The Stovebolt Site Forums The Parking Lot Early 'Bolts (1916-1936 1st Half) John's 1927 4 cylinder connecting rods

During Wrenchfest we discovered that the connecting rods on John's engine left a lot to be desired, both in the condition of the Babbit bearings, and the fit on the crankshaft. The crank isn't exactly round, either. I've been doing some number crunching in the shop specification catalogs, and it's looking like insert type rod bearings for a Farmall Cub tractor can be adapted to the rods, and the crank can be ground to fit the bearings for the proper clearance. The next time the engine needs to be rebuilt, if ever, it will be a simple matter to just replace rod bearings- - - -not fight with shims and Plastigauge and hope the oil clearance will be right. It also looks like the connecting rod oiling system might be able to be upgraded to resemble the spray tube and dipper system similar to what's on a 216 or a spray oiler 235 without making any modifications that would be visible from the outside.
Jerry

I know you can do it!

It looks like two of the Cub rod bearings will fit side by side in the Chevy rod, with a groove left between them for oil flow from the dipper hole in the rod cap as it goes through the trough in the oil pan at the bottom of each stroke. I'll add permanently-mounted brass thrust washers to both sides of the rod caps to keep the rods centered on the crank journals. "Standard" Cub rod bearings are the same diameter as the original 4 cylinder Chevy crankshaft, with 10 , 20, and 30 undersizes available. The two sets of Farmall Cub rod bearings needed to do the job will cost just under $100.00. Compare that to the cost of getting somebody to re-pour the rods, if anybody will even attempt to do that anymore!

Now on to the next project- - - -main bearings!
Jerry

Was the thrust excessive?

Over three times what it should be. Not sure if the crankshaft or the bearing was the problem, but I've got two other crankshafts and another block to measure. I can also "metal spray" crankshafts to build up worn or egg shaped rod and main bearing journals. I believe I can fabricate a brass or steel bearing shell on my lathe with the right thrust flange dimensions, and either do a Babbit pour or find a suitable insert bearing to fit to the steel backing piece. Once the final dimensions are correct, the engine doesn't really care how they got that way. I've also got a line bore machine if I need to modify the block for a different bearing shell outside diameter.
Jerry

Just wondering Jerry, if your metal spray outfit can coat steel bearing shells with babbit material. That would be an interesting setup. But may not be practical if you can find complete insert bearings to fit.

It works best on a rotating shaft that has had a spiral groove machined into it to give the metalizing powder something to grab onto. I've got the ingredients on order to mix my own bearing alloy, tin, antimony, and copper to mix with the lead I keep on hand for bullet casting. If I can get the Brinell hardness of the mix right, I'm going to experiment with pouring a layer of Babbit into a steel or bronze backing shell to duplicate the main bearings in the engine I brought back from Wrenchfest. Never tried to do that before- - - -should be a fun project!

Here's a video of a shaft repair using metalspray. His equipment is a little newer than mine. but the procedure is the same. Eutectic spray weld equipment has been around since at least the 1940s, and my father was building up stroker crankshafts on flathead Ford racing engines with it back then. Those engines got a lot harder use than a restoration job on a stovebolt will ever see!
www.youtube.com/watch?v=7pO7RUNSyRk

Jerry

I can't wait to turn this into a tech tip ...

For the 8 people out there actually working on this era truck ...

John, the same rod bearings your tinkertoy Cub tractor uses look like they might be a good fit for converting the Babbit rods to insert bearings. I believe I might also be able to adapt a 216 oil pump to the engine, which will give enough oil flow to build a spray-oil system like the 216 uses. The current setup is straight "splash" '- - - -not the external pressure lube like the 216 and early 235 uses.
Jerry`

Sounds great Jerry! Probably get another 100 years out of it, then.

OK- - - -i did some more measuring- - - - -It looks like 235 pistons of various oversizes can be fitted to the 4 cylinder block, the distributor housing is the same diameter as a Mercruiser Marine 4 cylinder distributor, and it looks like with a drive gear change, the Mercruiser distributor with its centrifugal spark advance could be fitted to the engine. Ditto for a 216 style oil pump- - - -do a little strategic whittling here and there and there should be about twice the oil volume available for modernized spray-oiled connecting rods with insert bearings.

Were these things similar to the Model A’s of the same timeframe….whereby the driver had spark advance controls inside the vehicle?

