The Stovebolt Site Forums The Shop Area Engine Shop 216/early 235

Where does the extra 19ci. come from? Is it bore, stroke, or a combination of both? The reason I ask is because if you look up pistons and rings in some catalogs, they only list a 216 in 1948. If I'm not mistaken, an "FEA" prefix is a 235, correct? So why don't some companies list stuff for the big truck, or RPO 235 in '48? :confused:

Keith,

These numbers from a 1948-1951 Shop Manual are not going to explain anything.

1948 Engine Specifications

Bore:
216 3 1/2"
235 3 9/16"

Stroke:
216 3 3/4"
235 3 15/16"

HP (SAE)
216 29.4
235 30.4

However, the Shop Manual only gives specifications for one size crankshaft, one size connecting rod, and one size piston. There might be different sets of rings (216 vs 235)? In 1950 and later, there was a different style of one compression ring on the 235 compared to the 216.

Maybe someone can answer your question and explain the increased stroke?

Sorry about not answering your question.

Tim

It is correct that FEA is a prefix for the 1948 235 (6000 series). Engine displacement is calculated using both the bore and stroke, and as Tim showed, both the 235 bore and stroke are different from the 216, so that's where the extra 19ci come from. The cranks for both engines have the same journal sizes--only the stroke is different. The connecting rods are the same, but the pistons and rings are different. The 235 pistons and rings are of course a bigger diameter, and the 235 pistons have a slightly different compression distance than the 216's.

I think the problem with many catalogs may be that they only consider the cars and light trucks (up to 1 ton). The 216 was the only engine available in the light vehicles until 1953, so some catalogs don't include the 235 that was only available in the 1.5 and 2 ton trucks before '53.

Another problem might be that the catalogs have the dates wrong regarding the availability of the 235. As one example, NAPA online doesn't show the 235 as available until 1952. In '52, they show it as available on the 3600 and 3800 trucks, which is wrong. For '53, they show the 235 as available on the 3100, and standard on the 3600 and 3800, which is also wrong. NAPA doesn't list trucks above the 3800. Another example is Egge Machine, a specialist in old engine parts. They don't show the 235 as available until 1950.

I don't think the year matters much, as all 235's shared the same bore size. As long as the piston matches the bore and the rings are correct for the piston. Jim Carter only lists one piston and one ring set for '41-'62, so according to him, one 235 piston fits all 235's. There were very slight differences in 235 rod length and piston pin diameter throughout the years, too, but that may not be of significance.

Edit: A 1964 parts manual shows replacement 235 pistons in two groups--'41-'53 and '54-'63. But certain oversizes are listed for all years.

Thanks Curt, I too was under the impression that most suppliers over look any thing bigger that a 1ton truck, they don't deal w/any other medium duty truck parts, so why bother with the motor parts. My next ? would be, will the same ring set work in the pre-'54 235's as is used in the '54 and up high pres. oiled 235's or did they change piston design in this "new" era?

I guess if Jim Carter lists the same pistons and rings for 235's from '41-'62 there shouldn't be any difference right?

seems the rings would just depend on the piston size, and all 235 pistons oughta be pretty much the same in size! but a 235 in 41? :confused:

Bill

The 235 rings did change a couple of times. For '41-'49, both compression rings were taper face 1/8". For '50-'53, the upper compression ring changed to a twist-type 3/32". For '54-'63, both compression rings were twist-type 3/32". All oil rings were 3/16".

