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Help with 312 old y block Thunderbird engine.

General engine tech -- Drag Racing to Circle Track

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gn69z28
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Help with 312 old y block Thunderbird engine.

Post by gn69z28 »

This is a fresh rebuild. 60lbs of oil pressure. But almost no oil to the top of the engine. With head off and running oil pump with drill oil barely runs out of hole in top of block. Online search tells me this is a common problem with this engine. There used to be oil line kits to bypass oil pumping through the block and heads. Don't want to do that. Any ideas or suggestions on what to do or look for. The middle cam journal that the oil flows around has a very small and shallow groove. Is that the problem? Does it need a bigger groove? Are there different can bearings other than stock replacement? Anyone here dealt with this before. Thanks for any help or advice.
donsboy
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Re: Help with 312 old y block Thunderbird engine.

Post by donsboy »

The head is off and there's no flow? Clogged oil galley?
gn69z28
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Re: Help with 312 old y block Thunderbird engine.

Post by gn69z28 »

Head is off. No clogged galley. Fresh rebuild with starting to break cam in only. Oil comes out of hole very slowly after running pump with drill a minute or so. Took engine apart this afternoon and it doesn't have the grooved cam bearing on no. 3 journal. Will that make that much of a difference. From what I've found online this has been a problem since the 50s. But I need to get oil to the top of the engine for the rocker arms.
bone6145
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Re: Help with 312 old y block Thunderbird engine.

Post by bone6145 »

The last one I did I cut a groove in block behind cam bearing to send oil to the heads then put a restrictor in each head to cut the flow down
Mummert
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Re: Help with 312 old y block Thunderbird engine.

Post by Mummert »

Its not a clogged oil galley. Its the center cam bearing that is causing your issue combined with the depth of the radial cam groove in the camshaft itself. A new hardened center cam bearing and increasing the depth of the radial groove in the camshaft by .025" will give you oil to the top end for days.
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pdq67
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Re: Help with 312 old y block Thunderbird engine.

Post by pdq67 »

Please check the clocking of your cam bearings because if the holes in them don't lne up with the passages in the block, no oil to the top end.

My Mom had a '56 Ford 292 engine that had a copper tubing outside oil system installed on it to oil the top end. Crude, but it worked until the copper tubing broke and she lost all the oil and ruined the engine.

pdq67
Krooser
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Re: Help with 312 old y block Thunderbird engine.

Post by Krooser »

The external oil line deal was needed because of sludge caused by using non detergent oil back in the day.

Ford wasn't the only one with that issue...those Stovebolt Sixes were good for that, too.
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piston guy
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Re: Help with 312 old y block Thunderbird engine.

Post by piston guy »

Trust Mummert. He's forgotten more than most will ever know about Y blocks.
liqu
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Re: Help with 312 old y block Thunderbird engine.

Post by liqu »

Mummert is the man
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