TOPIC: Bigtwin Cylinder Head Interchange?

I recently picked up a '58 35hp Lark which was missing the cylinder head. The motor was 'stuck', the prop would turn by hand in neutral. There was no visible rust or scoring in the cylinders, so I sprayed it with PB Blaster, and let set over night, after a little gentle tapping with a dead blow rubber hammer, I was able to spin it over with the starter. I want to try a compression check and possibly fire it up. I have a 1955 BigTwin parts motor, the cylinder head looks like it would bolt on the '58 Lark, except that it doesn't have the compression release set up. Does anyone know if these are interchangeable? My idea is to use this head to 'test' the motor, and if good, use it at least until I could locate a correct cylinder head...Any help would be greatly appreciated. Thanks.

I'd say if the '58 doesn't have a thermostat, the older head (as long as it's from a 35hp) should bolt up. The best way to confirm would be to look up the head gaskets for each model, and if they're the same part number, you're guaranteed the exchange will work.

Try www.marineengine.com as I believe they have parts listings going back that far.

HTH.........ed

Of course the '55 is a 25hp, doesn't have thermostat, and different gasket #, looks like 3 strikes... I figured that would be too easy... Thanks for the info.

The 57 35hp cylinder head had compression relief chambers and valves built into it. You need a head from a 1957-1959 35hp Johnson or Evinrude or a 58-1962 Gale (and all the store brands) try to get a complete parts motor so you get all the rods and levers to make the compression relief function as it makes rope starting these big motors a breeze, well OK a lot easier!

my original thought was, that although the '55 does not have the compression relief set up, (which you don't need anyway, without a pull start). The if the head would bolt up just to check compression, and maybe fire it up...??? I actually have a loose '53-'54 head, which fits the bolt pattern, but, it's not 'deep' enough, the pistons would hit. But the '55 and newer heads are deeper, so at least, the pistons would clear. I have '56, '57 '58 and '59 motors, but I'd have to pull a head off a runnable motor, which I really don't want to do, if I don't have to, so I do have a '55 parts motor... I may just 'try it any way, even if just to check compression... but if it has compression, I'd want to fire it...oh well, we'll see. Thanks for the input...