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Re: OPRV Leak Test [Re: DMadigan] #720075
12/26/17 11:21 pm
12/26/17 11:21 pm
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OK David i remember the previous thread. I think the mod you are doing there is great but the case half will have to be machined to get the seal to seat at the bottom,
you may get away with it on some motors but others will need the attention of a mill or at least a mill cutter. Just blanking the gallery is much easier and guarantees it works.
You have 60 years of catching up and redesign to do if you want to turn an A65 into a racing engine, you already know that i know.
Start with a Weslake/Nourish at least it was designed along racing lines.


Thanks for the explanation Kommando and Allan, i have read similar descriptions on sites like Penrite, Shell, Valvoline etc. and yes they all say it's the mutt's nuts.
None of the oil companies however will guarantee any greater longevity from an engine due to their oils, this is what creates my scepticism.
Any oil run past it's destruction level will be crap, i realise that but as most cars for a long while have had a 12000 mile change interval and many do not specify
synthetic oil, surely an SG oil will last 5000 miles at least. As Andy stated these engines are not producing huge power why would they need a fancy oil.

Plus with engines like these old things there are so many areas that would need improving before the quality of the lubricant will have any great effect anyway.

I think the Jaguar XE now list's a 24 month 34,000KM service interval on their 2.0L diesel so maybe the oil they use is even better?

Please don't take this the wrong way, i'm just saying it as i see it. When i strip one of my engines down and can categorically see evidence of wear or damage due
to poor or insufficient lubricant, i will change my approach and try a synthetic oil. As i have said before i expect 30,000 miles from one of these engines before rebuild,
if synthetics will give me 50,000 i may change, but i can't see how any oil alone will do that.



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Re: OPRV Leak Test [Re: DMadigan] #720077
12/26/17 11:30 pm
12/26/17 11:30 pm
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Before I went synthetic on the Commando the sump bolt magnet was furred up every oil change at 2000 miles and oil filter fitted, once I went to synthetic oil the furring disappeared even with oil changes out to 3000 miles.

Re: OPRV Leak Test [Re: DMadigan] #720083
12/27/17 12:19 am
12/27/17 12:19 am
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That's a positive review, thanks for that. It's the first one i've ever heard.(with the exception of John Healy's comment on synthetics with Vincent valve gear, as i don't ride a vinney i wrote that off.)
Do you think the furring is from ring/bore wear? Will it influence your decision to extend rebuild time?

When i raced which is more of a test on higher performance lubricants, i used R. I really must admit though, i never noticed any difference from the Woolworths 20-50SF i used
here up until R became readily/sponsor available. The woolworths stuff was at that time produced by Mobil. Oh, the smell was much better with R!



Re: OPRV Leak Test [Re: DMadigan] #720113
12/27/17 8:08 am
12/27/17 8:08 am
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Do you think the furring is from ring/bore wear?

Yes mainly plus cams, cam followers, cam chain etc but will not know until I ever open the engine up


Will it influence your decision to extend rebuild time?

This bike is unrestored, only engine work has been new rings fitted to cure blue smoke driveside on acceleration. One day I will strip and restore but not until the Combat is ready and that is a long way away unless something happens.

Re: OPRV Leak Test [Re: DMadigan] #720117
12/27/17 9:22 am
12/27/17 9:22 am
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No oil manufacturer will guarantee that it will prolong the lie of an engine, there will always be some [censored] who will thrash his Subaru till it blows up and then blame the oil company... being the big nasty corporation compared to a small guy.. the small guy might possibly win, so not worth it.

I’m a strong believer of when I ran my motor dry of oil in Italy that if it wasn’t for the quality of oil that I used at the time, the big end would have required a lot more work than a polish and nitiriding.

I too rarely check my sump plate/plug now for filings as there is never anything in there.

It might be worth adding that regardless of the viscosity, it will fail at the same temperature. So changing to a greater viscosity oil to suit a hotter temperature isn’t the best way to go, although using a 50wt instead of a multi grade will probably be better as there are no viscosty improving additives to break down. This doesn’t mean the oil won’t eventually fail if worked outside its temperature limit. Probably why SRM only guarantee their engines if used to monograde 40wt oil (least they used to)


beerchug
Re: OPRV Leak Test [Re: DMadigan] #720122
12/27/17 10:39 am
12/27/17 10:39 am
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Proper full synthetics revert to the original viscosity once the viscosity modifiers are used up, that is the highest viscosity so a 20/50 reverts to a 50, dino oils revert to the lowest viscosity eg a 20/50 goes to a 20 which was its original viscosity.

