2019: September part 1. Trying out new sprint motor

With the engine in and running I had a little tinker to tidy up and check settings etc.  The fancy (and expensive) Mangoletsi throttle linkage seems to be well engineered and was easier to fit than it looked. The engine idled quite nicely and I set the ignition advance at tickover to 10 degrees BTDC as a good starting point.

10 degrees BTDC using the Snap-On timing light.

Driving the car it felt good and responsive and with that fantastic growl from the carbs when you floor the pedal.  Almost worth changing the engine just for that sidedraught roar!  I booked a test in a couple of days time with Martin at Maynard Engines on their rolling road in Nailsworth to check what was really happening with mixtures etc.  A couple of days later I took the car over there and we strapped it down on the rollers.

First run showed it was actually set up quite well.  I had used the carb settings recommended by Matt at Eurocarb who are the Dellorto main agents in the UK. For the anoraks amongst you this is what he suggested as a starting point:-

Dellorto 45DHLA
Chokes    36mm,
Main jets  145,
Emulsion tubes  7772.5,
Air correctors  180,
Idle jets  60,
Accelerator pump jets  42.

I have been reading up on the carbs to try and get a better understanding of what all these numbers mean and how they all work together. This book was my main source of information.

I wouldn't claim to understand them now, but I do have a bit more of an idea than when I started.

Martin found it was running a little rich at the bottom end then went a little lean at the top so he made a few changes. We were not trying to achieve ultimate power but needed it to be a nice engine to drive on the road.

Turns out that folks have differing opinions about setup, Martin prefers to run bigger spec emulsion tubes so changed them from the recommended 5 to an 11 which gave a richer acceleration phase. They have more holes and in different places - see picture - and it certainly worked to make the top end mixture much better.

Dellorto Emulsion Tube Range from 1 ti 17

Driving the car afterwards it certainly felt smooth, with plenty of torque at low revs and pulling all the way up through the range.

Final carb settings are:-
Dellorto 45DHLA
Chokes    36mm,
Main jets  175,
Emulsion tubes  7772.11,
Air correctors  135,
Idle jets  60,
Accelerator pump jets  42.