93 Mercury 15 HP vs 92 9.9 Carb?

[Dukestek]

I've aquired a 92 9.9 HP Mercury as parts motor to replace the frozen tiller tube on my 93 15 HP. This motor came with a newly rebuilt carb (no signs that it's ever seen gas) and I'm curious if they will interchange? Same model and carb bore (34-315 on the butterfly on both) and parts apperar to be interchangable on diagrams.
Both have WMC cast in on the top
Stock has 3 B next to the fuel inlet, Doner has 1 B in same location
Stock has 3382 with 39 that punched onto the flat above the enrichment valve, Donar 2783/39.
Any help appreciated.

Thanks,

 

[flyingscott]

Look at the middle of the bore and make sure it doesn't narrow in the middle.

 

[Dukestek]

Look at the middle of the bore and make sure it doesn't narrow in the middle.

Doesn't appear to be different. There is a neck down in the center of both and "64" is cast on both at that point on the reed side. Too deep to get a caliper down there but there is a smaller ridge on the air intake side that appears to be the same on both and the diameter of the throat at the inlet there is identical. Possibly different jets? Any chances I'll damage my engine by trying it?

 

[flyingscott]

You will have to compare the blocks. That was right around the time the 9.9 moved up to the bigger block. If the 9.9 is the smaller block I wouldnt use it without at least changing the high speed jet. Even if it is on the bigger block may still need the jet will have to look up some parts.

 

[Dukestek]

You will have to compare the blocks. That was right around the time the 9.9 moved up to the bigger block. If the 9.9 is the smaller block I wouldnt use it without at least changing the high speed jet. Even if it is on the bigger block may still need the jet will have to look up some parts.

Thanks, blocks are the same other than the mounting method of the shift cam, mine bolts the the throttle/shift plate and the donar directly to the block (same location). I'd planned on using the original jet, easy as it's in the bottom bolt the holds the bowl on.

 

[flyingscott]

Then they may not be the same block the first 9.9 were on a 13 cid block I think or 10. The 15 came out on the 15 cid block. Some work on your part is required.

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[Dukestek]

Then they may not be the same block the first 9.9 were on a 13 cid block I think or 10. The 15 came out on the 15 cid block. Some work on your part is required.

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Further inspection revealed the cam was bolted to the block but doesn't go there. The plates where are identical (same part #). Guessing PO bolted it there to keep up with it when he removed the tiller arm, it was a parts motor I bought for the swivel bracket...

Parts lookup by serial on both show same piston assembly and crank as well as reed reed block assembly. Interested in where that extra 5.1 hp came from? Thinking I may be best to buy rebuild kit for the original and sell the other...

 

[Dukestek]

Further inspection revealed the cam was bolted to the block but doesn't go there. The plates where are identical (same part #). Guessing PO bolted it there to keep up with it when he removed the tiller arm, it was a parts motor I bought for the swivel bracket...

Parts lookup by serial on both show same piston assembly and crank as well as reed reed block assembly. Interested in where that extra 5.1 hp came from? Thinking I may be best to buy rebuild kit for the original and sell the other...

Combing thru parts lookups I've found the difference is in the main jet. 9.9 uses a .056 jet and the 15 uses a .061 jet They detuned the 15 in reaction to California restrictions according to a string on another forum.