Re: OPRV Leak Test [Re: kommando] #720124
12/27/17 10:58 am
12/27/17 10:58 am
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All this concurs with something I learned years ago , in relation to " dino " oil. Basically, as has been said, a multigrade will shear down to its lowest rating before a monograde will shear at all ! This is why here in Oz, I use a 25/50 multigrade,in my Triumphs, and take care to warm up in cold weather. I always believed in the benefit of a multigrade for plain bearings ( bigends in the case of my Triumphs ). I use a 50 monograde in my 1932 Matchless, though.
But, with the weight ( pun intended ) of pros for synthetics, I'm having a real rethink here. Although the 25/50 I'm using in my Triumphs ( Castrol Edge ) is now, apparently, semi synthetic !

Re: OPRV Leak Test [Re: DMadigan] #720125
12/27/17 11:05 am
12/27/17 11:05 am
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I refuse to use any Castrol oil, Mobil took them to court as they were incorrectly referring to some of their oils as synthetics when they were not. Sadly Mobil lost and Castrol won.

http://www.1st-in-synthetics.com/a_defining_moment_for_synthetics.htm

So now you have to look for a Group 4 POA synthetic oil to ensure it really is synthetic.

Re: OPRV Leak Test [Re: DMadigan] #720129
12/27/17 1:43 pm
12/27/17 1:43 pm
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Perhaps one way to fix the leakage past the first three threads would be to use a low strength thread locker such as Loctite 222. You would need to apply directly onto the inner threads in the oil gallery avoiding the outer threads. When the OPRV is screwed in, assuming the threads are aligned, a seal should form preventing leakage.


1968 A65 Firebird
1967 B44 Shooting Star
1972 Norton Commando
Re: OPRV Leak Test [Re: gunner] #720132
12/27/17 2:32 pm
12/27/17 2:32 pm
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Your trick suggestion has been propounded here before by Rich B. I had been doing it carefully (only the faintest smidge of Permatex on the relevant part of the OPRV housing, but found on a disassembly done over the last week that it can set quite hard, so that discouraged me). Thinking about this, it's unlikely to be blown into the feed side of the equation though. An anaerobic sealant along the lines of your suggestion would be the trick I think. I suspect one of the previous respondents might suggest a suitable Loctite product (515 or 518?).

I'm very interested to see this data. I reassembled the oil feed system with no thread sealant on the relevant part of the OPRV cavity this time for the first time. On start up oil pressure came quickly up to a stable 50psi at slightly above idle (cold). I now feel I want to check the pressure hot as that check was only to see if the oil system had primed correctly. End-feed crank of course.

I dont think there is any shortage of oiling in my engine as I see a lot of evidence of the effectiveness of the drain holes in the oil ring groove and lots of 'cooked' oil inside the cases. The latter was the factor that pushed my decision for synthetic oil, even though I previously changed my dino oil frequently. The engine in question did 35000 miles on a nitrided crank that was still in spec with no detectable 'feel' of looseness for the big ends and the shells could have been re-used but were replaced.

This time round I've now run full synthetic oil for the first time. I always ran synthetic in my race H**** as Ray Easson (drag bike guy in Perth, W.A.) who did some of the engine prep said in his experience synthetics reduced wear in the race engines he was involved with. Of course there is no double blind trial and any evidence is subjective.


Cheers
Ray


BSA 1969 A65F
BSA 1966 A65H
Triumph 1968 T120
Kawasaki A1R
& too many projects!
Re: OPRV Leak Test [Re: Allan Gill] #720190
12/27/17 11:38 pm
12/27/17 11:38 pm
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Originally Posted by Allan Gill
No oil manufacturer will guarantee that it will prolong the lie of an engine, there will always be some [censored] who will thrash his Subaru till it blows up and then blame the oil company... being the big nasty corporation compared to a small guy.. the small guy might possibly win, so not worth it.

I’m a strong believer of when I ran my motor dry of oil in Italy that if it wasn’t for the quality of oil that I used at the time, the big end would have required a lot more work than a polish and nitiriding.

I too rarely check my sump plate/plug now for filings as there is never anything in there.

