Crankshaft advice

[Bluebird7]

Although John did have his cranks nitrided, as I understand it - a number of cranks went missing around the covid time, when a series of crank manufacturers stopped trading. It is possible that some of these may have re-surfaced and could have been sold on.

I take it that is a pressurised crank, I notice no drillings in the oil pick ups.

Is that the issue??? a pressurised crank in a splash fed engine, just a thought.

[Belinni]

If it is not a pressurised engine, then that’s exactly the problem.

[Alan]

But, if so, why just one bearing?

[Bluebird7]

Think PARAZINE needs to establish if this is a pressure fed engine ??? £5 says it isn't !!!!
( Also be nice when people ask a question we all get a response ???? )

[Parazine]

Hi, an update:

It's actually a 1 5/16" splash feed engine, lightly tuned. I've extracted the crank and cleaned it up. The marks were due to corrosion, which is evident to a lesser degree on some of the other journals and has effectively written off the camshaft (severely rusted around all the bearings, particularly the centre). The crank looks much better after cleaning (sorry, don't have a photo at present); it is hardened and I would use it but my friend is considering the options:

1) New crank and new metalled rods
2) New crank and new shell rods
3) New crank, re-metalled Austin rods
4) Regrind existing crank, new shell or metalled rods
5) Regrind existing crank, re-metalled Austin rods
6) Leave existing crank alone, use re-metalled Austin rods, crack test them first
7) Leave existing crank alone, use a set of 2nd hand, standard Austin rods, crack test them and then scrape them in to fit

Now, me personally, I'd go with option 7) or possibly 6) but that's with fifty years of experience and access to the BA7C spares shed collection of rods, quite apart from being a cheapskate! The rods that were in the engine are sadly U/S with badly oversize little end holes.

I don't have good feelings about using modern, thin-flashed shells on a splash crank that is subject to whip but can anybody comment? I've used thick, white metal shells on a three bearing engine but that was eons ago 

Which option would you choose? 

[Belinni]

It appears to be a pressurised crank as there are no holes in the oil pick ups on the crank, ie no route for oil the get from the jets to the big end bearings. This is why you have had this problem. You need to change the crank or convert to pressurised, but your crank journals may be damaged.

[David Stepney]

Close examination of the third picture that Parazine posted initially appears to show a drilled hole at the bottom of the right hand crank trough. The left hand trough's lower end is partially obscured by the edge of the trough itself, so any drilling there is not apparent.

I think that the crank in question is indeed a splash fed crank. I am sure, though, that Parazine will confirm one way or the other.

[Belinni]

Actually there are marks in the troughs, so it could be drilled, although the holes themselves may be obscured in the photo.

[Greig Smith]

They look like the troughs of the Phoenix crank I have in my race car, except I spent many, many hours with carbide burrs opening up the holes and creating deeper feeder grooves into the bigger holes as I was concerned about the shallow troughs and small 90* holes compared to Austin's original cranks. Had it balanced afterwards. It also has a Forrest double oiler conversion with an overbore on the pump as it revs to 6500 rpm. No oil issues thus far

Aye
Greig

[Robert Leigh]

I would go with Parazine option 7, but you need to be skilled at scraping bearings to do this. I took 10 thou out of Austin rod big ends, scraping by hand to fit some good rods to a new Phoenix crank. It was okay up to 6500 rpm until a little end bolt lost its head, when it got slightly noisy. The bolt had been new 25000 miles earlier when the Phoenix went in. Some things you can't allow for.