Quote:
Originally Posted by Fred D Bartoli
Carl
Happened to notice your post about excessive bleed off with cam bearings with (3) holes. I am not a professional engine builder but I do build the motors for our super stock cars. I currently have (3) motors, (1) Dart and (2) bow-tie blks. all (3) blks. have Dura bond bearings with (3) holes. I have not had any issues with them. Just wondering how you are determining excessive bleed off, is there a specific test?. How must bleed off is considered excessive?
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I machine my own cam bearings and have had alot of calls about this issue. Like I have said prime the engine with the intake off and see how much bleed of there is. Then have the oil at 200 degrees now its even worse. Now add a vacuum pump and now your sucking oil out of every where cam bearings lifter bores ETC.
Some times depending on the journal size and and hosing bore you can have alot of oil clearance and having a cam bearing with oil holes every 120 degrees no matter how they are installed there is one hole near 12:00, Having oils holes form 8:00 to 4:00 is a problem with bleed off.
Richards Maskins called me about what I was doing with my cam bearings and said I was 100% correct but he had to make a bearing that was child proof. Richard said its nothing to see .006 to .008 oil clearance sometimes on cams.
On those blocks I use the GMP-8 drill another hole appox. 3:30 or 4: and groove on the OD of the bearing between the 2 holes.
Lifter bore clearance has to be spot on to much and you bleed off out of the lifter bores and the way the oiling is to the push rods they work off bore clearance to much clearance allows to much oil to the top end.
I machine alot of 55MM cam tunnels and with a 2.165 journal and a bearing with 3 holes you want to talk about bleed off. I had custom cam bearings made with one oil hole and groove one hole lines up with the one in the block and another hole can be machined at appox. 4:00
Spinning an engine 9000 RPM and having aluminum rods which take up alot of space and add alot of windage!!! oil control is a must.
http://www.dura-bondbearing.com/Port...20Bulletin.pdf
http://www.yellowbullet.com/forum/sh...d.php?t=449698