Matt Wilson

I know this is an older thread, but I am really curious about whether Mr. Petty was using stock 218 rods and rod bolts. I don't suppose there's any way for us to know for sure, unless it was known that he said that stuff was stock. But I'm curious.

The article I linked earlier in this thread supports your statement about the durability and longevity of these cars. Pretty impressive.

Thanks, Merle. I like mentally collecting little data points like this, showing that these engines are tougher than people often give them credit for. When I first bought my Power Wagon, over 30 years ago, I had a lot of people tell me these engines wouldn't tolerate anything over about 2500 rpm for any length of time. As time went by, I started learning that this doesn't seem to be true.

Hey Merle, mostly just curious, but which engine do you have in your truck? Also, how many miles on your engine since the rebuild? Thanks!

Here's an extremely detailed accounting of one original owner's experience with his 1951 DeSoto Suburban. He talks about driving his car many tens of thousands of miles between engine rebuilds, much of it at 3200rpm, and sounds like he occasionally went beyond that for brief periods, but generally avoided reaching 3600 rpm, his "mental redline." This car was equipped with a 251 cid engine (which was later converted to a 265), so it's a 25"engine, which some say are more durable in terms of the rod bearings, than the 23" engines, with their offset rods, such as the 230. Nonetheless, I think it points to what these engines are capable of, if in good shape and well-maintained. This article is a long read, but worth it. https://www.allpar.com/threads/the-1951-desoto-suburban-long-term-owners-report-of-a-truly-noble-motor-car.236556/

Over on dodgepowerwagon.com, there is at least one guy who says that when he was using his 3/4-ton WW2 trucks with the 230 engine as his daily drivers, he routinely cruised at 3200 rpm. He says he put around 250,000 miles on his trucks when they were his primary transportation (I don't think it was a single truck and probably not a single rebuild), but he says he never noticed any ill effects from driving that way. Mind you, the engine has to be in decent shape and maintenance is important to be doing this, but that can be said for any engine that is being pushed a little. Just a possible data point for consideration. I've heard similar stories from other people. But ultimately, it's up to you and your comfort level.

I bought my pistons from JE Pistons, for my 251 (25" engine) that I'm converting to a 265 by swapping the crankshaft and rods (same bore and piston sizes for both engines). The pistons are the same compression height as the stock pistons (1.977"), and the compression ratio will be the same as if I had used stock pistons. The sales person at JE recommended their ring set JG2206-3484, which is for a 3.484" bore. My bores are actually 3.480", but the sales guy said the rings would accommodate that difference without issue. This is 0.0425" above standard piston size (3.4375"), which is not a standard oversize for this engine, but was greater than the existing 0.030" overbore that my previous machine shop messed up (a separate story) and it's a more modern ring set that should work for my application. The two compression rings are 1.5 mm thick, and the oil ring set is 4 mm thick. The top compression ring is made of steel (not cast iron) and has a barrel-shaped face with a gas nitride coating. The second compression ring is cast iron and has a different shape. These rings are lower in tension than the stock rings originally used in our engines, but not as low in tension as the most modern ring sets, but I figured it would be a good improvement, nonetheless. I ordered the ring set through Throtl.com, as they had a much better price than JE themselves did. I think the price at JE was around $225, while Throtl was something like $160, if I recall correctly. The pistons are forged 4032 aluminum and weigh about 455 grams, whereas the 0.030" pistons I was originally going to use, from Sealed Power, are cast aluminum and weigh about 540 grams. You can see the difference in appearance between the JE pistons and the OEM-style pistons from Sealed Power in the photo below. The Sealed Power pistons are nearly identical to the OEM pistons that I pulled from the engine when I disassembled it, with the most obvious difference being that the OEM pistons used three rings, while the Sealed Power pistons use four. I opted to use the wrist pins from my Sealed Power pistons that I'm not going to use, and I had already gotten the rod bushings sized to fit those pins by a shop that has a bushing burnishing machine that is rare to find, so I didn't want to change pin size. Consequently, JE had to fabricate the pistons to fit my pins, which are not a standard size they normally use. The pins are the standard size for our flatheads, which is 0.8592" in diameter, and the nearest size that JE typically uses is 0.866", so they had to trick their system to get it to size the pin bores correctly. They got it wrong the first time, but made it right with the second piston set (no charge to me, and in fact a little bit of a discount for my inconvenience). One thing I should point out is that they sent me wrist pin retainers (wire locks) that are made for their standard 0.866" wrist pins, and after trying for hours, I finally gave up on trying to get even a single one installed. I found some Manley wrist pin locks, p/n 42270-16, which are a little smaller in overall diameter than the ones JE had sent me, but they are the same wire thickness (diameter), and I was able to fit both of the ones I tried in just a few minutes, so I think they will work fine. Cost for the pistons, including shipping and tax, was just under $900, before the discount I mentioned above, but that was in February of 2022 (yes, this project is taking me a long time) and when I had a need to talk again with JE a few months ago, they said the prices had gone up several percent. Hopefully this info is of some help.

