SRM Engineering

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.

 

 

                      (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%

 

 

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%

 

 

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