1973 evinrude 18hp head

[wauto]

What years of cylinder head will fit my 73 18hp? Can I use one from a 20hp ?

 

[RCO]

I believe any of the 61-up 18 hp heads will fit. The 20 hp of the same years is the same head as the 18. The older ones do have a slightly different thermostat housing, but will work.

 

[F_R]

25hp heads look the same but cannot be used on the 18hp because they are mated with different pistons.

 

[wauto]

My 18 uses external coils. The older heads don't have mounting bosses.

 

[oldboat1]

guess one simple thing you could do to narrow the search is to check for matching bolt patterns. Look up powerhead gaskets. If you get a non-match, that powerhead would not exchange.

 

[hardwater fisherman]

You might be limited because I think that was the last year of the 18hp, and the only year with external coils.

 

[F_R]

guess one simple thing you could do to narrow the search is to check for matching bolt patterns. Look up powerhead gaskets. If you get a non-match, that powerhead would not exchange.

Great idea, but won't work. All the 22 cubic inch 18, 20, and 25hp motors use the same bolt pattern and gaskets (during the thermostat years)

 

[oldboat1]

What years of cylinder head will fit my 73 18hp? Can I use one from a 20hp ?

apologies, wauto -- misread your post. Not looking for a powerhead.

(suggestion wouldn't have been helpful anyway....)

Curious, though. Is the head messed up beyond saving?

 

[boobie]

Post some pics of the head.

 

[wauto]

My head blew out a spark plug. Gonna remove and try a helicoil.

 

[boobie]

Why didn't you say that to start with ????

 

[wauto]

I thought it would be easier and more reliable to put a good head on.

 

[oldboat1]

Either way, resurface the head before installing/reinstalling (and fresh head gasket). I've used helicoils a couple of times, and had good luck -- can get up and running with one while looking for a replacement head.