The Stovebolt Site Forums The Shop Area Engine Shop Problem solved?

270 is the 'proper' engine for a GMC... Beyond that and the power advantage the parts for the 235 are easier to come by and usually cheaper.
The 270 uses a Y or wishbone type of front motor mounts.

The one at the mechanic's looks to have the same front mount layout as the truck and both 235s I have in the garage: 2 bolts through the plate on the bottom under the timing cover.
The use of the "proper engine" is what has me stalling. I think it would look nice under the hood with that beautiful "GMC" embossed on the valve cover.

Be aware that the GMC engine is about 2" longer than the Chevy, so some massaging of the front motor mount position and possibly the radiator mount has to be done.
Jerry

The engine mount was "moved" (a plate was welded in to extend the crossmember rearward and allow the 235 to reach). The rad mount looks to be unmoved.

Finally got to try to put the 235 in. I was working alone and was unable to get the input shaft to go into the clutch/pilot bearing. I wound up pulling the transmission out and noticed it weeps oil out the front and has play in the input shaft. Is this normal or should I address it while the tranny is out? (Tranny is 4 speed, SM420??)

Im confused on where you're at here. Did you get the engine installed with the transmission & then remove the transmission? Or am I misreading?

I'm not sure about having any "play", but a transmission will weep some oil. You might get some more help with a new thread on engine install procedure.

Good luck- I highly recommend having help during every bit of this install.

Brad

I will start another thread.
As for clarifying this one, I took out just the engine and tried reinstalling the engine onto the transmission with the tranny in the truck. Being unable to get them to line up for install on my own, I took the transmission out in order to mate the engine and transmission and install as an assembly.

A little up/down/sideways movement at the front of the transmission shaft is normal, that's why there's a pilot bushing in the crankshaft. Oil leakage isn't, unless it's just a tiny seep. Some SM-420 transmissions have an oil seal built into the front bearing retainer, while older ones just have an oil slinger and a drain hole to return any lube that gets past the bearing to the case. Pull the retainer (carefully) so the needle bearings between the input and output shafts don't fall out, and check to see if there's a seal in there. If not, be sure the drain hole back to the case is clear, and the retainer drain hole is aligned properly with the hole in the case.
Jerry

Mated the engine to the tranny and got it in yesterday. Boy that is one tight squeeze. Now I have the throttle return spring and rad mount pad on order. Hopefully I'll be able to test fire this coming week.

Installing the engine/trans as a unit with the front end sheet metal in place is a real challenge. That's why most folks move the trans back a few inches and support it on a jack or wood blocks while getting the bellhousing down onto the crossmember, then install the transmission. Good on ya for being persistent!
Jerry

Thanks for the complement, but I wasn't very persistent. The transmission didn't quite clear between the crossmember and the floor. Seeing as how I'm going to have to weld in a new floor anyway, I just cleared a little real estate with a grinder and cutting disk...
I'm working on some of the details to get the truck fired up soon: fuel line, baterry cables, new alternator (the old one had the longer bolt seize to the housing and it would not come out. I even welded a nut to it and the welds would break before the darn thing would even budge), vaccuum line from carb to vac advance, welding in front plate (due to shorter 235 vs GMC motor), replacing rear left wheel cylinder that leaked out every last bit of the brake fluid, bleed brakes, and hang all sheet metal back on rad support. It always seems all those little details take the most time.
I could use some advice on converting the vac line over to just tubing. Is it possible? is it worth the effort? I just dont want to deal with shaping, fitting, and flaring the steel line. I also have a large opening at the fuel entry point of the Rochester. What should go there? Is it a filter of some sort? a fitting?

