VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc no shims on crank -1940- 216

when I was fixing the rear rope seal , I noticed there were no shims on the rear main bearing cap. I didn`t check the others, but now wondering if I need to adjust the mains, and there are no shims , what are my options?? I read in another post about the rod caps could be "filed" down ....don`t really understand that. Seems like the caps would have to machined precisely to get it right to add shims to adjust . Confused...thanks ~D

You would need to plastigauge it to see what needs to be done. If the clearance is right without shims, that's how it turns out. If they are loose without shims, you may have to go to next size bearings/rods. How many miles does this engine have on it?

If the bearing gap is too wide and no shims there are two methods to rectify. One is the "backyard" method of filing the bearing cap to close up the gap. The best is to replace or renew the bearing shells and line bore (to insure proper alignment) to match the crankshaft dimensions.

Filing the cap may be a bit crude and machining on a mill more "professional" it is a matter of what is available (time, money, ability, preference, etc.)

While it is possible to file the rod bearing caps you can not really file the rear main cap due to the locating pins.
One other way to reduce bearing clearance is to place shim material (aluminum foil) under the insert. (between the insert and the cap). Years ago shim packs were made expressly for this use.
If the engine was rebuilt it may have been done with no shims. To replace the top insert it will be necessary to remove the crankshaft......or the bearing inserts could be just worn and all shims have been removed.

I have pretty good history on the car and it is supposed to be correct mileage, but there was a blank spot in the history and who knows. The mileage is 49K. I like Gene`s old style fixes. If Gene`s aluminum foil shim between the bearing and cap was tried , does that mean the top bearing needs to be done also dropping the crank....or can you get away with just the bottom??I suspect both need done.....then following the adjustment instructions in the 1940 repair manual. The engine runs so well, but there is either a slight piston slap...rod knock...or main bearing knock. I read so many posts about engine noises and not sure if it`s worth tearing into. Definitely in the lower end and kind of a hammering metal sound at different times....cold or hot engine doesn't seem to make much difference. Sometimes when the engine is floating and sometimes when it is pulling or working on a hill. Probably most people wouldn't hear it but I do. Not lifter related ~D

The "feathered" shim stock for placing under inserts was made like this. First strip was abot 2" long. Next strip that layed over it was 1 1/2" " long and the last strip was like an inch long. There were sets made for specific car engines so as to be the correct length wan width for a particular engine. Layers could be peeled away as needed for thicness. The sets I hve were made by Perfect Circle. They would be used only on te bottom - on the top they would have blocked off oil holes, etc.
Shims place in lower insert only so as not to destroy the front to rear alignment (level) of the bearings.

Engine knocks
rod under light load when oil is hot. This is the noise that can do the most damage. Easy to short out.

Main bearing -thumps under heavy load - worse when hot but can make a few thumps when firat starting engine before the oil gets to the bearing.Difficult to short out.

Piston slap. A loose fitting piston will make more noise when engine is cold. Often goes away as engine warms up....If your engine was rebuilt it most likely has aluminum pistons. Check with magnet if the pan is off.

A worn timing gear. Can't short it out and hard to put your finger on it.....also it is probably running "dry".The most common part to fail on an old Chevrolet engine due to the oil supply plugging up.

A common problem with the Chevy 6s is wrist pin wear. Typically louder when cold and diminishes as oil reaches the pins. That assumes that you use thin enough oil to lubricate the cylinder walls and wrist pins. It is annoying but not generally a problem.

