how to remove carbs from 1974 850

[sandhopper2]

Is there a special tool to get the nuts that hold the carbs on ? I can't get the socket to fit on 1 of the nuts on each carb
Do I have to modify a 7/16 scoket to fit in the space ?
Larry

 

[James R]

Re: how to remove carbs from 1974 850

As I recall an open ended is used but you need to remove everything to get in including the front plate and starter motor. A pain design.

 

[sandhopper2]

Re: how to remove carbs from 1974 850

can't get open end in there , I have everything off just putting the power head back together and thought now is the time to clean em up
Larry

 

[Doc279]

Re: how to remove carbs from 1974 850

I just finished doing this. With the front plate off, starter off and the distributor cap removed. It is possible with a stubby open ended wrench. A 1/4" drive swivel and a shallow socket can be used in a few places. Turn the distributor to the wide open position and it allows you more room. I changed the orientation of the double hoses coming into the top carb because of lack of room. I placed the double cap to the lower carb and ran the single hose to the top carb. I reasoned that the fuel pump was supplying pressure to both and it really did not matter???? I ran the engine earlier this week on a hose and it had no trouble running that way. I have not mounted the engine on my boat and I have not lake tested yet but I really don't think that it will make a difference. I have been working on the same engine and I found a Mercury Service Manual at the used book store. Shoot me a message if you need anything - I can copy and e-mail most anything that you might need.

 

[James R]

Re: how to remove carbs from 1974 850

Remember if man put it together man can take it apart. That has always been my engineering philosophy. Just have to apply thought.

 

[wired247]

Re: how to remove carbs from 1974 850

Just a plain old open end 7/16" end wrench.

 

[sandhopper2]

Re: how to remove carbs from 1974 850

Ok I will take another look at the open end wrench Idea , as so many have said they did it this way
I have the power head on a bench , so everything is out of the way
Larry

 

[Chris1956]

Re: how to remove carbs from 1974 850

Gee, I never had any issue. You do have the starter off right? Seems to me that a 3/8" socket and extension would fit some of the nuts.

 

[Chris1956]

Re: how to remove carbs from 1974 850

I guess I used a short box wrench or maybe an open end wrench on the rest.

 

[sandhopper2]

Re: how to remove carbs from 1974 850

Ok got them off
Had to pull the cover for the needle and seat 2 small 1/4 in screws
This design does not make sence to me , I took lots of pictures this time so I hope I can clean them up and put this back together
Larry

 

[James R]

Re: how to remove carbs from 1974 850

I did say that it was a pain design. Pleased you found a way.

 

[mercurymang]

Re: how to remove carbs from 1974 850

Yep. I always remove the float bowls first. I have never found an easier way.

 

[Doc279]

Re: how to remove carbs from 1974 850

My float bowls are cast to the carb bodies? The cover for the screen had to be removed first.

 

[Chris1956]

Re: how to remove carbs from 1974 850

Right, sorry I forgot about that. The bowl covers (3 on my IL6), have to come off before carbs. I routinely took them off, so I forgot about them. The fuel lines were in the way of everything....

 

[Doc279]

Re: how to remove carbs from 1974 850

When I re-installed my carbs on the 1974 850 - I moved the double hosed bowl cover to the bottom carb due to lack of room behind the starter. It was originally mounted on the top carb. The fuel pump supplies pressure to the double hosed cover and feeds the sister carb.

Does anybody think that I may have a problem because I traded locations? I've run the engine on my stand with water pressure from a hose and it had no problems running. Obviously, I did not have a load on the motor. I really don't see that it would make a difference but I am not sure until I run the boat later this spring.

Just thinking out loud here.

 

[Chris1956]

Re: how to remove carbs from 1974 850

Doc, That might increase the fuel pressure due to gravity on the bottom carb, and or starve the top carb. Watch for lean running on the top cylinder and leaking of the lower carb bowl.

Crap, I would switch it back to original, just to eliminate those possibilities...

 

[Doc279]

Re: how to remove carbs from 1974 850

I will attempt to move the double hosed cover back to the top position before mounting the engine. Between the starter motor and a set of vent hoses for the crankcase - there REALLY is not room for it on top? My hoses were rotten and I replaced with 5/16" line and clamps. The angle is what kills the space.

I will make an attempt to move it back - just because it bothers me. Thanks for the feed back and thoughts!

 

[Doc279]

Re: how to remove carbs from 1974 850

Looking at the on-line parts manual for a 1975 Mercury 850 it looks like that Mercury went away from the double lines into the top carb screen cover. They instead used a tee fitting between the two carbs and ran a single line to each. I believe that I am just going to remove one of the double barbs into the lower carb screen cover and install a plug there. I will install a 5/16" tee in the line between the two carbs and call it good. There is absolutely no room behind the starter that will accomodate the double lines into the top carb screen cover. I am waiting on it to warm up here before I venture back into the garage for any length of time! We will have a high today of 33 with more warm temperatures later in the week. This vortex has been brutal for us southern people!

 

[sandhopper2]

Re: how to remove carbs from 1974 850

Mine has 1/4 fuel line and that is what I replace it all with , also used normal clamps and not the crimp style
what is the small line on the side of the block for looks to be 1/8 lne did not have clamps so I guess it is vent
That line is hard and broke so I need to replace , what do I use ?
Larry

 

[racerone]

Re: how to remove carbs from 1974 850

There is a small line that takes oil / fuel from the bottom of the motor and pumps it back to the top of the motor.----Dealer likely has it in a bulk roll.-------Just buy what you need.