The Stovebolt Site Forums The Shop Area Engine Shop Rebuilding Engine

just to pipe in, I went the rebuild the 216 route.

Somehow I couldn't figure if it lasted 60 years ,that it wouldn't survive my driving a few more.

did cost more than it cost to do my '70 GTO motor in '78

So some more progress on the engine. I finally got the very stubborn oil pump out and ran into a sketchy fix for one of the pipes. I also got the timing cover off and found that one of the gears looks to have been replaced. They both seem to be in good condition. What worries me is that I noticed number stamps on the caps and connecting rods that didn't seem to match up with each other or the right cylinder. I also see that on part of the crankshaft it says GM 261? Here are some pictures
http://s300.photobucket.com/user/Bryce_Sheedy/library/Engine%20Rebuild

pressure test the block after you get all the freeze plugs in, I had to pull the engine to fix the ONE plug you can't reach with the engine installed. There were a lot of tears. (not really, but there was a lot of denial, and rationalization going on though....)

Thanks, I'm planning on having all the engine components gone through by a good machine shop.
So before I took anything else apart I decided to check the connecting rod end play (hope that's the right term). Some are so loose that when I move them side to side they make a clacking noise. I saw on Second Chance Garage that for a 48 216 clearance should be .004-.012 inches. On some I can fit up to .025 or even .030. What could cause this and how do I fix it?

End play isn't all that critical- - - -"too much" is a lot better than "not enough". What is vitally important is the oil clearance- - - -the difference in the outside diameter of the crankshaft journal and the inside diameter of the connecting rod, which has the bearing material bonded to it. That is checked by using a piece of precision-sized plastic called "Plastigauge", or the old-fashioned way by putting a small piece of shim stock between the rod and the crankshaft to see if the crank gets hard to turn.

A "normal" oil clearance is between .001" and .003". I like to shoot for .0015" if possible. The clearance is adjusted by installing or removing shims between the connecting rod and the rod cap. If an acceptable clearance can't be obtained by removing shims, the rods need to be replaced, or the crankshaft needs to be reground to the next undersize, and rods of the correct diameter need to be purchased to match the crankshaft diameter.

Connecting rod clearance is very critical, and the engine is VERY unforgiving of errors. Be sure your machinist is well-versed in checking and adjusting bearing clearances!

The main bearings on a 216 or an early 235 are also shim-adjusted, but those bearings can be replaced. Much older engines, like the Ford Model T and Model A have poured Babbit metal main bearings, as well as rods. Installing a reground crankshaft in one of those engines is a really interesting process!
Jerry

Thanks for clearing that up! I saw a video a while ago of someone doing the Plastigauge on a 216 I believe. So I should do that before sending it to the machine shop so then I will know if they need to grind the crank or get new rods?

If you have access to a micrometer, you need to measure the crankshaft to make sure the rod journals are round, and the same diameter from front to back. This requires an accurate micrometer, and someone who is skilled at using it. No, a dial caliper isn't accurate enough. .0005" (1/2 thousandth) is a strand of hair split into 4 equal slices. The maximum "out of round" needs to be less than .001". and "taper" from front to back needs to be less than .0005". If you start disassembling rods, be aware that the shims between the rod and cap are VERY thin and fragile, and unless you're adjusting bearing clearance they need to go back in exactly the same place they came from. The rod caps can also be reversed, so carefully observe any markings on them BEFORE disassembly. It sounds like someone might have already done some mixing and matching, especially if the rod numbers don't match the cylinder numbering- - - -1 through 6, from front to back. Following up behind "Mr. Bad Wrench" and correcting his mistakes was always one of my least favorite jobs!

Your machinist is going to want to do his own measuring, but be absolutely sure he is experienced at checking and adjusting Babbited rods- - - -if he's less than 60 years old, it's pretty unlikely!
Jerry

Hi. First off I want to thank everyone for helping the rookie with his rebuild! Here are some pictures I took a couple weeks ago of the rods. I marked all the caps and made sure to keep track of all the shims and how many/where they were. I don't know much about the Babbited rods, but how do these look? I don't recall there being any major scratches/wear on the bearing material, but there are some chips. Will these be a problem?

http://s300.photobucket.com/user/Bryce_Sheedy/library/Engine%20Rebuild/Rods

Those rods look very good- - - -no major scratches or scores, and the chips aren't excessive. See if you can get the machine shop to polish the crankshaft and go back with the same rods and main bearings as long as you can get a good clearance adjustment. It might be necessary to remove a shim or two after the polish job to get the oil clearance right. You'll need to remove the timing gear from the crankshaft snout and remove the camshaft retainer plate bolts so the front plate can pivot up and allow you to remove the crankshaft from the block. If you decide to remove the cam completely it will be easier to replace the gasket behind the timing plate. Just be careful not to score the cam bearings with the sharp edges of the cam lobes.

