7X camshaft

[Deleted User] · July 2005

Looks like I'll have to rebuild my 308 in my '53 Hornet due to low compression in #1 & 3 cylinders. I've decided that since I'll have the block stripped down to nothing and starting over again, I might as well do the engine up to 7X specs, and have begun doing the research for the shop that will do the machining and final assembly.

The first question that comes to mind is what the new cam specs should be? I have a friend who has a camshaft from a '54 Hornet that he says has lobes much flatter on top than the camshaft he put in a rebuilt '52 engine he was doing at the time, and we are wondering if this one is ground to 7X specs. The number between the lobes near the front of it is 309742, and there is a "C", and a "3", and a "K4" and a "D" and another "3", also visible in other places as well. Does anyone know just what cam we have here?

Also, somewhere I read that the '55 and '56 six cylinder engines were already done up by the factory to 7X specs, and were just "used up" until they were all gone when Nash took over. Is this true? Could I just find a good "55-"57 six and "drop it in" saving the trouble of rebuilding mine?

Thanks for all the help you Guys have given me in the past!! This forum is as always first class !!

By the way, I have started a Hudson website that may interest some of you.

Its at www.hudsoncollector.com and its focus is to try and be a place for new Hudson enthusiasts to explore the Hudson experience, as well as a to be a place for all of us interested in the marque to share their Hudson stories, pictures, trials, and tribulations with the rest of us. Check it out, -- you may even discover yourself in there !! :-)

silverone.

Unknown · July 2005

www.uncommonengineering.com

http://members.aol.com/stepdown53/STEPDOWNRESTORATIONAIDS.html#YOUR_STEPDOWN_COMPONENTS

[Deleted User] · July 2005

The 48-54 Master Parts Book lists the 309742 cam as 7X. The 7X writeup states the 7X cam is a long-dwell camshaft that holds the valves open longer allowing a greater volume of fuel-air mixture to enter the combustion chamber. Clifford still sells the 7X factory spec cam and the hotter cams for the 308. Pretty good price as well. That should be a duration--268 and lift--391 cam.

55-57 engines had a deeper block relief but were not true 7X engines. If you read Sloane F. McCauley on Ken Cates site you quickly see there's a difference between 7X from the factory built by the factory race team which spent a lot of time on the polishing of the engine relief to get the correct effect. If you haven't already read Sloane's writeup I would, its a good starting point and gives you the basics. Then its up to you and a good machinist to work that relief to get the proper flow characteristics.

I am 7X'ing two 308's right now and after machining I will polish the relief and do the finish work by hand. Takes a while but I'm not in any hurry.

Anyone have a copy of the 7X Specs Hudson factory technical bulletin dated 2/2/52 which covered the 7X build. I saw mention of it in the old WTN's and Sloane mentions it as well. Wouldn't mind a copy of that as a reference myself.

Unknown · July 2005

this might give you an idea of what's involved.

this is on a Rambler,i knocked off the sharp edges to help prevent detonation.

i took out a little extras while i was at it,to lower the compression after the head and deck surface were both milled.

Park_W · July 2005

The 7X 309742 camshaft was indeed used in production '54s until pretty late in the run. There were a lot of complaints about rough idle and premature timing chain problems, so a milder cam was brought out near the end of '54 production.

Unknown · July 2005

Hi

The following link will get you a pdf copy of the camshaft availablity announcement ... I do have two sets of pictures that show the machine relief work that needs to be done to ... duplicate... the 7X engine. I will try to find a place to post them so you can down load .... they are too large for emails.

Good Luck and nice website.

http://members.aol.com/sanjuana/Camshaft.pdf

[Deleted User] · July 2005

Have camshafts in stock--372 lift with 254 duration good low end power and super smooth idle--391 lift with 268 duration--great highway cam, good idle with sight notice of the 6 degree overlap at the tailpipe. Expect 13 mpg with this cam and really starts to want to run at 60 mph on up. 402 lift with 276 duration--need bigger valves, reworked twin H carbs or four barrel carb. Run with the 8 cly boys on the street. Loppy Idle.

Randy Maas

maasfh@ntslink.net

[Deleted User] · July 2005

It never ceases to amaze me how much raw knowledge there is out there about even the most technical detail of these Hudsons!! Thank you all for your very helpfull advice!

Please correct me if I'm still off a bit on exactly what I need for a camshaft to build a smooth idling, but very strong street mannered Hudson. It appears that my Friend does indeed have a 7X cam there, and that if I use a good modern roller timing chain, do the machine work to 7X standards, install oversize stainless valves, and hardened valve seats, I should have a reasonably smooth idling, (but not perfectly smooth), significantly more powerfull engine, that will purr at highway speeds, but still be "paradeable" when the need arises. One thing I should mention is that I intend to keep the stock 4 speed automatic, so will that affect my choice of cams??

Thanks for the favourable comment on the website Ken! Your site is second to none anywhere on the web, so a "thumbs up" from you is high honour indeed!! I shall eagerly await your posting of the machine relief work that needs to be done to achieve true 7X specs !! That is exactly the kind of information that I and no doubt many others will find worth its weight in gold when we turn a machine shop loose with our engines. One question that immediately comes to mind is just how deep to cut the relief area from cylinders to valve seats.

Randy, --- by your specs for the super smooth idle cam you have available, I'm assuming that the 254 duration, (as opposed to the stock 7X -- 268) is a grind aimed at correcting the rough idle complaints of the factory 7X cam with the 268 duration?? I see the 391 lift is the same, so would one even notice a power difference between the two cams without a dyno to prove otherwise? I'm thinking maybe the best choice for me would be your 254. What do you think?

Park, -- do you know the specs for the milder cam brought out in late '54, for comparison purposes??

Once agan, thanks to all for helping me out!!

silverone

Unknown · July 2005

the 54 flattop cam you list is listed as a 7x cam, but the true came used in true 7x engines was a 311040, ILf you find one use it, If not bet one from randy Maas, tell him what you want and he will have the grind you need. BILL ALBRIGHT, VINTAGE COACH, FONTANA, CA

[Deleted User] · July 2005

Folks,

I am in the process of trying to build some documentation and find the specs for the 7X engine and show the difference between the "True" 7X factory engine and what I call the 7X street build. You can see what I have compiled so far at my site www.hudsonmotorcar.org I have created a topic about the 7X and its on the main page below the forum listings when you find it hit the "Read More" to see the whole article. if anyone has anymore information or specs I would appreciate any info you have.

Thanks

Unknown · July 2005

Hi

I believe the following link will allow all to view a photo album I posted to INTERNET. It contains pictures documenting machine work require to convert a conventional Hudson 308 engine to 7X specifications. The pictures were provided to me by Randy Maas.

http://www.imagestation.com/album/pictures.html?id=2123371526

Enjoy

[Deleted User] · July 2005

Thanks they showed up fine.

Unknown · April 2006

Was wondering for the following two cams, what is the duration (s) and lift (s), if different for the following two cams:

304073

309742

ALSO, does anyone know what ENGINES these two cams were originally designed for and used in??

thanks

[Deleted User] · April 2006

AT 268 DURATION, THE HUDSON CAM HAS 6 DEGREES OF OVERLAP WHICH MEANS THAT THE INTAKE & EXHAUST VALVE ARE BOT OPEN FOR 6 DEGREES OF CRANKSHAFT ROTATION. ONE HARDLY NOTICES THE "ROUGH IDLE" AT THE MOTOR, HOWEVER, LISTEN TO THE EXHAUST AND YOU CAN TELL. tHE 7X WORKS FIND WITH AN AUTOMATIC.

RANDY

7X camshaft

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