I did this to mine a few years ago, got it re ground and its still running and frequently exceeds 6000 rpm. The starvation was caused by a broken drill bit in the new Phoenix starter dog partially blocking the hole so check this. Just realised that my Phoenix crank is getting on for 30 yeas old! The discolouration caused by the heat is not as serious as it looks, the failure of the white metal in the shell occurs at around 200-250 degrees C or thereabouts. this is plenty hot enough to burn the oil in the vicinity, thereby 'blueing' the crank by depositing carbon on the steel, rather like blueing a gun barrell, this temp, i imagine, is not in the least bit harmful to the steel. Good Luck. Winston

Location: Worcs.

Yes, I did mine like that maybe 15 years ago. Fixed it and no problems since. Probably over 100 sprints/ races / hillclimbs in that time, so I guess it's well tested.

plenty of good input for you above.

charles, i heard the same rumour about only being able to regrind them once.

but since then with the input i have had with cranks, we had one rockwell! tested and it went of the scale. thraight to 70.

so i would expect the nitride to be preity deep. (if i see you at prescot remind me and i will tell you more on this).

the rumour could be like many things on the forum, a bit of an unprooven chinese wisper.

if you are worried about the structure of the steel changing from the heet, you could always have it rockwell tested again, but as suggested above i dont think it will effect the crank.

tony

Location: back in the warm

I have been involved with other cars which used nitrided cranks, and am aware of some factors, altho not an expert.

The purpose of the nitriding has to be born in mind. On commercial diesels with hard bearings it is primarily for wear life. I presume that with Phoenix cranks the increased fatigue life is the prime reason for use. (The original Austin cranks were of quality HT steel so something must explain the longer life of Phoenix. High wear was not a problem on the 7 or many other makes with wm and an unhardened crank despite no filters.)

The crank temper temp approaches dull red heat so is unlikely to have been met. However heating may have started cracks, as does unskilled grinding of nitrided cranks. If cracks cannot be detected, and the nitrided layer is not to be removed, esp in the radius, reasonable life should still be expected.

Bob Culver

Location: Auckland

Thank you to all the people who have offered advice. Crank is out, and going to specialists Monday to see what they think on grinding. Will update. Many thanks. Tim

Location: Bedfordshire

Obviously you have,or previous owner has had insuficent oil pressure to overcome centrifugal forces etc on no4 journal,you need to find out why,or it could happen again.

No experience of a race engine,but road I wouldn't be happy with less than 50 lbs,better more, at 3000 and above and would fit a filter.
Part of the problem,in my opinion is the starter nut,the holes being too small,and why not drill out through to the end instead of the cross hole?

I tried to get Doug Kiddie to make the counterbalanced cranks with the original bolt on side cheeks,but he didn't,this is why I have a box full of new side cheeks somewhere.

Riley fitted radial copper tubes on the 9 engines,any one know what Bugatti did on the brescia engine?

Frank Hernandez fitted 2 pumps on his race engines,his experience means it may be necessary to avoid big end failure on a high revving engine.

I can't figure out how a splash fed shell bearing supercharged race engine can survive.

About 10psi per thousand revs seems normal.

The Bugatti Brescia apparently had a jet system as the basic Seven.
Whilst this has its limitations, the problem of conserving flow and thus maintaining sufficient pressure to force oil back to the crank axis twice over does not arise.
In the absence of flow losses, pressure in the big end increases as crankpin outside radius from crank axis squared, and rpm squared! At high rpm pressure at the big end is considerable and flow also unless clearances small.

Bob Culver

Location: Auckland

I don't think Yhe Brescia had jet lubrication like the Seven. I always thought the main bearings were pressurised and the spillage from these was used, via grooves in the crank webs to the big end bearings. The con rods were low pressure lubricated, but not in the same way as our cars.

I've always taken the view that with a shell bearing pressure fed engine you should never start the car until you see pressure on the gauge when turning it over on the starter. Priming no 4 seems a good way to protect it. The extra wear on no 4 is normally visible when you strip a worn pressure fed engine and my total unproven theory is that the gradual faster wearing of no4 could be a contributory factor in the path to catastrophic failure.
Last time I stripped my engine no4 was no more worn that the other 3 big ends. Might prove nothing but it gives me some comfort.

Charles

Hi Alan

I have no knowledge of the Brescia other than a sketch in Amhurst Villier's autobiography. This shows a system like the Seven. He added scoop extensions to Raymond May's car and extended max rpm beyond 6,000 at which they had encountered endless trouble.

