QF M600 flame arrestor

Message Topic Search Topic Options Post Reply Create New Topic Printable Version Translate Topic

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.

QF M600 flame arrestor

About CCF

Donate

Partners

Contact