The Stovebolt Site Forums The Shop Area Engine Shop 1979 chevy 250 Eng ???

I have just recieved a free bee!!! 1979 chevy 1/2 ton with a 250 cu. motor (head gasket problem??). I am looking for a better motor to put in my 1950 2 ton chevy w/54 235. Ive toyed with many ideas. What kind of motor is this compared to other sixs, good choice, problems with motor, expensive to rebuild/refresh better choice. Plan to use truck for local use and it has 4 speed w2 speed rear. Thanks for your imput.

There are several possibilities with the 250, and some up and down side considerations when it comes to replacing your 235. It won't bolt in without a bellhousing change, and the fabrication of a crossmember or two. The rear of the 250 block has the same bolt pattern as a Chevy V-8, so a bellhousing for one of the old 265's or 283's will be similar, but not identical to the way your bellhousing mounts. It might be possible to modify your existing crossmember to accept the early V-8 bellhousing, which has provisions for a hydraulic clutch system on some models. The forward mounts are about mid-engine, which will require fabricating some mounting brackets.

The pistons in the 250 are dish-top for proper compression for unleaded regular gas. They can be replaced with 307 V-8 pistons which are flattops, for higher compression and performance. The size, weight, wrist pin, etc. of the 307 piston is identical to the 250, the only difference is the dome shape. Late-model 250 cylinder heads with the built-in intake manifold are a POS, so try to use the earlier head with the removable intake. Lots of work to make the swap, but parts are a little more available, and it's a newer design engine. A good-condition 261 would be an easier, more powerful swap.
Jerry

What Jerry said - if your head doesn't have the bolt-on intake manifold, throw it into the nearest large body of water and watch the satifiying splash. Then raid the boneyard for an earlier head.

I recently changed out a 235 out of my 54 6100 to a 250 out of a 75. The bellhousing bolted up just fine with out any trouble at all. The water pump was too long but so was the water pump on the 235. The PO had cut the radiator frame and it in front so i just left it that way. If you want more info on motor mounts and linkage stuff come on back. Redcoat

Thanks for the info, you have all but convinced me to move on to the next idea,I looked into the head on this motor and it does have the one piece head and intake. With all the mods that have been metioned, motor mounts and crossmembers. I hope they didnt hack your Rad. frame as bad as my PO did as well as the hood latch panel in front of the rad. I think Ill wait and see what comes up next, if anyone needs a 250 out of a 79 chevy they can have it. Dale

Sorry one more ??? does anyone know what three speed manual chevy put behind 250's in 79, I have the tranny as well. Its still in the truck and havent looked at that yet!!!

Most likely, you've got a fully-synchronized Saginaw 3-speed. It's a considerably stronger trans than the previous model, and it can be shifted into 1st. gear at any reasonable speed without coming to a full stop. I've run them in roundtrack race cars behind 400+ HP engines without problems.
Jerry