At 05:57 PM 6/3/98 PDT, you wrote:
>My Tiger had low oil pressure when hot for many years so I decided to
>replace the crank bearings & oil pump. Because the engine was old I
>figures that .001" undersize bearings would probably fit, so I got a set
>of .001" under main & rod bearings & some plasticgage & a high volume
>Melling oil pump & went to work. All the mains took the undersize
>bearings & fit well, and after about 1/2 of the rods fit well I stopped
>plasticgaging & put the last 4 or 5 bearings in & found that I had
>locked up the engine. I found that the #8 rod bearing just was not going
>to work, so I went out & got me a standard bearing for that position.
>The next morning I crawled back under the car for what I expected to be
>a quick finish to my project, only to find out that the standard bearing
>also locked up the engine! I took the bearing out & looked in vain for
>some burr or flaw in the crankshaft or connecting rod that would account
>for this problem. I polished the crank, the rod & the standard bearing,
>but to no avail, when I put the torque wrench to the #8 rod, the engine
>locked up. I went through my old rod bearings & found that the bearings
>that came out of the #8 rod were marked differently than the others. In
>30 years of auto repair I've never heard of an oversize crankshaft
>journal, but now I had one. I put the original bearings back into the
>connecting rod & now had good oil clearance. In went the new oil pump &
>everything is now happy, with my one antique bearing and a dozen new
>ones. the oil pressure, that would drop to about 20 psi hot now stays up
>around 80 psi with a thinner oil than I'd used before. & the old heap
>sounds better. Still smokes at high rpm though. Probably needs an off
>size piston to fit an undersize bore.
>
>Doug Leithauser
Doug,
Maby the crank journal swelled up when it was soaked in oil. Ha!
I have heard of different "color" of bearings to take care of manufacturing
tolerences, but yours must have been off the scale.
The first time I had to overhaul a motor I put every rod cap on backwards
because it seemed logical to me that the numbers stamped in the rod and
cap should be oppsite one another. That motor was really locked up.
That pin in the lower main cap can be removed if you care to
use the later model rubber seal. Have to lower or remove the crank
to put the upper in.
James Barrett Tiger II 351C and others
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