The 235 pistons and rods changed too. '53-down, the rod was 6 13/16", the piston compression distance was about 2 1/16", the piston length was 3.75", and the piston pin diameter was around .8645". '54-up, the rod was 6.81", the piston compression distance was 2.08", the piston length was 3.58", and the piston pin was slightly bigger at .866". Of course, we all know the rod bearings changed to inserts for '54-up. Also, the pistons changed from cast iron to cast aluminum for '54-up

Again, I don't think any of this really matters, as long as the replacement rings go with whatever replacement piston is obtained. If you only want replacement rings to use on the existing pistons, that's another story. The only thing I'm not quite sure of is if the piston end of the earlier connecting rod would expand enough to fit the larger pin of the later piston. It's only a .001"-.0015" difference, so it probably wouldn't be a problem. I suppose the compression distance should be checked, too, to be sure the piston doesn't stick above the block deck, though were only talkin' about .0175" of difference. One advantage of the larger compression distance on the later piston would be that the compression ratio might be raised ever so slightly.

All this info is believed to be correct, and was sourced from the '48-'51 shop manual, the '53 and '54 truck resto packs, and a '64 Chevy master parts catalog.

Sealed Power makes a '53-'62 235 piston, cast aluminum, flat top, 3/32, 3/32, 3/16 rings, and 2.062" (same as the early piston) compression distance. It's part #1009P with pins (they don't mention pin diameter), available in std and 5 oversizes. Only $98 a set at Fast Engine Parts. They have matching rings too, of course.

My pistons, cyl. walls, clearances are good. I just want to lightly hone and replace rings. On three of my pistons, the top comp. ring was stuck in the ring groove and required some less that gentle persuasion to remove them. (in other words, little pieces of ring) Now I'm looking at my options as far as the mail order/internet suppliers are concerned, and I'm finding myself scratching my head alot. I think I'll go visit my friendly Bumper to Bumper who is a Sealed Power dealer and see what he has to tell me.

Keith,

I checked Sealed Power's online catalog, and they, too, seem to ignore the '49-down 235's. I did find a listing for a Hastings Manufacturing ring set part number 5585 that looks like what you need ( see here ), with the two 1/8" comp. rings. Now all you need to do is find a Hastings dealer.

Also, I found this set on eBay. The guy says they are for GMC 235, but he probably means GM or Chevy. The sizes are correct.

Another reason the early 235 pistons and rings don't show up in the catalogs---apparently very few companies are still making them!! It is strange that they ignore the early 235's, but stuff is still available for the 216's.

Curt, do you ever work, or sleep, or do anything other than study up on old trucks and check in on the forums? :p I think you spend as much time in the Big Bolts, and the Engine Shop as Joker spends in the Spoon!

Thanks for the heads up on the ring set by the way, it sounds right so I bought it, and it shouldn't take too long to get here, the guy that has it is only about 150 or so miles from me. I guess we'll just have to see when they get here. Even if they aren't correct, I couldn't pass up the price! $10.00 for a ring set is pretty darn good, even if it's not right. If it turns out they're not right, I'll put them on the swap meet. Thanks again.

Work? Sleep? What're they?

Glad I could help.

o.k., I got my set of "Koppers" All American "Hammered" Piston Rings, still in the original box from the guy on e-bay. My next question is, did GMC use a different ring style in their 235 than Chev. did?

The reason I ask is because the new rings are nothing like the orig. ones I took out. They are the same size (1/8 x 3 9/16, 1/8 x 3 9/16, and 3/16 x 3 9/16) but they are considerably different in style. The 2nd comp. ring has a groove in the face, and has 3 "pressure ducts" (so called by mfg.) on the bottom. Also, the oil ring is a cast ring with slots milled in it, instead of the more common zig-zag style (VVVVVVV) ring.

They also seem pretty tough to compress with my ring compressor. I haven't tried putting any pistons in the block yet, but I checked the end gap and they seem to be right on.

Just wondering if this was a GMC thing, or "Koppers" own variation of the original?

GMC didn't make a 235 engine. The GMC engine series did use a completely differant piston, ring, and rod arrangement than Chevy, until the mid 60's when GMC six cylinders became rebadged Chevy six cylinders.

So regardless of piston ring design...

rings with correct bore dia.
+ rings with correct groove size
_______________________________
should work just fine

Is this equation correct?