather than 3/8". You can find these various items in the "Z" section of the Parts book.
Such things as the 7X exh. system & Twin H were "add ons" to the basic block & could be purchased & put on any engine.
Think that about covers it.

schillaz

here is a good link. Scroll down to read the article.

http://www.hudsonmotorcar.org/News/article/sid=7.html

RL Chilton

Also, do a search here on the forum. There have been lots of past discussions about the mighty 7X.

duncan

Thanks for the info. Ray

ski4life65

I just picked up a "new" project. A 53 Super Wasp coupe. The previous owner got it a few years ago and never touched it, but he was told the motor had been rebuilt and never used. He was not a Hudson guy and told me it was a 262. Turns out to be a 308 with a 262 head and 1/2" studs, twin-h, 3 sp. W/OD. Nothing is hooked up, and I need to get the correct Twin-H linkage for a wasp, but I may see if I can get it running on my next day off. I will have to pull the head to see what valves are installed, but maybe it was built to some kind of 7X specs..... It does not have the dual exhaust outlet, but I have one I can install. Based on the serial number, can anyone tell me when the motor was manufactured?

Tallent R

Dont for get 7X also had the dual exhaust adapter on the manifold and no heat riser
Roger

duncan

I was wondering if a stroker crank was used. Ray

maasfhcenturylinknet

Would like to find and 51,2,3,4 short wheel base coupe. Retiring Sept. 1 and the Illinois Vintage Race car assoc. wants me to build a Hudson to run with them. They do compete without trying to wreck each other. Would like to do this if I can find a car. Anyone have one they will part with?

Randy Maas
maasfh@centurylink.net
1-309-267-6158

dougson

Ray, easiest way to build a 7X is to find an intact '56 Hornet six. It will have 1/2" head bolts (easy to convert to studs), "long dwell' (old 7X flat top) cam, nearly identical valve relief. Also has better cooling, one piece rear main seal and some other improvements, and later twin-H with additional vacuum ports.

Browniepetersen

I had a 308 block in my 52. We broke it down, did some close tolerence machining, matched and balanced the pistons that we machined ourself from castings and installed our slotted rings so we could have matching weight. Slight turn of the cam, enlarged intake and exhust valves, and went with the 308 steel head flattened .025. Our hp on the stand was 220. It was so smooth that in the engine bay you could start it up and stand a silver dollar on its end. That engine ran on the Salt Flats at 122.683 (double run average.) That was faster than the sedan that the Hudson group in Salt Lake City ran in 1952. The proper machine work will exceed the mythical 7X any day of the week....

lostmind

Dougson , you are correct on that. I had a 56 Hornet 308 in my 52 Coupe,
greatly improved performance over the 52.It used the dual range hydro.
I had to fabricate a crossmember and rear mounts , but it was worth the effort.
Roy

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