This blowing of head gaskets on the 3" bore seems to be the bane of all those engines, clone or Honda.
There are certain facts of nature/engineering. The 3" bore is a bad idea on these engines. Better to keep the bore
smaller and go with more stroke to get max performance/dependability.....from these engines.
Oddly enough the model 15 Briggs (basically an Animal with a near 3" bore, does not have that problem.
Having said that, when you go to 12 to 1 compression, or above, it's wise to use a thin copper wire, in a groove which it fits snugly, between the head/or block, and the gasket. This precaution should be done on any of the engines in this discussion. This will eliminate all blown gaskets. This technique would also eliminate the blown gasket problem on the 3" clones or Honda.....but those engines do not have sufficient room to put in this safeguard.
A person could alter the locating pins, and a couple of the bolt holes and create enough space to do this. Then, of course, you are getting into
the need for some skilled machining. If you have the mill and cutting tools, this is the very doable cure for the notorious head gasket issues of
the 3" bore Honda/Clone.
It's always struck me that the better option is just to get the Briggs model 15, which has a 2.970" bore, put in the fhead crankshaft and have an immediate beast, for much lower costs, and very available quality "speed" parts, for this engine. This combo produces about 280cc's and is a truly baaaad boy, combined with it's lower weight.....which greatly enhances handling.
The appropriate crank, rod and piston are available from ARC. The piston is actually a JE which is also available from CV4 Products.
You can also go really economically with the model 15, by staying with the stock stroke (the crank is forged steel, like the animal and the WF).
Obtain the WF rod, hone the wrist pin end of the rod, to match up with the stock piston's wrist pin (no problem) put in your cam....carb....
billet flywheel (Animal stuff all fits this) and run the stock piston. The stock piston has very thin rings, and is a very fine piece, for racing......especially on a budget.
Hope this helps!! ......Paul Doss ....
PDPower@tampabay.rr.com