Correction: Sintering does not actually melt the metal--in this case
iron--but uses heat and compression to form shapes.
On 12/30/2019 7:58 PM, Bob Spidell wrote:
> [If this is a double-post please disregard, my mail server is acting
> weird]
>
> Well, this is distressing. Using the Torrington thrust bearing would
> spare the thrust plate, but you'd still get the wear on the gears and
> stretched timing chain, no? Given this, and the alleged problems with
> their 'constant clearance worm' steering box I'm beginning to wonder
> what's up with DWM/R. They race, they have fancy new CNC machines and
> appear to be profitable; why would they be offering (possibly)
> defective parts (and advice)?
>
> My dad and I rebuilt my BJ8's engine at about 80K miles; I bought most
> of the parts from Sports&Classics in CT--they still around?--and I
> bought whatever pump they were selling. I always assumed since it was
> for a BJ8 it was the gear type, but when I rebuilt the engine again a
> couple years ago I disassembled the pump; it was the vane type! I had
> some wear on the pump driveshaft, but it held up for 120K miles, and
> I'll likely not put more than a few thousand on the new engine/pump in
> my remaining years. I'm also re-thinking my use of 20W-50 oil (but I
> have 3 dozen qts. so ...).
>
> I know of a problem with aircraft engine oil pumps with 'sintered'
> gears; I believe this is a method of producing the gears by basically
> melting iron powder in a mold, anybody know if the gear-type Healey
> pumps use sintered gears?
>
> On 12/30/2019 5:47 PM, richard mayor wrote:
>>
>>
>> 100/6 rotor style oil pumps were an engineering disaster. While the
>> design itself is OK, the large physical size of the rotors in the
>> pump creates a lot of resistance and stress in other engine
>> components. It puts great pressure and increased wear on the oil pump
>> driveshaft gear and the camshaft great. This back pressure also
>> results in the camshaft being driven forward more forcefully into the
>> camshaft thrust plate. It also stretches the timing chain.
>>
>> As this problem became apparent, Austin modified the camshaft thrust
>> plate with the addition of a circular oil groove. When that was not
>> sufficient they changed the thrust plate to a bronze type of material
>> with a circular oil groove. Eventually they replaced the rotor style
>> pump with the gear style.
>>
>> I the photo I have attached, the plate on the left is the stock steel
>> thrust plate. The middle plate is a late 100/6 bronze style thrust
>> plate. The thrust plate on the right is the result of using a Denis
>> Welch 100/6 "high volume" oil pump. The cam has ground itself into
>> that thrust plate about 1/8th inch.  Look closely at the oil pump
>> driveshaft in the photo and you will see that the gears have been
>> sheared off. The gears on a very expensive Denis Welsh camshaft are
>> also sheared off.
>>
>> Calling a 100/6 oil pump a "high volume" pump is like calling a
>> prostitute a "social worker". They both do the job but the
>> consequences can be tragic.
>>
>> My advice: Do not use a 100/6 oil pump. The gear style pumps are
>> more than adequate. And, don't believe everything you read in the
>> Denis Welch catalogue.
>>
>> If you insist on using the 100/6 oil pump then you should get the
>> Torrington bearing camshaft thrust plate from Denis Welch as well.
>>
>>
>
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