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View Full Version : will a 35 hp powerhead fit on a 48hp mid? OMC



gotboostedvr6
08-26-2007, 09:10 PM
I have a 81 35 hp PH and a 8748 hp complete motor with low compression.

# 1 Will the powerheads interchange?

# 2 Are the bore sizes the same?

# 3 Will the 48 hp front half fit the 35 hp block?

if not what OMC 2 cyl powerheads fit what and interchange with what
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JohnsonM50
08-27-2007, 03:34 AM
Those that your asking about wont interchange at the powerhead and I doubt the intake will even be close. A 50hp powerhead might tho.

Bill Gohr
08-27-2007, 03:41 AM
1980 thru 88 40-50-60 will bolt on

gotboostedvr6
08-27-2007, 09:26 AM
is the 60 hp you are referring to a commerical ?

Bill Gohr
08-27-2007, 12:37 PM
55 would be a commercial 2 cyl 60's were 2 cyls built for 3 yrs out of 50's

gotboostedvr6
08-27-2007, 07:24 PM
I picked up a 71 50 hp electric will the powerhead bolt up if i use the 87 48 front half?

gotboostedvr6
08-27-2007, 09:21 PM
also are these loopers or crossflows?

gotboostedvr6
08-28-2007, 07:55 PM
ok they look the same so here is my plan.

The electric PH is off here is a pic of the base w/o the exhaust tuner installed...
http://i24.photobucket.com/albums/c24/gotboostedvr6/50hpEbasepic.jpg

heres my plan

I'll be using the 48 front half on the (e) 50hp block use the 48hp crank rods and pistons. Cut the piston even with the exhaust ports, but only after the ports have been squared and opended up slightly. I'll also port the intake and clean up the casting flash.

Next will be to go 4 sizes larger on the high speed jets for break in. I'll use all the 48hp electronics, charging system and flywheel.

i hope the 50 block doesn't need a bore

JohnsonM50
08-29-2007, 03:45 AM
the wire harness for the electric shift. [the main plug] might be different

DKL
08-29-2007, 08:17 AM
You may not want to swap block halves ,they are line bored and machined from the factory to match each other. internals ok , why cut the pistons, and no need to go 4 sizes bigger on the jets either

What exactly are you trying to accomplish? cobble a powerhead together?
YOUR ASKING FOR TROUBLE

Go FIND YOU A 60 HP 2 CYL OMC powerhead ,mid 80's in good shape and run as is, check to make sure your spline count for drive shaft is the same as the crank splines.

JohnsonM50
08-29-2007, 02:28 PM
I agree, from doin all that chang-in a 60 will still deliver more. Its hit or miss that a miss-match will perform even as well as the least of the donor motors. If there were an easy hop up,, everybody but those missin out would know.:D

gotboostedvr6
09-02-2007, 01:43 PM
someone want to help me find a good 60 block or complete powerhead ? :)