Packard Forum Index » Pre-War (1899-1942)

For the lack of a 3cm piston and spring (quantity 2) the '47 356 engine couldn't be rebuilt.

The restorer tells me the Tappet Oil Regulator piston and spring (parts 351713 and 351712) need to be replaced. The figure below shows the location of the forward Tappet Oil Regulator (5.1718), and there is also one at the aft end of the block. The spring and piston reside within this assembly. My review of the 1941 through 1954 Packard parts manuals shows that these parts were only in the 1946 and 1947 356 engine (despite the 356 being available 1941 through 1954, war-years excluded).

I've checked all the regular suppliers of NOS parts - and some others. As expected, no one has these parts.

Does anyone know why the Tappet Oil Regulator was discontinued in the 1948-1954 engines?

Next, does anyone have a secret stash of the piston and spring? Or, a recommended source? My restorer suggests that I get the piston custom lathed and the spring custom made, and I have names of a couple of metro-Denver companies that can do this work. The spring maker has a minimum order of $150, so looks like I may end of with a hundred or so of these, and become the "go-to guy" for these parts for anyone rebuilding a 46 or 47 356.

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As a V8 enthusiast I've been acutely aware of complaints regarding tappet noise and low oil pressure in those engines. Although I never worked on a 356 motor, over the course of compiling data for the site's online Service Index, I was surprised to find similar complaints for this straigth eight engine.

WRT to this regulator valve, the bulletins only reference a problem of sticking, with redesigned assemblies developed for 18th/19th and 20th/21st Series.

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The answer can be found in the 1946-1950 Service Manual, under "Section V - Engine" (specifically, pg. 35). Basically, the valves were eliminated from this engine in favor of some new oil passages, effective with the 22nd Series Custom 8. However, I don't recall any bulletin recommending a retrofit for earlier Series.

I can't offer any advice on where to locate these parts - not even a complete valve assembly.

Perhaps others can shed some additional light.

Don -- I sold you some parts for your Clipper limo years ago. Regarding your tappet bits, call Steve Messenger,
Just Packards, Napa, CA 1 (707) 254-2046. He's there seven days a week, a real labor of love, specializes in late '30s/'40s Packards, has done untold number of 356s over the decades. Tell him a black '47 Super Clipper in Walnut Creek sent you.

Brian, thank you for your comments on the topic. I checked-out the Service Manual link -- and what a wealth of inside information.

Super8OD. I owe you a PM response, and also many thanks for the contact info on Steve Messenger. I spoke with him this morning, and in the afternoon, he called back to say he had spoken with everyone he knew from coast to coast who might have the part, and came up with the same result as I -- 'not available" But, then he said that he knows a machinist who can duplicate the piston! Yeah. So the parts are on their way to Napa. Looks like I won't become the goto guy for Tappet Oil Regulator inards -- but maybe Steve Messenger will.

Interesting event surrounding the replacement oil tappet pressure regulators.

Let's review. These parts are only used on the 1946 and 1947 356. And the Clipper Parts Manual only lists one part number.

When my restorer went to install the excellent used specimens provided by Steve Messenger, he found they wouldn't fit in the oil galley. He ended-up boring the oil galley .002 inorder to insert them.

Any thoughts on this mystery?

Just speculation. Perhaps that regulator was custom made or fit to order at the factory to avoid scrapping a block.

There is one SC mention for 21st series where dealers were notified because of material shortages some engines were shipping with .020 oversize pistons to avoid having to scrap the blocks. A star after the motor number was the indication of that non standard item.

Maybe some of the oil passages also had problems with clean up in the area for the regulator and had to go slightly oversize. You just happened to get a used item from one of those engines.

IIRC, for the same reason there were some Ultramatics with oversized valves for the 52 or 53 year and a special designation at the motor number.

At first Howard's speculation seemed reasonable, but then I'm reminded -- there's just one part no. There are apparently two pistons, one .002 larger in diameter than the other.

I am going to try to get the block number from the donor block and see if it has a star.

One other possibility. There was a regulator kit along the lines of the postwar item made for prewar engines to replace the jiggle pin setup. In SC 20 #1 there is an article describing it but no idea if exactly the same. Also a note mentioning the pre and postwar items were not interchangeable so maybe size is the reason.

Both of my assumptions were false:
1. tappet oil regulator only used on 46 and 47 356's
2. only 1 part number

From SC Vol 20 No. 1, I read the following with respect to the tappet oil regulator piston on the 18, 19, 20 21 series:

Part No. 324579 18th and 19th Super 8s
Part No. 351780 20th and 21st Super 8s
"These parts are not interchangeable"

So I think the mystery is that 18/19 series regulator pistons are now installed in my block. These were replaced in the 20 and 21st series because they didn't work well.

Oh well. This packard documentation is so helpful. Thank you for pointing me in that direction.

Rather than using the motor as a paper weight, why not make up a fixed orifice feed plug for the front and rear cam bearings? What that regulator gadget is doing is starving the cam bearings to increase gauge pressure the same way as the old time used car dealer trick.

That is a ridiculous piece of engineering and gives credence to the old timers I knew who were always trying to pin the oil pressure gauge in Packards. Although I'm sure they would change their ways if they ever had high oil pressure blow a hole in the 11th series and later oil regulation circuit.

It's way ahead of its time though if you look at some of the crap they pull in modern cars with similar disastrous results.