The Stovebolt Site Forums The Shop Area Engine Shop Boring a 235

I’m planning on rebuilding my ’53 power glide 235 over the winter. It’s been 45 years since I’ve done one and can’t remember some of the basics. So here are the dumb questions.

First boring the cylinders. Are oversized rings made for standard pistons? If so how much oversized are they? What over sizes are pistons made in?

Second the crank, How much can a crank be ground both the main journals and the rod journals?

This engine will not be raced, but I want it to be dependable for long drives.

I’m sure there will be more questions later

You have to match the rings to the pistons .10 over pistons need .10 over rings and so on .The over size is determened by the damage or wear on the cly. Than the clys. are bored to match the next size standard piston .Most are offered in .10 ,.20,.30 up to .60 over . Same holds with the crank it will depend on what is offered in over size bearings .If there is no damage or little wear as in My 216 I just took apart, the clys. and the mains and rod bearings are in great shape so I am replacing the rings , got the engine and head cleaned , I also found two bad exh. valves so after honing the clys and reseating the valves she goes back together .


Good luck, Pete

A minor detail, but ya all missed one zero in those numbers Pete, just don't want the nebees to get cornfused.
An engine shop would use a bore gauge to check the cylinders for wear then order the oversized pistons and bore the cylinders to fit the pistons. There can be very subtle differences in the piston dimensions so it's always best to have the replacement on hand before you bore. And as Pete posted, the rings are bought to match the cylinder overbore. The rings need to be inserted in the cylinder and the end gaps adjusted before they are installed on the pistons. If there is a lot of wear in the cylinders then the 235 can be safely bored to .060” over.
The crank undersize bearings usually run .010”, .020” and .030” being the limit and above that you either need a new crank or need to have it welded.
Denny Graham
Sandwich, IL

OLD AGE , I can'nt remember , I think.

Pete

OK add a .o to all

Darn without that Zero, I thought I could get all the way to 321 cubic inches. :-) Too bad.

I think I have my answers, looks like no such thing as oversized rings on standard pistons

I believe what Kip meant on the oversize rings for the standard cylinders, many years ago I am almost certain that there was a slightly oversized ring made to fit badly worn cylinders. It wasn't very much oversize, maybe a couple of thousandths. I may be completely all wet on this, but it kind of jogged a distant memory of mine.

Kip, if the cylinders are worn to the point where the standard ring gap is to large, then you’ve got more than ring problems. Your probably gonna get some piston slap which you would be hearing now before re-ringing it.
Years ago when all they offered were cast iron rings they would wear out before the cylinders showed much wear. So it was practical to break the glaze with a hone and just do a ring job. As the chrome rings came onto the scene they lasted longer but at the expense of more cylinder wear. If the cylinders are worn then just a ring job won't cure all the problems. At that stage the proper fix is to have them honed or bored and fit new pistons with the correct clearance, which should only have .0015" to .003" clearance. So you see, if you have .006” or .008” taper in the worst cylinder then they would need to be bored to .010” over for .010” over pistons and ring sets.
Many people who haven’t worked with close tolerances find it hard to adjust to or accept that we’re talking about clearances that are the thickness of a human head hair (blonde of course) on many of these parts.
Get your self a good (calibrated) 1” mic with a vernier scale to the tenth and pull one of Blondie’s curly locks while you watch the Ed Sullivan Show tonight. This will give you some incite for exactly what .001” or .0015” feels like, then when you start to check for wear on your L6 you may have second thoughts about whether you should use those original pistons in and cylinder that is .005” or .006” over size. I’d guess that about 95% of the guys that are rebuilding engines here don’t have the measurement instruments to properly measure a 3.5” cylinder bore or piston or even a 2”-3” mic to check a crank journal.
Is it gonna run if you just put it all back together with out measuring everything for wear? Probably, but is it going to be reliable enough to drive out of state to Kansas City for the Big Show next summer, probably not, and your most likely still gonna have some gremlins and odd noises under that thar bonnet.
Denny Graham
Sandwich, IL

OOps, just noticed, that be 3.5625" bore fo you Kip. And also we haven't even talked about the connecting rods and the wrist pin fit, that you taint gonna mess with your self unless you work in an engine shop of have access to a Sunnen hone.

mine's in the shop as of last saturday afternoon, after i discovered that my mains had a few issues. i'm having them do the usuals, hardened seats, mag etc, and have it balanced. a customer/acqaintance owns the shop, (he just dumped $25K? into a computerized balancing machine), and he impressed me when i mentioned the 'extra' oil line from the block to the head, and he finished the sentence by asking if that head bolt had a hole in it. i'm off to a good start, and have to spend the money before i get the dr bills from my emer appendectomy, also from last saturday

Yep ya better bring a bushel basket full I’m allowing about three grand for a complete over haul on an L6 now days.
I’ve just been going over my short block rebuild parts list and with out any machine work to the block, crank or rods I’m looking at $800 plus. Mind you that’s just the short block no head work here.
About everyone I know that started down the road to restoration has said to me at one time or another, “man, this thing is just a money pit.”
Denny Graham
Sandwich, IL