Please help identify

[N3tT3chMan]

I bought a boat from the neighbor it has a Merc 700 on it.. Its an inline 6 and appears to be in decent shape. I need a new timing belt as the one that was on it snapped. I dont know the year of the engine or anything else about it so i dont know what size belt i need. I found some numbers on it but they don't match anything i have found online. Here are some pictures i took of it.

any help would be appreciated.

 

[Chinewalker]

Re: Please help identify

That motor is commonly referred to as a 700 FGS, where FGS stands for Full Gear Shift. It is either a 1961 (serial 1413611 thru 1436114) or 1962 (serial 1482212 thru 1534386) model year and was when Mercury was transitioning their 6-cylinder models from the Dockbuster models to the full gear shift models.

If you're planning on keeping the beast, I highly recommend finding a copy of the 1965 & Prior OEM Mercury Service manual. It'll cover timing, ignition set-up, service procedures, etc. Start with a compression test on all six cylinders. You want less than 10% variance between high and low readings. If it passes that, then it's probably a good candidate for revitalization.

 

[N3tT3chMan]

Re: Please help identify

can i do a compression test without the engine running? I took all the plugs out last night and turned it over by hand it spins freely. I ended up giving the neighbor 75$ for the boat, trailer and motor. He said last time he ran it (years ago) it worked fine.

also you call it a beast.. i assume its a good engine to have?

 

[steelespike]

Re: Please help identify

The guys at Johns Old Mercury web site may be able to help with your belt problem.
The inline 6 is a proven design dating back to 58 and in production till at least 88.
Sure you can do a compression test.Just carefully jump directly to the starter.Don't do any thjing until you have manual in hand.I think careless trouble shooting could ruin the ignition system.