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I am finishing up a real nice Mc7 that will be going on the block soon. It is definitely a beauty with a beautiful block and all the stock trimmings. Stock ports, fresh 0.010" over bore with a new Wiseco piston. Mostly stock with the exception of an Mc91 rod to go along with the piston. Stock ports, never modified. Excellent original Mc7 crank and all. I am going to have to use a later tall type plug boot because I couldn't find a good original. Other than that and the upgraded rod it is all original. My usual detail job on the paint.

I should have it finished after Thanksgiving, just need to do the manifold and carb. I'll post pics and try to sell it right here on the forum. If it doesn't sell here I'll have to list it on esteal for more to cover the 18% I'll have to pay them.

Happy Thanksgiving everyone,
Scott

Scott,

Why do you say ebay charges 18%? Last time I looked they charged 9% with a cap of $100.
Did I miss something?
Steve O'Hara

+ listing fees + pay pal

scott, question, on the piston, 9-port or original design, non 9-port ?? thanks for reply

Listing fees, final value fees, PayPal fees, might be a little less that 18% but that is the mark up I figure whenever I am selling something. Comes out pretty close.

Full skirt Wiseco piston, see pic

Hi Scott,
Nice looking block for sure. Did Wiesco make that piston in .020 over? I'm still looking for a piston for my MC 30. I have a 91 rod I could use. The next option would be a 9 port piston, which might require a different manifold.
Pruit

Hey, Pruit. Wiseco made all common oversizes. A stock +.020 Mac piston will also do you fine. Unless you're going to 9-port your block, or carburet through the bottom of the case, don't block your third port. I don't care which of the "gurus" tell you that there's no performance difference, there IS with a single top small carb/manifold. Believe me, we tried all combinations in the olden days. The McCulloch engineers realized that the "back" ports were more evenly fed when the case was charged using the third port. Why else would they have gone through the engineering/manufacturing hassle of making the third port system? When you bottom feed the case, things even out better. Good hunting, Pal! Ted

According to McCulloch literature they included the piston controlled port for ease of starting and good idle characteristics for the saws.

Yep, at WOT and racing speeds that system contributes nothing to the performance but it makes a big difference in starting when using the recoil or any type of rope pull starting method.
Just don't use a 9 port type piston in one unless you close off the piston port induction path in some way or the engine will hardly run at all and it will spray fuel vapor in your face if you get too close to the carb
Steve O'Hara

The third port nonetheless evens out the flow to the back ports thru the fact that it charges the case on the downstroke. Pop and I tried every combination of carbureretion there is back in '60/'61. Every Mac we had ran better WITH the third port, ONLY IF we were running a single or dual top carb. The minute you switch to bottom carb with the third port blocked, the engine ran better. The third port is admittedly a small boost. Most early dual carb manifolds added the second carb only to the third port, and they did add power, if only 5-8%. TJ