It might be worth adding that regardless of the viscosity, it will fail at the same temperature. So changing to a greater viscosity oil to suit a hotter temperature isn’t the best way to go, although using a 50wt instead of a multi grade will probably be better as there are no viscosty improving additives to break down. This doesn’t mean the oil won’t eventually fail if worked outside its temperature limit. Probably why SRM only guarantee their engines if used to monograde 40wt oil (least they used to)


I understand you are a strong believer in your synthetic oil but without carrying out a similar exercise with a mineral oil, there is no real case.
I have seen several A65 engines with failed DS rods and little crank damage, even a rod out of the case only requiring a -0.010 grind. It's the luck of the draw how it will fail nitrided or not.
The main reason SRM specified monograde oils was to stop people using synthetics and heavily friction modified oils with new motors. The bloody things don't bed in.
I must admit i have never checked my sump plate, i'm a lazy sod and i put the engine together so that give's me a little confidence as i've done a few. I'll do it today and post the result.
I totally agree with the viscosity statement, i see blokes using 40-70 oils in these bikes with a 26-28cst weight at 100C AND 250+ at 40C flow would be about a litre an hour! (joke)
Oil is a much a coolant as a lube in these old heaps, flow is essential.
Kommando will probably remember the test Glacier did with STP and a few other additives in the 60's. 3 cans were sufficient to actually block off the oil feeds to some overhead cam engines. It would achieve it's end by
actually coating the oil galleries thereby increasing pressure. Unfortunately the galleries feeding the cams on some engines were very small so yes, lots of pressure but no flow!

I hear all the explanations of the benefits of ester based oils but only kommando has listed a positive actual result/comparison.
Ray, if you were getting evidence of oil burning onto surfaces in the cases, the oil you were using was crap or the motor was overheating. A lot of residue on the pistons says the same.
With an end fed motor and an iron pump (or a good late one) the relief valve will spend most of it's time open if the ends are in good nick so loads of oil will be relieved.
Just returning it to the tank is a bloody waste of effort by the pump.
I used to use a sealant on the oprv inner threads on rebuilds as it does help especially on the older engines, for my own use now, i pipe externally.
In my cynical way i suspect that most of you blokes change the oil so often that you could be using fish and chip oil and would notice no difference anyway!



Dave Madigan will probably be a bit pi**ed that this thread has been degraded by this pommie idiot so maybe we should call it a day.

Sorry Dave please continue the thread with your findings etc.



Re: OPRV Leak Test [Re: DMadigan] #720270
12/28/17 6:13 pm
12/28/17 6:13 pm
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There’s enough pommie idiots degrading this so don’t feel like your alone out there. Haha joke! Your certainly no fool.

You do however have a point, i have only damaged the motor once, and that was when it had a smere of semi synthetic on the shells... as you can imagine I don’t fancy repeating the exercise.

Another thing worth noting is that when I did use Dino oil I found after 3000 miles a soft sludge in the trap about a 1/4 full but not compacted either (I’ve seen some traps look like they are half full of cake) I did some work to the engine, ran it in again and post run in I switched to semi synthetic. After about 3000 miles I changed the cam and checked the trap again... it was still spotless, when I starved it of oil I checked again and still spotless. So it gives me a lot of confidence in the oil I am using and the length of time I may need to go before rebuild.

As for the leaking past the oprv. I run mine with an anealed copper washer under the head, I’ve never had a leak issue. The factory piston oprv units used something like a locktite under the acorn nut threads. When I bought my nos unit I stripped and checked it first, cleaned the threads as the sealer had crumbled away and used an RTV sealant instead.

Nick, thankyou for using cts, a unit I understand and work to.


beerchug
Re: OPRV Leak Test [Re: DMadigan] #720276
12/28/17 6:39 pm
12/28/17 6:39 pm
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Kommando will probably remember the test Glacier did with STP and a few other additives in the 60's.

Not there at the time but they would have also checked Slick 50 in the test as they had lead PTFE bushes known as DU which they had invented in the 50's so they knew its properties .

