Quick Fuel float adjustments

When I installed a QF carb, my original flame arrestor would not clear the float adjustment screws, so I replaced it with a barbron 5-3/4" dia. aluminum arrestor. Float adjustment issue fixed.

I wasn't happy with the cold start idle.   I went down early in advance of the skiers and dialed the choke in while cold.   Shut down, buttoned it up, restarted and pulled away from the dock.   Idle was terrible. Pig-rich, Stalled.   Float bowl sites show normal fuel level.    Restarted & cleared it with a little throttle.   Idle is now perfectly fine. Huh? Does not compute.

What was happening was the 5-3/4" arrestor was interfering with the choke butterfly shaft. Depending on very slight shift in arrestor centrality, arrestor rotation, bolt torque, engine vibration, etc. the choke would intermittently stick until the bi-metallic spring overcame the friction of shaft against the arrestor.   

There was a small witness mark (burnishing of the black coating) on the choke shaft on the end opposite the bell-crank. If you are running a 5-3/4" arrestor, check for interference.

Which K&N are you using?

The page in the link has some "other brand" applications listed and also has a listing of vent hose adapters that you can get separately like the fuel pump overflow fitting etc.

link

No doubt those external barbs work fine for venting crankcase gasses. I'd be interested to know k&n's official position on using them for fuel pump overflow.

I don't have a sense of how much fuel could flow when a diaphragm fails, but I'd think you would want raw fuel to be dumped directly down the throttle bores (like a 4160) rather than outside the arrestor. I'm assuming the nn-85-1325 does not penetrate the arrestor/filter.

It's a shame QF didn't just put a fuel overflow barb on their marine carb..

93xs2003@gmail.com wrote: No doubt those external barbs work fine for venting crankcase gasses. I'd be interested to know k&n's official position on using them for fuel pump overflow. I don't have a sense of how much fuel could flow when a diaphragm fails, but I'd think you would want raw fuel to be dumped directly down the throttle bores (like a 4160) rather than outside the arrestor. I'm assuming the nn-85-1325 does not penetrate the arrestor/filter. It's a shame QF didn't just put a fuel overflow barb on their marine carb..

Sounds like you need to talk to K&N to see how they justify that it meets USCG standards.

Probably through their own testing and not by Underwriters Lab testing for Coast Guard Approval.

There's a difference between "meets Coast Guard standards" and "USCG approved'

A good example of that is a DUI marine distributor. It meets the standard but it hasn't undergone the UL testing.

The testing is Expensive (with a capital E) and their legal department must be comfortable justifying that it meets the standard through their own testing. (The uscg says if you meet SAE J-1928 or UL-1111 requirements, you're OK)

I could modify a flame arrestor or modify a distributor to meet the standards pretty easily but come testing time, it's a whole lotta money involved.

People on here have modified their flame arrestors and distributors and might also throw in carburetors to become "marine" to them, but that's their choice for personal use. and in the case of older stuff they improved on the original 60's equipment.