Dar, or David, or Pe:
With a new MVVS .49 (purchased in Canada) the head is all blue, with no cylinder insert to be changed. (this was a surprise even to David). So, with no insert change to allow for 15% nitro fuel, how many of the thin shims (or washers) do I need to use? Why did MVVS discontinue the insert using head? Was it only to save money? Will shims not be more liable to leak?

With a new MVVS .26 (also just purchased in Canada), it comes with a removable head insert, but comes with 2 shims. Do I use this supplied head and insert with both shims to allow use of 15% fuel? - or should the engine have been supplied with the 15% head insert?

Thanks,
Bill O.

<All> new glow engines now are of single item head construction, without exception.
I do not know for sure if the engines shipped to US and Canada have a lowered compression ratio to compensate for the higher Nitro content as compared to europe. (the quickie has different heads)
You can quickly find out if you need the extra shim by checking the glow plug. If it looks sand-blasted after a run, add a shim.
The extra shim is not prone to leak, because it is made of soft metal. Just do not over-tighten the screws.

Bill,


According to the MVVS head engineer, the engines can all be run as they come, on up to 5% nitro.

If you need to use up to 15%, add one head shim (a total of 2) and off you go.

The RPM gain from going to 15% with the extra shim is 100-200 RPM.

Make sure you use only fuels that contain plenty of castor oil (over 50%).

...Unless it is Cooper's and then you can use less.