Cam / Oil Pump
Discussion
revingtosh said:
...Provided you have the matching cam and oil pump, are all drive types compatible with any A Series block?
The actual drive type, pin, spider or slot makes no difference, but there are a number of different pump types, which are not all interchangable, the drive shaft is longer on big block pumps and the number of bolt holes varies.Another area of complication.
There are three types of oil pump drive: pin, spider and slot.
There are two pump shaft lengths, short for 850 & 998 and long for 1275.
There are 2-bolt, 3-bolt and 4-bolt pumps.
Early engines have 3-bolt. The later engines went to 4-bolt, but now the pumps most commonly available for 1275 engines are 2-bolt.
Now, you can fit a 2-bolt pump to an engine drilled for 4-bolts so long as the 4th bolt hole has not been drilled through into a waterway which, if the engine is an early 3-bolt type modified to take a 4-bolt later pump, it may well have been. If a threaded bolt hole has gone into a waterway and a 2-bolt pump is to be fitted it is vital to either drill out the pump casing to take the 4th bolt, or blank off the redundant hole in the block. If you don't you may get what I got on my Cooper 'S', 2 pints of Valvoline oil in the water!
Now I check each time before I fit an oil pump.
Also, the AP technical spec sheet lists the same pump for a pin-drive 998 as it does for a 1275. Whatever you do don't fit the 998 pump to the 1275 if you have a pin drive cam as it only engages on the pin by about 1/16" and will probably snap off with loss of all oil pressure. Just buy the correct pump from Mini Spares. I sent AP a drawing of the two types a few years ago, but I believe they have not altered their spec sheet or part numbering.
There are three types of oil pump drive: pin, spider and slot.
There are two pump shaft lengths, short for 850 & 998 and long for 1275.
There are 2-bolt, 3-bolt and 4-bolt pumps.
Early engines have 3-bolt. The later engines went to 4-bolt, but now the pumps most commonly available for 1275 engines are 2-bolt.
Now, you can fit a 2-bolt pump to an engine drilled for 4-bolts so long as the 4th bolt hole has not been drilled through into a waterway which, if the engine is an early 3-bolt type modified to take a 4-bolt later pump, it may well have been. If a threaded bolt hole has gone into a waterway and a 2-bolt pump is to be fitted it is vital to either drill out the pump casing to take the 4th bolt, or blank off the redundant hole in the block. If you don't you may get what I got on my Cooper 'S', 2 pints of Valvoline oil in the water!
Now I check each time before I fit an oil pump.
Also, the AP technical spec sheet lists the same pump for a pin-drive 998 as it does for a 1275. Whatever you do don't fit the 998 pump to the 1275 if you have a pin drive cam as it only engages on the pin by about 1/16" and will probably snap off with loss of all oil pressure. Just buy the correct pump from Mini Spares. I sent AP a drawing of the two types a few years ago, but I believe they have not altered their spec sheet or part numbering.
Confusing, ain't it!! LOL.
The 970 and 1071 blocks were nall 3-bolt short shaft pumps, just like the original 1275 'S'. The 1100 is the same as the 850 and 998 pumps.
No wonder BMC/BLMC/Austin-Rover/Rover had problems, unlike Ford and GM where most parts are fully interchangeable within any one generic engine.
The 997 Anglia oil pump is the same as that on a 1558 Lotus Cortine.
The 970 and 1071 blocks were nall 3-bolt short shaft pumps, just like the original 1275 'S'. The 1100 is the same as the 850 and 998 pumps.
No wonder BMC/BLMC/Austin-Rover/Rover had problems, unlike Ford and GM where most parts are fully interchangeable within any one generic engine.
The 997 Anglia oil pump is the same as that on a 1558 Lotus Cortine.
Cooperman said:
Confusing, ain't it!! LOL.
Yes!Cooperman said:
..The 970 and 1071 blocks were nall 3-bolt short shaft pumps, just like the original 1275 'S'. ...