Yes- - - -the distributor I just removed from John's spare engine has a bracket similar to a vacuum advance mount, and a slot that allow the housing to be turned through a short arc with linkage from inside the vehicle. It's too far gone to use- - - -badly rusted, with the gear teeth worn down almost to a point. I haven't gotten a look at the camshaft yet, but I'm going to guess that the distributor drive gear on the cam has a similar wear pattern. I'm on the lookout for a better condition cam and lifters now. The 4 cylinder distributor gear is smaller in diameter and has fewer teeth than the one on a 216/235 distributor.
Jerry

I had a short phone conversation with a parts salvage guy today, one who specializes in early Chevy stuff. He says the camshafts are very scarce, and he doesn't have any on hand at the moment- - - - -"I can get your cam reground" (no mention of a price for something I can get done for myself)- - - - -which doesn't help if the cam I have has a worn out gear in the middle of it! If anyone has a source on a cam or two, please let me know about it. Lifters shouldn't be a problem- - - -unless they're totally trashed, I can regrind the surface that rides on the cam lobe.

Does anyone have a current subscription to "Hemmings Motor News"? Their website wants me to subscribe to the magazine before I can do any meaningful search for parts through that organization. In the past, Hemmings has been the source of some very scarce bits and pieces I've needed for other projects. I let my subscription to their quarterly magazine lapse a few years ago when it got outrageously expensive, and I didn't need any more "reading material" for the little house 40 yards out of the back door! Since we've gotten indoor plumbing, it's even less of a priority!
Jerry

Here's my rationale behind upgrading the connecting rod oiling- - - -"Splash-oiler" is actually an incorrect term for the Babbit rod 216 and 235 engines. "External oiler" would be a more accurate description. The 216 and 235 engines use spray tubes aimed at the dippers on the connecting rods as they reach the bottom of their travel (where load on the rod bearing is at a minimum, just as it reverses its direction of travel) to squirt a stream of oil into the dipper. The faster the crankshaft turns, the more oil will be forced into the bearing as the rod intersects the stream of oil. The 4 cylinder engines do not have the spray tubes- - - -the oil pump simply fills the troughs in the pan with oil, and the rods dip into the reservoir of oil as the crankshaft turns. It looks like it would be a fairly simple job to fit a higher volume oil pump (like one for a 216) and add spray tubes to increase the velocity of the sprayed oil for more efficient connecting rod lubrication. Improved design dippers can be fitted to the rod caps to direct the oil into the rods more efficiently. The current system looks like it was designed by Fred Flintstone! As long as the load on the distributor drive gear on the camshaft doesn't exceed safe limits, I believe the added oil volume won't have any downsides. Here's a view of the interior detail of the oil pan:

www.ebay.com/itm/325926327712?

The angled troughs at the side of the pan align with tubes attached to an oil distribution manifold on the crankcase which receives the output of the oil pump to fill the troughs. Those same tubes could be incorporated into an improved spray-oil system.
Jerry

Jerry I just picked up a complete running 27 engine that I will not have a use for the short block. I bought it for the head only as it has a 28 head on it. I need a head for my 28 truck engine.
I am not sure the cam is different in a 27 than a 28, but I know the lifters do appear to be smaller in diameter in this 27 engine than my 28 engines. I have a spare 28 engine also (so I have 2-28 cams)
Maybe some trading could be worked out if your in need of a cam for Jim's 27?
I would be in need of some additional machine work on my 28. Once I access the condition of this 28 head I just bought it will need work I am sure. I also need to get a cam and lifters in condition for my rebuild.
I have my original block here, with one cylinder sleeved and all 4 bored out 60 over. New pistons and rings. I did not have crank turned or bearings redone as I have shims that can be removed to hopefully get all fitting good.
Interesting read anyway. Will be following!
David Siedschlag

David,

Send me a PM. We can discuss other parts needs. I have a bunch of spares, including cab wood. I have some needs, as well.

Regards,
John (But I have a brother in law named Jim ))

Thanks for the reply, David, and I'm definitely interested in doing some horsetrading. The engine I'm working on actually belongs to John, (who also owns this website). I'm just the resident mad scientist who force-fits all kinds of parts into places that they were never intended to go, and on rare occasions I even come up with some useful ideas. I'm located in south central Tennessee, near Interstate 65 and the Alabama stare line. I've visited John and his friends in Maryland just south of the District of Corruption on several occasions and we do a lot of swapping of parts and ideas. You're out of "moderated" member status, so you have access to the private message system. Drop me a PM and I'll respond with an email and phone number.

I'm headed out on another road trip today- - - -Indiana and Illinois this time. I'll have the laptop with me, so I will probably have at least some type of internet access for the rest of the week- - - -back home next Tuesday or so. No smart phone, though- - - -I'm still a Luddite with a flip phone!
Jerry

Interesting engine mods.

Being that I'm not knowledgeable about the 216+ oiling systems, I'm wondering how the squirt nozzles for the rod bearings will affect the oil splash system that other parts of the engine rely on. For example, the 'oil splash zone' provides oil to the piston skirts and the oil reservoirs that feed the cam and main bearings.

The directed streams of oil for the rod bearings seem like a good idea, but will this engineering change diminish the oil mist that feeds the reservoirs?

