Distributor / Trigger replacement '74 850 Merc

[tjerzak]

Hi have a bad trigger and need to repace it. I have already disassembled the distributor once and replaced the trigger with a used one, only to discover it was also bad! I purchased another used whole distributor on ebay but the rotor shaft is the short version. I wired it up and jumped the main coil out close to ground and get spark when I manually turn the rotor. I now must disassemble both distributors and swap rotor shafts. The last time I damaged the casing on the top bearing.
Does anyone have any tips for removing that top bearing without damaging it?
I can get a new trigger for $300. Should I bit the bullet and get the new one instead of messing with these used ones? I've owned Mercs all my life and never had a trigger problem. I'd hate to go through all this distributor work just to have the use trigger I put in go in a month.
Thanks,
Tom

 

[timmathis]

Re: Distributor / Trigger replacement '74 850 Merc

The new one you get will have to be put together also with bearings etc. Same job both ways. The new one could last longer like you said. It's your call, your money and time.

 

[Chris1956]

Re: Distributor / Trigger replacement '74 850 Merc

TJ, I do not have any tips for you, however, I have always been told that the triggers on those distributors are non replaceable. I also have seen rebuilt triggers (comes with the whole dist casing) on the web. Were you able to find just the trigger for replacement?

 

[shearpin]

Re: Distributor / Trigger replacement '74 850 Merc

Alot of these 70's merc's are fun trying to get replacement parts. Their is a company out their that will rebuild the distributor placing a new trigger in it. Been down this road with a no spark 73 65hp merc. Don't know if Iboat will allow me to drop the name of the web site but the company name is "rapair incorported ". You may have to find a repair shop in your area to deal with them.

 

[emckelvy]

Re: Distributor / Trigger replacement '74 850 Merc

You may be able to get the top bearing pried out without a lot of damage by using a couple of very thin screwdrivers or small rods thru the holes in the side of the housing. These are the holes directly below the bearing and if you're careful you can try prying upwards, directing the tools to the outer race rather than onto the bearing shield.

A couple of very important tips when disassembling the distributor: Mark the copper 'chopper' disc so you know which way goes outwards, this orientation is very important; also when you're tapping the rotor out, hold the disc in place so it's not driven into the trigger.

Be sure to replace the snap ring which holds the lower bearing in place. This snap ring will rust and become brittle over the years and many a distributor has been destroyed by chunks of snap ring coming loose and flying around inside the distributor cap. You can get a new one at the dlr or most auto parts stores.

HTH..........ed

 

[tjerzak]

Re: Distributor / Trigger replacement '74 850 Merc

Thank you all!
I found 2 sources for rebuilt triggers. This guy quoted me $275.00 and even said if I send him the old distributor, he would rebuild it for me with the new trigger for around $50.00 more.
http://stores.ebay.com/S-and-J-Marine
Has anyone ever dealt with him?

My issue is I want to use the boat before the summer is over. Upstate NY has a short boat season. I'm going to try and swap triggers tonight.
Thanks,
Tom