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Do I need a grooved rear journal ?

 
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Cr500joe
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PostPosted: Wed Jun 15, 2011 12:28 am    Post subject: Do I need a grooved rear journal ? Reply with quote

I've got a 1965 396 in my 1973 4+4 sb truck. I built it a long time ago but haven't tagged it sence 2001 because it will only run on premium fuel and only gets 7 mpg $$$. It has 10.5 compression and a dinky cam( 204-214@.50 500 lift) I want to put a cc XE274 4+4 cam in it (to lower dcl) do I need to groove the rear cam journal if I have the grooved brg?
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Big Dave
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PostPosted: Wed Jun 15, 2011 12:43 pm    Post subject: Reply with quote

You should have a grooved cam (you can not just install 1967 and up grooved bearings you have to remachine the block by adding two holes behind the bearings to feed the top end on each side of the block).

You can buy your favorite cam and have the cam grooved by whomever you buy the cam from.

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Knarley Darley
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PostPosted: Fri Jun 17, 2011 3:20 am    Post subject: Reply with quote

As long as either the cam or the bearing is grooved it should be fine. You shouldnt have to do both.
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Cr500joe
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PostPosted: Fri Jun 17, 2011 6:41 am    Post subject: Reply with quote

This is what I was afraid of who is right? Mad
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Big Dave
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PostPosted: Fri Jun 17, 2011 5:07 pm    Post subject: Reply with quote

You need a grooved cam and the old style (1965-'66) rear cam bearing with three holes in it. The old style bearing has to be aligned so the three holes line up with the three oil gallery holes in the block. This allows the oil flow to go from the main gallery around the cam by way of the groove to feed the two lifter galleys.

Later blocks starting in 1967 have an annular ring machined into the block at the rear cam journal that connects all of three oil galleries and only needs a bearing with one hole in it (that can go in any orientation though I like mine pointing down). This allows the oil flow to go around the cam behind the bearing to feed the two lifter galleries. The 1967 and up (new style) one hole cam bearing only provides oil to lube the bearing surfaces without your 1965 block being machined to accept the newer style cam bearings.

Where did you find a grooved bearing? The bearing material is not thick enough to have a groove cut into it to to feed the oil needed on the top end. The cam groove is 3/16ths to a quarter inch deep just from memory.

Here is the difference in the grooved versus non-grooved:



and a picture of the groove (it's a small block but they have the same groove in 1967 and up big blocks) that you do not have in your 1965 block:



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Knarley Darley
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PostPosted: Sat Jun 18, 2011 4:18 am    Post subject: Reply with quote

They make a 3 hole bearing with the groove in it so you can run any cam without having to modify it first. I have 2 right now that have run for years this way with no problems. You are right about the bearing groove being shallower than the cam groove. To correct this they slightly widened the groove in the bearing to increase the volume. What else would be the point of having the special grooved bearing if it was not to eliminate the need for the grooved cam journal? If the cam has to be grooved regardless, then what would be the point of making a special bearing? You dont need to have both grooved. The grooved bearing is so it isnt a giant pain every time you want to change the cam.
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