Chevy 6 cylinder

Need a little edumacation here. I've got a '62 Chevy dually (10,000 lb GVW) with a very smoky 235 that I use for hauling. Already replaced the old valve seals and did a tune up but it still smokes bad. Compression test came out around 150 on all six cylinders though. Am I looking at bad rings? It still runs okay but I don't want to get into an expensive rebuild.

If I go the engine transplant route, what 6 cylinders should I look for? Any to avoid?

 

When I was young(er) I re-ringed a smoking, rough running engine and then found out the float had sunk in the carburetor...

 

How gunked up is the cylinder head? Bad enough to prevent adequate oil return? Were the valves loose in the guides? All 235 heads had replaceable valve guides, and they're still quite inexpensive and available from most engine parts companies. If it were mine and I had reason to remove the head, I'd probably ream the cylinder ridge, hone it with a ball hone, and throw a set of rings in it anyway, as long as I was there.

 

If you decide to replace it you might think about a 292. You'd be glad you did.

 

The bolt pattern on the trans will accept a new style bell, so you can run any small block or post 62 inline with some motor mount changes, i think you need a 3rd gen f-body bell to keep the hydraulic clutch or adapt the stock system to a wilwood slave. if you can find a big jimmy, that would be drop in, i think.

 

Try changeing the oil.
Old fouled broken down oil will make one smoke.
When you get clean oil in it take it out and drive it at highway speed for about an hour or two. it'll burn a quart, top it off and drive it home.

A lot of times when one doesn't get driven at speed or gets lugged around town alot the oil rings will get clogged (especially if you use a high parafin oil like Pensoil or quaker state or haveline) the oil rings will clean up and smokeing is gone.

if that doesn't work and the float isn't stuck like the Dr has suggested it was still cheaper than tearing it down or changeing it without the need to do so.

 

yup...but it could just be plumb wore out, like all the 235s I've ever had.

Usually they burn a quart driving home 10 miles.

 

The head was fairly clean and guides were in decent shape.

The stuck float is something I hadn't thought of but will check that out. It now has fresh oil so we'll see what happens after a long drive this weekend.