And Charles, at cranking and starting speeds conditions inside an engine are more analogous a slow speed steam engine or Victorian era engine and just drops of oil as normally remain suffice.

Bob Culver

Location: Auckland

Excuse my naivety,not being familiar with A7 racing engines,but does anyone race an A7 engine with just splash feed,and if so how reliable is it compared to a fully functioning pressure fed system?
Dave.

Location: Sheffield, the home of Henderson\\\'s Relish.

I have raced a splash fed phoenix crank for a number of years now, my car regularly exceeds 6000 rpm with no problems. The camshaft bearings are restricted and fitted with O rings, oil pump capacity increased, jets alignment tweaked and the crank pick ups relieved. Oh yes it also has a full flow oil filter and I replace the oil prior to most major circuit events, I will occasionally run several short hill climbs between oil changes.
Cant give a comparison with pressure feed as I only have experience of that in my road going Nippy!

Location: NZ

Austin and many others early realised that to be "fully functioning" at high rpm a pressure system should not have to pass oil back to and through the low or no absolute pressure zone on the crank axis. Hence, as is generally known, the circumferential hoops on Rileys and others and the competition Sevens. Oil is maintained near the very high centrifugal pressure attained in the big ends at high rpm.

Bob Culver

Location: Auckland

Is it worth the extra complication of pressure feeding a crankshaft if the reliability is worse than a splash fed crank? Or are most pressure fed cranks nearly always reliable and on A7 friends we just get to be informed about the ones that have had problems? (mainly with poor oil supply to no.4 big end)
Just curious in case I ever have the funds to build a decent engine.
Dave.

Location: Sheffield, the home of Henderson\\\\\\\'s Relish.

I remember a conversation with Tim Myall when he was still actively racing, he was very much of the opinion that pressure feeding was not worth the trouble. However there are also other very successful racers who disagree with this, I can only say splash feed has worked for me. I have been very interested to hear about the recent developments with splash fed supercharged engines, it would be good to hear from someone with a couple of seasons experience in this area.

Location: NZ

Hi Alan

I am often astonished and dismayed by the tenor of many responses on this Forum.
I did state that the Brescia "apparently" has a system like the Seven.

On page 102 of "The Man Who Supercharged Bond" the autobiography of Amherst Villiers, is a sketch labelled "How Amhersts rat traps overcame the problems of Bugattis spit and hope lubrication at high revs."(attributed to the Bugatti Trust.) Villiers and Mays were noted for their success with a Brescia in the early 1920s. Maybe Amherst's memory failed him and the ancient sketch applied to something else.

The arrangement is as per the standard Seven with a jet, or, as I learned thru this Forum, actually more like the Phoenix. Scoop extensions were added.

All sources are suspect not least this Forum, but one has to accept some things. If this Forum was limited to facts proven absolutely beyond all doubt it would shrink to about 1% of its size. It seemed to me that the apparent similarity of the unusual Seven lubrication system to that of a Brescia is probably of as much interest to the more curious viewers of the Forum than 50% of the posts. The solution to a lubrication problem seemed quite pertinent to the current discussion. As I have asked before related to other topics, would it have been better not to mention at all?

Bob Culver

Location: Auckland

This note from "Grand Prix Engines" talks about the Bugatti lubrication system.

"Although relating to a non-Grand Prix pure sprint engine, (446) gives an interesting account of how in 1923 a customer specification “Brescia” IL4 1.5 L Bugatti with white metal bearings lubricated by a “Squirt and hope” system were made to stand an MPS of 20 m/s for a very short life by fitting oil pickup scoops on the crank webs, a modification designed by Amherst Villiers."

Marcus

Location: Auckland NZ

"All sources are suspect not least this Forum, but one has to accept some things. If this Forum was limited to facts proven absolutely beyond all doubt it would shrink to about 1% of its size."

I like to think that most posters on this forum usually offer very sound advice on all things Austin Seven - other vehicles are usually of much less interest on the 'Austin Seven Friends Forum'

Tony.

Location: Malvern, Melbourne, Australia

Thanks Marcus

And Tony, as about the only other car so far identified as using the jet lubrication system, the Brescia and its lubrication modification seems at least as relevant to this Forum as much else which appears. If not interested in that, what are users interested in? Just mystery clonks?

For the champions of jet lubrication, and others following the discussion but perhaps not familiar with the MPS 20 m/s, this refers to Mean Piston Speed, about 3900 ft per minute.

