DR/FGS parts compatibility

Mercury Outboard  general discussion

DR/FGS parts compatibility

Postby mark 55 » Fri Mar 08, 2019 6:15 pm

I realize the gear cases are obviously very different between DR models and FGS models of the same motor. I'm mainly curious about the merc 700 model. Conrad says the crank shafts are probably different. Does anybody know for sure? Also curious about the crankcase. Will they switch out from one to the other? Am told the rods/pistons would change out too. Both are 66 cubers, correct?

I have done some checking on part numbers but with superseded numbers, I wasn't having much luck.

I have a merc 700 DR and also the chance to get ahold of an FGS, though it is a long shaft.

Scott
People in a hurry to get married should be trusted as much as people eager to get elected.
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Re: DR/FGS parts compatibility

Postby Kiekhaefer » Fri Mar 08, 2019 7:08 pm

My understanding is that the 700FGS crank shaft is for that motor and no other. It was made to accept the larger drive shaft which were interchangeable with the 700fgs 800fgs 850 1000 etc.

The block is the same as a mark 78 block and can be swapped out. In fact I’ve heard that Kiekhaefer switched foundries and had some water intrusion problems with the 700 where they had to go back to the factory to be replaced. You’re ok to use pistons, rods and block from mark 78 and 78a for a 700 but must have the correct crank shaft.
John Stoltz

'59 Mark 35aE
'53 Mark 15
'60 Merc 400E
'61 Merc 700 FGS
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