Re: OPRV Leak Test [Re: DMadigan] #720305
12/28/17 10:39 pm
12/28/17 10:39 pm
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This is not really relevant to what the OP is addressing here, but it is similar, so I will briefly weigh in. I have roadraced the same Triumph T140 for about 25 years, and have done a fair amount of development of the oiling system to get it to live, and to avoid a long tale of problems, I will just kind of narrate where I have ended up. First, over the last 50 years I have raced other Triumphs in dirt track and motocross, and the stock oiling system worked well enough that I left it alone, but not true for road racing. Perhaps modifying the oiling system for a road bike is in the "perfecting something that is more or less ok" category, but if you ride hard (road speed, revs, high air temperature, long mileages) perhaps that is not the case. Anyway, on with what I discovered over the last 25 years.

As a base case, ever since I built this bike, I always have used Mobil 1, and a Norton oil filter in the return line.

First, using Mobil 15-50, I had oil pressure, oil temperature and windage/ring seal/leakage problems. I added a triple oil cooler, and a Morgo rotary oil pump, and since I was using a belt primary drive, I vented the crankcase through a standard T140 vent fitting I welded on the timing case over the end of the exhaust camshaft. That worked on a hot track, on a hot day, to solve a lot of the problems I had but I introduced some new ones.

In particular, the pump provided very good volume and pressure, but it did create some new problems I had to solve.

I encountered problems in the early morning practices on cold race days with turning the oil seal on the crank end inside out from overpressuring, with the cold pressure up around 90 psi. Eventually I figured out I could not warm the engine up enough at, say, Savannah in February and 40 degrees, using the Morgo high flow pump, 15-50 oil, and the very large triple oil cooler, so I kept the high volume oil pump but substituted a much smaller oil cooler that had a thermostat built into it, and I started using Mobil 1 10-30, still with good 65-75 psi pressure hot at high rpm, much less pressure cold starts, and the seal problem was solved. (Pioneer seals, of course.)

Also, I encountered big time oil pump priming issues with the Morgo rotary pump until I figured out it needed to be bled, and bled, and bled, by rotating the rear wheel in 5th gear, with the timing cover off and the spark plugs out, until absolutely no bubbles came out. Much more bleeding than the directions said, is the point here. And to make sure it didn't pick up any air while running and had proper pressure at every startup, I put a liquid filled oil pressure gauge on it in place of the oil presure switch. Any time the supply line is off or empty for whatever reason, I have to bleed the pump.

To solve the windage and heat problems, I wanted to get the oil out of the engine, so I also welded up the relief hole into the crankcase for the relief valve, and instead drilled a new hole the same distance in, but aimed to the bottom, and welded on a bung on the bottom of the valve body on the crankcase, and returned the relief oil directly to the tank with a new oil line. The hole is double the area of the stock holes to make sure it does not constrict flow. As I have blown this thing up and replaced crankcases, I have experimented with the hole venting into the timing case, and have now left it alone.

That brought to light the leakage problem around the threads of the valve that is discussed above--there were only 2 or 3 threads on the inside of the relief hole in the case at the lead end of the pressure relief valve, so I did what someone above mentioned--carefully put Yamabond 3 on the inside of the hole each time the valve is out, problem solved. Oil now flowed through the valve first, then to the relief hold and line, and not up the threads and directly to the relief hole avoiding the pressure relief. I still do this, and although pretty subtle, it was an important discovery in maintaining oil pressure at high heat and rpm.

And, you cannot have oil filter problems if you don't have a filter, so when the chromoly bracket I welded up failed, I finally took it off, and so I have no filter these days.

So, Morgo rotary pump to create modern levels of flow and pressure, modern oil weight-10/30 synthetic Mobil 1, Pioneer seal, small oil cooler with thermostat, external oil return for relief valve, oil pressure gauge, and putting Yamabond 3 on the threads of the valve orifice inside the relief hole. All seems simple, except it took me a couple decades to figure all this out.

I know other Triumph roadracers and tuners have done it differently, with external oil feeds, filters in the feed side, etc., but this is what worked for me. Here's a couple pics--not much shows on the outside, but for what it is worth.

