MGB & GT Forum
Oil pump differences - 3-main vs 5-main
Posted by larrym
larrym
Larry M
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Topic Creator (OP)
Jul 22, 2014 02:33 PM
Joined 20 years ago
1,012 Posts
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OK - so why the differences & is either one better?
picture
looks to me that the later pump was simply cheaper to make - the inlet port does not match to anything on the block
(or did they use this later pump in some tractor that had a block inlet?)
.
******************************
ASE Master Tech 35 yrs
******************************
MGB parts FS & '63 MGB FS
- view pdf on Google docs ..... https://tinyurl.com/MGB-FS-list-06-2022
my car: https://pbase.com/emoze/1963_mgb_
picture
looks to me that the later pump was simply cheaper to make - the inlet port does not match to anything on the block
(or did they use this later pump in some tractor that had a block inlet?)
.
******************************
ASE Master Tech 35 yrs
******************************
MGB parts FS & '63 MGB FS
- view pdf on Google docs ..... https://tinyurl.com/MGB-FS-list-06-2022
my car: https://pbase.com/emoze/1963_mgb_
fast-MG.com
Dave Headley
Cortez, 4 corners, Colorado, USA
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Jul 22, 2014 03:26 PM
Top Contributor
Joined 15 years ago
9,605 Posts
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Larry, compare the spindle gear extension length. The 5-main is longer and the block mounting surface is at a different depth. Both pumps draw oil in from the sump in the same way. The 3-main suction port is fully machined and you will find a plugged hole in the side. The 5-main pump replaces this plug by sealing off the die cast port against the block surface. Good question BTW.
Jul 22, 2014 04:41 PM
Top Contributor
Joined 17 years ago
7,209 Posts
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Larry.
The 5 main pump is a bit longer because the extra main bearing was in the way of the machining for the pump.
The 5 main engine was designed to be more rigid for the Front Wheel Drive Austin/Morris 1800 application where the transmission was mated to the bottom of the block in a similar manner to the Mini/Austin 1100, 1300.
The Austin/Morris 1800 was available as an automatic and the extra port you see on the oil pump fed the transmission hydraulic system.
It's important to take a step back from the sports cars and understand that many upgrades and modifications were a result of the domestic saloon car program that really was the bread and butter.
Kelvin.
The 5 main pump is a bit longer because the extra main bearing was in the way of the machining for the pump.
The 5 main engine was designed to be more rigid for the Front Wheel Drive Austin/Morris 1800 application where the transmission was mated to the bottom of the block in a similar manner to the Mini/Austin 1100, 1300.
The Austin/Morris 1800 was available as an automatic and the extra port you see on the oil pump fed the transmission hydraulic system.
It's important to take a step back from the sports cars and understand that many upgrades and modifications were a result of the domestic saloon car program that really was the bread and butter.
Kelvin.
fast-MG.com
Dave Headley
Cortez, 4 corners, Colorado, USA
Sign in to contact
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Jul 22, 2014 06:10 PM
Top Contributor
Joined 15 years ago
9,605 Posts
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