I am looking to build a sports engine over the winter to power the Ulster bodied special I have built this year. Currently, it is powered by a 'cooking' engine - though it has to be said that that performs surprisingly well with a Bosch distributor and Ulster works exhaust manifold and semi-downdraught inlet manifold with a 30 degree HS2. Anyway, I would like to build something more robust and am planning a pressure fed Phoenix crank but then am not sure after that. Phoenix rods (1 5/16") seem prohibitively expensive so I wondered about the Renault option, which I assume has to go on a 1 1/2" journal crank, but can these fit in a standard crankcase? When Austins did this, the crankcases had big bulges on them to accommodate the turning circle of the big ends. Any opinions, advice or experience would be very welcome.

I too would be very interested to know if a 1 1/2" journal crank fits within a standard crankcase and what rods to use with it.

Jeff

I've fitted a 1.5" pressure fed phoenix crank and phoenix rods into both an early coil and magneto crankcase.
They both fit in with only some minor fettling of the centre camshaft mounting casting. The phoenix rods are too large to fit through the bores so putting it together is a painful job single handed (pistons and rodes in bores and then lower the block down). I never use baffles.

The pressure feed on the magneto engine is easy to engineer if you have a lathe. A lump of aluminium easily turns down to replace the starter handle casting. The coil engine is more difficult to machine since the front timing casting is in one piece but I seem to remember that people like David Cochrane now sell pressure feed adaptor kits.
I've never attempted to run a starting handle with pressure feed so the nose feed is close fitting blind bush with 7/8" oil seal and a retaining platem to stop the seal blowing out.

Oil wise I run a full flow filter with Castrol R (when you have shells a full flow filter is a must). Various filter heads are available from Think Automotive or Flexolite.

Regards

Charles

BTW Austin sports crancases didn't have bulges for the pressure fed 1.5" Ulster engine - only the 65 and Nippy which were jet fed.

Charles

Hi Charles,

Thanks for those replies, I'm reasonably familiar with Flexolite products - I assume looking at David Cochrane's gallery page http://www.a7c.co.uk/gallery.htm and the BA161p nosecone for pressure-fed crank that one of the oil feeds comes off the side of the nose itself (the brass pipe fitting), presumably the Flexolite filter head is positioned and bracketed somewhere within the engine bay, but whereabouts on the crankcase does the other oil feed enter and what's involved in engineering this?
I presume also that you're using a standard though bored out / uprated pump or perhaps a different pump?

Jeff

I've overbored the oil pressure gauge outlet and fed it from there. I've also gone slightly further off piste and made a remote oil pressure relief valve (Tim Myall makes one for sale). This is bulkhead mounted and negates the problem of the inaccesible relief valve. So the oil goes from the gauage outlet, into the relief valve, onto the filer and into the nose piece. The oil from the relief valve goes into an extended filler neck (the foot mounted magneto engined one spills oil when driven with spirit).

This is my collection of blown engine photos that I collected when building mine - plundered from the internet and other sources:

http://www.flickr.com/photos/47438069@N00/sets/72157601344230727/


Charles

Thanks Charles, that's very helpful, but what about your oil pump specification?

Cheers, Jeff

Charles,
I was interested in your comment that you do not use oil baffles - is this for ease of assembly or because your are concerned about lack of cylinder lubrication with a pressure fed engine?

I am particularly interested because earlier this year I built a pressure fed engine fitted with oil baffles. It ran fine at tick-over but on the first outing (at running-in revs) it failed after about 3 miles. The sides of the pistons were scored/gouged and the removed piston material seized the piston rings. The damage was minor on no.1 cyliner and progressively worse towards no.4. I have not been able to find any obvious reason for the failure. Of the various knowledgeable people I have spoken to the only suggestion has been that the problem was lack of cylinder lubrication.

Dave Griffith

I run a Paul Bonewell pump; the gear type one.
People with greater knowledge of fast Austin 7 engines than I have (and whose opinion I respect) say that a standard pump is fine when in good condition - and that may well be true. However after running the number 4 big end I didn't want to take chances and whilst I had it all apart the extra £130 didn't seem too bad.

As for baffles in a pressure lubricated engine what is their purpose? I can accept that they might have a value in a spit-and-hope engine with crankcase oil flying everywhere but not in a pressure fed engine.

Charles

Hugh,
Based on my experiences of travelling round the world in A7s I suggest.... A Phoenix crank, but splash, (pressure fed are not worth the trouble unless you are doing serious racing), a splash fed engine with good standard A7 rods is very reliable and good for 5500 rpm if balanced. It is important to put an inline oil filter and HC oil pump this gives 15lb psi, more than enough for what you are doing. The filter will also probably double the life of your engine plus no more blocked jets. Keep it simple for reliability.

Chris

Thanks for replies so far. My intended use is for reliable and robust 'spirited' driving, but not for racing. I would like to think I would end up with a car that would allow a 60 - 65 mph all day touring ability (and a higher top speed of course ) and will be no slouch away from the lights. As I say, the lightweight nature of the car I have built would indicate that shouldn't be difficult to achieve. Charles' helpful replies perhaps suggest a route for racing or other serious sporting events but the bottom line is this will be a road car with an eye on the odd hill climb here and there.. Chris' last reply about spit and hope with Austin rods is certainly the easiest route (and, frankly, most economical) I have already planned oversized pump, in line filter and have a Paul Bonewell cam/followers under the bed which should allow 5,500 - 6,000 rpm. I had thought pressure fed would be the way to go, but now am thinking differently...

