QF M600 flame arrestor

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Lots of people buy a QuickFuel M600 and figure out that there's nowhere on the carburetor to hook your ruptured diaphragm overflow line from a Carter marine fuel pump
The later Holleys have a fitting up high on the carburetor for this purpose. It'll dump fuel in well above the venturis and there's basically no vacuum at this fitting

The QuickFuel has a timed spark port on the side of the primary metering block that looks like a spot to hook your overflow line to......but it's not a good spot at all because there's a vacuum  there that'll drive your fuel pump crazy and that in turn drives your engine crazy, which then drives you crazy trying to figure out what's wrong. 

It's not the normal manifold vacuum that is normally talked about, it's above throttle plate vacuum sensed in the venturi above the throttle plate.

The engine will run good at idle and at full throttle, but in between in the midrange, itll be affected.

So needing a place to hook that hose, you can look for an arrestor that 
1) clears the adjustment screws for the floats on the front and rear bowls
2) has the 5/8 fitting for the breather hose going to one valve cover
3)  has the 1/4 inch fitting for the overflow line

It hard to find one with all 3 either new or used.

If you take the arrestor you have now and test fit it on the Quick Fuel and it clears the float adjusting screws, you're halfway there.

If it doesn't clear sometimes you can take a ball peen hammer and dimple the bottom plate on the arrestor to give clearance and let it sit properly on the carburetor

Or you can buy a spacer that goes between the arrestor and the carburetor, it'll raise your arrestor by 1/2 inch or so, meaining that you have to make sure the engine cover still closes with the arrestor installed.

link to a 1/2 inch spacer

Assuming that the arrestor now clears the adjusting screws and the engine box, there's an easy way to make a fitting and install it with no special tools etc.

You go to any auto parts store, tire store etc and buy a metal threaded valve stem for a wheel. This 2 pack cost 6 or 7 bucks

Take one of the stems, take the rubber grommets off and you have what's in the next picture

Pick a spot on the arrestor and drill a hole for the valve stem For this stem a 27/64ths hole worked good. Started small and worked up to the final size.

Put the stem in, slide the washer on the outside and tighten the nut. You could use a little loctite if you're worried about it coming loose.

And don't forget........unscrew the valve from inside the stem and get rid of it.

Now, with a little effort you can push the 1/4 inch hose on and hose clamp it if you want to. It's a tight fit.

It took a lot longer to write this than it did to put the fitting in.

There are other way, I've put a fitting in from the top before, but it takes up some height under the box depending on what you use for a fitting and it involved more work.

I'm sure there are other things people have done, but this works good, looks good and is cheap

One no real work involved choice would be the one in the link from SkiDIm or nautiqueparts, or wherever but you'll need a spacer or need to be bangin' on your new arrestor to dimple it for clearance.

link

Or.....you can go the real high priced K&N route and try to find their 1/4 inch adapter that seem to be unavailable these days. They still list a 5/8 inch adapter on their website with a part number but that's the only size it seems.