I`m thinking it`s a main...Last summer I did the test removing each spark plug wire and I still heard it ..also I replaced the timing gears last summer along with Genes leaking rear rope seal fix......Going back to Gene`s explanation of the old type of layered shims ....I`m sure that stuff isn`t still available. Did the mention of " tin foil" actually mean it could be used in a repair of this type these days? And I guess if I just found one or 2 bearings that needed shimmed, I would be safe doing that and leaving the others if in specs? The tin foil fix is intriguing! I need to pull the pan again and check it out .Oil pressure is good.....great info !..thanks ~D

The shims were nothing but foil.....now before you dig into the main bearings a would suggest one more test. To make sure it is a main drain out all the oil and start the engine. If it is a main the noise will get much louder. Now I know most people will think I am nuts to suggest such a thing but it will not harm the engine. An engine will run with no load for at least an hour with no oil so a minute or two will cause no harm. The rods will get oil for a short time due to the troughs being full, some of which will throw up on the cylindre walls.....just don't drive the car. This is no worse than starting a cold engine at 25 Deg. below zero.
If you do Plastigage the mains either the engine must be up-side-down or the weight of the crankshaft must be supported with a jack. With the crankshaft sitting down on the Plastigage you will get a false reading. Plastigage is OK for the mains but not accurate enough for the rods on a 216.
Years ago the Plymouth and Dodge engines were great for loose bearings. This caused low oil pressure and oil consumption. The "used car fix" suggested by the CHEVROLET used car reconditioning tips was to use paper from a brown paper bag and place it under the rod and main inserts,

There is a lot of great information in this thread. Very useful as always! Keep us posted on what happens and what the successful fix was.

OK...really gives me something to think about and possible I can pinpoint the noise. I will definitely follow Genes instructions on the oil drain test . I did the spark plug test and have read different post on rod ,piston and wrist pin noise. Process of elimination and that can get a little confusing for a back yard mechanic, but last summer I went through the same thing with timing gear noise. I had about 6 professionals listen to it and 2 of the 6 had it right. Went from clutch to distributor, to water pump, rocker assembly etc, etc. So ....alls good tho because it isn`t something dire at this time , but it will bother me till I figure it out and I will be reporting back as I gather info over the summer. Thanks for the great info !...~D

OK...It`s been awhile since I asked the experts about my no shims on the crank and a bit of an illusive noise in the engine. I have driven the car all summer with no real change in the noise. Had a local mechanic that has a history with the old 216`s....he thought possibly a wrist pin or a bit of piston slap and said to drive it and not worry as long as it doesn't get worse. Today I drained the oil and thought I should try Genes test of running the engine with no oil for a short time to test for excessive main bearing clearance. Within about 5-10 seconds I heard a very obvious knocking -rattleing noise. Shut it down after maybe 20 seconds. So....it seems that the mains need to be plastic gauged? Do you all agree that within 5-10 seconds this would indicate the mains and not rods, p-pins etc?? Also , Gene said to support the crank to get accurate reading on plastic gauge. How? Before loosening the bearing caps , support the crank with just enough jack tension on one of the nearest lobes of the crank to the bearing cap I`m removing?? Engine has great oil pressure....runs well. ALSO.... water pump just started tweeting the other day, engine has 50/50 anti-freeze in it .Is there anything that can be added for water pump lubricant , or is the pump needing replaced?? any input into the main bearing business? Thanks

When I take the major step to run an engine without oil, I remove the pan, wipe all oil that is likely to drop on me and use safety glasses. You only need to run the engine less than 30 seconds to get your ear up to and identify the problem. It is a drastic measure to find a problem, but is basically fool-proof.

Let me just comment on a subject that I know something about. Water pump lubricant is worthless. Actually water itself without the soluble oil is a good lubricant. It has low viscosity, excellent surface tension and attraction to metal. Its major drawback in low boiling point. If there is too much heat water will not boil away. What the soluble oil (aka water pump lube) does is provide some lubrication when the tolerances get too wide for water. It is only temporary and covers up the fact that the pump should be rebuilt. The Ethylene Glycol in permanent coolant (aka antifreeze) provides nearly as much lubrication as the soluble oil. If lubrication to the front bushing (or bearing) does not help with the noise, it is best to rebuild or replace the pump.

The rods will not loose the oil that quickly as the oil in the trough will feed them for 20 seconds.....I would bet on the mains. It may have some type of rebuilt engine that was remanufactored without shims or all the shims have been removed from the rear main.

