1972 Sea Ray Mercruiser 165

[Will Fish]

Re: 1972 Sea Ray Mercruiser 165

I had a similar problem..same motor but had a fresh rebuild. Timing was way off. I'd take the distributor out and start over, dropping her in correctly. I also advanced the timing to 8. Runs a lot smoother and get another couple of rpms.

As for the carb, you need to adjust it after the timing is right. My adjustments were 1 3/4 turns.

 

[Ike-110722]

Re: 1972 Sea Ray Mercruiser 165

I think you are right. I have been looking at the timing and advance and it is just not right so I am going back to the beginning and starting over.

My carb adjustment was about the same. I started at about 2 1/2 but ended up at about 1 3/4.

I put a new fuel pump on it today. It needed a new one anyway so no harm done, but no improvement either. Took only a few minutes to change it out.

 

[bruceb58]

Re: 1972 Sea Ray Mercruiser 165

My carb adjustment was about the same. I started at about 2 1/2 but ended up at about 1 3/4.

REPEAT...your carb idle adjustments mean nothing at 2000 RPM.

 

[Ike-110722]

Re: 1972 Sea Ray Mercruiser 165

Update: I finally decided to let a pro look at it. Took it to them in mid August. They had it for a month. I won't list everything that was done but the major ones were, replace distributor with fully electronic, and Carb rebuild. A lot of other stuff was done that had nothing to do wit misfire/backfire but needed doing. Got boat back on Sept 11. Lousy weather prevented me for doing anything until 13th. Still doesn't run right, back fires, stalls. Arrgh!

I keep a log on everything I do or have done on the boat. Went back through it. The last thing I did was replace the coil with a new mallory coil with ballast resistor. So what the hell. I took it out and put the old one back in. Now it runs almost perfect. Had it up to max rpm. No misfire, no stalls no backfires. This one fooled us all. People usually don't suspect a new part. But problem solved for now.

 

[998cc]

Re: 1972 Sea Ray Mercruiser 165

I keep a log on everything I do or have done on the boat. Went back through it. The last thing I did was replace the coil with a new mallory coil with ballast resistor. So what the hell. I took it out and put the old one back in. Now it runs almost perfect. Had it up to max rpm. No misfire, no stalls no backfires. This one fooled us all. People usually don't suspect a new part. But problem solved for now.

Good thought keeping the log. Great that she's up and running nearly where you want her!

I am curious as to why the ballast resistor was necessary with the Mallory coil. I assume there was already one in the boat's electrical system for the original points/coil setup. Assuming there was another method of resistance in the circuit such as an ignition resistor or resistance wire, adding yet again a secondary resistance inline with the coil, which likely has a lower resistance (higher current demand) than the OEM coil, it makes perfect sense that the Mallory coil would perform very badly. There may well be nothing wrong with that Mallory coil.

998cc

 

[Ike-110722]

Re: 1972 Sea Ray Mercruiser 165

There may well be nothing wrong with that Mallory coil.

Exactly my thought. I want to research this a bit No the original did not have a ballast resistor. So I am going to look into it and may put the coil back in without the ballast resistor. I called my mechanic to ask what he thinks, but he hasn't called me back yet. I tend to be cautious about these things. I just put a new fully electronic distributor in it and I don't want to fry it.

 

[Ike-110722]

Re: 1972 Sea Ray Mercruiser 165

I went over the instructions several times. Mallory is very explicit that the ballast resistor must be used to prevent destroying the electronic ignition module in the distributor. If you leave the resistor out, over time it will ruin the ignition module. I made sure when I first installed it to follow their instructions to the letter. The mechanic also checked it over and found nothing wrong either. I talked to him this morning and he said that there was nothing to indicate that it was the coil that was causing the problems.

But Mallory does say that the distributor will work with the stock coil. Well it does, but it doesn't work with their coil. So there must be something wrong.

 

[Volphin]

Re: 1972 Sea Ray Mercruiser 165

I had the same issue with a Mallory coil on my 4.3L. I went back to my old one. I'm still on my old '89 coil and it runs flawlessly.