MPS was often used as an indicator of general stress level in an engine, and bearings in particular. It is a vague common comparitive measure applicable to widely different engines. In the day of white metal bearings 2500 fpm was considered high!

With a 100mm stroke Brescia engine, the attainment of 6900 rpm after scoop modification, as claimed by Villiers, represents a considerably greater technical achievement than would the same rpm with a 3" stroke Seven, with 3/4 the piston speed.

Bob Culver

Location: Auckland

I might be being thick here, but how is piston speed relevant to what happens in a big end bearing? I'd have thought it had more to do with speed of rotation and bearing diameter.

hi Alan

For those curious and who do not already know....

Mean piston speed is a very flawed indicator of general stress but it was nevertheless widely quoted both for cars and aircraft.

The inertia loadings, related to both stroke and rpm, which piston speed vaguely accommodates, are the ultimate limiting factors to engine performance. The general increase over the decades in what was considered a reasonable upper limit of piston speed closely followed improvements in bearing materials. Old texts (ie early Ricardo) were concerned with bearing rubbing speed but with modern materials and high pressure lubrication, this is now largely ignored and just the pressure handling ability of the material is considered. Hence the small diameters and the length of vintage bearings and the large diameter of modern bearings.

An example of very high piston speed at an early date was the freak V2 racing Peugeot voiturettes of 1911 or so, contrived to cheat the RAC rating. Some were 80x280mm. A Sizaire Naudin single, 100x250 achieved 3900 fpm.
High piston speeds were also attained in the Merlin etc.

The Seven, with 3" stroke, is wondrous easy to calculate; 2000 fpm at 4000 rpm, about 55 mph for lwb cars.

The limitation of piston speed as a relative measure is well recognised and the term has dropped out of use.

Bob Culver

Location: Auckland

But that doesn't answer my question. A hydrostatically lubricated bearing, which this is, creates pressure of a consequence of the rotation between the outer and the inner. I agree the inertia loading caused by piston acceleration will cause a fluctuating load on the bearing, but that isn't relevant to this discussion.

Hi Alan

I did not devise the measure!

Inertia loadings inrease stress on all components and the pressures in the bearings. There are limits to how massive conrods etc can be and limits to the load carrying abilty of bearing materials(and the frictional losses at high piston speed). The ability of an oil film to support the pressures is not usually the limiting factor. Some engines do not employ sliding bearings but similar piston speed limitations were considered to apply.

We are getting a long way from a damaged crank, but the link is not as tenuous as some may think! The recognised top piston speed of the day assumed current best practice and an oil feed with a centrifuged void in the middle would not have been in that category!

Bob Culver

Location: Auckland

Thinking a bit about full flow oil filters (feeding pressure-fed cranks):

1. How much does a full flow oil filter impair flow?

2. Any particular make or size of filter better than another?

3. Is it a false economy to use cheap oil filters in our type of engines?

2. How low a viscosity oil should we choose to counteract filter resistance in a highly stressed engine?

Collective wisdom appreciated!

Thanks,
Damian.

Hi Damian I use 5w50 fully synthetic oil in my blown splash feed engine with full flow oil filter. As recommended by Alex Mayal at pigsty racing.
Regards Ian.

Location: Work(sheffield)

Thanks Ian - that's really helpful. I am currently using Synthetic 10w40 and a standard screw-on filter, which seems to work well, but the other day at Prescott my oil pressure dropped significantly and it got me thinking as to how critical the filter might be to ensuring adequate flow to the fourth journal.

I've never measured pressure drop across an oil filter but I'd guess it's not a lot because if you take a pipe off downhill of the filter the oil comes out at a hell of a rate.
One thing about oil filters in race engines is that it's worth finding a filter that doesn't have a bypass valve. Can't remember the part number- when I find it I'll post it. You do have to warm the engine up before thrashing it, though.

When you say the pressure has dropped- by how much? Mine, when hot , shows 20psi at tick over and 60psi at 2000 revs and above. You need to have 10psi per 1000 revs minimum. Personally, I tend to the view that flow rate is more important then pressure.

