Mercury 2.0lt head interchangeability

**WayneMac2** · 06-04-2019, 02:54 AM

Hi,
I have a V175 Mercury early 80`s with the two piece heads type 1 ( Diamond shape water jackets )
and was looking to convert to the performance single piece heads, Are they compatible and any other advise would be great.

The reason for this is while stripping the engine down most of the bolts from the water jacket plate snapped in the head so instead of trying to extract them
I thought a conversion would be easier.

Cheers.

**rock** · 06-04-2019, 07:37 AM

Welcome to the site. There was a change in the bolt pattern in the 80s. Early models had the bolts attach to the cylinders as opposed to the newer ones bolting to the block. Other than that almost any head will work. I don't understand how the bolts can break off in the heads. I have had them break off in the block but using different heads sure wouldn't fix that. Have any pics?

Rock

**nitro_rat** · 06-04-2019, 05:21 PM

"diamond" heads don't interchange with any of the newer one piece heads. you're stuck with that style head only. cut to 26cc's for best performance with premium fuel. Those old 175's are built to run. best mod is changing the choke plates to the late style enrichiner. otherwise they'll turn 7500-8000 rpm's as is. I like to run a 260 small bearing top cap and light flywheel. tdr reeds from jay smith. mix 40:1 to 7500 (24 pitch prop), 32:1 if you like to touch 8k (22 pitch prop). just don't cruise long distances over 7500 or she'll stick the top piston! 80 mph rig on a 15-17' hydrostream...