I am looking at converting a 65 to 70cc engine to put in ziroli P-40. What brand would best suited? stihl, echo, poulan etc. anyone try one in this size? I know a lot of guys are converting the smaller ones but haven't seen much about the larger ones.

Sachs Dolmar model 120 or 120 SI, 4.2 cubic inches, VERY good conversion...The basis for all the 4.2 engines sold by Fox, Brison, J&A, and others......

Where do you find this engine, I mean what brand of Chainsaw?

There's a model 143, 5.8 cubic inches, on E Bay today for $102....
SACHS DOLMAR MODEL 120 OR 120SI

Oh, come on, mean nobody converted a stihl 039 or 044? These are the two I am considering.

The stihls have a tremendous resale as a saw in good shape. Plan on spending big for one or wait for one to come along on ebay with damage from being dropped. The P-40 responds very well to a stock zenoah 62 they really scream. Have a Husky 61cc needing a conversion artist if interested.

Waco I have a Stihl 62cc converted (I measured that and I think the chainsaw was a 039). It runs great! I'm using now a 22x8 MenzS, it turns about 7500rpm with stock muffler, I'm not done yet with the conversion. It weights 1.775grs without muffler.

I believe Makita markets essentially the same Sachs Dolmar chainsaw. The model number would be similar to the Dolmar model -- just under the Makita name. I know because I have a Dolmar PS401 and couldn't find parts for it anywhere until I found this little factoid and was then able to get any part I wanted through Sears! Ha! I do have some experience in some things!

It IS the same..Makita bought Sachs a few years ago, changed the color to blue, and uses different numbers...