Buick nail head snap ring in block

machinedave · Post by **machinedave** » Mon Jun 29, 2015 1:19 pm

I just got done machining a 425 nail head and the oil galley plug kit includes a new snap ring that installs between the #5 cam bearing and the rear cam plug. The snap ring that is included is way too small to fit in the block register. I have never seen any other block that has this. What is the purpose of the snap ring? Is it there to control rear cam thrust? Would you try to find the right one or am I okay to not install the snap ring?

machinedave · Post by **machinedave** » Mon Jun 29, 2015 2:07 pm

I just found the original snap ring so I will put that back in.

Post by **Schurkey** » Mon Jun 29, 2015 2:43 pm

First I've heard of that. I'll have to ask on the Buick forum and see what they say.
[Edit] http://www.v8buick.com/showthread.php?2 ... ost2472492 [/Edit]

The Nailhead uses some oddball engineering for the valvetrain--lifters don't spin, aren't crowned, the lifter bores are centered on the cam lobes, and the cam lobes aren't tapered to name a few--but I've never heard of the snap-ring before.

I'd just love to see some photos...

machinedave · Post by **machinedave** » Mon Jun 29, 2015 3:22 pm

Sorry I already installed the cam plug but here is a picture I took from the inside of the block.

Post by **Schurkey** » Mon Jun 29, 2015 3:58 pm

machinedave wrote:What is the purpose of the snap ring? Is it there to control rear cam thrust?

Wild-Ass Guess: Prevents the rear cup plug from being driven in far enough to dislodge the cam bearing. Non-essential--as long as the cup plug isn't shoved in with a sledge-hammer.

Just for giggles, is there an oil drain hole between cam bearing and cup plug so the cam bearing oil can escape, or does oil pressure between cam and that cup plug thrust the camshaft forward?

machinedave · Post by **machinedave** » Mon Jun 29, 2015 4:32 pm

Schurkey wrote:
machinedave wrote:What is the purpose of the snap ring? Is it there to control rear cam thrust?
Wild-Ass Guess: Prevents the rear cup plug from being driven in far enough to dislodge the cam bearing. Non-essential--as long as the cup plug isn't shoved in with a sledge-hammer.

Just for giggles, is there an oil drain hole between cam bearing and cup plug so the cam bearing oil can escape, or does oil pressure between cam and that cup plug thrust the camshaft forward?

At first I thought that too but the rear cam plug when flush with the rear surface of the cam tunnel is still a good .100" away from the snap ring. There is no oil drain plug in there.

ProPower engines · Post by **ProPower engines** » Mon Jun 29, 2015 7:36 pm

Be sure the cam has holes in the end to relieve the oil pressure build up.

machinedave · Post by **machinedave** » Mon Jun 29, 2015 10:33 pm

ProPower engines wrote:Be sure the cam has holes in the end to relieve the oil pressure build up.

I didn't see the cam that they are using. The test fit cam I used has a full groove in the 1st journal. Are you referring to the rear camshaft journal?

1989TransAm · Post by **1989TransAm** » Mon Jun 29, 2015 11:19 pm

Maybe it is to insure that the cam does not bump or ride on the cam plug.

ProPower engines · Post by **ProPower engines** » Mon Jun 29, 2015 11:53 pm

machinedave wrote:
ProPower engines wrote:Be sure the cam has holes in the end to relieve the oil pressure build up.
I didn't see the cam that they are using. The test fit cam I used has a full groove in the 1st journal. Are you referring to the rear camshaft journal?

Rear journal.
I have done a few and all the cams had an oil relief. While there is some stock replacement cams still available the last engines I did I used a Melling and Isky cam and both had oil relief.

machinedave · Post by **machinedave** » Tue Jun 30, 2015 8:16 am

ProPower engines wrote:
machinedave wrote:
ProPower engines wrote:Be sure the cam has holes in the end to relieve the oil pressure build up.
I didn't see the cam that they are using. The test fit cam I used has a full groove in the 1st journal. Are you referring to the rear camshaft journal?

Rear journal.
I have done a few and all the cams had an oil relief. While there is some stock replacement cams still available the last engines I did I used a Melling and Isky cam and both had oil relief.

Thank you. I will call him and ask him about the relief.

ProPower engines · Post by **ProPower engines** » Tue Jun 30, 2015 1:16 pm

As I am sure you have seen old engines alot of times are missing certain machining operations and missing drain holes can be an issue.
I got a sm blk GM engine in this morning with an oily fuel pump issue. Turns out the oil drain hole was not drilled 30 years ago at the factory and it would fill the fuel pump cavity after a short run and mess up the fuel pump.

Post by **Kevin Johnson** » Tue Jun 30, 2015 3:28 pm

1989TransAm wrote:Maybe it is to insure that the cam does not bump or ride on the cam plug.

http://nailheadbuick.com/buick-camshafts

Our oil galley kits come with the sometimes missing snap ring that installs behind the rear cam bearing, this will keep you from knocking out the large cam plug while installing the cam sprocket that sometimes is removed and installed many times when dialing a hi-performance cam.

machinedave · Post by **machinedave** » Wed Jul 01, 2015 9:57 am

Kevin your ability to find information continues to amaze me. Thanks.

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Buick nail head snap ring in block

Buick nail head snap ring in block

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