Water leak

[Ruairidh Dunford]

Hi Nick,

If what Malcolm said is true, and he knows the engine in question, follow his advice. Paul will have done what he was asked to do, Malcolm knows what that was.

I was using the knowledge that a lot just ask Paul for top speed, without considering the pitfalls, even if he explains them.

[Malcolm Parker]

I think the engine has an original sports crank and rods.  Derek told me that he didn't like to rev the engine beyond 4500 rpm out of kindness to the original crank but always felt that it would keep on revving.
I know that he discussed the cam with Paul Bonewell before he had it ground and it is a very nice piece of kit.   The engine was run up on my test bed and it was remarkably smooth and quiet, much more so than my engine with a 'trials' cam of different origin!

[Ruairidh Dunford]

I must admit, have never heard of someone selling an A7 engine because it was too fast.

Hopefully it will be running properly again soon.

[Austin Nippy]

Hello again and thanks for the further reassurance about the engine which sounded a really good one both prior to and immediately after I bought it - hence my puzzling over what could possibly be causing the issues I'm experiencing.

Is it worth trying a new coil on here at least to eliminate that as being the issue assuming that we're back to it being an ignition issue?

How critical is it that the exact SU item is fitted or will any spring of suitable length do please? If it is, where can such an item be sourced from please? Sorry there are so many questions so much of the time but the answers are much appreciated.

It certainly sounds good when not under load and feels like it wants to go - as it obviously did in Derek's 65. It's still a bit of a mystery as to why it won't go properly at the moment when nothing has really changed other than a change of location.

On another positive note, the new gears seem to be much quieter now which is a result as, initially they made a real row so guess just needed a while to get bedded in?

Hopefully everything will get sorted and the Nippy can enjoy some more adventures soon...
Best wishes,
Nick

[Steve Jones]

I've been away these last couple of weeks, Nick, and so have only, just, caught up with this. Like Malcolm, I know the engine you have and I think we both suggested that it would be a good buy for you when it was advertised. I agree with Malc that this does sound like an isssue with the engine timing or, perhaps, an induction leak. If the engine hasn't been stripped since you got it (and I don't imagine it has) then the valve/cam timing will be as it was so I'm sure that can be discounted. I think you've sealed the carb/manifold joint but what about the manifold/block joint if that's been apart? After that I come back to an issue with the ignition timing/distributor. I'm not sure what distributor your using but did I note DJ4? Not much to go wrong with those but if you want to try fitting one that's proven to work then I have one here you can borrow. I'm not that far from you, on the A19 mid way between Doncaster and Selby.

As to the C/R gears, if you had these done where I think you might have done then, yes, the are noisy at first but do quieten down with running.

Steve

[John Cornforth]

Hi

With regards to the spring in the SU, on a downdraft SU the spring is the only thing providing a returning force to balance the suction on the piston. The spring will therefore tend to be stronger than one for a sidedraft SU which has both spring force and gravity acting on the piston weight.

Different strengths are available, rated in ounces and color coded with paint dabs. The general principle is to choose one that allows the piston to move to close to being fully open at maximum airflow (= max RPM and wide open throttle). You really need to get the spring right first before playing with needle profiles, as if you change spring you then have to start again with needle selection. Any old spring that fits ain't really good enough !

[Malcolm Parker]

I think Nick was enquiring about the spring that pulls the choke operating lever back to the closed position (ie the short spring that gets in the way when you adjust the brass nut that raises or lowers the needle.   The other spring is a long floppy thing within the dashpot.
Regarding the short spring, almost anything will do.  A rubber band would suffice at a pinch.

[Austin Nippy]

Good morning and, once again thanks for the replies.

The current distributor is a DK4 Steve which I've taen straight off my other engine on which it seemed to work fine. Whilst I've no real reason for doubting it, it was the only thing I could think of which didn't come with the engine so, in the increasing mystery was clutching at straws as to whether this could be the culprit. Thanks for the offer of the DJ4 although there's nobody at home until the weekend other than early morning or late evening. I've got someone coming over on Saturday morning to "play" who lives in the Adwick Le Street area of Doncaster if that would be more convenient Steve to try your distributor?

The engine hasn't been stripped at all other than the head and manifolds had been removed so I could have a look inside which all looked really good. There is a new gasket between the Nippy manifold and the block. Is there some sort of sealant that could be used at this joint and, if so, what's the recommendation please?

The gears are indeed becoming much quieter so I'm not concerned about that at all now.

I was indeed talking about the choke spring Malcolm and John so I'll see what I can find. Thanks for confirming that pretty much anything will do Malcolm. What the spring and needle in the SU are I've no idea but they were obviously working fine previously so I doubt they'll be the culprits to be honest. I've got a large box of rubber bands to try if nothing else!

Like the apprentice, the search continues!
Best wishes,
Nick

[Steve Jones]

I've sent you a Private Message, Nick.

Steve

[Austin Nippy]

Thanks Steve.
I've just replied.
Best wishes,
Nick