The Stovebolt Site Forums The Shop Area Engine Shop Let me get this straight

Ok, I am about to start into my first project which is going to be a 51 half ton. I have studied the archives so as to attempt not to ask stupid questions. The goal of this truck is to be a daily driver, in other words my main means of transportation. I have a few questions and/or clarifications to ask of the other board members.

I know for my application I need to get away from the original 216. I have a full pressure 235 that I could use. I understand that this motor is not a full flow motor. What difference will this make for a daily driver in reliability and longevity? Should I consider going with a 270, 304, etc., for my application for any other reasons than added power and torque?

I certainly want to go to a open drive line. I think my best option would be to switch the transmission back as opposed to going with a patricks gear set. I think that I need a 1955-1963 transmission to make the simplest swap. Is this correct? I want to use a four speed with a granny first, what model should I find that would work best for my application?

With the modifications that I want to do I think that disc brakes are a must. Does anyone make a stock looking wheel in a five lug pattern or one that I can use the original hub caps? I know that I can retain the six lug pattern but this some what limits my rearend options.

This going to be a long term ground up restoration and I would like to do it right the first time. I am currently in the planning stages and have yet to turn a wrench. This website is fantastic and I greatly appreciate all the help that I have received. I hope that as I learn more, I will be able to answer the questions instead of asking them all the time. Thank You!

The 235 will make a good engine for you. I think there's a tech tip on converting it to a full flow filter. The 235 & 216 were built without oil filters, but have fittings to equip them with a bypass filter, which filters about 10% of the oil that is pumped, and drains it back into the crankcase. With a full flow filter, all of the oil pumped passes through the filter. Don't know how much difference it actually makes in engine life, but it can't hurt. Conversion is easy if you already have the engine apart.

As for the GMC 270 & 302, they are better engines, and with a higher nickel block they will last longer. GMC made a better engine, no doubt about it. They are harder to put in, the block is longer. You might want to consider the 261, Chevy's truck engine.

As for the five bolt wheel, you can bolt the hubcap clips on a later model GM wheel.

Sounds like you're on the right track by doing your homework first.

The easiest tranny for you to use is the SM-420(built by Muncie I think). This is the granny low 4 speed that was used for many years in the Chevy & GMC trucks. It will be a bolt in and is a good stout transmission. It's not a quick shifter like a car 4 speed though.

Eric, do you know what years the sm-420 was used? Is there any year that is better than any other? Ralphy, I guess I didn't use the proper terminology. The proper term I suppose is a "resto-rod" that I am looking for. I am not trying to be over complicated, I just want to stay as stock as possible while achieving my goal of a dependable daily driver that is safe as possible. I know that this vehicle is over fifty years old and that these goals are relative, but it is not like I want to clip it and drop in a V8. I feel that the mods I want to make are necessary "evils" for where I live in the suburbs of Atlanta with a very high level of traffic. If I lived in the country, or if my mods were going to be any more extensive than they are, I would probably agree with you. Thank you for your thoughts though.

Well, I'm kinda going along the same line as you. I just transplanted in a 1962 261, which is full flow/pressure oiling. I converted to 12 volts with an alternator, and I already had the stock SM420. There are basically two flavors, open and closed driveline. I have an open driveline version to go with the '67 six-lug Chevy truck rearend I got with 3.07 gears. You can also use an SM465, it is very similar and replaced the SM420. I'm going to go with disk brakes eventually too, either Nissan 6- luggers (reqires machining) or a conversion kit. I want to stay with six lugs and bolt-on modifications. You will want to add a vacuum pump if you are keeping the vacuum wipers and a fresh air heater/defroster. 3- point seat belts are good too.

My daily driver is a '55 1st series GMC Suburban, which means its very similar underneath to your truck.

I have a GMC 270 with the granny gear 4-speed suggested by others. I've got the rear end from a '73 Chevelle and used a kit to put the disk brakes from the same car on the front.

I think the combination works real well, but I also have a 454 I plan to put in someday...

Ingo Swan, I know I've read the dates for the SM-420 but I don't remember exactly what they were as it wasn't important to me. Basically I think it was made for about 20 years, roughly from the late forties to the late sixties. If I remember correctly the SM-465 has a bigger cap diameter for the front input shaft bearing which means the hole in the bell housing has to be bigger for the tranny to plug into the bell housing. The bell housing can be machined to take the SM-465 which is even more heavy duty than the SM-420.

I finally found in the archives a link to a jeep site with more information. It was made between 1947 and 1967 and there were only two flavors, closed driveline and open driveline. There are also models with a parking break and those without. I understand that it is a pretty "gappy" transmission but I am hoping that won't be a problem. It is supposed to be a rock solid unit that will give few problems. Thanks for the thoughts!

The ranges between the gears are wide, for sure, so you can't shift it like a car. It's a nice transmission for hauling stuff, though. The 261 in mine has enough torque that it still accelerates pretty good.