That rear oil seal surface looks very rough- - - -definitely get it polished, and replace the rope seal with a "Best Gasket" brand seal. Follow the seal installation instructions EXACTLY!
Jerry

I find it interesting, the difference between what acceptable babbit bearings look like compared to what acceptable insert bearings look like.
If those pictures were of insert bearings, they would be considered trash. The design of babbit bearings are all to often incorrectly discounted.
carl

Deleted. (I am the king of double posting. I can only hope joker isn't watching. )
Carl

The nice thing about poured bearings is the fact they're thick enough to be scrape-fitted. A thin layer of Prussian blue identifies the tight spots, which can then be scraped with a razor-sharp tool made by hollow grinding a 3-cornered file, gently removing the high spots in the bearing material. Once there's just a smooth blue smear with no shiny streaks, the bearing is an exact fit to the crankshaft journal, and shims can be added to establish the right oil clearance. A smooth, round crankshaft and a little time and effort fitting bearings can result in a better fit than most insert bearings can achieve.
Jerry

How much horizontal clearance?

Never heard that term. Side clearance, maybe? .005"-.010" for most rods if that's what you're asking about. Methinks this is a trick question!
Jerry

Thanks guys. It's good to hear that I can use those rods again. How do you remove the smaller timing gear? Can you use a hb puller? And with the timing plate, I removed the regular head bolts but as soon as I tried to remove the slotted ones they stripped immediately... Not so fun

I'd suggest using a 2 or 3 jaw puller on the crank gear, but be careful not to damage the teeth if you intend to re-use it. You might need to drill off the heads of the slotted screws and use an EZ-out on the remaining stubs if there's not enough sticking out to grab with vise grips.
Jerry

Hi everyone. It's been a long time since I posted, but I've been slowly moving along with my rebuild. However, I ran into a problem. I was test fitting the front main bearing cap with the proper torque (100-110 ft/lbs) and the crank wouldn't turn at all after I tightened it. I made sure to put plenty of assembly lube on before, but still no luck. I did keep track of the shims and had them in the right place. The front bearing did have an insert style bearing, I'm not sure if that's correct or not. I did plastigauge it but it came out looking the same as when I put it in. The crankshaft does say 261 on it, I hope that doesn't mean it's from a 261 since the engine is a 216. What is causing this? Can a machine shop sort it out? Thanks

If it were mine, I would pull the crank and look for dirt or a chunk of something on the bearing surface.
Are the bearings new? If so, check to see if they are marked with the correct size for the crank. I had an issue with rod bearings just like you are describing. Turns out the .001 that the shelf jockey pulled at the warehouse was actually .002. The "2" was a barely squiggly line which was mistaken for a "1".

What was the clearance on the main cap/bearing (as read by the plastiGuage)?

When you test fit the front bearing did you have the bottom halves of the other bearings in? If not your crank could have gotten cocked ever so slightly and just enough to lock the crank down.
When test fitting the crank it's best not to install the rear oil seal as it will tighten things up enough to make it very hard to hand turn the crank.
Install all main bearings but don't torque them all down, the idea is to try to true the crank up as mush as possible for the fitting/measurements.
Do one at a time checking the clearance and the ability of the crank to turn.
If you had 2ea shims on each main bearing cap do your preliminary fitting with both installed and adjust/remove shims to get your clearance right if/when necessary.

Good luck
Dave

The front main bearing shells and the next one back look almost identical. They are different sizes but are easy to mix up.

The other thing I would mention is that if one of the main bearing shells in the block didn`t seat correctly, if the other bearing are snugged down, tightening the front one could cause it to bind.

The bearings aren't new. It looks like the engine was rebuilt before I got it as the bearings were all in good condition. I believe they are the babbitt type bearings, except the front main cap has an insert type.
When I test fitted them I did have all of the other main bearings in, but not torqued down. Also, the plastigauge came out looking the same as when I put it in, there was no difference in width.

