Building a hot vintage engine with Jonny69

[Jonny69]

My mate has a Spitfire 1500 in his 1200 Herald. Goes quite well I thought for an engine that hasn't had much work. In fact none other than a rebuild I think. Can't remember if he's got twin SU's on that or just the one.

Penski - that's Seth's Herald, the blue one.

I think the secret to engines with flawed designs like 3 bearing bottom ends is to just look after them and respect them. You wouldn't build it as a 9000rpm screamer but some sly headwork and a cam and it'll bring that power and torque up nicely. Keeping the oil in good condition is a must.

 

[Jonny69]

Heh quality! I love the A series too, would love to build one. It's small enough to have to rely on revs, revs and nothing but revs

 

[Jonny69]

Was this legend of ultra short-throw cranks for the A series to build a super screamer true?

 

[Jonny69]

Bump from pits of hell

I should have done this when I built the engine but the clutch is on its last legs and shuddering the car to hell when I pull away. There are 3 things that can cause this and I plan to remedy all of them because I don't want to have to pull the engine out again once I'm done.

First is a warped or worn friction plate. That's the disc bit here with the springs in the middle:

I can get a new one of them and I'm going to replace it. Second is a warped or worn pressure plate. That's the spring loaded cover that goes over the friction plate and again I can get a new one so I'll replace it.

Third potential problem area is the surface on the flywheel and I can get it refaced to make sure it's flat. Since it's on the lathe it would be rude not to get rid of a bit of excess material wouldn't it? I got my friend to shave my spare down a bit:

So the clutch mounting face and the back face were trued up by the same amount so the clutch depth remains the same. I got him to machine down the ring round the outside that locates the clutch and the ring-gear so it's just a minimal lip to locate the clutch and a chamfered step to hold the ring-gear. Then on the back face I got him to machine a few millimetres off the surface all over and chamfer the squared-off back edge right down:

That's a lot less weight on the outside edge so it should spin up a lot faster with no loss of strength. It's not as light as an aluminium flywheel but it was only £20 compared to £200! All I know is it's over 2.5Kg because the scales for weighing the mail can't take it

 

[Jonny69]

Should make a little more revvier. Have you fitted all the bits you wanted to fit to it yet? When you have please get it rolling roaded.

Not yet, picked up another pair of SU's on Monday night and they seem a bit better than the other pair I've got. I need to give them a clean up but I'm hoping the throttle spindles are less worn.

 

[Jonny69]

Yes HS2's. Doubt I'll gain that much out of this old boat anchor though

Cheers for the recommendation to ML Motorsport though, I'll be looking them up when the time comes

 

[Jonny69]

RIP engine - it expired last night in a spectacular ball of smoke

 

[Jonny69]

Yup, it's well dead

Drove it to Chelmsford at the weekend and I noticed it started breathing really heavily on the way back. Yesterday night the knocking noises started followed by smokescreen and there seems to be as much coming out the breather pipe as out the exhaust

Guess I've just been hammering it too much

 

[Jonny69]

Ok, so missed a bit which I posted in a different thread for some reason but one can view the damage here

Roll forwards a few months and the engine is back in, run in and I've been using it daily. I've cured the detonation which was a combination of running lean and the ignition way too far advanced. A few goodies went in with the new engine namely the lightened flywheel, new clutch and a new head so I could try soemthing else with the flow.

Oh and overnight something funny seems to have appeared under my desk.

More info in a bit, hope it fits