I'm absolutely POSITIVE you've heard all this before, but I think it bears repeating *grin*

Just a few suggestions for the engines:

Redesign the heads to use turbo plugs. They're available in a range of heats, they perform just as well as inserts, and you folks don't have the expense of being in the plug business.

Ditch the wire-clippy-exhaust-diverter 'muffler' on the .049 and .061. They really aren't all that effective for silencing OR goop diversion. Bolt-on or clamp-on would be much more effective. The .074 has it right.

Lastly, there's really no reason to not have an adjustable idle mixture (although I heard something somewhere about an improved carb in the works?)

Thanks for your time!

Thank you for your comments - they are 100% appropriate. Here are the answers to them:

1. You can use any plug you want - just get our glow plug adapters (Head adaptor for std. glow plug 04-06 100148
Head adaptor for std. glow plug 07 300001)
2. You are right about the wire and it will be eventually gone. It was originally designed to minimize the crash impact, but it may not be so effective as bolts.
3. We will later come with a new carburetor that will lower the RPMs
on 061

For the .049/.061, the Galbreath head / Nelson plug combo works really well, and was what many of us did while the engines & parts were unavailable. There are turbo-plug heads on eBay as well - "cox_hyper_speed" is one vendor, and I have both his .061 conversion head and one for the Cox TD .09.

Seconded on the muffler design for the .049/.061. Those wire clips drive me mad and I mostly don't bother using the muffler at all! The .074 muffler design is so much better.

My other request is a control line version of the .074.

I am also intrigued by the potential of the diesel conversion head. I - very briefly - ran a BigMig .061 with a Davis diesel conversion head. Starting was very difficult, and the teflon discs inserts burnt out constantly. On the positive side, running as a diesel it was one of the quietest model engines I have ever run - so quiet that it was possible to converse with someone standing outside the control line circle. The NV diesel head looks like a conventional contrapiston / adjustment screw design to me - hopefully it will be more successful than the Davis head was.

cheers,
Colin

074 CL is available. Those who want to convert from RC to CL need Venturi assembly 04-07, part #101159-02

Standard plugs are a huge no-no on engines this small. It'll lower the top end at least 1K. Turbo plugs preserve the shape of the combustion chamber. Nelson plugs are swell and all, but turbo plugs are available everywhere.

*EDIT* I made a couple of turbo heads on my own lathe. Didn't run 'em on an NV, but I was able to get 19K out of an AP Wasp spinning a Graupner 6X3 on Sig 1/2A fuel.

A turbo plug has a tapered base which seals into the head, which removes the need for the copper washers. But those washers are important to adjust compression