Mercury V6 175hp SYNHRONISING

[TUGSGF]

Hi all, I have two problems that I am sure someone will know the answer to point me in the right direction. Mercury V6 175hp 1979 Blueband. The general problem is starting, if the carbs are stripped down cleaned and reassembled then she will start and run for about 3 to 5 minutes before stopping then will not restart. There is plenty of clean fuel in the line and all carb bowls are full. Problem one: the carbs are WH7 1A , WH7 2A and WH7 3A. According to the standard jet table the vent jets in cylinders 3,5 and 6 are ?none? now does this mean that there should be a blank jet or no jet at all? Currently there is 80,80 and 90 respectively. Could this be a problem? Unfortunately I have no history on this engine. All the main jets and idle jets are to the standard jet table.
Problem two is synchronising the engine if I set up No 1 at tdc and bring it back to 0.462in the 0.462 mark on the flywheel is not even in the timing window let alone near the pointer so as you can see I have a problem in trying to synchronise the carbs and timing. Could this be the wrong flywheel cowl? Or is there another way to synchronise the engine?
Any help in this would be greatly appreciated
Thank you
Graeme

 

[j_martin]

Re: Mercury V6 175hp SYNHRONISING

First, if you're cleaning the carbs and they gum up in a few minutes, you have some old rubber parts, or even the fuel tank that is disintegrating and contaminating the fuel. If there is one of those little finger sized filters on the engine, it is just a screen, and at that is likely to plug up quickly.

If it's getting fuel, check for spark when cranking. The energy for the spark is generated by the stator, so a weak starter or battery will not spin it fast enough to get a good spark.

None means just that. You should be looking at a threaded hole.

If you have the 16 amp flywheel with the ring of bolts holding the flex plate to the hub, someone has disassembled it and put it back together wrong. You should be able to remove all those bolts and turn the flywheel to the right position.

hope it helps
John

 

[TUGSGF]

Re: Mercury V6 175hp SYNHRONISING

Thanks john, when the carbs are removed and stripped they appear to be in good clean condition with very little or no sign of contamination but it seems strange that she starts on reasemble. there is a good spark but will check the flywheel.
fingers crossed.....

 

[TUGSGF]

Re: Mercury V6 175hp SYNHRONISING

Hi, well i have removed vent jets where stated and engine runs a lot better and for longer albeit a bit lumpy but not too bad. you was right about the flywheel, guy before must have reassembled it wrong...
one thing i noticed though is when i set it up to TDC on No 1 and then set the pointer to 0.462 as prescribed when i put it back to TDC i noticed that the pointer does not align with 0 degrees on the flywheel. is 0 degrees TDC?

 

[j_martin]

Re: Mercury V6 175hp SYNHRONISING

TDC and Zero are the same. It should line up. The reason they use the .462 thing is that it is theoretically much easier to be accurate than to detect TDC directly. A few thousandths error at .462 is a small fraction of a degree. A few thousanth's at TDC could be several degrees. (just a sine function deal)

The bigger flow carbs came off a horizontal front engine, and I think your's is vertical front. (reed orientation) Also, they would flow more air on a 200. You may have to play with your jets to get them tuned good for your motor. They should give you a strong top end, but they may have a lousy idle no matter what. Usually it isn't recommended to put on bigger carbs unless you do some porting and stuff to increase flow and HP.

hope it helps
John