Damian, I can't really address your question about the flow through a filter but maybe the following will be reassuring.
When my Dad ran my blown cars, he ran both in "normal" Ulster mode i.e no inline oil filter. Eventually both cars ended up with Allen cranks and shell bearings.
The first car I recommissioned (the ex Almack car) stayed unfiltered. I have run it for ten years like that but after fitting new timing gears recently I began to imagine steel shavings swimming merrily down into the sump. I fitted a magnet in the sump plug (should have done that before) and an in line filter. Space considerations made me end up with a Nissan Micra filter of no special merit from my local motor factor.
I am using a semi-synthetic 10W40 Total (was Elf) competition oil and have done so for the last 8 years or so. I was cautious about overloading the oil pump gears (overbored Austin pump) and was of Alan's mind about flow.
I have an oil temp gauge. Once the 10W40 gets over about 50 or 60 deg C the oil pressure drops from 65psi cold (circa 15 deg C ambient) to 45 at 3000 rpm and about 20+ at tickover. It's always been the same. I keep thinking I could screw up the adjustable PRV a bit but I don't want to burst the filter seal when it's really cold.
The car's probably done 5000 miles like this without a filter. The only difference I notice with the filter is that the gauge takes longer to move off zero. I always used to spin it on the starter with the ignition off and not switch on 'til the needle moved. I also have an idiot light (pressure sensitive oil warning light) that comes on at < 20 psi. I now find the idiot light goes out before the needle moves - vice versa pre filter - so I switch on then. The lag in the needle is the only difference I've noticed since fitting the filter. The filter is downstream of both gauge and idiot light takeoff. I don't quite understand why it is different! Anyway, the big ends survived a very hot journey from Lincoln to Peterborough on Monday plus Autotests! Coming back at 10 pm was much cooler. I wouldn't be too alarmed by your oil pressure readings especially with full synthetic.
Regards, Stuart

As an indication of likely max pressure drop across a filter, some older books used to quote the bypass pressure. (ie 7 psi, although even this seems a lot to subject the filter to) Can be calculated from area of the valve and force to lift it. Many BMCs had a lamp which lit when bypassing as an indication of a blocked filter. Presumably these never operated normally or would have given rise to complaints.
The period when at risk of bypass was reckoned to be cold start up.
So it would seem that normal pressure drop is very low, as suspected.

With an engine with modern large dia bearings, all pressure fed, the total flow path can be considerable, esp when worn (not that moderns seem to ever be!)and vastly greater than a pressure fed Seven with just 4 bes and two tiny cam bearings.(Incidentally I cannot see how modern miniature filters can cope if modern engines ever did develop wear as of old!).

The pressure drops inside the crank must for some reason be considerable. Any pressure lost pumping oil to the axis against cf is recovered on the other side. If just modest gauge pressure could be maintained in no 3 the life of 4 would seem assured. It is only 1 1/2" to the axis; many moderns have to traverse near this distance to cross the feed entry main bearing.
(If Sevens were end fed at the crank centre, and fitted with true circumferential ducts, should draw in oil with no pressure!

Bob Culver

Location: Auckland

Why not try fitting a pressure gauge either side of the filter and see what you get? Maybe swap the gauges round to double check the readings.
I would always fit a magnetic sump plug too.

Thanks. Great advice as always..

Santa Pod? Just realised what time I have to get up to arrive on time.

It is 50 years since I last had to do such arithmetic and may be very wrong, but the centrifugal pressure in psi seems to be about .47 the revs squared (in thousands) x the radius squared in inches. About 37 psi at 6,000 rpm at 1.5" as in the Seven.

May be of interest to those with straight drilled pressure fed cranks.

I am not very confident of my arithmetic. Can someone more acquainted confirm the figures please.

To disrupt the flow another 15 psi may be necessary to pull a full vacuum, but with bubbles, possible complete loss from no 4 etc certainly risky at 37 psi inside no 3.

It is a fact that this additional pressure is acquired in no 1 and 2 and 3 so no apparent problem! Which is presumably what Herbert thought.

The problem with conventional engines is that the great centrifugal force at high rpm centrifuges so much oil from the bes that the feed main bearings become starved(I did say my other interest was Jowett Javelins!).

Note that pressure at the outside edge of bes is notably greater still.

Bob Culver

Location: Auckland

Santa Pod.

For those who don\\\'t know ( and wildly off topic) Santa Pod is England\\\'s premier drag strip.
The VSCC were there yesterday. Various forum regulars were there. It was great fun and very different to normal twisty sprints.
Standing quarter times? I\\\'ll let Frank tell you that.

You are out of date. 7000hp is nearer the mark, and terminal speeds approaching 300 miles/h.
I've been to Curborough today. Missed class win by 4 hundredths of a second. We are going tomorrow as well, hate driving in the rain. You get soaked.
Santa Pod was brilliant. I hope they do it again.

It's sometimes a matter of side clearance and well as bearing to rod throw. If there's not enough side clearance the oil will not form a proper wedge and this kind of problem results. Just a thought