Hugh

I also reckon that spit and hope will be fine given your ambition - as long as the rods are good and you keep the revs within a sensible limit.

Charles

Not wishing to tempt providence, but does anyone have any actual experience of Austin rods failing (ie the rods themselves, not the big ends) I only know of one person in 40 years of Sevening, but as he also has a bag full of broken cranks, he's not a reasonable standard to go by!! Careful choice of rods without file marks or other 'work' is clearly important here..

Hugh, All,

Austin rods do fail, they crack from the sharp corners where the top of the rod is slit to allow the little end bolt to be clamped. This area of the rod needs to be inspected carefully and polished to look for cracks. I have known a this to happen in a few cases normally the crack causes the little end bolt to break, the head of the little end bolt then gets between the rod and the bore bending the rod so the failure is blamed on the bolt and not the rod. I know of one engine that broke two little end bolts and bent two rods in a week because the first time the cracked rod caused the little end bolt to break the head of the bolt managed to bend an adjacent rod.

Dad bought a box of Unbrako 1/4 BSF cap heads for the purpose of little end bolts, they are much stronger than the original specification R grade bolts used by austins. They are also much easier to get in and out.

If i were building an engine with standard rods i would drill a small hole at the end of the slit to remove the stress raiser caused by the very sharp corners left by the slitting operation.

Incidentally, i am building an engine for my ulster rep using an original nippy crank (1 1/2" spit and hope) and rods in an early sand cast coil crank case. I am still sorting out bits, (and building the rest of the car) I did try to get the crank into the crank case and could not thread it in. As far as i could tell removing the front lip will give enough space (was going to do it anyway). Will have to work the crank in with the steel front lip loose then bolt it in.

I will run the engine with either an oversized standard pump or i will rehouse a yamaha R6 oil pump to fit. I will fit oversized oil jets as discussed previously on the forum. I will also fit a full flow oil filter. I do like the idea of a remote pressure relief valve as suggested. Reading the VSCC forum it is suggested to fit O rings on the outside of the front cam bush to seal it into the crankcase and prevent wasted oil.

Regards

Rob

IMHO the fact that the damage to number 1 was mild and number 4 was severe points to a heat related issue (cooling is worse at the back). If it was simply the baffles then this marked graduation wouldn't be logical. They may have been a contributory factor but the picking up that you describe is symptomatic of clearances and heat build up.

Regards

Charles

The O rings on the cam bush are a Dave Dye mod. Like pretty much everything he does, they work well.

STEVE

Under NO CIRCUMSTANCES drill a hole in your rod ! as they will bend I've got some!!

Chris

Chris

I mean a very small hole a few thou bigger than the width of the slit to change the sharp corners to a radius, this would vastly improve fatigue performance without effecting the bending strength.

Can you post pictures of the bent rods?

Regards

Rob

Presumably the cautious approach to the use of austin rods is to crack test and shot peen after careful pre-selection. For purely gut feeling, I'm assuming earlier rods whitemetalled, not shell bearings would be the way to go...

I recently rebuilt an engine which had little end problems. Numbers three and four little end bolt heads had broken off at some time, one of them being picked up by No4 big end and pushed through the side of the crankcase. Two of the rods were also bent.
There was evidence of extreme heat between the little end bolts and gudgeon pins causing the bolts to be wasted away to less than half their width with tiny blobs of once molten metal still attached. this in turn caused the gudgeon pins to badly score Nos 3&4 cyliners.
This engine had at some time been built for 'performance' with oversize inlet valves and was in my '32 van when I bought it. It had not been run for several years and the errant little end bolts must have lain in corners of the crankcase for some time. The engine ran quite well in this unknown state until the awful clattering and bolt through the side.
The bores were plus 80 thou, the crank splash fed and the baffles were fitted. I think the problem with it was the lack of cooling, both water and oil. With the standard cooling method of thermo syphon all the cooling tends to happen on the first two cylinders, especially when the waterways in block and radiator are partially clogged. Also with baffles fitted the little ends could not have enough oil to lubricate as well as cool them.
Austins must have encountered these problems, hence the use of fully floating gudgeon pins and water pumps on the supercharged engines.
I have also encountered the problems above on a standard magneto engine, maybe this is why the radiators were made much taller on the later models?

The fretting of the little end bolts is covered in the technical section of the Cornwall Austin Seven club website.

Steve

I haven't seen a mention of the Mike Forrest 4-jet crank lube system as shown in the Special Builder's Guide or A7 Companion (can't remember which). For someone who wants to keep things simple yet reliable I think it does the job very well. I have been using it for 13 years in my road-going special and for 4 years in my RN saloon. I have broken 2 cranks in the special but don't let that put you off. One was a Remax and the other had reached the end of its fatigue life or perhaps it got tired of 5000r/m plus too frequently. If you do make up the pipework for 4-jet you must silver solder the joints,not soft solder.