Over the years it seems Ma Mopar did things differently for timing chain oiling, someimes a small hole in the gallery plug, sometimes a bolt with a hole in it. and sometimes nothing. I am building 2 408 Cu In Magnum based motors for a marine application, I am running the marine timing chain covers, and mechanical fuel pumps with the snout adapters from Hughes engines and reground Magnum roller cams. I purchased the Cloyes timing chain tensioners from a 3.9 Magnum application, and see there is no 4th hole by the cam retainer did they eliminate the hole because it was unnecessary? Is it unnecessary because they went away from the mchanical fuel pump? I need these motors to run for minutes and even hours on end at 4500 RPM under full load. On top of that all my boating buddies are giving me crap about not swapping in twin Small Block Chevy motors, so I am trying to make sure I get them right the first time. It looks like it would be a simple procedure to mark and drill the 4th hole in the tensioner, the What? do I drill a hole in the galley plug? If so what size? TIA Murf
mechanical fuel pump and timing chain oiling questions
- Thread starter murfman
- Start date
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FJ5
Well-Known Member
This procedure is discussed in the book "how to build big inch small block mopars"
FJ5
Well-Known Member
According to grumpy performance it's a .035 drill bit
Rapid Robert
Well-Known Member
instead of driving in a mini cup, drill/tap the front of the gallery for a 3/8 aluminum NPT pipe plug & drill a .015" hole in it then drill a larger hole in the cam plate (iirc I did 3/8) for it to squirt thru. In the rear of the gallery install a similar 3/8 NPT alum plug with the .015 hole for a constant squirt onto the intergear/cam gear. you can see it squirt when you preoil (it'll convince you!)
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