Bearing shims

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GJBINSC
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Bearing shims

Post by GJBINSC » Tue Feb 27, 2018 7:02 am

Does anyone know if Packard used brass shims on rod and main bearing caps ? I know some manufactures, Packard included, used lamp smoke to blacken the bearings and then shim the bearing caps to fit and allow for a .001 oil film. My 1932 901 has brass shims of .001 under the caps of both the main bearings and the rod bearings. My machine shop who has done some of these straight 8 blocks in years past says that Packard did indeed shim the caps. There is mention of this in my shop manual at ( Section M515 for the 626 model ) on" Bearing Take Up". Others on this forum say Packard never did that. So has someone added them to my engine, or are they original ? Odometer says 51,000 + but not sure that is accurate, with no way to verify. Oil pressure is on the low side of the recommended 20-50 lb range. Suspect I may need to remove some of the shims to tighten up the bearings and get .001 clearance as a way to improve oil pressure. When removed rod caps seemed tight, and no sign of bearings being burned. Much sludge in the pan mostly at the rear portion away from the oil pump screen.

Dave Czirr
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Re: Bearing shims

Post by Dave Czirr » Tue Feb 27, 2018 8:11 am

Does anyone know if Packard used brass shims on rod and main bearing caps ? I

Not to my knowledge, at least not for 1929 and later. Not mentioned in any Parts List or Service Letter between 1931 and 1934 (last year for poured bearings). I've seen plenty of these engines apart, never seen shims. The M515 reference applies to an earlier engine and it apparently applies ONLY to the rear main bearing cap. If you look at M520, it speaks of scraping, not removing shims for connecting rods, as does the related procedure for main bearings.

Sounds like it's time to get some Plastigage and start checking bearing clearances. For my '34 Eight, not much different that your 901 engine except for the oil cooler, carburetion and ignition, I've set the oil pressure relief valve to knock off at 55 psi *(higher than that and you risk rupturing the oil filter canister). Cold starts always reach 55, cruising at 40-45 mph during spring/summer/fall months pressure is typically 45 psi, a bit lower if I push the speed higher. Hot idle about 15-20 psi. Rods were poured and sized by Paul's Rod & Bearing about 8 years ago. Many consider Paul's to be the gold standard for poured babbit bearings, you might contact him and ask about shims on Packard engines.

GJBINSC
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Re: Bearing shims

Post by GJBINSC » Wed Feb 28, 2018 8:33 am

Interesting indeed. My hot idle is around 10 lbs even with 15/40. So looks like bumping up the pressure at the pump is in order. It appears two turns of the adjustment screw might yield 6-10 lbs additional pressure. I was reluctant to remove any shims without knowing what clearance would result. The manual talks about placing a feeler gauge of .001 in the bearing and then withdraw, and scrap down to fit. It should come out with some resistance. If the caps were scraped previously, and then new bearings poured at some point, then the shims make sense or the caps would be too tight. This is really a mystery, but I don't want to damage anything by doing something ill-advised. I am not sure I want to run my car above 45 with 30 yr old tires, crashing one of these could prove deadly, that steering wheel is really big. I read that "Medium" oil was likely 40w, so maybe that is the first thing I can do and see what happens. Might also try non-detergent available from Restoration Supply, the old fashion stuff.

Dave Czirr
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Re: Bearing shims

Post by Dave Czirr » Wed Feb 28, 2018 8:54 am

Some thoughts.

If your oil sump and engine are relatively clean, it makes absolutely no sense to use a non-detergent oil - take advantage of today's better oils.

The feeler gauge method of checking bearing clearances is long into the annals of antiquity - use simple Plastigage to measure.

When rods are repoured and sized, you give them the crankpin diameter and they sized to fit properly, no shims, scraping, etc. Scraping came into play when the clearances opened up but rather than face the cost to renew the bearing, folks took the shoddy way out and filed the mating faces of the cap to reduce the diameter of the bearing. If you went too far you had to scrape the high spots. Factory reconditioned rods were also poured and sized the predetermined undersizes, no shims, no scraping.

I just replaced 27 year-old tires on my '34, they still looked good but it just wasn't worth the risk to continue, I had lost confidence in them. But even with new tires, you really don't want to push a 901 much over 45 mph as a regular cruising speed unless you've installed some sort of overdrive or higher speed rear axle gears. For tires, give consideration to Bedford Famous Coach tires.

Tightening the spring on the oil pressure relief valve may or may not increase driving pressure depending of many things incluing bearing clearances, but I wouldn't be too optomistic that it will result in any increase in hot engine pressures. It can only increase the pressures if it's already limiting them.

GJBINSC
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Re: Bearing shims

Post by GJBINSC » Wed Feb 28, 2018 10:01 am

Dave: Yes I realize it may be a long shot to increase the pressure at the pump, but as long as it does no damage, then maybe worth a try. I think ,maybe 40w oil can help, I never drive the car in winter, or below about 60 degrees. Summers can be hot here, and the heat in the front seat is already uncomfortable, so car will only be driven on good days, when not too hot. As for miles, not likely to see that many miles either, maybe 15-20 at the most each time out. Just local and some country roads. Yes car will not go over 45, but mostly around town at 35 or less.

Dave Czirr
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Re: Bearing shims

Post by Dave Czirr » Wed Feb 28, 2018 11:33 am

OK, I understand your situation. Wishing you happy times and miles in your Packard.

I am a particular fan of the '32-'34 Packards, other Packards have come and gone now but I've owned my own '34 Eight (1100) for a bit over 50 years. What body style is your 901? Pictures?

Would you be willing to share with me via PM your VN, theft-proof number, and motor # for my continuing research on these models?

Dave

GJBINSC
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Re: Bearing shims

Post by GJBINSC » Thu Mar 01, 2018 5:52 am

I need to figure out how to upload photos.

Dave Czirr
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Re: Bearing shims

Post by Dave Czirr » Thu Mar 01, 2018 7:50 am

When writing or replying or editing a post, go to the bottom left of the screen and click on "Upload Attachment". Select your photo from your PC, click to open, and then click (again at the bottom of our screen) on "Add the file". Note there is a size limit on the photo file, and only 7 photos per post.

Dave

GJBINSC
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Re: Bearing shims

Post by GJBINSC » Thu Mar 01, 2018 10:23 am

OK, Numbers are engine mount drivers side *342662* same number on the frame rail near the steering box. Fire Wall number 157307, Ser # 503-1956 Delivered to Earle Anthony 8-28-31. Photos are too large to attach will try to zip.

Dave Czirr
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Re: Bearing shims

Post by Dave Czirr » Thu Mar 01, 2018 12:56 pm

Thanks for the numbers, they fit in quite neatly with other 503 models, nothing unusual or noteworthy.

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