Slightly off topic, but kinda not, are you modifying the oil system to deliver oil to the rocker arms and the top of the push rods? The original oiling system design did not include these items, so they need to be oiled via a squirt can.

Thanks, Dean

There should be plenty of splash in the crankcase from the oil spinning off the rods to provide the necessary lubrication to the cylinder walls and other parts that rely on passive lubrication. With increased oil flow from a bigger pump, supplying oil to the head via a small diameter tube with a needle valve to meter the flow shouldn't be much of a challenge- - - -getting the excess to drain back to the oil pan might take some creative tinkering, as well as dealing with possible overflow leaks. One pipe dream at a time! Didn't the original top end lube system include a quilted lube pad made from wool felt riding on the rocker arms- - - -saturated with squirt can oil? How was drainage addressed in case of over-oiling of the pad?
LOL!
Jerry

A total lack of valve seals, perhaps?

More likely "external rust proofing "- - - - -the truck marks its territory with oil drips! The frames never get rusty, either!

LOL!
Jerry

Indeed. My frame is remarkably free of rust pitting in the engine area....

It's a good thing we hit the "pause" button on John's supposedly "rebuilt" engine during wrenchfest. I did a little measuring and checking today, and at least one connecting rod has almost NO Babbit left- - - -the rod to crankshaft interface would have been steel on steel within just a few hours of runtime, even if we had managed to get the oil clearance correct with shims. I just received the raw material to fabricate new main bearings, which will end up being Babbit metal poured into a bronze backing shell, assuming I do my job of pouring the Babbit correctly. Once the new main bearings are machined and honed to the proper finish, then the crankshaft will be reground to match the bearing inside diameter, with enough shims included to allow for future oil clearance adjustment. Fun stuff!
Jerry

Yep- - - -sort of dodged a bullet there! Since I came up with a spare crankshaft at a ridiculously low price on an Ebay auction, I'm thinking of using the worst of the three I have on hand at the moment as a test bed for the Eutectic "metalspray" system I acquired some time ago. That's a method of applying very durable powdered metal to a crankshaft journal (rod or main bearings) and building the surface back to above standard diameter, then regrinding it round again. That method was used for making stroker crankshafts for racing engines back in the early 1950s, so it's definitely not new, untried technology.

www.youtube.com/watch?v=kyqh_KIzthc

Fun stuff! One of the metalspray powders I've got has a very high nickel content- - - -probably a better alloy than was available a hundred years ago, with much better wear resistance. My spray torch is the same one used in the video. Using the improved alloy would be roughly equivalent to putting a hard chrome finish on the crankshaft.
Jerry

That's really cool, Jerry! I wish I could be there to see that happen. That video was cool -- Peggy even watched it.

Yep., even with the "down under" accent to boot! Doing the buildup procedure on a connecting rod journal is a little tricky, as the crankshaft must be offset in the lathe to make the journal centered for undercutting and "threading" (actually just a series of V grooves works as well as a thread to give the spray powder something to grab onto. That's important, as I've seen the built-up area spin on the shaft if it doesn't get a good bond.

"Being here"- - - - -the roads between Tennessee and Maryland run both ways, and we've got a guest room, too! Come on over when it's time to do some of these modifications!
Jerry

Over the years I have prepped pump shafts for metal spray and grooving works just as good as a thread. I would also set the tool bit at a negative rake so the metal would be torn off and leave a ragged finish.
There were two things in that video I would have done different.
First, three jaw chucks are never used in job shops. All the lathes will have four jaw chucks so you can hold and indicate in all types of shaped parts.
Also offset center, to line up a crankshaft journal.
Second, I would have checked the bore for runout, right before the finish cuts.
Other than those two minor items, it was a great video and the guy knew what he was doin

Don

On John's 4 cylinder crankshafts the flywheel bolt holes just happen to be aligned with the connecting rod journals, so attaching a bracket for an offset center is going to be an easy job. Just measure off one half the stroke length and drill a hole in the bracket with a 60 degree center drill, one for each end of the crankshaft. On stovebolt 6 cylinder cranks like the 216, 235, 261, etc. those three dowel pins that index the flywheel are also clocked to match the three companion cylinder journal pairs. I also have a bunch of heavy steel counterweights to balance the weight of the crankshaft as it's suspended between the offset centers. Yes, I have a good assortment of 4 jaw chucks, and I use them almost exclusively.

On a stroker crankshaft, the shaft is offset to half the desired new stroke, the shaft is machined or ground until the shaft is round, and then it's metalsprayed back up to the desired journal diameter, if necessary and finish-ground. I believe I can offset-grind a 235/261 crankshaft to get an extra 3/8" of stroke, or possibly 7/16", depending on which connecting rod/bearing combination I choose.
Jerry