My "L29" build.

[SeanDezart]

U der man !

 

[richiep]

Yes, had a fair bit of welding on the chambers to reshape and reduce the size. It's down to 39cc (so far from radical, CR in low 11s).

Where did you get the head welding and porting done if you don't mind me asking?

 

[jonbills]

I don't actually know! I know those jobs were farmed out to different peeps that specialise in them. My friend Phil managed it and did most of the rest of the work. He does a lot of race engines.

 

[Rob Gaskin]

Jon, what is the plan for the cooling of 5 and 6.

 

[jonbills]

Jon, what is the plan for the cooling of 5 and 6.

Not really decided on that yet - either I'll run a line from the taps to the thermostat housing or to the return line from the heater to the water pump inlet.
The first keeps all the cooling under control of the thermostat, but the latter has better flow out of 5 & 6. Or a hybrid of both. There's a mega thread on this topic on hybridz.org.

The deciding factor will probably be the fittings I find to do the plumping

 

[Alphabettispaghetti]

Any pics of the welding?

 

[jonbills]

Any pics of the welding?

Here's a couple -
in progress:



finished article:



Beautiful eh?

 

[racer]

Very nice john.
I can't remember are you running 40's or 45 Webbers?

 

[jonbills]

Webers? wash your mouth out Matt. They're Dellorto 45s with 39mm chokes

 

[racer]

Webers? wash your mouth out Matt. They're Dellorto 45s with 39mm chokes

Lol
Ok so big enough. I guess the RR will tell.

 

[jonbills]

Yeah I think so. New plugs came today but not the new plug spanner

 

[jonbills]

Seems to be all sorted now - I've kept the ignition to about 30 deg and got the fuelling ok (a little rich much of the time, but safe and smooth)
I've also plumbed in a coolant line from #5. It works ok, doesn't seem to slow thermostat opening noticeably.

 

[racer]

Why Number 5 John and not 6 ?
Have you had any hot spot/overheating issues?

 

[jonbills]

Well, I took the plug out of 5 first, thinking I'd do both and then I got worried about having too much water bypass the thermostat. So I just did 5.
Anyway, I guess I could argue I can help 6 by opening the heater valve.
I've not had any over heating issues that I'm aware of, more a preventative measure!

 

[Rob Gaskin]

Jon, a couple of observations re heat.

Your waterpipe from Cyl 5 goes downhill to the junction on the side of the block. Hot water wants to flow uphill so it's perhaps not as effective as it could be. Header tank?

I'm admiring your work and I have experienced overheating on number 6 - when I ran my car with the rear jacked up to test the gearbox.

Your fuel line (and especially the filter) are in a very hot area - wouldn't the route be better from the front in the airstream/fan area? I know however that many cars are fed from the bulkhead forwards when using triples/electric pump.

 

[jonbills]

Thanks Rob, sounds like we should be careful going down steep hills!
it is true that cold water will sink below hot water due to the relative density, but I don't think that is going to put up much of a fight against the suck from the pump on the other end of that pipe!
If the pump couldn't over come that, then water couldn't flow through the rad (hot in at the top, cold out at the bottom)

I have thought about the fuel route, and although there's lots to not like about how I've lashed that filter up - I don't think heat can be a problem: the filter is before the (bypass) pressure regulator, so there's a constant flow of fuel through the filter returning to the tank. In terms of the pipes after the regulator: they only hold a few cc, very little compared to the volume of the 3 float chambers.

So it's the float chambers in the carbs that have a heat soak challenge, the routing of the fuel lines to them has a negligible effect.

 

[jonbills]

Quick update. I've added water extract from cylinder 6 without drama, and just added vacuum advance to the distributor. Haven't tried it yet, but hoping for good things.

 

[jonbills]

Yes, vacuum advance makes a decent difference. I'm going to take it to Manchester tomorrow- will find out what it does for economy. I know that's a question that always comes up on here

 

[jonbills]

OK, time for an update, since it's quiet on here.

I did attempt to go up to Manchester in it the week before LMC, but it died in the roadworks on the M1 between J16 and 17 so I didn't go to Manchester & I also ended up to going to Le Mans in a Renault Spider for punishment.

I got the pistons out today and the problem revealed itself.

So I'm dropping the nice people at Kameari a line tomorrow to see if I can buy a single piston, and in the next few weeks the block will be off for measuring & honing.

I'm wondering if the vacuum advance or the coolant extraction from #5 & #6 had anything to do with it. I'll definitely be checking max ignition advance on the rolling road when I get it together again, and I think I'll reduce the coolant pipe bore down from 13mm to a lot less - maybe 8mm. Then time will tell.

That's not the only problem either - the compression on all cylinders is down - between 140 & 155 PSI, compared to with a little oil in the bores when I get compression of around 220 PSI.
For the 2 pistons I've measured, the ring end gaps are fine - just as they were when I built it 18 months ago.
So where'd the compression go? I'm looking at the angle of the squirt hole in the rods and any out of round on the bores.

Very frustrating, now my awesome looking Zstory exhaust has arrived!

 

[johnymd]

Sorry to hear this John. How do the Pistons and chambers look? Are they all the same? Are there signs of det on a specific cylinder. Have you been monitoring for changes in carbon deposits? If the carbon starts to disappear then you are a bit too close to det.