mk1 square four . oil issues

[GuyWalton]

I'm going to use an additive . This one , https://www.amazon.co.uk/Competition-Ca ... =158370502 , Ive only had the bike started twice since I put the castrol 30 in so I will add the recommended amount and see how it goes .

[john.bebb]

Hi Peoples,
Why ruin a rebuild by initially running with unsuitable lubricant? - you do NOT require any of the modern oils with "super slippery substances" - the motor will NOT bed in with these!!! - similarly do not assemble new parts with the "marvels of molybdenum disulphide" (Molyslip etc.) as such will prevent the grind-off of surface inperrfections... there's loads of SAE 30 "running-in" oils on the market -"Millers" is one such...
You gotta have some friction to remove the sticktion - else the motor will NEVER bed in properly to give a sane lifetime's service.

[GuyWalton]

Hi Peoples,
Why ruin a rebuild by initially running with unsuitable lubricant? - you do NOT require any of the modern oils with "super slippery substances" - the motor will NOT bed in with these!!! - similarly do not assemble new parts with the "marvels of molybdenum disulphide" (Molyslip etc.) as such will prevent the grind-off of surface inperrfections... there's loads of SAE 30 "running-in" oils on the market -"Millers" is one such...
You gotta have some friction to remove the sticktion - else the motor will NEVER bed in properly to give a sane lifetime's service.

Done it bought it off amazon . millers sae 30 running in oil .

[Simon.Gardiner]

Grinding off surface imperfections?
Surely only necessary if you've found someone using 50-year old machinery to 50-year old tolerances?
I'd hope that anyone doing my machining was using modern equipment that could produce better finishes, to better tolerances...and accordingly I wouldn't need to run the engine with grinding-paste to make things bed in!!

SG

[john.bebb]

Agreed - IF and ONLY IF ALL parts are machined to modern tolerances - but take a look at any cylinder liner that has just been rebored!
On the simple principle that you can't fit a 1" dia rod into a 1" dia hole - the microgrooves // cross hatching // diamond scoring - call it what you like... are there to be WORN smooth - which will not happen with the super-slippy stuff..

[john.bebb]

Hey Peoples; - plz - who stated that the the small bore feed should be to the rockers & the larger bore feed to the pressure gauge?
... as far as I'm concerned such a suggestion is absolute insanity! - possibly Draganfly - to increase the sale of camshafts?
It's absolute lunacy and against most principles of physics & sensible, rational engineering practices.
I've no idea how old my pipework fitment is - but the (shorter) large bore pipe feeds the rockers
and the (longer) small bore pipe routes up through the tank "hole" to the oil gauge
The mere length of the pipes (+ common sense, + understandingd of physics & engineering) determines that this is how it should be!
... if it smokes - it ain't been properly run in or it has suffered internal damage because it ain't been properly run in,
... or it weren't built properly in the first place!

[simon.holyfield]

John, clearly the larger bore pipe will flow more oil for a given pressure drop, but that is just the problem. The rockers need enough oil, but it's the mains and big ends that need oil under pressure to maintain their oil film under load.

Using the smaller pipe to feed the rockers allows the oil pressure at the mains to remain higher, because the smaller line flows enough oil while creating a 'back pressure' at the bottom end.

I researched this long and hard amongst the technical gurus on this forum before I changed mine.

[john.bebb]

Hi Simon,
Thank you for your message -
Reference https://www.draganfly.co.uk/ariel/4-str ... nd-1949-51
I've since enquired of Drags as to "which goes where"... (transcript attached).
The response was "non-commital" wrt bore size but referenced the pipes by their length; -
Drags stated that the LONGER pipe (which in the pic-photo of 5172-49 is the larger bore) goes to the tank (i.e. the pressure gauge)...
... but look closely at the exploded drawing of the motor,
... note the difference in appearance of the two unions,
... compare same with the pic-photo,
... now which is correct???

[john.bebb]

Hi Folks, Oil pipe sizes; - rockers & pressure guage on a Mk1
I am well aware there is contention here - so I checked it out with Bruce Longman (probably the most knowledgeable gent wrt Squares)
It is DEFINATELY the Large bore to Rockers & the Small bore to the Pressure guage!
(Apparently the 4G which preceeded the Mk1 such may not be the case, but the 4G had different pipework).
It matters not what "research" one might have done on the web... nor which "scientist / physicist / enginer" one may have consulted...
For a Mk1: - ROCKERS = LARGE BORE & Pressure guage = small bore
If on a Mk1 you reverse these in order to prevent "over oiling" you are effectively patching over a problem without identifying the source...
much to the detriment of the rockers, the cam & followers... do so at your own expense!!!
Ask youself this question; - is it more important to you that the oil pressure guage should be reading what you THINK it ought to say
or would you prefer to assume that your engine internals are receiving adequate lubrication???

[GuyWalton]

Hi Folks, Oil pipe sizes; - rockers & pressure guage on a Mk1
I am well aware there is contention here - so I checked it out with Bruce Longman (probably the most knowledgeable gent wrt Squares)
It is DEFINATELY the Large bore to Rockers & the Small bore to the Pressure guage!
(Apparently the 4G which preceeded the Mk1 such may not be the case, but the 4G had different pipework).
It matters not what "research" one might have done on the web... nor which "scientist / physicist / enginer" one may have consulted...
For a Mk1: - ROCKERS = LARGE BORE & Pressure guage = small bore
If on a Mk1 you reverse these in order to prevent "over oiling" you are effectively patching over a problem without identifying the source...
much to the detriment of the rockers, the cam & followers... do so at your own expense!!!
Ask youself this question; - is it more important to you that the oil pressure guage should be reading what you THINK it ought to say
or would you prefer to assume that your engine internals are receiving adequate lubrication???

I have a new rotary oil pump fitted to my 51 square four and since I have swapped the pipes to the smaller one to the rockers i now have 30 to 40 pressure on my gauge when hot . With the extra pressure there seems to be more oil into the rocker covers than when i had the bigger pipe running only 10 on the gauge when hot . So you makes your choice . Im happy with mine .