Wet Sumping Problems

We frequently get asked the question about wet sumping.

We DO NOT recommend fitting any such non return valves on the feed side of the pump as gear pumps are not designed to suck with no oil in the body. This can result in instant engine failure.

The non return valve (A10) sits inside the crankcase (inside this casing the spring and the ball gets dirty with old oil deposits and stops working to the best of its ability and is impossible to reach without a complete strip down of the engine. This is not an issue on the Needle Roller Conversion or the A65 model because the ball and spring sits outside the crankcase and up against the pump.)

We have discovered that when the pumps are worn, oil can either leak past the oil pump drive spindle, or through the scored internal body of the pump and into the return line, or simply a distorted pump body. Later A65 pumps were better because the drive spindle is fitted with an “o” ring inside the driveshaft of the pump. Our new pumps also have this fitted. Due to the inherent design, the problem cannot be eliminated entirely but by fitting our new pump this wet sumping problem can be restricted.
Here at SRM, being a team of dedicated enthusiasts, we have an ongoing commitment to all our customers to get the very best from their BSA’s. Due to the general poor quality of parts available on the market, we like to be able to be in control of our own products by manufacturing them to strict controls with in house testing of all our products. Our latest batch of pumps and special products are no exception, going through a vigorous testing procedure before we bring them to the market.

 

Note the efficiency of the SRM Pump and how it outperforms the BSA pump in all areas, especially at low RPM.
(The SRM pump did not fall to Zero Psi during testing)

SRM
Drop Test 180 - 240 secs from 55Psi toZero
 
 
 
 
 
 
Pump RPM
Measured Volume open flow
Time in sec
cc/min
Measured volume @ 60Psi
Time in sec
cc/min @60Psi
efficiency
104
500
330
90.91
500
390
76.92
84.6%
203
500
177
169.49
500
186
161.29
95.2%
300
500
123
243.90
500
130
230.77
94.6%
400
1000
183
327.87
1000
188
319.15
97.3%
501
1000
144
416.67
1000
148
405.41
97.3%
1005
1000
72
833.33
1000
73
821.92
98.6%
2009
1000
36
1666.7
1000
37
1643.84
98.6%

 Note the low volume and the low efficiency of the BSA item
(this was a good high delivery pump) 

BSA
Drop Test 15 secs from 55Psi to Zero
 
 
 
 
 
 
Pump RPM
Measured Volume open flow
Time in sec
cc/min
volume @ 60Psi
Time in sec
cc/min @60Psi
efficiency
99
550
429
76.92
500
680
44.12
57.4%
205
500
195
153.85
500
249
120.48
78.3%
300
500
135
222.22
500
154
194.81
87.7%
402
1000
202
297.03
1000
230
260.87
87.8%
500
1000
164
365.85
1000
180
333.33
91.1%
1000
1000
82
731.71
1000
87
689.66
94.3%
2000
1000
42
1428.6
1000
43
1395.35
97.7%

 

All tests were performed Using 20WT oil at 21o Centegrade
NB. (Engine rpm= 6000, Pump rpm =2000)
3:1