Re: 1963 merc 850 to merc 1000 conversion
Not sure on your project here, but there is SO MUCH involved, that it needs a Merc guru to figure out. And I'm talking one with YEARS of experience. There is a lot of difference in the exhaust/tuner plates, MAYBE, but I don't know for sure. I'm getting a motor built now (fact, up and running now), but this guy knows his stuff and been at it for 40 years. And it ain't free to me, so don't ask me to ask him. He has probably 40 motors and can show me the diff on all. Heres just what was done to my motor (and this aint even all of it)..
"The powerhead I am building for you was originally a '72 1150.
The '72 1150 is a choked down 1350 with a few flow restrictions to give the lower HP rating so Merc wouldn't have to come up with a different powerhead to fill that HP range for the consumer market.
Initially this 1150 needed a rebuild because the inner water jacket had cracked and let water into #3 which was trying to die when I rescued the beast. It still had 95 psi on #3, but the rings had started to seize and consequently had scored the bore.
I had #3 bored .015 and installed a new piston there.
I had all holes pro-honed while I was at it and mic'd for roundness, etc to insure the beast was still within factory tolerences.
The block surfaces were machined too to insure everything was flat in the water jacket areas for a correct sealing.
All other pistons were carefully inspected, mic'd, & cleaned. I replaced one standard size piston too, but (4) of the (6) original pistons went back into their original holes.
Everybody got brand new rings & needle bearings.
The crankshaft got new main bearings.
The end caps got new seals & so did the crankcase.
I installed 1500 reed blocks and reeds, which meausre out the same as the original 1350 reeds.
I am installing '73 1400 carburetors - which are virtually identical to the original 1350 carbs & I am installing the original .0785main jets required for the 1350 at sea level. (now we have decided on .080 jets)
The exhaust tuner plate and inner water jacket are both NOS 1350 parts that I had machined to insure they too are flat so they will seal correctly.
These modifications: Main jets, reed blocks, tuner & inner wj complete the conversion of the 1150 to a true 1350.
The only difference between the 1350 and the 1400 blocks is the 1350 had an oval tuner to the mid-section and the 1400 had the dual square port tuner to the mid-section. And,...The inner wj & tuner plate configuration changed barely.
