308 7X engine question

blondwookie

I have been told not to build a 7X race engine for my 48 coupe. Others have told me to build a 7X race engine, that it will work fine in my car. I like to build performance engines, and this would be my first Flathead engine to build. I would like to hear the pro's and con's on building the 7X race engine over the stock 308 engine for my 48 Super Six coupe.

54coupe

I built a 56 Hudson 308 for our '40 two door sedan. Big valves, deeper and wider than 7x block relief, 1/2" head bolts, 3-7/8 bore, bigger than 7x cam, long tube headers, Clifford intake and Edelbrock 500 cfm carb. Trans is a 700r4, rear end is a 9" with 3.56 gears. I had a 232 head on it, but after 7 or 8 months of daily driving, the carbon buildup made it start to ping. I'm using a 262 head now, and it works real well. The car weighs 3300 pounds, and gets 22-23 mpg at 65mph. 

cchancel

The original Hudson standard transmission and rear axle might not hold up well with the extra power.  I think the weak point of the transmission was soft splines on the input shaft.  If it is an overdrive transmission, the R-10 unit at the back of the transmission might not appreciate the additional abuse.  The Hudson-built rear end was switched over to the Dana 44 in 1952 because the racers kept breaking axles.  The carrier bearing mounts might have to be replaced with hardened bolts pushed through rubber/polyurethane bushings to handle the additional torque. Basically, you will likely spend more money and time chasing new problems than you may anticipate at this time.  Don't let me dissuade you, it sounds fun.

It would be very interesting to see how a 262 responds to 7x treatment. 

54coupe

My cam is from Randy Maas. .402 lift, and 276* duration.  With this much lift, and the 262 head, you have to be careful of the spark plug gaps being closed up by the valves. I modified a set of plugs, and side gapped them to avoid any problems.

7XPacemaker

Had one in my 51 coupe. It was bored out to 4” and had a 232 head on it. I had an isky cam in it with no problems. As was mentioned earlier, you have to be careful with detonation. My car still had the Hudson rear end- maybe I just got lucky! I can’t say that I ever had any issues with my single lever overdrive. I didn’t really do many holeshots in it either. I would have probably used a hydramatic from the old quarter mile racer that was in the junkyard if I were going to beat it too much along with the spicer rear. It all depends on what you are trying to do with the car...

blondwookie

My engine is a 55 308. My head is a 308, Larry @ Clifford told me to shave my head ,060. All of my intake and exhaust will be Clifford performance. I'm not into light to light racing anymore. My car will be for show and pleasure driving. I want to cruse for fun now, but want the horsepower for the sound

7XPacemaker

I had the original 7x manifold on mine with 12” glass packs. I will honestly say that I believe that the Clifford header sounds better than the 7x manifold. Just my opinion though..

Browniepetersen

Randy sells 4 Cam's for the Hudson Engines.  Standard, 7X, Street legal and full race cam.  In building an engine to the 7X standard, you are leaving a lot of horse power on the table.  I have had two 308 engines built to beyond 7X standards and love them both.  My current daily driver (1954 Hornet Special) has 225 hp....  You might ask Randy what you should do with your engine to get the performance and bragging rights you want.