I have everything dialed in (I think).  Float levels are set so that the level is centered in the sight glass on both bowls, idle mixture screws are set to the highest vacuum achievable, idle is set at 675 in gear.  Accelerator pump is adjusted so that the arm is just touching the screw with the spring at idle.

Engine starts and idles great, and has tons of power compared to the old 4160 that was on it.  I love this carb, except for one thing.  

Upon medium to hard acceleration from idle, it bogs badly.  Almost always to the point that it will stall.  If you ease into the throttle, it runs great. 

ALSO, if you're running down the lake and accelerate into the secondaries, it bogs there too.  Not as bad, but definitely noticeable.  Half a second later it takes off like a rocket ship though.  

I have checked and rechecked the accelerator pump adjustment.

I pulled the accelerator pump nozzle and found that it was a 35.  Out of curiosity, I pulled the one in the old 4160, and it was a 25.  Is there a chance that the new carb is getting too much fuel with the 35 in there?

- Boat tied up at dock, running in neutral

- Remove spark / flame arrestor

- Remove throttle cable linkage from carb (so you can manipulate the throttle by hand)

- Verify fuel level in carb bowls sight glass

- Shut off engine

- Look down through carb throat and manipulate the throttle linkage from idle to full throttle (fairly quickly)

- Verify that there is a steady stream of fuel squirting from the nozzles down into the carb throat

I'm a big fan of QF carbs, but even new stuff can have a hiccup -- ask me how I know...

Also, the QF M-600 is not a "double pumper" carb, so there is no accelerator pump circuit on the secondaries.  In my 1994, I installed a QF M-650 which is a double-pumper carb based on the 4150 design.  I like having the extra accelerator circuit at mid to upper throttle levels.

JQ

Bog is still there.  Both at initial acceleration, and when the secondaries kick in.

Yeah, I was thinking about this last night, and I thought it might be a good idea to actually check to see if fuel was being delivered by the accelerator pump.  Meant to look at that this morning, but I forgot.  I'll check that in a bit.  That would be something if that was the problem.  

It is doing it very quickly though.  I wonder if that is the issue.  Should I try putting the 25 that I have in there and see if that makes a difference?

https://youtu.be/BB4BG_w_Fwc" rel="nofollow - Video of Fuel Delivery

JQ

Most people do just that and have no issues.

They definitely aren't changing squirter nozzle sizes, pump cams, etc.

The .035 nozzle is the stock size in the M-600

Your distributor as shown in the PN thread is good for about 30 degrees total advance when it's set at 10 degrees initial. It was let's say conservative to keep warranty claims down on 87 octane gas

10 plus 20 from the weights, so I' do like TRB said and crank up the advance a little to 12 or 14

Have you looked at the transition slots with the carburetor upside down to verify that you have a square opening showing and not a longer rectangle. The rectangle means you're idling on the transition slots and that makes for a hesitation issue on takeoff if the exposed part of the slots are too long

You may have some "twiddling" to do to get that right balance of idle speed, timing, exposed transition slot, and idle mixture screw adjustment for a no hesitation takeoff.

It all starts with a square transition slot opening.

The M-600 also has a screw on the secondary diaphragm housing that can be used to vary the opening point and rate of the secondaries. It's normally open about 1 1/2 turns and needs no adjustment in most cases.

In neutral, it was about 1 inHg higher.

I will certainly try adjusting the timing again.  I would have tried it today, but it has been raining and I didn't feel like getting soaked on a test run.  Should be nice all week though, so I'll probably try this tomorrow.  

THANK YOU ALL for the help so far!

Just as a side note, I also went to the QF M600 this summer and the throttle arms on the new carb are slightly different from the original 4160 on my '77.... I did have to make some mounting adjustments and change the brackets (location) slightly... The arms look very similar, but had slightly different actuating rates. Just something to check.

There's something that's just not quite right about this statement above.

Substitute open for closed in the sentence and it works a lot better 

Touching at idle and .015 clearance at full throttle position

I readjusted the idle mixture screws again today, setting the idle as low as possible first, just in case the transition slots were the problem.

No change.

Tried adjusting timing to 14 BTDC.

No change.

It is running great, other than this crazy bog.

I'm going to upload a video of exactly what it is doing.  Maybe seeing and hearing it will make a light bulb go off in one of our heads.

https://youtu.be/PtyKapmZTQk" rel="nofollow - Bog Video

Or supply the one you have now with the temporary tank

Or check the anti siphon valve and the suction in the tank clear of any debris.

Or............well you get the idea, I don't think it's the carburetors fault 

I'll try a temp tank.

https://ibb.co/fpN4r7L" rel="nofollow">

https://ibb.co/nw8Ybdr" rel="nofollow">

Did you misplace it somewhere in the pile of other boats?

Got too may other things going on?

Lost interest?

So many questions 

http://www.planetnautique.com/vb5/forum/nautique-topics/general-nautique-discussion/671943-silver-cove-marine" rel="nofollow - link