I have rebuilt one carb in my life.   

Would you recommend:

A)  Trying to just swap the accel pump diaphragm

B)   Attempt the full rebuild

C)  Do the QF M600 & fuel line change  (Have heard about from JQ and read about in other posts).  

Anything else I should check to decide?

Starting to get warm here and don't want to miss the start of the season.

If you do want to step-up to a new carb, then the QF M-600 is a good choice.  It has features that the 4160 should have but doesn't.  If you do choose to go this route, keep in mind that the fuel line inlet on your existing set-up may be just a bit different than on the QF carb.  No big deal, but it's not 100% plug-and-play.  To make it über simple, you can go with the Sierra fuel line with the 90 degree elbow at the carb end.  USCG approved and everything.  Then, the QF would be plug-and-play.  I think that it's Sierra part number 8-8114 (31") or 8-8115 (25").  Don't forget new carb / spacer / intake gaskets.  

JQ

If you rebuild what you have for around 50 bucks, you'll know how to work on carburetors forever. 

If you buy a M600 and bolt it on, you won't really have any experience beyond bolting it on and hoping for the best.

Your problem with a hard start after sitting for 5 months is that some of the gas evaporates/drains/leaks and a slow turning engine while it's being cranked by the starter takes a while to fill the bowls.

If you dump a little gas down the carburetor primary throats and turn the key, the engine should fire and the fuel pump will pump gas to the carburetor quicker. You may have to do this a couple or few times to keep it running, but it's a lot better than what you had to do and a lot easier on the starter and battery..

That's just "life with a carburetor"

Hopefully your life with a carburetor involves starting a cold engine by pumping the gas a couple of times to accomplish the same priming as dumping gas down the throats after the winter layup. It should start without much cranking at all when primed like this. Sitting for a week won't empty the bowls so the priming with the throttle makes the accelerator pump squirt gas down the primaries.

Or ...........you could get the M600 and then learn how to "fish" with the Holley afterwards since there's not much difference in the 2 carburetors  Most obvious difference being the needle and seat assemblies and the floats are different between the internally adjustable Holley you have now and the externally adjustable M600

If you do that the 18-8115 line JQ mentioned is the right length

PS you did the DUI replacement, you can rebuild a carburetor.

At startup this season, after cranking for a while, did end up pouring gas in the carb about 3 times to get it to start.    Normal life with the carb was the couple pumps to start....but last season that started to not be enough... then I noticed the fuel leaking.

Any specific video or printed instructions you recommend for the marine 4160?   Had watched some car video before asking and the guy made it seem complicated. 

Here's a link to a good video in a CCF thread 

http://www.correctcraftfan.com/forum/forum_posts.asp?TID=49871&title=video-holley-4160-carburetor-rebuild" rel="nofollow - link

JQ

https://www.youtube.com/watch?v=OFcVI5YdHHA

JQ

I went thru a leaky accel pump last year. The advice I got when looking into it was to make sure the sealing edge of the pump was flat, not sure if they warp over time or from the heat of the motor... anyway, mine was infact warped... easy enough to check against a flat surface.  and the part was cheap.  the 2nd advice I got was to use one of the extra thick base gaskets that ski dim sells. my boat (88 mastercraft, indmar 351w) uses a spacer so I needed two of them.

part number on ski dim gasket

Carburetor Base Gasket,  RM0054B

I had to also get some other parts as well and these guys were very helpful on the phone www.allcarbs.com/

That is a great skill to have, but it takes time and there is a learning curve.  Buy plenty of manifold gaskets in case you have to remove it  from the engine and pull it apart if it's not quite right .

I've found it very satisfying to bolt on a new Holley or QF and turn the key and it fires up and runs great. I don't know what the attraction is for a QF 600 over a Holley 4160 600.  They are both vacuum secondaries. I've never had to adjust the floats on the Holleys and they don't need an after market fuel line. 

You could at least quote a little more of what I said like the part below 

Who knows , maybe he'll get the carburetor off and find a loose screw or 2 or 3 or 4 on the bowl mounting screws or on the accelerator pump mounting screws and get off real easy with the fix if there were no other problems with how it runs

KENO wrote: . Or ...........you could get the M600 and then learn how to "fish" with the Holley afterwards since there's not much difference in the 2 carburetors  Most obvious difference being the needle and seat assemblies and the floats are different between the internally adjustable Holley you have now and the externally adjustable M600

Stuff that QuickFuel has but Holley doesn't

- Changeable jets in secondary metering block

- Billet metering block

- Adjustable air bleeds

- External float adjustment hardware

- Float bowl site glass

- Black coating (QF claims there is some magic ju-ju with the black)

- Fuel inlet at 90 degrees (3 o'clock)

- Toolbox sticker in shipping box 

- Air vent for cooling the electric choke element (acknowledgement to KENO for this tidbit)

- Vacuum port for clear safety tube from mechanical fuel pump

- Fuel inlet at 135 degrees (5 o'clock)

That depletes my knowledge base.

JQ

Thank you for the video links and suggestions.  Have done the rebuild and hope to get it back on the boat (30 minutes away) in the next day or 2.  

I was surprised how easy the primary bowl bolts came loose... they were not much more than hand tight...wish I had checked that before removing the carb from the boat, but had already brought it home and opened the rebuild kit ... so went ahead   The accel pump cover had the face warping I have heard was typical, so sanded that flat.   Didn't see anything else "wrong" internally in the carb, but didn't expect to since it ran fine before...just leaked.

Was more than 1/2 way thru the rebuild when I hit a few snags.   Let me know if you think any of these require redoing:

1.  The kit (from nautique parts) did not have the pump discharge needle valve, so used the old.

2.  The kit did not have the right size cork gaskets that go between the choke and the carb and the one between the diaphragm housing and the carb, so I very reluctantly used the old ones...

Same with the pump discharge needle valve, probably just fine.

I wouldn't worry about either issue 

Now you've rebuilt 2 carburetors in your life 

And JQ, if you use a 9/16-24 banjo fitting on the M-600 bowl, you can aim that hose connection anywhere you want at a right angle to the bowl instead of straight out. 

You remove the adapter that's screwed into the bowl and replace it with the banjo fitting 

Same threads as Holley uses on a number of their carburetors with the same inlet arrangement.

You can get one from a variety of places with a part number like Holley 26-25 for 5/16 fuel line as one example. Or you can find them for different size fuel lines.

JQ

This was my first time opening a carb of any kind and I was a bit anxious to dive into it and potentially leave myself with an extended downtime if I messed anything up. Now, I'm fairly confident I've done it correctly and I'm looking forward to putting it all back together and tuning it.