Re: 1967 427 400HP cam
[quote=Duke Williams (22045);478815]I never quite understood this. I assume that the rear cam bearing clearance is in the same range regardless of what cam bearing/cam is used.
A grooved cam will likely result in a bit more oil passing through the rear cam bearing, but I don't see how this can be significant, since the typical .001" clearance on either side of the groove is still going to be a significant restriction to oil flow.
The Power Manual instructions say to solder up the oil hole and drill it to .060", but what is the size of the original hole. I assume it is larger.
Do you recall the thread where is came out that Chevrolet rescinded the this advice?
the original cam bearing hole was about 1/4" and with a non grooved cam journal the hole which is on the bottom of the bearing a direct feed from the rear main bearing was closed off because the valve train is pushing down on the camshaft and only some oil got by the cam bearing journal. with a grooved cam bearing journal which lined up with the cam bearing hole allowed full flow of oil in around the groove. this could cut down on the amount of oil passing thru the groove in the block behind the cam bearing and not allow enough oil to get to the hyd. lifters
[quote=Duke Williams (22045);478815]I never quite understood this. I assume that the rear cam bearing clearance is in the same range regardless of what cam bearing/cam is used.
A grooved cam will likely result in a bit more oil passing through the rear cam bearing, but I don't see how this can be significant, since the typical .001" clearance on either side of the groove is still going to be a significant restriction to oil flow.
The Power Manual instructions say to solder up the oil hole and drill it to .060", but what is the size of the original hole. I assume it is larger.
Do you recall the thread where is came out that Chevrolet rescinded the this advice?
the original cam bearing hole was about 1/4" and with a non grooved cam journal the hole which is on the bottom of the bearing a direct feed from the rear main bearing was closed off because the valve train is pushing down on the camshaft and only some oil got by the cam bearing journal. with a grooved cam bearing journal which lined up with the cam bearing hole allowed full flow of oil in around the groove. this could cut down on the amount of oil passing thru the groove in the block behind the cam bearing and not allow enough oil to get to the hyd. lifters
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