Mabey you could help me out with something - I need some cylinder head measurements. Say this bolt pattern on your head:<br /><br />1---2<br />3-o--4<br />5---6<br />7-o--8<br />9---10<br /><br />o's are sparkplug holes.<br /><br />I get:<br />3 3/8 (86mm) centers between 1&2 and 9&10.<br />4 7/16 (113mm) centers betweeen 3&4 and 7&8.<br />3 9/16 (90mm) centers betweeen 5&6.<br />7 5/8 (194mm) centers betweeen 1&9 and 2&10.<br /><br />Could I get one of you to confirm if your head has roughly the same measurments? There's no need to be super-precise here. Thanks a million!<br /><br />I have an older 28hp engine that has no thermostat. I'm thinking that I might be able to use a 33hp head on it, but I would like to make sure it comes close to fitting before hunting one down. They appear very similair so I think it might work without too much modification.<br /><br />Thanks again!
<br /><br />Thanks for the heads up rodbolt, and the offer. I've got a couple 28hp heads already though. Mabey I'll try modifying one of those.<br /><br />Along that line of thought, how is air purged from the powerhead on thermostated motors? Is a little allowed to leak past the closed thermostat?