Weasel Tinkering

[Tony Fearn]

I've been chatting with Ken about the changing of camshafts for a Bradford one for slightly more output.

I used a Bradford CA camshaft in the engine of the 1933 'Flying Fox' and it seems to rev better than the 1934 'Short saloon' which has its original pre-war camshaft.
I bodied the FF in half-hard aluminium so there was a weight advantage over the saloon. There doesn't seem to be much difference between the two of them engine-wise, but the FF is marginally quicker off the mark - (tongue in cheek). Both have the 4-speed gearbox fitted.
Roy Braddock suggested to me that the CA camshaft would be preferable for the FF.
Tony.

[BarryCambs]

I was recommended to put a CA camshaft in the 1934 engine in the Long Two by John Box and others. Before the rebuild, the engine had no compression at all and would struggle to reach 30mph, so difficult to say how much difference it made.

Sadly, on the way back from the Shuttleworth Collection Vintage Flying Day yesterday, it developed a very alarming knocking on the overrun a mile from home and had to be recovered The oil pressure is still fine and compression's good. It will tick over beautifully, so I suspect something is wrong with the cam as the knock sound like the old engine did with excessive cam end float but 100 times worse. It's always had 1 noisy tappet since it was rebuilt which has remained the same over several 1000 miles, so I may investigate this if I have to have it apart.

John Box also told me they seem to go better with a Bradford distributor, but as I'd just paid to have mine rebuilt and recalibrated by the Distributor Doctor, I left it.

[Tony Fearn]

Hi Barry.
Thanks for joining this discussion.
Have a look at:- viewtopic.php?p=21410&hilit=camshaft#p21410 on JowettTalk.
It might just save you a strip-down.
Tony.

[BarryCambs]

Hi Tony

Thanks for reminding me about the bush. I was going to take the timing case cover off and see what I can see before rushing in to major surgery.

The knock on the old engine was so loud and heavy I thought the flywheel was loose to begin with and stopped to check on more than one occasion. I can't remember the end float I measured on the old cam, (20 thou?) but remember thinking that it couldn't possibly be responsible for such an impressive noise. It clearly was! The noise on Sunday came on very quickly after probably after probably a 60 mile round trip, starting as a rattle on the over run and then a terrifying knocking on the next over run 100 yards later. I'm convinced it's the cam noise, as you suggest, so maybe the sprocket has come loose somehow.

Bit disappointing as it could well be I made a mistake when I put it together, though I was still very sleep deprived with the baby and young children. I've rebuilt many, many engines professionally, from earth movers and lorries to lawn mowers and apart from a JCB engine that failed to seal the liners and lost all the water into the sump, the only ones I've ever had problems with are my own!!

Barry

[Forumadmin]

Hi guys, I see some of you are subscribing to this topic. I also noticed that some of the emails notifying you of a new post in this topic were being rejected by your mail server. So this is a test to see if the problem has been fixed!

[Forumadmin]

Well it appears it has not been fixed...so more investigation. The problem affects AOL and YAHOO users as far as I can tell and is a problem with how PHPBB (the forum software) forms its message.
Please bear with me.

[Forumadmin]

Just trying something else.

[ian Howell]

It appears to be working? I just received an email from you apologising for the delays and I can get into this dialogue now.

Thanks Keith

[Keith Clements]

Great. I manually sent the notification after it was sent by the forim and rejected by your mail server.
Hooefully, you get the notifocation of this posting in the topic.

[ian Howell]

Keith: -

Yep! All Ok.

Carry on, regardless!

[AlanBartlett]

Good Evening All,

After my enquiry things have taken a turn in a different direction.

The day before heading off for Revival taxi duties, the last test run after some minor fettling the engine developed a rather ominous rattling sound. I coasted it back to the workshop. Tracing the noise to the offside barrel, I removed the cylinder head to find what I thought was a liner moving in and out. Bonnet down and off to enjoy revival with a mad scramble to get the saloon ready in its place.

Skipping ahead a few days after Revival.

I decided it would be easier to whip out the engine rather than wrestling with barrel in situ. Removing the engine and on the bench I could see something was a miss with the piston, it was moving in and out like a light switch so suspect a broken piston! I withdrew the barrel to find half a piston still attached to the conrod and what looked to be a broken baffle plate and casting smashed into the sump. The remaining baffle plate a piece of shaped aluminum in place of the steel original ones. Looking more at the piston it was also put in the wrong way around.

The Con rod had alot of side play on the journal which it would appear that some of the big end bearing also missing. After browsing over this I decided to strip down more of the engine, the main bearings especially the rear having a gouge out the bearing surface along with being a less than tight fit inside the back cover.

Searching for the pieces of broken piston in the sump, revealed no broken baffle lug or plate either. So it would appear it was assembled without it!

It would appear this engine has been rebuilt at some point recently, but lots of little things which do add up to a lot on poor assembly. So my schedule has moved up to a winter rebuild! I've also realised its been ten years since I rebuilt the engine for the long saloon! Lets see how much I remember!

After a brief chat with GW at our south west meeting it would also appear the pistons were not actually Jowett either!

[Tony Fearn]

Hello again Alan.
I have more than enough spare pre-war engine casings on the shelf. I think most of them will have the cast bits in-situ to allow attachment of the baffle plates.
You'll have to re-build entirely from scratch though, and they're rather dirty and oily.
Let me know if you need one, and how you will get it from Lancashire.
On another tack, you mention the piston 'was put in the wrong way round'.
For the benefit of others, what is the correct way? I seem to recall a machined split in the Jowett piston.
Tony.

[AlanBartlett]

Morning Tony,

Thanks for your offer of bits, my plan is to rebuild the original crankcase. I'm looking into getting it repaired at the moment as it seems the baffle lug had been missing for quite sometime. I was referring to the pistons labelled as having "Front" indication, which I believe is to be in connection with the thrust side of the piston, though I'll be having a longer chat with my local engineer.

Inspection of the barrel has revealed a rather deep score from the piston failure which being already at 40 thou its too deep to bore out. My new plan of action is the machine out the crankcase to take a set of 8hp barrels which I have spare to fit.

On another note, Would anyone know if there is a difference in Piston use between a stationary engine and a pre war engine? The saloon has thrown up a new problem with a lack of compression on one side, further delving into the revealed a broken ring and broken crown. So I'm currently dealing with that in between various Jowett tinkerings.