The Stovebolt Site Forums The Shop Area Engine Shop Conformatic pistons 216

I pulled the pan on my 216 as the gasket was leaking. I found about a half of an inch of sludge in the bottom. i pulled the rear main cap to replace the rear seal. It has the neoprene style in it and .040 bearings. I was going to change them but so far no luck finding that size. They look good so I may reshim and reassemble. I noticed it had conformatic pistons. I assume they are aluminum because a magnet wont stick to them. Do the rods need to be reshimed? i removed one cap and they look fine The scoops on the end look as though they have a little dent in them. Not sure if that is normal? The truck ran fine just fixing some leaks? any suggestions. The rear cap only had one shim on it. Is that an issue?

A 216 with a neoprene seal in it is a guaranteed leaker. The only type of rear main bearing seal that was ever used on a 216 was a rope seal, and the only one available currently that has any chance of working right is the Best Gasket brand. Follow the instructions that come with the seal exactly- - - -taking any shortcuts or ignoring the instructions will probably lock up the crankshaft. Both rod and main bearings need to be shimmed to as close as possible to .0015" oil clearance, and the spray nozzles in the oil pan need to be checked and adjusted for proper alignment so the rods will get lubricated properly at any speed above idle. There is also a fixture to check the depth of the troughs in the pan to keep the rod dippers from hitting them.
Jerry

Does anyone have dimensions on the depth of troughs and measurement on dipper height. I understand there is proper tooling for this. But finding the tooling is another thing.

Some of the resto-ripoff parts sellers rent the tooling, with an outrageous deposit required. The dipper height and the depth of the pan troughs can be measured with a carpenter's square and a bit of ingenuity. Aiming the spray nozzles can be done with water from a garden hose and a few golf tees to plug off all but the single nozzle you're adjusting.
Jerry.

So if I measure distance from block to the bottom of dipper and then measure from pan flange to nozzle. I should be able to calculate the clearance? The nozzles should spray in a straight line to side of oil pan parallel to the sides of the oil pan troughs? I read i a couple other sections about widening mouth of dippers? Also Mr. Lincoln you said in another section something about fabricating a oil pump for high volume on 216 engine. Any luck?

I have made an adapter fixture and a drive shaft to adapt an oil pump for a 250 inline six to the 216 and early 235 engines. The later model 235 pumps won't fit because of oil pan clearance problems. That's why 55-up 235's have a dogleg in the passenger's side pan gasket rail. From what I've been able to research, the clearance problem between the connecting rods and the oil pan troughs has two components- - - -the bottom of the dippers can't contact the bottom of the troughs, and the reinforcing ribs at the edges of the rod cap need to clear the sides of the troughs by a little bit. The top of the troughs can be ground down if necessary. Yes, the oil stream needs to squirt at an exact 90 degree angle to the pan rails so it hits the dippers as the rod reaches the bottom of its travel. Use a ball bearing and a pair of vise grips to widen the dipper if you choose to do so, but it's not really necessary if the spray nozzles are aligned correctly. That's when the load on the bearing is at a minimum, and the speed of the rod and the velocity of the oil stream forces lube all the way around the crankshaft, and out of the spit hole in the rod to lubricate the cylinder walls. Be sure the spit hole is clear with a small wire drill and a pin vise, but don't enlarge it.

There's no reason a Babbit bearing won't outlive a steel backed insert bearing, plus the Babbit can be scrape-fitted to the exact contour of the crankshaft and shimmed for the proper oil clearance, repeatedly. The original "soft" bearing material used in GM rods is so tough it will dull a high speed steel boring tool bit when I'm boring rods for insert bearings. "Reconditioned" rods use a much softer bearing material and must be adjusted more frequently. As with any other mechanical project, the alleged "mechanic" has to be smarter than the hunk of metal he's attempting to fix. That's becoming a lost art these days! Have fun!
Jerry