Tapered Shims

Steve@Advance · Apr 5, 2017

In the post below, Janicholson attached a link to the Deckwar Tapered Shims website.

I had never heard of tapered shims...

My first thoughts were "snake oil, how could that possibly work!"

But evidently they have been around for a long time, something must be viable about the product. Got to reading the FAQ and testimonials, looks like there might be something to it. Especially on an older vehicle, something not driven daily or parts not available. Even talked about adding them to a new rebuild after break in to prolong the engine life.

But as a patch, looks like it would take some careful measuring, and as long as the crank were somewhat still round, and the bearing hadn't spun "too bad" it just might work!

Not that I'm hoping for a reason to use them (Murphy keeps too close an eye on me! LOL), but has anyone had success with this?

Opinions?

Thanks!
Deckwar Tapered Shims

Janicholson · Apr 5, 2017

I was prompted to use them as needed for antique restoration when a polished crank journal was some indeterminate size smaller than a standard reground undersize. They have worked on several things from a Le Roi 2 cylinder stationary engine, to a Fiat engine in a weird old van. Jim

caterpillar guy · Apr 5, 2017

Dad had something like that made from Aluminum Didn't like since it was to thick in the middle of the pack. Wound up micing a pop can and used that on the bearings in a 53 dodge. This was 40 years ago or more. That pop can is still in there to this day.

Dick L · Apr 5, 2017

The most wear on the bearing and crankshaft journal is on the bottom of the crankshaft at the pressure point from fire. Very little on the sides and top. You can see this with plastigage by checking at the bottom of the cap and then at 90?. Using new bearings on an unground crankshaft and shimming under the bearing insert it can be necessary to file the end of the insert to keep the ends of the bearing shell from dragging on the journal. When torqueing the rod cap it is necessary for the ends of the bearing shell to go to the only space open to make up for the shim under the shell. That space is between the inside bearing surface and the crankshaft journal. I personally used snap gauges and mic's. I never shimmed this way more than .002 because of fear. I have shimmed for this problem but never used taper shims.

Earl-IL · Apr 5, 2017

Popular in the 1940's 50's. The reason behind the taper on both sides, picture it as .002 in the direct btm. of the cap & .001 on each side. That give you the correct shimming of the insert. The original shims were custom made to each rod, main bearing due to the diff. crank journal dia.The instruction were to shim the insert & then take a file and dress the bearing at the parting line to eliminate too much crush on the insert.

Moonlite37 · Apr 5, 2017

They were used years ago when engines ran slower and money was hard to come by. I remember poor people even using paper but next best was aluminum can stock and shim stock as better. On old redneck boy, casual friend, liked a performance Ford flathead. He did not have $ to get heads shaved for increased compression; so he made head gaskets from galvanized screen wire and red Permatex. I never knew the final result. Some old vehicles were forgiving.

Richard G. · Apr 5, 2017

Many years ago, I rebuilt a F226 Continental engine in my MH 101SR. Did not have much money to spend.
Bought new bearings and rings and gaskets. One rod journal was worn more and I shimmed under the inserts with layers of aluminum foil till it felt right.
Ran that thing for many years pulling my sawmill.
Richard in NW SC

pete 23 · Apr 5, 2017

Perfect Circle used to push the use of the tapered shim back in the early 60's. I went to few of their seminars when the local parts stores held them. That was also the time when they were pushing their Teflon insert valve seals really hard. Soon after, IH parts department offered the use of the valve seals by offering a Perfect Circle valve seal cabinet with the valve seals and guide refaceing tools to the dealers. I never did use the tapered shims but many many seals. Another thing they pushed for a short while was the Perflon oil ring. It had the similar or same coating on the expansion spring as the cooking skillets I think. That one did not last long though as it could not withstand the heat . I did install a few sets of them with no particular problems though.

mite-help · Apr 5, 2017

I also recall those perfect circle products of early sixties. That company was also trying to change the image of the auto mechanic, & the ''grease monkey'' label. Their ads had shop people in white lab jackets. I was in auto tech school at the time, some shop teachers carried on that theme. also saw PC seminars. boy, it was unreal how common re-ring jobs were back 'in the good old days!

Earl-IL · Apr 5, 2017

Thanks for reminding me, I was in a jobber machine shop in those days started in 1956. Perfect Circle put on those Clinics and then you became a "Doctor of Motors" with a nice certificate to hang on the wall of the shop. The 1955&56 Chev.V8 265 was using a little too much oil. They would really smoke a little. The PC rep & I went out to a shop & to prove the oil was going down the valve guides. PC had a set of pushrods with the oil hole brazed shut.The PC rep. would install them and start the engine & they would clear up in a few minutes. Customer removed the heads & we machined the guides & installed the seals. It made one happy customer. I can't remember who made the first taper shim stock. They were more universal in length. PC was first with the custom fit shims.

pete 23 · Apr 5, 2017

Yup, Dr. of motors. I no longer have the certificate but I do have the little booklet they gave us. It actually had a lot of good information for the day. Remember the day when you drove the old cast iron 6 cyl chev in to the garage in the morning and got a ring and valve job by evening. I saw it happen but I never did it.

Another thing I just though of. Pontiac had a real brain storm to reduce oil consumption through the valve guide. They drilled a hole in the head into the guide to reduce the vacuum on the intake valve guide. My boss bought one of those cars and I had the job of installing the update which was to put plugs in those little holes. I cannot remember what else we did. Must have put on valve umbrellas or seals , just don't remember. I think it was a 1960 model because he traded every two years and had a 58 Plymouth.

Tapered Shims

Steve@Advance

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Janicholson

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caterpillar guy

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Dick L

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Earl-IL

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Moonlite37

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Richard G.

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pete 23

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mite-help

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Earl-IL

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pete 23

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