[HPseeker]

I will take the block to install new cam bearings and need some help with the type of bearing needed went using a solid roller billet cam

Clevitte 77 or Dura Bond CH 12 or use the CHP12 or 12T ?

 

[Wolfplace]

I will take the block to install new cam bearings and need some help with the type of bearing needed went using a solid roller billet cam

Clevitte 77 or Dura Bond CH 12 or use the CHP12 or 12T ?

=
CHP12 will be fine but I like the 12T

Also not a bad idea to add a second hole at about 3-3:30 & put a groove on the backside of the bearing between the two holes for added lubrication
You can add a groove all the way around if you have access to a lathe or you can just use a dremel with a carbide tip to groove from one hole to the other
Make it about 20 thou deep
Don't forget to deburr the hole on the cam side of the bearing if you add one

 

[CNC BLOCKS N/E]

=
chp12 will be fine but i like the 12t

also not a bad idea to add a second hole at about 3-3:30 & put a groove on the backside of the bearing between the two holes for added lubrication
you can add a groove all the way around if you have access to a lathe or you can just use a dremel with a carbide tip to groove from one hole to the other
make it about 20 thou deep
don't forget to deburr the hole on the cam side of the bearing if you add one

x2

 

[70SSOBSESSION]

They just lowered the price $27 on the CHP 12T There only $48 at Summit now I just payed $74 a couple months ago.

 

[HPseeker]

Mike , Carl , I will try to get the CHP 12T build the hole at 3-3:30 and groove them .0020 deep, and how wide ?, the side of the holes?

Thanks Chris for the special news :thumbsup:.

 

[Wolfplace]

Mike , Carl , I will try to get the CHP 12T build the hole at 3-3:30 and groove them .0020 deep, and how wide ?, the side of the holes?

Thanks Chris for the special news :thumbsup:.

.020 not .002
I make it about .050 wide with a cutoff or parting tool in the lathe but if you use a dremel or die grinder with a carbide burr that is 1/8" in diameter whatever it ends up for width will be fine if you go about 20 thou deep
This will put a nice groove in the bearing for oil to get to the second hole
Just a little channel between the two holes is all.

I suggest you practice on an old bearing first,,,, the coated ones get knd of expensive if you have to buy replacements

 

[HPseeker]

THANKS Mike for the help ,you allways teach us how to make our motors live faster and longer :thumbsup:.

It is a good thing to sanblast the top of a new piston set ? ,one of the employes of the shop told me they can do this and will help burn the fuel mix ,

 

[engineguy]

THANKS Mike for the help ,you allways teach us how to make our motors live faster and longer :thumbsup:.

It is a good thing to sanblast the top of a new piston set ? ,one of the employes of the shop told me they can do this and will help burn the fuel mix ,

Do not sand blast (or glass bead) the tops of the pistons. If anything you would be better off to polish the piston tops. The polished surfaces (piston crown and combustion chamber) will help contain heat during the power stroke and let it escape to the atmosphere during the exhaust stroke, and thereafter. (Thereafter means that the heat of the exhaust gas "plug" will travel quicker through the header primary tube and help develop the negative pressure pulse that will help evacuate the next exhaust stroke during a very short, but important, RPM range)

 

[Smokey1961]

=
CHP12 will be fine but I like the 12T

Also not a bad idea to add a second hole at about 3-3:30 & put a groove on the backside of the bearing between the two holes for added lubrication
You can add a groove all the way around if you have access to a lathe or you can just use a dremel with a carbide tip to groove from one hole to the other
Make it about 20 thou deep
Don't forget to deburr the hole on the cam side of the bearing if you add one

Doing some searching for SR install coming up on new build. Just want to clarify that the clock position you are stating is 12 o'clock being lifter side and 6 o'clock being main saddle side when viewed from the front of block? This makes sense to me but that doesn't always mean I'm right.

Thanks, Jeff

 

[oldtimr]

http://www.dura-bondbearing.com/Portals/3/pdf/Cam bearing oil holeTechnical Bulletin.pdf

yes, noon is up, 6 is down. Down is bad.

Durabond uses degrees, and the engine is a 90° vee, so durabonds 60°(2 o'clock) is just past the left bank(driver side) area. That always helps me when I'm installing them because I have them upside down, and I don't do them everyday like these guys do.

 

[Smokey1961]

Thank you just double checking!

Jeff

 

[BillK]

yes, noon is up, 6 is down. Down is bad.

.

Tim,
This is a Big Block .... you have no choice but 6 oclock. The bulletin you linked to is for engines that have a groove around the back of the cam bearings, like a small block does. On the Rats the oil hole is at the bottom and there is no groove. That is why Mike's suggestion helps.

 

[Smokey1961]

I knew he was quoting a SBC but I just wanted to confirm the clock reading, all is good here!

Jeff

 

[Wolfplace]

Doing some searching for SR install coming up on new build. Just want to clarify that the clock position you are stating is 12 o'clock being lifter side and 6 o'clock being main saddle side when viewed from the front of block? This makes sense to me but that doesn't always mean I'm right.

Thanks, Jeff

Hi Jeff,
I see you have been answered but just to add

A special thanks should go to Carl (CNC) for this info as it was he that found the issue of low RPM oil pressure that can be problematic with the standard Dart supplied bearings in some cases & is where the modification to the single hole bearing idea came from

 

[Smokey1961]

Thanks Carl! Thanks Mike! Not that I have any valves that can dance yet.

Quick question, I have been searching and have not found a part number or length of ARP bolt to use with the AFR's on the four bottom ones?? I already have the ARP's from my 781's, just need the bottom four.

Thanks, Jeff

 

[Wolfplace]

Thanks Carl! Thanks Mike! Not that I have any valves that can dance yet.

Quick question, I have been searching and have not found a part number or length of ARP bolt to use with the AFR's on the four bottom ones?? I already have the ARP's from my 781's, just need the bottom four.

Thanks, Jeff

No valves,, I can fix that ,,,,
If you have the other bolts ARP 135-3605 is the abbreviated set

And you are welcome :beers:

 

[oldtimr]

Bill,
Although I can't remember ever putting a set into a bbc, I recognized it didn't have an annulus or why else grind an oil passage. I also recognize you posted to clarify for future readers. I should have done so myself, but on occasion I try to practice brevity although I suck at it.

Here's a c/p from the pdf I attached previously that made it valid, as well as the fact it clarified clocking.

Note: If the oil feed passage in the block or head is just a hole without a 360°
groove, the bearing oil hole must line up with the oil feed passage in the block or
head. In some instances, the bearing oil feed hole in the cam bearing also lines up
with a groove cut in the camshaft journal. In those instances, the location of the​

bearing oil feed hole in the bearing is also very critical fore and a