1500 mercury no spark

[cturboaddict]

If you have the mercury switch disconnected, on a 1973 it will be right in front of the 3 wires on the port side of the switchbox, then jump 12V to the red wire on the starboard side, then jump 12V from there to the white terminal right above it, on it is hot wired crank it over see if it sparks, if not most of the time it is the trigger, but possibly the switchbox.

If it doesnt spark, while its hot wired, take a jumper from the black on the port side and just momentarily tickle it to the brown see if you hear it spark inside the cap, if so the trigger is bad.

And if you dont? Mine made no noise?

 

[wired]

I think the trigger is inside my distributor? Im stuck on how to diagnose the switchbox and coil. I do need a spark plug wire though with the 10-32 threaded end... One of the ones in my dis cap wasnt connected, and i found out why.

The trigger is molded into the distributor and gets changed as a unit. Sometimes I'd like the ability to go back in time and punch a factory engineer in the mouth.

 

[cturboaddict]

The trigger is molded into the distributor and gets changed as a unit. Sometimes I'd like the ability to go back in time and punch a factory engineer in the mouth.

WELL BROTHA... Looks like im now in the same boat as you.... I went to do this test...
http://www.cdielectronics.com/InstallSheet/114-2986.pdf
And it chugged the first time i touched ground. but after that nothing more than some little fizzles of arcing sounds coming from somewhere (im guessing the distributor). Put it all back together and I GET SPARK but only at first part of the cranking and when I let off of it.....

 

[cturboaddict]

CLEANED CONNECTIONS~~~~~~~ RUNS!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[wired]

Sounds like you had the same old motor syndrome I had.

CLEANED CONNECTIONS~~~~~~~ RUNS!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[cturboaddict]

Yeah... Seems as if. I now gotta get a new plug wire and find out how the lower unit is. Think I might have me some water in the lower?

Thanks for letting me barge in!!! What did all that stuff from CDI end up costing you? If this motor works out, I might want to pick up some of that stuff too.

 

[Bill Gohr]

If

And if you dont? Mine made no noise?

It doesnt the trigger is bad, and yes the trigger is part of the distributor body, and yes, its a pain in the butt if you don't know what you are doing, probabaly something you dont want to tackle really. Just to make sure rotate the motor by hand a little bit if you get the rotor to line up with a wire in the cap it will spark on tthat wire, but generally it will be arcing inside the cap.

Wired, if it is a 1973 longshaft, is the exhaust cover smooth or does it have ribs cast into the cover?? Which piston went, 1 or 3?

 

[wired]

It doesnt the trigger is bad, and yes the trigger is part of the distributor body, and yes, its a pain in the butt if you don't know what you are doing, probabaly something you dont want to tackle really. Just to make sure rotate the motor by hand a little bit if you get the rotor to line up with a wire in the cap it will spark on tthat wire, but generally it will be arcing inside the cap.

Wired, if it is a 1973 longshaft, is the exhaust cover smooth or does it have ribs cast into the cover?? Which piston went, 1 or 3?

Smooth cover and it was #3

 

[wired]

Wired, if it is a 1973 longshaft, is the exhaust cover smooth or does it have ribs cast into the cover?? Which piston went, 1 or 3?

I guess this is whats referred to as a circle C block. The "C" is on a round raised area anyway. I dont have a frame of reference but the exhaust ports do look larger than some pictures of other non J block 1500 blocks Ive seen. In any case it does have the smooth cover. Any advantage to using a ribbed cover over a smooth?

 

[Bill Gohr]

Ok so that should be the very rare 73' square port block, it only came on early production 73' 1500's and only on long shafts, we used to look for them for circle race boats. If you look at the exhaust ports closely they should look like the port was machinedand then the inside corners were milled again with a smaller tool.

Since it took #3 that usually means it had too much timing, it was originally timed at 23 then we would retard them to 21 or less

 

[wired]

Ok so that should be the very rare 73' square port block, it only came on early production 73' 1500's and only on long shafts, we used to look for them for circle race boats. If you look at the exhaust ports closely they should look like the port was machinedand then the inside corners were milled again with a smaller tool.

Since it took #3 that usually means it had too much timing, it was originally timed at 23 then we would retard them to 21 or less

Yep. Thats the one... You can see the burned away piston dome through the port.

 

[hotdaddy27]

So you gave up a running OMC for a messed up Merc?

Isn't that the opposite of the way it usually works???



HD

 

[wired]

The lure of the big Merc is strong. I'm a mechanical engineer and I can fix whats wrong with things. I'll take form over function most times.

So you gave up a running OMC for a messed up Merc?

Isn't that the opposite of the way it usually works???



HD

 

[Bill Gohr]

Well that 1500 will never out run a good 140, been pairing them up for years.

You can the the triple machined ports in you pic, that is the 73 squareport

 

[Jimway]

"The Lure of the Big Merc is Strong".... and in the words of a Big Guy who knew a little bit about the force...."You don't know the power of the Dark Side"

 

[wired]

Well that 1500 will never out run a good 140, been pairing them up for years.

You can the the triple machined ports in you pic, that is the 73 squareport

How do those ports compare with the later J or XS blocks?

You nailed it on cylinders 1 and 3. Both pistons need to be replaced and the rod on #3.

 

[hotdaddy27]

Well that 1500 will never out run a good 140, been pairing them up for years.

You can the the triple machined ports in you pic, that is the 73 squareport

I should just send you my "88 Special" and have you make me a nice stout 140!

HD

 

[Bill Gohr]

I should just send you my "88 Special" and have you make me a nice stout 140!

HD

Yes you should

 

[Bill Gohr]

How do those ports compare with the later J or XS blocks?

You nailed it on cylinders 1 and 3. Both pistons need to be replaced and the rod on #3.

If you look at the upper corners of the exhaust port you can see the secondary maching operation, these were the only ones that came that way.
J blocks never had this and the intakes are loer than these are so they had more punch, the circle boat guys in stock classes loved them because they came stock this way and that made them legal to run.

Also you don't need 2 pistons, you need 6 these had the small locating pins for the ringsand they tend to sink into the pistons, so replace them all, just bore it .020 and put 6 wiescos in it, be done with it, I have rods if you need one. This is not a job you want to do if you havent assembled one of these before so you may want to send me this one.

 

[wired]

If you look at the upper corners of the exhaust port you can see the secondary maching operation, these were the only ones that came that way.
J blocks never had this and the intakes are loer than these are so they had more punch, the circle boat guys in stock classes loved them because they came stock this way and that made them legal to run.

Also you don't need 2 pistons, you need 6 these had the small locating pins for the ringsand they tend to sink into the pistons, so replace them all, just bore it .020 and put 6 wiescos in it, be done with it, I have rods if you need one. This is not a job you want to do if you havent assembled one of these before so you may want to send me this one.

I'm just getting it together for the season right now. I know its not going to be fun but I'll have it together by memorial day. Its coming apart in the winter for a full rebuild. I did pick up a full set of rods for $20 shipped on ebay so I'm good there.