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KENO Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11254	Post Options Post Reply Quote KENO Report Post Thanks(0) Quote Reply Topic: QF M600 flame arrestor Posted: Yesterday at 7:16pm
	Lots of people buy a QuickFuel M600 and figure out that there's nowhere on the carburetor to hook your ruptured diaphragm overflow line from a Carter marine fuel pump The later Holleys have a fitting up high on the carburetor for this purpose. It'll dump fuel in well above the venturis and there's basically no vacuum at this fitting The QuickFuel has a timed spark port on the side of the primary metering block that looks like a spot to hook your overflow line to......but it's not a good spot at all because there's a vacuum there that'll drive your fuel pump crazy and that in turn drives your engine crazy, which then drives you crazy trying to figure out what's wrong. It's not the normal manifold vacuum that is normally talked about, it's above throttle plate vacuum sensed in the venturi above the throttle plate. The engine will run good at idle and at full throttle, but in between in the midrange, itll be affected. So needing a place to hook that hose, you can look for an arrestor that 1) clears the adjustment screws for the floats on the front and rear bowls 2) has the 5/8 fitting for the breather hose going to one valve cover 3) has the 1/4 inch fitting for the overflow line It hard to find one with all 3 either new or used. If you take the arrestor you have now and test fit it on the Quick Fuel and it clears the float adjusting screws, you're halfway there. If it doesn't clear sometimes you can take a ball peen hammer and dimple the bottom plate on the arrestor to give clearance and let it sit properly on the carburetor Or you can buy a spacer that goes between the arrestor and the carburetor, it'll raise your arrestor by 1/2 inch or so, meaining that you have to make sure the engine cover still closes with the arrestor installed. link to a 1/2 inch spacer Assuming that the arrestor now clears the adjusting screws and the engine box, there's an easy way to make a fitting and install it with no special tools etc. You go to any auto parts store, tire store etc and buy a metal threaded valve stem for a wheel. This 2 pack cost 6 or 7 bucks Take one of the stems, take the rubber grommets off and you have what's in the next picture Pick a spot on the arrestor and drill a hole for the valve stem For this stem a 27/64ths hole worked good. Started small and worked up to the final size. Put the stem in, slide the washer on the outside and tighten the nut. You could use a little loctite if you're worried about it coming loose. And don't forget........unscrew the valve from inside the stem and get rid of it. Now, with a little effort you can push the 1/4 inch hose on and hose clamp it if you want to. It's a tight fit. It took a lot longer to write this than it did to put the fitting in. There are other way, I've put a fitting in from the top before, but it takes up some height under the box depending on what you use for a fitting and it involved more work. I'm sure there are other things people have done, but this works good, looks good and is cheap One no real work involved choice would be the one in the link from SkiDIm or nautiqueparts, or wherever but you'll need a spacer or need to be bangin' on your new arrestor to dimple it for clearance. link Or.....you can go the real high priced K&N route and try to find their 1/4 inch adapter that seem to be unavailable these days. They still list a 5/8 inch adapter on their website with a part number but that's the only size it seems.

Jonny Quest Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: August-20-2013 Location: Utah--via Texas Status: Offline Points: 3031	Post Options Post Reply Quote Jonny Quest Report Post Thanks(0) Quote Reply Posted: Yesterday at 11:03pm
	Genius hack Ken. I went with the K & N version when I modded my 1994 -- but it wasn’t cheap. As you stated, the K & N hose fittings appear to be NLA. I used part numbers and did a Google search. Several hits, but every rabbit hole I went down stated NLA, Unavailable or Back-Order. The Holley 4160 marine version carbs that I'm familiar with all have a vent port for the clear fuel hose...strange that the QF M-600 does not. JQ
	Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum

KENO Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11254	Post Options Post Reply Quote KENO Report Post Thanks(0) Quote Reply Posted: Today at 8:15am
	Another choice is the one in the link below from Marine Parts Source No extra work involved at all. Bolt it on and hook up your hoses. link

fanofccfan Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum Member Joined: December-13-2009 Location: North Bend NE Status: Offline Points: 1798	Post Options Post Reply Quote fanofccfan Report Post Thanks(0) Quote Reply Posted: Today at 8:57am
	Ken. Could you post a photo of the project showing the fuel pump and such so all (mostly just Me) can see the hoses and how you routed them? I love this idea and am going to do it soon. The way I did it upon install has worked but is so ugly I would never allow a picture of it to be shown anywhere and especially here! Please?
	2004 196 LE Ski 1969 Marauder 19 1978 Ski

GOODMAN Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: September-17-2024 Location: NorCal Status: Offline Points: 6	Post Options Post Reply Quote GOODMAN Report Post Thanks(0) Quote Reply Posted: Today at 9:38am
	Thank you for sharing your R&D, KENO. These options come at just the right time as I wrap up the conversion from the ProTec with EFI system to QF carburetion on our '94. Finding a suitable flame arrestor has been a bit of work. It's good to know the OEM device has a chance for survival in new and improved version of our Ski. Perhaps it's time to delete the "EFI" decals along the hull exterior.

QF M600 flame arrestor

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