Quick fuel carb install questions

I just pulled the holley 4160 and put a m600 QF carb on my '86 Martinique 351...everything swapped over easily except the QF carb came with its own ground/neg wire (from carb body) connected to the neg tab on the elect choke module. The holley elect choke was connected to both a neg & pos wires from the engine wire harness. I know to attach the pos wire off the engine harness to the new QF carb elect choke pos tab, but what do I do with the neg wire off the engine harness? Can I leave it loose or should I try to slip it under the same neg tab that the carb's neg wire is ttached to?

Id just leave it loose... It's no more a danger than that big piece of grounded metal under your carb.

I would guess they supplied it since not all engine harness has a ground wire for the choke. PCM does but I had to make one for my HM to ground the choke when I put the Holley. Not having seen it I wonder rather than not hooking it up,if it can be removed completely?

What was the fix

I doubled up both the qf carb supplied ground with the harness ground on the choke neg connection tab in a temporary fashion untill i can get to the hardware store for the proper connection (soon to fix).
Otherwise, the install was pretty straightforward. .....just had to adjust the throttle linkage & associsted support (which required unbolting the support and moving it forward to the next set of bolt holes). That 25" flex fuel hose connected up nicely.
The QF carb primed itself pretty quickly and fired up nicely. Required a little adjust on the idle set screw the it ran like a charm.
I noticed the QF instructions said to retighten associated bolts after running a while, so I'll check those again soon. Again, it appears so far to be a great upgrade...boat has never run better for me, but only my second season with the old girl...i hope to get severAl more years outa this 30 yr old beauty....I'm 53 so this boat reminds me of my heydays. I love the vintage...
Many thanks again...this is a great forum.

Cheers..,,
Jeff in Alabama

I always got rid of the pig tail. One time the pigtail was sparking at the carb base so I trashed that idea and stuck with the factory stuff. You won't find a better running bolt on carb for stock applications on the market. They seem nearly fuel injected. Congrats.

You calling me a liar ? It was sparking. I think I ended up putting a new choke puck on that one too.

TRBenj wrote: Grounds don't spark, man. The entire engine is a ground. .

Tim,
They will spark when there's isn't another ground wire connected to the block and there's a connected load somewhere!

My only critique so far is that the QF carb doesn't come with its own (top hat) air filter unit, the Holley filter fits fine, but the center connector bolt is a different size that the Holley air filter connector bolt (the Holly bolt with the nice round black screw knob is too large in diameter for the QF carb). I tried a smaller, 3-in diameter metric machine screw, but the thread is wrong (the mach screw thread too fine I think). This center bolt screws down into what appears to be a plastic (black) threaded receiver hole on the QF carb.

I can't tell if the QF receiver hole is a black plastic coating over a metal receiver hole, or really jsut plastic...either way, I don't want to strip it with the wrong size/thread bolt.

I have a question in to the QF guys, but thought I'd ask here as well.....anyone figured out the specs on the correct center bolt for bolting down the top hot air filter element to the top of the QF M600?

Not sure how it can be the same as the holley, when the the center bolt I took off my holley is too large for the QF M600....it/the holley center bolt, is noticeably larger than the boss (threaded receiving hole) on the M600...this size difference can be seen with the naked eye.

The connecting bolt that came off my Holley had a nice black hard- plastic screw down knob at the top, a little less than an inch in diameter. Is this the one that should fit the QF M600?

If so, the only thing I can think is.....if the "boss" isn't plastic, is it metal underneath some plastic-like protective coating, and would the original Holley bolt actually fit the M600 boss if I force it and grind through the black coating on the "boss"?

Otherwise, it needs a smaller diameter bolt of some thread type that I can't find. I tried an M6 (or M8?) diameter machine screw, which will make about 1 & 1/2 turns before tightening up because the thread pattern is wrong (too fine).

When I get back to the house, I'll go look at my QF M-600 and see what I did with the flame arrestor bolt. If memory serves, I found a bolt in my bin that was the right diameter and thread count. Then I bought a new S/S bolt that was the correct length from the local big-box hardware store.

One note...I had to change-out my original flame arrestor as the QF carb has adjustable floats. The adjusting hardware did not allow my original flame arrestor to sit flat on the carb. I needed a raised flange type of arrestor. I decided to go for a little chrome bling and bought a K&N marine flame arrestor/air filter unit.

JQ

Tim, the 600 has shorter bowls than your big dual feed. The stock flame arrestor swill generally run into the adjustable float screws and won't seat on the carb flange. You could make a spacer or seek a different arrestor.

It could also be that the rear bowl doesn't have a metering block I can't remember exactly.

TRBenj wrote: You shouldn't need a raised flange arrester to clear the adjustable floats. I have used a few different non-raised 8" diam arresters on my qf750.

Tim:

I tried to use the standard flame arrestor, but it would not sit flush on the carb body -- due to the float adjust hardware. I probably could have used several gaskets in a stacked configuration to get over the obstruction. Instead, I went with a raised flange arrestor.

JQ

https://www.youtube.com/watch?v=mE_xTUXQJQ8

gun-driver wrote: https://www.youtube.com/watch?v=mE_xTUXQJQ8

Informative video , worth watching if you have questions.   You are going to like your QFT carb.   BTW Holley owns them now.