Very interesting.

James R

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Just now completing a rebuild on a 1979 140 Johnson. Had to buy a replacement stbd head. When I came to mount the coils I found that the holes for the bolts were missing in the head. Didn't notice until this point. No biggie just had to pull the head and drill and tap four holes.
Anyone any idea how this could have come about.
The head showed evidence of being a used head.
 

jimmbo

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Earlier V4s didn't mount the coils on the heads, actually they used just one coil. Sounds like the head you procured is older than your engine. There were several versions of the head over the years. How does it compare, combustion chamber size/contour to the original?
 

Joe Reeves

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The part number of a cylinder head is normally inscribed on the head in a raised number fashion... either towards the side between the cylinders or in a smaller circular fashion somewhere near the top front portion of the head

What is that part number?
 

racerone

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Earlier V-4 motors used 4 coils mounted on a bracket on top of the block.----73 to 77 I believe.
 

James R

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Sorry, no numbers on the original or the replacement. I purchased a pair of heads purportedly from a '79 140 but they were not the same cavity. Cavities were evenly hollowed out dome style. The original head cavities were partially filled on opposite sides. I bought the head in question and it matches the original and the shape shown on the parts drawing. Compression's on both banks are the same at 120. I will check some more of the parts drawings to see what motor the first pair came from.
Your inputs are greatly appreciated.
Jim.
 

Joe Reeves

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Sorry, no numbers on the original 1979 140hp or the replacement.Jim.

If the part numbers aren't on those heads, it'll be a first. OMC continued that I.D. practice up until the 140 became a looper.
 

interalian

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So the replacement head had the mounting lugs for the coils but there were no tapped holes? Odd. Older engines where the coils were mounted on a plate on top had no lugs on the heads.

Combustion chamber on the '79 should look like the one in the attachment.
 

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James R

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Joe, the numbers are stamped into the original heads but no number on the replacement.
Inter', the combustion chamber is as your pic shows and is the same as the original.
I said it was interesting. I thank you both for taking the time to input on this. If the cold rain will go away I'll put it in the tub and fire it up.
 

James R

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Fired up fine but as they usually do hates the extra oil for break in. Its a goodun.
Thanks for the input guys.
 
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