Chevgene...so, in you previous post you said to jack up the crank to get an accurate plastic gauge reading. I`ll be working on my back to check this. where do I place the jack? ? Next to the main I`m checking ,or the tranny ? or? and if I find excess , do you think the shimming of the bearing you talked about would be worth a try? Or , would the machining of the bearing cap removing some material be a better option?.....anyone one want to chime in on this ,have at it !.....Got the oil drained and ready to pull the pan....first time for plastic gaugeing too. Thanks

My name is not Gene but what I used to do when I was checking main bearing clearance with the engine installed was use a business card in the main next to the one I was checking. For example - remove #2 main cap put a businees card between the bearing insert and crankshaft and retorque the cap bolts. You can then use plastigauge to setup #1 and #3, etc., for the other mains. The business card is enough to take the hanging slack (clearance)out of the crankshaft. A jack should work too, but for a fat, old guy like me, I need all of the room I can get under there.

Thanks Mike for this tip!! This is the type of info I need at this point!

You also can place the jack under a close crankshaft balancing weight or for the rear under the flywheel.

getting back with my results on this long thread from last year. Having a undefinable noise-knock at different speeds ,prompted me to drop the pan and attempt to adjust rods and mains. I found no shims on anything. Not wanting to pull engine for rebuild, I opted to try some of the suggestions in this thread. May sound nuts to some , but I set up sandpaper on a flat piece of tile and worked the rod caps down to "about" .002...some seemed to be at around .003+. The mains were the same . First time for anything like this , I was a bit worried over the winter , being about half finished when we went south. Back in NC now and finished up the rope seal to upper rear main as Gene has described doing by pounding pieces of rope seal into the upper cap. Then a new lower rope in the lower cap. A good fix .....no leaks ....maybe won`t last , but does work. I also added the foil to the rear main cap to boost up the bearing( love this fix) . All this took many off and ons to get it close .....I was trying for about .002 on most of it , being afraid to do too much . Had to order new rod bolts , as these were worn out ...threads looking messy.... Anyway, got them close ......no shims , so had to plastic gauge and "feel " drag by turning the flywheel laying on my back under the car. Could`nt get to the front main , as I did the reverse drilling and tapping of the front cap to timing cover lower bolts. Did`nt want to pull the balancer again , so the front main is the same. Also had the radiator boiled out,good engine flush, and sent my water pump off to Arthur Gould-NY, rebuilders. Fast reasonable rebuild-$90. So...fired the old girl up and kept my fingers crossed and wow ! RUNS GREAT...don`t detect the noise I heard last summer now......must have touched that problem. It`s never ran better and it`s a joy to have the Miss Sadie back on the road! Thanks for all the help on this one!....... Oh ,I do have a question ....How does one pop off the hub caps without chipping the wheel paint?

David,
Thanks for posting your results. Always good to hear of a persons success. Not all things tirn out that good.

The answer to your last question should probably be a new thread.....I can not take credit for this......I read an article about an older hot rod that had hub caps of the era. To remove them without damaging the paint on the rims there was a single hole drilled along the edge. The size I can not remember. But the hole size matched a firm hooked rod attached to a handle to create a " T " . ( Take capital " J " and mate it to a capital " T " ) Slip it into the hole and pull.

Hi David,

What and interesting post. Hats off to your success. Please update us again at the end of your driving season. Tell us about your noise and also about how the rope seal worked out.

To remove my hubcaps I try to slide a piece of duct tape or electrical tape under an area where you want to pry up on the hubcap. I also put a couple of layers of duct tape/electrical tape on the end of my screwdriver. I use a good size Screwdriver that is over a foot long.

Good luck, Mike

There are plastic prying and scraping tools that can be used. They are sometimes available at auto part suppliers or auto glass shops. They are sold for removing moldings, trim, glass, etc.

I use a bondo spreader. I push it in between the hubcap and the wheel and then take a thin screw driver to pop the hubcap off.