[Linked Image]

[Linked Image]

Re: OPRV Leak Test [Re: DMadigan] #720307
12/28/17 10:53 pm
12/28/17 10:53 pm
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I was comparing the leak area of the main bearing with the OPRV to show the relative magnitude.
Here is the output of the journal bearing calculations for 0.002" main and 0.002" rod bearing clearances.
[Linked Image]
SAE40 oil at 170F, 1000 RPM producing 4 HP with the ideal pump output the pressure is 10.4 PSI (iterate until pump output and required flow are equal).
If the OPRV has 1/3rd the leakage of the main bearing the pressure would certainly be below the switch pressure.
So the pump does not have 2 times the capacity with clearances that are "supposedly" within specification.
Viscosity does affect pressure which is why thicker oils produce higher pressure with the same clearances.
Forgot to mention, I tried sealing the last three threads inside the OPRV cavity (below the relief holes) with Marstan Hylomar and retested the ball valve. The cavity drained in 30 seconds. Not as good of a seal as the O-ring on the face of the OPRV but better than nothing. Loctite 518 may be better
NickL - no worries, it is all about the exchange of information.

Last edited by DMadigan; 12/28/17 10:58 pm.
Re: OPRV Leak Test [Re: DMadigan] #720316
12/29/17 12:32 am
12/29/17 12:32 am
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Great stuff Dave, you've obviously taken a lot of time and effort to produce this info.

The classic case of the threads leaking is i suspect, more due to owners removing the valve then reinstalling with grit in the threads,
this area on the bike is normally covered in road crap so winding the valve back in with crap either on the valve threads or in the cavity
will chew the threads up nicely! Plus the actual relief drilling on some of the early ones was terrible and less than 3 threads were there
at the bottom. Hylomar was the gear i used on the threads as well, i wanted something that did not go solid. Since i've tried that 518 gear
i tend to think it may be better, it is a very good sealant.

Allan, i would think that as your engine is end fed, you won't get the pressure problems most blokes get as your pump is only supplying
a pair of big ends and for that job alone it's massive, pretty much like the norton. The copper washer under the late type oprv is good
as it is slightly thinner than the fibre type. The later style of the early ball valve had a proper o-ring groove machined in, that was the best way.
When racing on an end fed engine we used R30 and always had 60+ psi above about 2k rpm. In fact keeping it below about 80 as the
revs went up was the issue without external piping.
Interesting about the sludge build up comparison, it may be due to the higher temperature capability of the synthetic not creating the residue.
Maybe a higher detergent mineral oil (diesel type) would be able to keep more of that in suspension and the filter could remove it.

Kommando, The tests at Glacier were done on the proprietary 'oil boosters' at the time by their R+D mob, i don't think ptfe additive stuff was
around at that time. Their findings were very enlightening, the cumulative effect was the interesting one as the additive actually
coated the galleries and remained there for some time. So if a can was added every oil change the coating got thicker etc.
The test cars included 2 x Lotus Cortinas which were blown up a few times by the guys.
This was around the time they did a car up for the London to Sydney rally which was fitted with a centrifugal oil filter. (Bloody long time ago! '68 i think)

I still haven't checked the sump plug, maybe later on...........

Last edited by NickL; 12/29/17 12:35 am.


Re: OPRV Leak Test [Re: DMadigan] #720353
12/29/17 9:40 am
12/29/17 9:40 am
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Originally Posted by Simon
Any leak on a pressure system contributes to pressure loss so it dosen't make sense to compare one leak to another and then ignore two other leaks.


Oil reaching the big ends is important. The oil that leaks in and around the relief valve plunger and threads and through the main bush does not reach the big ends.


Amateur Loctite enthusiast.
Re: OPRV Leak Test [Re: DMadigan] #720409
12/29/17 8:21 pm
12/29/17 8:21 pm
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Unless you look at the equations on the Machinery Handbook for journal bearings, most of the numbers in the spread sheet will be meaningless.
What are these "other two leaks"? The rod bearings? They are included in the second column.
What pressure the OPRV opens is not significant to the problem of leakage past the threads and piston when the engine is idling.
The line labeled "flow required" (0.222) is the sum of the main total flow (0.065) and two rod total flow (2 x 0.079) bearings. The label "pump flow" is the theoretical output of the pump (assuming all the space between the teeth is moved). The total flow is the sum of the hydrodynamic and pressure flows.
To find the system pressure will be for the input conditions the "oil pressure" variable has to be iterated until the required flow equals the pump flow.
With the same bearing inputs except 7000 RPM, 50 HP, 50 PSI, the required flow is 1.522 in^3/s and the theoretical pump flow is 1.566 in^3/s. Not much margin there.
If the HP at 7000 RPM were reduced to 4 HP (say throttle closed to shift) the required flow reduces to 0.959 in^3/s. To keep the oil pressure at 50 PSI the OPRV has to flow 0.606 in^3/s. The drilling to the OPRV on an A65 is 0.205" diameter so the flow is 1.53 ft/s through that drilling. Without the OPRV the oil pressure would go up to 116 PSI.
I do not see where the "hit and miss" comes into it. The "centrif pressure" is the pressure from the main bearing feed to the centre of the crank. The centrifugal pressure of throwing the oil out to the rod journals is much higher and will help pull the oil to the bearing. This is not a Triumph Wheeze-Squirt oil system.
Many engines feed the rod journals through the main bearing. The 911 and VW W12 engines come to mind.

