Overhauling a knackered engine.

[Gargo]

Now we have to set this engine up; ignition and fuelling. Tuning SUs is a new thing to me. I started fiddling with engines when DIY fuel injection was not heard of. I bought one of the first Emerald ECUs and arrived at the rolling road with two laptops. Spend a few hours taping the keyboards until we had a very sweet running engine. The owner of the rolling was amazed at how quick and painless it all was. So now I'm doing something new to me, the pain of setting up the fuelling for a carb.

In preparation the SUs have been fitted with a richer BBW needle, yellow springs and throttle disc kit WZX 1321 from Burlen which gets rid of the emission poppet valves in the butterflies.

As always you need feedback to achieve the goal. So I've made a couple of rods that sit in the pistons to indicate the fuel governing position of the needle.

And added a Wide band sensor to the exhaust. Here it is showing 0.92 lambda at idle. So far so good, setting the SU fuelling for idle could not be easyer.

One thing to note so far is I was told the cam would produce a 'loopy idle' (what ever that is), but not at all, it is so smooth, rock solid. I suppose the lack of over sized carbs is helping.

A gentle run up the road, shows that the Lambda is within safe limits over the first 1/3 of piston/needle travel.

Now I'll need to get to the rolling road. I bet the rolling road owner will reminisce about the old days, the black art of setting up carbs!

 

[PeterZRH]

I assume you mean don't spend to much time trying to acheive the impossible and then worry it's not right, rather than a firm "don't attempt it". I realise I've not posted pictures of the work around the valves, but it has been done.

That and you can weaken the casting unnecessarily.

 

[mrtask]

Like that airbox mod. I reckon you were told that the cam would have a "lopey" idle, the internet tells me that is caused by "reversion (from overlap) at low rpm with exhaust gasses going into the intake and messing up the signal". Looking forward to hearing about the outcome of your rolling road session.
...went back and read your thread from the beginning; very interesting! At some point I'd like to build/rebuild an engine myself, so I'm fascinated to see all the mods Des Hamill suggests actually being done! Shame those sexy rockers aren't visible once installed, eh!? I'd want to put transparent polycarbon panels in the tops of the rocker covers so that the rocker gear is visible!