Sniper, I think you're right. I went out and looked at the 230 pistons from the engine I rebuilt 20 years ago (and took apart about 10 years ago), and they have four rings. Also, the Sealed Power pistons I have for a 25" block (237, 251, 265) use four rings as well. I had forgotten about that. The custom pistons I ordered for my 265, and the original 251 pistons from the early 60's 251 I disassembled do indeed use only three rings (see photo of original piston below), so that's probably where I got mixed up.

According to my Chrysler Six Cylinder Industrial Engines Manual, No. D-12154, Second Edition, sodium-cooled exhaust valves are standard equipment on some models - In. 7, 7A, 8 and 8A engines, which are the 236.6 cid and 250.6 cid engines. It seems that your engine would have come with sodium-cooled exhaust valves, originally. The manual goes on to say that engines equipped with sodium-cooled valves were fitted with a plate, attached to the right side of the engine, just behind the engine serial number. Of course, that might be gone from yours by now, after all these years. I don't see anything in the manual about valve rotators for any of the engines. As for full-flow filter capability, look for a diamond-shaped raised pad on the left side of the block, just behind the distributor, below the freeze plug (see attached photo). I don't know the answer to your question about the flywheel/crankshaft flange/starter gear aligment. As for pistons and rings, the industrial engine manual show images of pistons with four rings, and contains discussion of there being two compression rings and two oil rings, and I believe all of the early flatheads (industrial and otherwise) came with 4-ring pistons. However, the later flathead six engines came with 3-ring pistons. I know this because I took apart a 251 from an early 60's Power Wagon, and I'm quite certain it had never been rebuilt, and it had 3-ring pistons (it's not an industrial engine, though). The newly made pistons I've ordered for these engines, such as those made by Sealed Power, are made to accommodate 3 rings and are made of cast aluminum. Interestingly, the pistons for the Ind. 5, 5A, 7, 7A, and 8, 8A engines (217.8 cid, 236.6 cid and 250.6 cid) came with cast iron pistons, according to the industrial manual. Only the Ind. 6, 6A (230.2 cid) engine is stated to have come with aluminum pistons. Having said that, I would have no hesitation in using aluminum pistons in their place. I'm not sure if cast iron pistons can even be found for these engines now. If they can, they would be NOS, and I've never heard of such pistons.

Thanks, Jim! That's interesting stuff. Sounds like my valves and seats are just about right the way they are, in that case.

Be careful when removing the coolant temperature sending unit from the side of the head. Make sure the little tube that goes through the middle of the nut does not twist with the nut, or it will twist off into two pieces (believe me, I know). Your engine could be a 218, as you said, or could be a 230. Either way, the head gasket should be the same. Vintage Power Wagons self the Best Gasket brand (or used to, anyway).

This evening I pulled out my Haynes manual for 1980 - 1994 Ford pickups. It has various bearing clearances depending on which engine we're talking about, but there are some that show as little as 0.0001 - 0.0015 for mains and 0.0008 - 0.0015 for rods, and other that show 0.001 - 0.0014 for rods and mains. These are all new part clearances. I don't know if Haynes reflects the factory manual accurately or not. I still say the smallest of these seem too small, especially 0.0001, compared to everything else I've read, including clearance information that I've read from companies that make bearings.

The 1952 Army/Air Force manual says 0.003" crankshaft runout is for new parts. Yes, the same manual that allows down to 0.0001" and 0.0002" clearance for rod and main bearings, respectively. Crankshaft runout wear limit is stated as 0.005". The later 50's industrial engine manual says 0.003" is the maximum limit, presumably meaning the wear limit, although it's not 100% clear. In any case, the manuals are not consistent.

Then on the other hand, some of my manuals allow as much as 0.003" runout before it's deemed necessary to regrind the crank. That seems really large. But I'm sure there's plenty I don't understand that goes into that.

Fair enough. But it was not just race guys saying this, but also guys who have rebuilt plenty more engines than I have, so hopefully you can see the origins of my question. Another guy quoted an old-time machinist who said it's very difficult to achieve the same tolerances as the factory, when it comes to crankshafts, with aftermarket crank work (at that time, at least - talking decades ago) being as much an art as anything else. Or who knows, maybe that particular machinist was actually lazy.

Right, I can understand what you're saying. These couple of guys I'm talking about, I would not characterize as lazy, but they deal a lot with higher performance engines, and have seen the result of cranks or blocks flexing under high torque and small clearances, which resulted in bearings getting eaten. They are staying on the side of caution. That concern may not apply so much to our engines, with their lower power output levels, but they were just advising to be more on the safe side. Other folks who are pretty experienced with engines, even flatheads, usually prefer to stay on the larger clearance side of things. I know that it's possible to achieve near-perfect crankshaft out-of-roundness and taper within each journal, and near-perfect runout across the whole crankshaft, but I think they were being a little more realistic with regard to what is much more commonly the result, and knowing that blocks and cranks deflect under load.

I've read so much about people who are more experienced than I, and their machinists, tending toward larger clearances, like 0.0015 - 0.002, or larger. I've also talked with a couple of long-time engine builders who said they think it's a bad idea to aim for such small clearances, as all it takes is some tiny little something not being exactly right, and it'll wipe out a bearing, when a bit more clearance would have prevented it. And these are guys who are extremely picky about the work they do. Certainly the 0.0001 and 0.0002 seems way beyond the limit for good practice, and even 0.0005 seems like it's taking undue risk.