Re: OPRV Leak Test [Re: DMadigan] #720434
12/29/17 11:35 pm
12/29/17 11:35 pm
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The oil feed on an a65 is not working against centrifugal force, the bush is feeding oil to an annular groove cut in the crankshaft journal.
This groove has the receptive gallery hole up into the centre of the crank for the big end feed. Many engines use/have used this system.
The main factor with this arrangement is the supplied oil must be clean. With an end fed engine the oil will pass through the centrifugal
crank filter before supplying any bearings whereas here the bush will be subjected to the contamination before any filter.




Last edited by NickL; 01/04/18 3:06 am.


Re: OPRV Leak Test [Re: DMadigan] #720440
12/30/17 12:47 am
12/30/17 12:47 am
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Reference: Machinery Handbook pages 561-571 (in the 21st edition). These are the equations for designing journal bearings.
A number of these values come from charts that I scanned and put curve fits through so they could be used in the spreadsheet, for example - SAE30, SAE40 and SAE50 oil viscosity as a function of temperature, bearing pressure parameter P' and torque parameter T' which are functions of the eccentricity ratio ε and l/d of the bearing.
The second bit about 7000 RPM at full and idle load is to show that the oil flow to the OPRV is not just proportional to engine speed but also a function of bearing load. The crank seal on a Triumph might just be blowing out from fast unloading of the engine (such as shifting at high RPM) and the OPRV cannot keep up with the sudden increase in flow causing much higher pressure and inverting the seal (sound familiar?). This might be the cause of linker48x's problem.

Re: OPRV Leak Test [Re: DMadigan] #720441
12/30/17 12:58 am
12/30/17 12:58 am
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Mr Richard Head, don't get it wrong, but statements along the lines you have made will get peoples back's up. I should know that, i do it often enough myself.
There are a few blokes here who have done a fair bit of work on and around these motors with huge experience of using them.
Dave's spread sheet is based on calcs etc from the engineers handbook. Have a look at it.
Although it points to ideals a lot of the info is very good. It will help you translate the spreadsheet.
The old 10psi per 1k rpm is the aimed for pressure, many motors, not just the old beezers never achieved that.
One of the largest manufactured engines of the '60's in the uk was the ford 'kent' series that would never achieve that with a standard pump.

Last edited by NickL; 12/30/17 11:31 pm.


Re: OPRV Leak Test [Re: Simon Ratcliff] #720474
12/30/17 11:24 am
12/30/17 11:24 am
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Originally Posted by Simon Ratcliff
You're the second poster to make an unsubstantiated claim regarding content of my posts. Your self and NickL obviously find it stressful reading them so do yourselves a favour and in the future I suggest you don't.



Maaaaate. I'd say substantiated. What I see is you being argumentative for the sake of it. Does it matter if DM hasn't provided any 'recognised' units. I think he's showing you his workings to suggest that he has an idea of what he is talking about. My quick look at that said I'd need to see the formulae in XL sheet (if that's what it was) to make any sense of it. You could always come up with an alternative approach. In my line of work we look for solutions not problems.

If you want to argue with 'theoretical', take the time out to do your measurements. First you better get yourself a BSA for this, generate the real world data, then come back with some constructive suggestions, theories, hypotheses or whatever. I'm a scientist not an engineer, but that's what I do. I can tell you the hot and cold oil pressure because I checked them on my run on my A65 this morning. I can also tell you today I have performed the experiment of sealing the last 3 threads on the OPRV of an A65 and will run the bike tomorrow to check the outcome.

