Hudson had to recall a lot of 1956 308 engines as the hydraulic lifters got noisy after a few miles. Reason, not enough oil pressure as Hudson only has 38 to 40 lbs. lifters need 60 lbs. Walt.

I did not know this. The first thing I should do then, if I end up with this engine, is to stick an oil pressure guage on it and see just what I have. Can you tell me what the solution was to the problem? A higher pressure pump, perhaps?

Thanks for your input Mr. Mordenti

Also another issue with the hydraulic lifters is that replacements are next to impossible to source. When I finally get my engine sorted out I am strongly considering putting in a new camshaft and converting the lifters to manual tappets.

Ray

Mike,

I just looked in my 1951 Hudson service manual, to see if the 6 cylinder engines an Oil Check Valve. They do. On page 8 of the Engine section, the location of this valve is shown. It is below and a little bit to the rear of the distributor, and a bit in front of the dipstick. The statement which describes it says, "Oil pressure is regulated by a built-in non-adjustable oil check valve consisting of a plunger, spring, plug retainer, and plug gasket, Figure 5". The spring in this valve is set for 40 lbs.

The purpose of this valve is to prevent the oil pressure from becoming too high, which would be likely to happen when the oil is not yet warmed up. In my 1982 Jeep Wagoneer, the spring regulates the oil pressure to 60 lbs. I have seen Volkswagens where it regulated to 80 lbs.

Naturally, when engines get old, the pressure when warmed up often is less than the regulated amount. However, since the engine you are considering is new, I would think the valve could be fitted with a stronger spring, so it would have the 60 lbs. when warmed up that Walt indicates the lifters need to work properly.

Walt, have you had any experience with this?

Per

Hello Ray,
Thanks for your input. I have no problem with solid lifters. The reason my old friend hung on to this motor, is mainly because it was a low-miler he thought it was a pretty good motor, generally - it just happened to have hydraulic lifters.
But having hydraulic lifters would indicate that it was a 1956 motor. My original question was how to identify it as a 1955 or 56 motor. Are you familiar enough with casting numbers or serial numbers that you can help me out with this? If you have a motor with hydraulic lifters, the casting number from it might help me.

Thanks again. I really appreciate your help
Mike

Hello Per,
Yes, the problem does not seem to be insurmountable and thank you for your advice. If I get this motor, I will be paying close attention to the oil pressure. Your suggestion seems quite simple. Perhaps that was what Hudson did with their recalls.
Can you tell me what casting or serial number would indicate a 1956 engine?

Thanks Per!

Mike, Same casting for 1955 and 1956. Might check the casting date code found "hidden"by the distributor. Will be a 3 or 4 character code with a letter for the month,(A = January) and 1 or 2 digits for day of the month and last digit for the year.
So C255 would be March 25th, 1955. . Look for late 55 or 56 date codes for hydraulic lifters.

Fred "Ric" oops, for got to list the casting # for 55-56 is 532500.

The oil pressure springs Hudson had listed was for the guys that raced the Hornet engines. Oil pump gear was changed after every race. Normal driving used the 38 to 40 pound springs. Higher pressure wears out the oil pump gear and the cam gear match. 55 and 56 blocks are the same, but went to hydraulics in 56 because to adjust the tappets you had to drop the engine in the 55's and ended up the same for 56. With todays higher speeds on roads, the oil pump gear will not last long with higher pressure. Walt.

Mike, RIC has supplied the numbers. This is the for sure way to identify. Other ways to identify, include, dipstick location. If it was originally used in a 55-56, the oil pan will have a center sump oil pan, also, the dipstick location will be in the middle of the block, not towards the back, the frt.support plate is different, engine mounts have 45degree mounting ears instead of horizontal, rear support plate is different-[starter location is much higher on the bell-housing]- If it is equipped with the manifolds, look to see if the exhaust pipe flange is horizontal or it is at least vertical, or not straight. acrossed from each other. If it was sold new as a replacement '54 and earlier engine, the crankshaft flange will be much smaller by comparison with 3/8th's-24 threads, '55-6 has 1/2 cap screws and also has a large dowel to locate the flywheel. There is also an extra shelf on the deck, left front side of the block, usually starts with an F followed with 4 or more numbers. Also look at the location of the block drain, located more forward than the '54 and earlier engines. I hope this helps

Mike,

Last night I took a look at a Motor's manual that covers American cars from '35 to '52. I found oil pressures for various makes ranging from 35 to 60 lbs, with most being 40 lbs or less.

Those listed with 50 lbs are '52 DeSoto 6 & 8; '40 Packard large 8. With 57 lbs are '52 Ford 6 & 8. With 60 lbs are '38 Packard 12; '51 Chrysler 8.

Thanks, Doug for the interesting information about the differences of the '55 and '56 from the stepdown sixes.

Per

Hello Fred,
Thank you for the information. This is what I was looking for and hopefully I will end up with a low mileage, newer, model of a 308 this coming spring, when the snow is gone!

Thank you!

Rick, this is perfect! You have so much helpful information here! It's really nice of you to help me out with this.

Thank You!