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Another 1929 Pontiac Engine Question!!


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Hey guy's...


I have another question in regards to the 1929 Pontiac Split six engine...

I have included pictures of the subject matter..

On the side of the block and under the valve covers, there are 4 holes that lead into the cam mains..


  • I was told by a fellah(who pours babbits) that these holes are for brass dowel pins to aid in holding the babbits stationary, but if the babbits were tight enough a short dowel pin could be used just to prevent oil leakage?


  • According to the book (Oakland / Pontiac) this engine did not require cam babbits?.....I found this rather odd..but tolerances are to spec.


....If anyone can verify the information above it would be greatly appreciated!.....


.......This engine will be used for "Vintage Auto Racing Association" events.......

  • Question?....Would it be beneficial to thread these holes to accept brass oiler lines from the oil pressure fitting to help aid the lubrication process?..


  • Question?...Would this result in too much of an oil pressure drop feeding the other components?

Above pic....two holes just under cover..leads to center cam main.



Above pic...hole to rear cam main under cover....another is provided for the front main as well.



Above pic..Holes lead into top of all cam mains..

Edited by Paranoid (see edit history)
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Post # 165

Q:..What did you do about oil leak from side hole where brass plugs are installed?


Post # 166

A:..I'm pretty sure I'm going to try a dab of Yamabond and a lead split-shot driven into the hole...At least on one or two of them to see if it works...



I appreciate the reply!...I really do..but this just doesn’t quite touch on the info I'm looking for.

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My engine has 500,000 miles on it.  Why would you use any other plug than the original Welch plug.  There is nothing wrong with a camshaft running in a cast block.  When I had my camshaft reground it was only because of lift they did not touch the bearing surface at all.  The oil that is sprayed around seems to be enough for the camshaft.

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I currently have 5 of these engine in service, they do not run cam babbits. The only lubrication that the cam gets is oil run off from the lifters which drains down plates attached to the lifter assemblies and is directed to these 4 holes, blocking them will starve the cam of oil and the engine will seize very quickly. The holes to the outside of the block need to be plugged however or this oil will all leak out. I have found the most certain way of doing this is tapping the holes and installing grub screws. I did have one of these engine that had oil starvation problems to the cam, never could work out why. My machine shop ended up drilling passages up through the block and taking two small oil lines from the main supply, fitting a small orifice to the end of each and just letting the oil escape into the channel in front of the lifters. The oil pressure can be adjusted externally to compensate for the oil taken away from the mains. Hope this helps.

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