I'm from a technical background but not the automotive or engineering world and I'm learning heaps here in some cases because of some of the discussions. What some consider general knowledge I have no idea about. I'm sure others are learning stuff too, but a constructive approach would be really helpful. If you are playing the devil's advocate instead of being a smart ar#e then say so.


Having looked inside the OPRV cavity today I appreciate that the drain gallery is 'minute' and a potential issue as noted by Nick. Something I didn't consider until I took the time to digest this thread. I second Nick's comments about the value of the collective knowledge here. I'd hate to see that disappear because of toxic posts. I suggest that as an educated individual you take the time to digest the information of value here. As a kid I was told "sit back shut up and you'll learn a lot". Might be better put as " if you dont have anything constructive to say, say nothing"


BSA 1969 A65F
BSA 1966 A65H
Triumph 1968 T120
Kawasaki A1R
& too many projects!
Re: OPRV Leak Test [Re: DMadigan] #720479
12/30/17 11:55 am
12/30/17 11:55 am
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As a user of a piston type valve in another well-known make of 650 twin, I had never considered seepage between piston and bore before.

The ball relief valves in BSAs were replaced by Triumph types as an improvement, but it looks like they brought with them the issue of loss at low rpm.

Ball valves have a safety disadvantage in that the ball can be held open by dirt, allowing serious loss of oil. With full-flow filtration by a real filter between pump and relief valve, that wouldn't be a problem, but there is no real oil filter on an A65 (or a Bonneville).


Amateur Loctite enthusiast.
Re: OPRV Leak Test [Re: DMadigan] #720485
12/30/17 12:59 pm
12/30/17 12:59 pm
Joined: Oct 2012
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Running from demons in WNY
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Originally Posted by DMadigan

Many engines feed the rod journals through the main bearing. The 911 and VW W12 engines come to mind.

Probably 99.9 percent of car/truck engines feed through the mains to the rods. And 99 percent have piston type PRV's....The common Chevy V8 stock oiling system can support 70 HP per cylinder with a 2 inch diameter rod bearing slightly wider than a Triumph using 55 PSI oil pressure. Oil flow on the 8 cylinder engine is 7-9 gallons per minute.... I believe air cooled two valve belt cam drive Ducatis feed the oil into the crank end...They are like a Triumph with the roller/ball crankshaft mains and plain bearing connecting rods because there no other way to feed the oil with this design. Ducati oil pump flow is 2.6 liters per minute at about 3000 rpm......In WW2,the Rolls Royce Merlin aircraft engine was experiencing bearing failure at higher power levels...The best fix was feeding the crankshaft from both ends rather than from the mains...This was likely more to do with oiling system design rather than saying end feed is better ....
I've had oil pressure issues on my dual engine 650 pre unit Triumph LSR racer...The oil pressure was to high when cold, I converted the pre unit timing covers to a rubber lip crank seal.The engines have stock oil pumps and filters on the return lines... I bought a handful of relief springs and OPR valves and messed around with shims until I got about 80 psi..Then a valve might stay closed for no reason so I increased the piston clearance on the PRV..That worked for a time but now one valve is stuck open lowing the oil pressure to about 35 psi...


650 Triumph modified production LSR record holder 133.1 MPH... Twin 650 engine Triumph LSR that goes sorta fast...
Re: OPRV Leak Test [Re: DMadigan] #720489
12/30/17 2:11 pm
12/30/17 2:11 pm
Joined: Oct 2012
Posts: 3,260
Running from demons in WNY
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I have some info on modified vehicle engines that might be reverent here...I used to modify vintage GMC truck inline 6 cylinder engines for "racing". The oil pump pressure was always a problem and changing the OPV spring required removal of the oil pan, very messy time consuming job. So I set up a test rig...oil pump and pick up submerged in oil with a gauge hooked up to the outlet having having an adjustable orfice to simulate oil flow past the bearings..Due to pump design it was easy to use a variable speed corded drill motor to spin the pump...Ok ,so what does this have to due with Triumphs? I found on a pump flowing 7 gallons per minute at 3000 rpm pump speed with 10/30 room temperature oil, a 5/32 inch hole could maintain a maximum 45 PSI compared to about 80 psi with no relief opening....On a Triumph or maybe a BSA, the pump flows about 1-1/2 pints per minute? How big does the bypass hole need to be ?


650 Triumph modified production LSR record holder 133.1 MPH... Twin 650 engine Triumph LSR that goes sorta fast...
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