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MG MGB Technical - Oil pump modifications?

Just finished fitting a new oil pump to my 1950cc 5 brg engine rebuild. I followed Peter Burgess' advice and went for the standard oil pump this time without the double porting modification from the Special Tuning manuals. Just flow smoothed the inlet passage on the bends and transitions.
I realised one reason this setup is better is that with the oil entry on the top the rotor chamber, it remains full when the engine stops meaning it is full when the engine starts so pump immediately primes (with the double porting the rotor chamber drains when the engine stops, meaning longer time to prime on start up). Also hopefully less wear on the drive gear using standard rather than high volume pump (+9/16" steel ball relief valve).
Mike
Mike Ellsmore

How's the rebuild going Mike
Can't go wrong with Peter's input

Keep it simple---best policy

I've always used Austin 1800 pumps with Mgb endplate
Might have a relook at that------

willy

Can't recall what happened to your engine ---have you got your sump baffled--???
William Revit

Original pumps rarely need to be replaced. Usually, a bit of freshening up is all that is required to bring them back to factory specifications. RAY
rjm RAY

Willy,
I destroyed a piston with too much advance at a Sandown sprint meeting earlier in the year - found camshaft and followers were knackered so went for a total rebuild. It has taken me sometime but getting there! Yes, sump is baffled.
This photo shows shiny new JE pistons!
Mike

Mike Ellsmore

Bottom end before the oil pump and camshaft fitted.

Ray, camshaft and follower metal debris destroyed the old oil pump.
Mike

Mike Ellsmore

OOOOH Shiny
Bruce Cunha

Bruce,

You took the words out of my mouth.

Charley
C R Huff

Cheers Mike
The bores look fairly close together for a 83.5mm job
I like to offset them a bit further apart--You'll really need to take care making sure the headgasket lines up correctly
My 85mm motor has 5mm between the bores
Thanks for the pics
willy
William Revit

Hi Willy,
Gap between the bores 1&2, 3&4 is 4 mm. New pistons have only resulted in the bores being honed out 5 thou. I had no problem in the past with head gaskets (touch wood) so hopefully will continue even though HRG Derrington alloy head is on the soft side! Using Payen composite AK660 gasket and 7/16" head studs.
Mike
Mike Ellsmore

Cheers Mike
My mention of the bore spacing was no more than an observation / comment A thinking out loud sort of thing
A constructive comment
I'm sure you will be ok with 4mm

It just reminded me of a block I spent heaps of time on once, grinding it out smooth inside and making it special- did the offset bores and got that all sorted and sleeved and looking great
All that was left to do was a minimum skim off the top to true it up, so I went home to get the ute to pick it up while a guy who wanted to be involved did that and when I got back he had skimmed it ok but went around all the edges with a die grinder to clean it up
Including a monster chamfer on the top of each bore
There was nothing there for the h/gasket to sit on
P^ss%d off--yep
Started again
I always advise now not to touch the top of the bore and leave the edge square-simply, JUST take the corner off with a scraper
Getting the rings started takes time and patience/care
I have found the best method is to make up a tapered funnel the same size as the bore--works a treat
Power on young man
willy
William Revit

My edges are square with just a run around with a small diamond file to prevent me cutting my fingers on the edge! No trouble getting the pistons in - normal ring compressor, plenty of oil, a little wriggling and a light tap with the hammer handle.
Mike
Mike Ellsmore

The stock pumps put out a crazy volume/pressure which is why there is that oil pressure relief valve to control the pressure to managable levels. If the pump is ever the cause of low oil pressure you will be able to hear the gears grinding against each other in the pump. Not something that should ever need 'upgrading" to something different, or a racer part.
S Cole

My B has an Oselli 1950cc fast road engine (About 17yrs old)with an "uprated" oil pump. On cold mornings if the oil level gets anywhere near the low mark on the dipstick the pump will empty the sump before the cold oil has a chance to find its way back through the engine. I live with it by always keeping the level at the max.
G Britnell

This thread was discussed between 30/12/2016 and 05/01/2017

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