[INchief]

I have a replacement camshaft that doesn't have the same holes in 2 of the journals as the original camshaft. The shop I'm working with is questioning the differences and they want to know if the replacement camshaft will get proper lubrication without the holes. I asked the vendor and they told me it's an updated cam and will work as a direct replacement.

I tend to believe the vendor that the cam is an updated replacement and I know the shop is being cautious for good reason. The shop is going to use the replacement based on the answer from the vendor. But, I thought I would ask on this forum if anyone has experience with this difference and if there are any cautions.

Any help would be appreciated.
Thanks

[INchief]

[Bill Hanlon]

Those holes are used to meter oil up into the galleries in the heads that feed into the bottom of the rocker arm studs and eventually to lubricate the rocker arm to rocker ball area and the rocker tip to the valve stem on early (55 to some as new as 64) Pontiac V8 heads.

IF (big if) your rocker arms have a spurt hole where the pushrod touches the rocker arm, the stud-oiling system is not needed. If it is needed, make sure the oil galleries in the heads are opened up and well cleaned while the engine is torn down. Also, make sure the #2 and #4 cam bearings have the matching holes and are properly installed in the block to allow the oil to flow.

If you need more information about his system let me know and I'll dig it up.

[INchief]

Originally Posted by Bill Hanlon

Those holes are used to meter oil up into the galleries in the heads that feed into the bottom of the rocker arm studs and eventually to lubricate the rocker arm to rocker ball area and the rocker tip to the valve stem on early (55 to some as new as 64) Pontiac V8 heads.

IF (big if) your rocker arms have a spurt hole where the pushrod touches the rocker arm, the stud-oiling system is not needed. If it is needed, make sure the oil galleries in the heads are opened up and well cleaned while the engine is torn down. Also, make sure the #2 and #4 cam bearings have the matching holes and are properly installed in the block to allow the oil to flow.

If you need more information about his system let me know and I'll dig it up.

OK, thank you for the information. I will get with the shop owner and
determine if I have the stud-oiling system. If I have the stud-oiling system then I need an original style camshaft and bearings with the required holes?

[Bill Hanlon]

More threads on this subject:
https://forums.maxperformanceinc.com...d.php?t=783279
https://forums.maxperformanceinc.com...d.php?t=449523

This page is from a '57 GMC Maintenance Manual. GMC used Pontiac V8 engines from 55-59. The oil distribution drawing and text on this page may be helpful in understanding how the system works. Use the "next page" at the bottom of the screen. http://chevy.oldcarmanualproject.com...5559mm435.html

[242177P]

Agree with Bill, if it isn't stud oiled you don't need them. So that needs to be determined first.

But if it is... Thinking out loud, but early 396s used a grooved cam journal for engine oiling. Shouldn't be hard to add one. The real fun begins when trying to determine their size, because metering. There's also a chance that grooved cam bearings have addressed this already?? Again, just thinking out loud. I'd reach out to someone like Ken Crocie or Nunzi Romano.

[Jack Gifford]

I would not want to try to design grooved bearings to imitate the early Pontiac rocker oiling. The "pulsed" oiling through the drilled cam journals only occurs for about 4% of each cam revolution (1/4" out of the journal's 5.97" circumference). A groove to duplicate that small flow volume would be extremely tiny, and prone to clogging by the tiniest of particles.

[INchief]

Thanks for all of the input. We got it straightened out between the engine builder and the part vendor. The correct cam is on the way. I really appreciate the knowledge shared here. I learn something every time I come on here.