F

Flying Scotsman

Well Known Member
Working on the snorkel, I used the "plug" of wood to align it to the intake of the fuel injection servo, move the sucker around and trim the top end to match the baffles, etc. After drilling the holes on the flange on the snorkel to mate to the the servo, and bolting it up, I can see using an inspection mirror a very slight offset between the round hole in the snorkle and the entrance to the servo, maybe 1/32-1/16" step-off (the snorkel is just a hair low relative to the servo). I'm guessing it was a combination of things, like the wood plug not fitting exactly into the tapered hole in the servo, and the fact that the hole in the snorkel is about 1/32-1/16" larger than the plug, plus just the difficulty of drilling the stupid holes precisely in the first place.

So...I'll probably "fix" it by building up a little epoxy w/ flox and microballoons, and sanding down to match, plus sanding a touch off the top of the hole, since I have other fiberglass to work on, too, but my question is...

Would this slight step-off matter or have any effect? Or am I just being a perfectionist? :)
 
Hello Steve

I would fix it too, but I'm also a perfectionist ;)

Think about this: on a IO-320 vertical induction, the fuelservo has 59mm diameter, the oil-sump 49mm ... :eek: WHAT?!

So there right after the fuel servo, the air bangs on a hard diameter change from one part to the other. There is no transition just bang, smaler diameter.

This is a "normal" setup from Lycoming and Bendix. I know, it hurt's and it is nearly unbeleavable, but it is like this ant the engine produce 166BHP.

There are sump's that have a ramp/conical part or you are using a mounting plate inbetween from AFP (they also have a radius for a smoother transition) to change this, but it is not standart.

Regards, Dominik
 
Last edited:
Yeah, I'll fix it...but stuff like that bugs me and also makes me think about what's going on in there. Would there actually be a risk of some slight turbulent flow across that step causing a very slight loss of power? Or not?

It's easy enough to fix, if hard enough to spot while drilling (no way to look in there with the plug in places, and with it out, you can only inspect with a mirror and see the bottom of the snorkel...so I'll build the bottom up, then use the plug to sand the top down so that it's circular...what a *pain*).

Can't believe there isn't a better way to install this thing...sigh...
 
You must log in or register to reply here.