All stovebolt main bearings are insert type, at least since the introduction of the 216 engine in 1936. It sounds like you got some bearing shells mixed up during the disassembly/reassembly. Better recheck your work or find someone with a set of inside and outside micrometers who can do some accurate measuring and sort out the problem.
Jerry

Whoops, my inexperience is showing again. I realized the main bearings are insert type as Jerry said (the bearing material is built directly into the pistons, correct?) I torqued each individual main and the crank spins freely with all of them except the front one. I made sure to keep all of the main bearings separate during disassembly and in the correct orientation.

No, Babbit metal is in the big ends of the connecting rods instead of having an insert bearing there. Check the front main bearing for debris between the bearing and the block or the cap, and/or add another shim between the front main cap and the block to see if it frees up the crankshaft. There is a dowel built into the back of the upper main bearing shell that must align with a hole in the block, also.
Jerry

Sorry, I meant connecting rods. I will check to see if there is debris and/or order more shims. I noticed that on the back of the insert bearings there is a 020. Does this most likely mean those are oversize bearings and the crank was ground? Thanks for helping the newbie.

The .020 means the main bearing journals are reground to .020" under standard size. Since a 216 and a 235 have the same size main bearings and each main is a different size, here are the specifications for a standard diameter and a reground shaft:

Std.

#1 2.6835-2.6845"
#2 2.7145-2.7155"
#3 2.7455-2.7465"
#4 2.7765-2.7775"



-.020"

#1 2.6635-2.6645"
#2 2.6945-2.6955"
#3 2.7255-2.7265"
#4 2.7565-2.7575"

The factory shim pack part number for 216 and 235 main bearings is a Federal-Mogul part number FSM-104S. For Babbit connecting rods they list a shim set part number of FSM-105S.

Jerry

Thanks again, Jerry. I had time to plastigauge one main cap with the shims and the plastigauge didn't change, so I removed the shims and did it again, and it came back being more than .003". I torqued it to 110 ft/lbs. How can I fix this?

I had a long reply written and hit a wrong key and erased it! It looks like the main bearings don't match the crankshaft diameter. Have you done any measuring? If you've got standard mains and a .010" undersize crank, for instance, there's no way it's ever going to have the right oil clearance. Drop me a PM with your email and I'll scan and forward a page from the shop specifications manual with standard and normal undersize crankshaft measurements. You'll need an accurate micrometer, not a dial caliper, to make accurate measurements.

No, there are no shortcuts- - - -this has got to be exactly right if the engine is going to live for more than a few minutes.
Jerry

Hi. It appears my crankshaft is pretty out of spec. Here are the measurements I took. There is also a noticeable ridge in the middle of the main journals.

#1 2.6545-2.6600"
#2 2.6925-2.6955"
#3 2.7225-2.7265"
#4 2.7545-2.7565"

OK, it's .020" undersize, and worn. You either need to have it reground to .030 under and change to the corresponding main bearings, or find another crankshaft that is in better shape. Next question- - - -what size are the rod bearing journals? Since you're dealing with a splash-oiler engine you'll need to find a crankshaft that matches your rod diameter, or swap all six rods to match a replacement crankshaft.

I have a huge supply of reconditioned Babbit rods, and the machining project I'm working on can use worn-out ones easily. I hate to trash good rods. PM me and we might be able to work out a swap.

There is a big salvage yard in Albert Lea Minn. that auctions crankshafts on Ebay all the time, including splash-oiler Chevy 216 and 235 shafts. Search Ebay for "216 Chevy crankshaft" and I'm sure you'll find them.
Jerry

Here are the rod journal diameters.

#1 2.2815-2.2835"
#2 2.2815-2.2915"
#3 2.2785-2.2820"
#4 2.2795-2.2840"
#5 2.2795-2.2840"
#6 2.2805-2.2830"

Which option would be best? Having the crank ground seems easier. There's a good machine shop close to me.

The rod journals are already 30 thousandths undersize, and a few are also worn out of round. You need to replace the crankshaft, and probably the rods.

There's a "standard" diameter crank on Ebay right now that would probably regrind to .010/.010 on the rods and mains. If you keep the clearances adjusted, that's a crank that would last another 30-40 years.
Jerry