I'd like to get a better understanding of crankshaft main and rod bearing clearances. I have five rebuild manuals, which indicate the clearances listed below: Army Technical Manual 9-808, Truck, 3/4-Ton 4x4 (Dodge), dated 11/14/1942: 230 engine should have 0.001 - 0.002, rods and mains (other engines not covered). 48 - 49 B-1 Series Dodge Truck Manual: 218, 230 (23" block), 236, 251 (25" block) are all supposed to have 0.0005 - 0.0015 clearance, rods and mains (other engines are covered, but they are much larger flathead sixes in a class of their own with bigger clearances, so I opted not to list them here). Army Technical Manual TM 9-1840A (a.k.a., Air Force Technical Order TO 19-75B-15), dated June, 1952 (M37/M43 manual): 230 engine should have 0.0001 - 0.0021 clearance for rods, 0.0002 - 0.0022 clearance for mains (other engines not covered). Yes, you read that correctly (yes, I typed it correctly); 0.0001 (one ten-thousandth) and 0.0002 (two ten-thousandths) are the min specified clearances for the rods and mains, respectively (other engines not covered). Chrysler Six Cylinder Industrial Engines Maintenance and Parts Manual, D-12154, Second Edition (only two dates I could find were 1946 and 1953, in the parts list section): 218, 230 (23" block), 237, 251 (25" block) engines should have 0.0005 - 0.0015 clearance, rods and mains (other engines not covered). Motors Truck Repair Manual, 19th Edition (don't know publication year, but last vehicles covered are 1966): 1955 - 1960 230, 251 & 265 engines should have 0.0005 - 0.0015 clearance, rods and mains (other flathead sixes not covered). As you can see, three manuals call for 0.0005 - 0.0015. The other two allow as much as approximately 0.002 or 0.0022 for the max end of tolerance. Anything less than 0.0015 seems small compared to what I hear most people like to aim for on these engines. Half-thou (0.0005) seems very much on the small side and questionable, and 0.0001 or 0.0002 seems ridiculously small and just begging for trouble. Have any of you guys actually built your engines with anything approaching 0.0005" (I'm not even going to ask about 0.0001 or 0.0002). In a discussion with someone at Vintage Power Wagons a few years ago, I was told to try to get down as close to 0.0005 as possible, as it is good for maintaining a healthy oil pressure, but it just seems kinda small to me....and yet there are three manuals that allow it, and another that allows even less. It seems like 0.0015 - 0.002 is what a lot of people aim for, and some are even happy with up to 0.003 in these engines during engine rebuilds. I did find the thread below, in which DJK tried bearings with 0.001 clearance and he couldn't turn his crankshaft by hand. When he bumped the clearance up to 0.002, everything was free-spinning and the engine ran great. It just kind of bumfuzzles me that Chrysler would specify such tight clearances.

I'm thinking I'll add the use of some light-duty thread locker to my engine assembly checklist, for the oil pan bolts. Maybe the timing cover bolts too.

Welcome aboard! I'm sure you'll enjoy the forum. Lots of knowledgeable people here.

How about trying what's called a dial test indicator. It's not the same as a dial indicator, but similar, but has a probe that extends sideways from the tool so it could probably reach into the tappet area to get a reading of the valve clearance. You could place the end of that probe onto the tappet and move the tappet up and down by hand (when the tappet is on the base circle of the cam, not on the high part of the lobe, of course) and see what the clearance is. Then adjust the tappet screw till you have the indicator reading you are looking for. Some manuals say a decent initial tappet setting for a cold engine is 0.014" (I believe this is for intake and exhaust). This would get you close and then you'd have to run the engine to warm it up, shut it down to set up the dial test indicator on the first tappet you want to check, adjust it while the engine is still hot (not running), then run the engine some more and move the dial test indicator to the next tappet and so on.

Talking about not over-tightening the pan bolts, I've always had the tendency to do just that, for fear that the bolts will come out if I don't tighten them enough. Manuals that provide a torque value for these types of bolts state a really low value, like 10 ft-lbs or so, and that just seems like it will allow the bolts to fall out and oil leakage to begin or worse. So if we follow the proper recommended torque, what keeps the bolts from coming loose? Should some type of low-strength thread locker be used?

The crumple zones are: (1) The occupants and (2) The other car. Regarding #1, as Bob Riding said, it's just best not to think too much about these things. We all should be aware of these things by now, so it's best to just have fun.

Ok, great update and great news! Thanks for checking in with him and reporting back to us.

Thanks, TFC. I had been considering this one, or one like it, on Amazon, but decided to try the one I ordered. We'll see how it works out. The upsides to the one I ordered are that it's less expensive and at least in some cases, it should be usable on the vehicle. The main downside that I know of so far is that it only works for two tubing sizes, as opposed to the one you bought, which can be used for more sizes. Anyway, we'll see how it goes. If it doesn't work out, I'm pretty sure I can return it. Thanks!