You saying all Cooper S blocks use short shaft pumps? Never realised that, you can tell it's a long time since I worked on an original Cooper S!Edited by Dino42 on Friday 5th December 22:45
dino
its easy (ish) all the s motors 970/1071/1275 are the same 'big block' engine. all that alters is crank strokes, rod lengths and the amount removed of the top of the block. so externally a cooper s motor is simply a 'block height' until the crank and rods are fitted. as a result all the other bits and bobs will interchange with no problems.
then the 850/997 is based on the 850 'small block' block with crank/rod changes, though there are early and late 850 blocks with different main bearings and lack of cam bearings on the early ones
then the 998/1100 is based on the 1000 'small block', again with a crank stoke to alter them
i think that clears it up..........
its easy (ish) all the s motors 970/1071/1275 are the same 'big block' engine. all that alters is crank strokes, rod lengths and the amount removed of the top of the block. so externally a cooper s motor is simply a 'block height' until the crank and rods are fitted. as a result all the other bits and bobs will interchange with no problems.
then the 850/997 is based on the 850 'small block' block with crank/rod changes, though there are early and late 850 blocks with different main bearings and lack of cam bearings on the early ones
then the 998/1100 is based on the 1000 'small block', again with a crank stoke to alter them
i think that clears it up..........
guru_1071 said:
dino
its easy (ish) all the s motors 970/1071/1275 are the same 'big block' engine....
then the 850/997 is based on the 850 'small block' block with crank/rod changes,..
then the 998/1100 is based on the 1000 'small block',...
i think that clears it up..........
Hi Rich, indeed that's what I'd always understood...but.. no that doesn't help !!its easy (ish) all the s motors 970/1071/1275 are the same 'big block' engine....
then the 850/997 is based on the 850 'small block' block with crank/rod changes,..
then the 998/1100 is based on the 1000 'small block',...
i think that clears it up..........
The issue is oil pump shaft lengths:
I'd always believed that 'small block' motors used short shaft pumps and 'big block' motors used long shaft pumps.
Pete seems to be saying that all 'S' blocks, although 'big block' also use the short shaft pump, .. that's what I was querying?
no
a pump used in a s block (or any 'big block) needs to be longer than the same pump used in a small block.
its a common mistake for people to stick a 850 pump into a s block (due to old cam drives and what not) and have problems with the drive shearing off. sometimes (dependant on the drive) the pump and the cam will 'just' mate so you thing its all ok, then when the timing gear starts to pull the cam back and forth in use it will drop out of drive and thats no oil pressure.
thats why i always advise to upgrade to a modern metro 'spade' drive cam and pump. then its easy, one cam, one pump either long or short nosed.
the trouble with the modern '2 bolt' pumps is that in stuff like old s blocks with 3 or 4 bolt fitting is that you will (or may) need to re drill and tap the block to accept the new pump. if you do this its important to cap the old unused bolt holes with cap head screws (as pete found out....)
as the old pumps go nla (like the cooper s one) is proably best to prep blocks to suit the metro spade pump whilst the engines in bits, as its solves any problems years down the line.
i think that the only time a pump will do both big and small blocks is with an automatic, as the pump is a huge thing.
a pump used in a s block (or any 'big block) needs to be longer than the same pump used in a small block.
its a common mistake for people to stick a 850 pump into a s block (due to old cam drives and what not) and have problems with the drive shearing off. sometimes (dependant on the drive) the pump and the cam will 'just' mate so you thing its all ok, then when the timing gear starts to pull the cam back and forth in use it will drop out of drive and thats no oil pressure.
thats why i always advise to upgrade to a modern metro 'spade' drive cam and pump. then its easy, one cam, one pump either long or short nosed.
the trouble with the modern '2 bolt' pumps is that in stuff like old s blocks with 3 or 4 bolt fitting is that you will (or may) need to re drill and tap the block to accept the new pump. if you do this its important to cap the old unused bolt holes with cap head screws (as pete found out....)
as the old pumps go nla (like the cooper s one) is proably best to prep blocks to suit the metro spade pump whilst the engines in bits, as its solves any problems years down the line.
i think that the only time a pump will do both big and small blocks is with an automatic, as the pump is a huge thing.
The golden rule is to measure the cam position, and th4e length of pump shaft engagement before finally fitting.
If you use a pin drive and a short shaft where a long one is needed, as Rich says, you may think it has engaged, but start it up when it's really cold and with 20-50 oil and it's easy to shear the end of the pump shaft off if you have a hot cam and have to rev it a bit to keep it running from cold. "Been there, seen it, done it!"
If you use a pin drive and a short shaft where a long one is needed, as Rich says, you may think it has engaged, but start it up when it's really cold and with 20-50 oil and it's easy to shear the end of the pump shaft off if you have a hot cam and have to rev it a bit to keep it running from cold. "Been there, seen it, done it!"
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