Also known as Glow Head Gaskets.

www.nvengines.com/index.php?page=shop.pr...uemart&Itemid=65

www.nvengines.com/index.php?page=shop.pr...uemart&Itemid=65

Don't we always use head washers to adjust the compression anyway? The main reason why standard plugs rob performance in these wee beasties is because the volume in the threads alters the compression.

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.

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!

Add my thanks as well. I'll be placing an order soon!