Update:
I had some other projects to finish this Christmas break: graphics on my 2000 CR250R, a thorough cleaning of my girls' Christmas present (2002 Yamaha PW50), and welding some fire pits for family. The latter nearly cost me a finger as I dropped an uncut sheet of 1/8" sheet metal, with me kneeling on top, on my right hand. I busted the nail out of the back of my ring finger, broke the finger, and the nail matrix. A friend of mine who is an MD in the ER numbed it up and took the rest of the nail off.
Regardless, I was able to put in some work yesterday and get the engine to fire up. I didn't have spark at first but did have 12v at the coil and points. Initially I thought it was timing, but I pulled a plug and it was dead. So, I cleaned the points and voila!! I tried to get it to run from an auxilary tank but could not get the fuel line to fill. I will need to check the fuel pump. Hopefully it will work fine and we'll be off on a maiden voyage soon.

Good news! (for anyone still following this thread):

Any tips for cleaning out the tank?? I'm about that far from driving it down the street to check for any weird noises in tranny/diff. I have it out and rinsed with gas, soapy water, and some vinegar, but it still looks pretty cruddy.

Good job!
As far as your gas tank, I usually lean on the side of replacement. Assuming it has been sitting a while and rusty on the inside, it's hard to get it the way it should be. I've cleaned and sealed them, but would still get a new one if I could. I always dreaded the coughing and sputtering that happens when your driving down the road and the fuel filters begin to fill up with crud.

Thanks, VEW! It most certainly is rusty, but I'm on a very tight budget at the moment (wife quit work in August to stay home with kids).

A good temporary solution to the gas tank problem is a 5-gallon plastic tank for an outboard motor, mounted on the frame or in the bed, if there is one, with a couple of strong bungee cords. It will be sufficient for short trips and running the engine during shop work. No point in taking a chance on engine and/or carburetor damage from a trashed-up fuel tank!
Jerry

The problem with crudded up tanks is that ethanol-infected fuel is an excellent crud stripper. The crud sloughs off in sheets onto the bottom of the tank. Chunks of rust are not your friend either. An inline filter will not prevent clogging of the outlet at the bottom of the tank. A '54/early '55 sending unit has a fuel pipe at the top of the tank, eliminating this type of blockage. They fit the earlier tanks, so you can just put a pipe plug in the hole at the bottom of your '47-'53 tank.
Carl

Thanks for the suggestions, fellas!! What do you all think about a phosphoric acid bath?? Most of the crud, at least that I could see, is gone. However, it still has a rough rusty texture and when I agitate it the water comes out with a fine rust powder.

Phosphoric acid (such as Ospho) will leave a white powder on the surface, which is a byproduct of the rust conversion. This can be flushed out with water. Make sure to completely dry the tank after the last rinse. A shop vac down the filler hole a little ways for a good while works good for this.
Carl

Bought some Evapo Rust. Seems to be working well thus far.

Finally got around to putting the tank in and plumbing the vac advance (which doesn't seem to be working...). I went for a short trip down the block and it went ok aside from the front left brake dragging (stuck). When I back of the lugs it turns freely, but as soon as I snug them down things bind up. Ideas?

They could just be rusted from sitting. Driving around on another short trip, if safe, apply the brakes frequently to see if they free up.
Brad

Cracked brake drum ???

The drums are new, but I'll look them over. There was some rust in there, but nothing to excessive. O think it may be the springs or a seized wheel cylinder. I'll have a look and let you guys know.

Found it! It's not the brakes; the tie rod just rubs the lip on the rim and causes resistance. I guess I'll have to buy wheels or run spacers... any other ideas?

Modern style tie rod ends may clear the rims.

That's what's on there. I got some 1.5" spacers since I have about 3" to the outside. Hopefully they will be in by Wed.

Well apparently I didn't clean the tank well enough... It's clogging up the fuel filter about every two miles. I took it to work (2mi roundtrip) today to have the mechanic next door look at it and it clogged on the way home. He also said I need to take care of my kingpins.

Pull the tank and take it to your local paint/rust removal company (Chem Strip) and let them soak it. It will come out looking new inside and out...my guy charges about $130 per tank.

Mike B