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Plunger oil pump, why two holes on return?

4K views 10 replies 3 participants last post by  oskar866 
#1 ·
When fitting my oil pump and taking care to make sure the gasket doesn't cover any holes I wondered why on the return side of the pump there are two small diameter holes in the crankcase, anyone know the reason? I guess one is from the suction tube, the other...

Thanks
 
#6 ·
On late 1960s engines, there's a bleed-off from that, to the exhaust tappet block.
So, I'm trying to get my head around what oil ways are where. I've attached a pic of the crankcase timing side when I stripped the engine down, I've labeled some areas up. Where would the exhaust tappet block feed be, in the blind hole I've labelled up 'what's this for'?

I think I read somewhere what to look for/measure on the exhaust tappets to know if they were the later engine (mine's 61745) tappets that didn't need the oilway, something about the flats, is this right? I've attached a pic of mine, are these the later tappets? Do they need a mettered valve?

Am I right in thinking the point of having a metered dowel is to stop low oil pressure at the crank end? I have 80 psi when the engine is cold, rev about 3000, 60 when warm and about 3000rpm. warm at idle, 20 psi.

Sorry for all of these questions, I'm trying to learn how these things work.

Thanks

Chris
 

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#7 · (Edited)
something I forgot to add to my last post, when I take the PRV out and look into where it threads into, I can see a brass looking tube at the end of the hole with two holes in it, it goes across the bottom of the hole.

Is this the metering tube?

If I've got later exhaust tappets (I think I have as they only have the very small flat cut into them), think they're called 'timed tappets', should I have this tube, should it be removed altogether?

Leave it in, it's meant to be there?

Also, when I remove the timing cover plug - where the pressure gauge tube goes in, there's a filter gauze in the hole, E6804. Should it still be there if there's no metering dowel? Has it anything to do with the metering (hollow) dowel?


thanks again

Chris
 
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