i looked at my case and cylinder and it has the echo(E) shaped x-mas trees like ralph said.i just printed the timing circle and port data from a thread here on rcu.it looks pretty easy to figure out.im going to look at my scrap mans pile of weedies a little bit better in the next few days.he has a metal scrap buisness and has quite a few macs laying around.plus a lot of others.thanks for the reply ken. i figured it was an echo but the E proved it.your muffler looks great on it.one thing nice about these engines the carb is already straight shot from the start.i have the tim6 but im going to get a different hall sensor that doesnt have the angle on it.mine has the bridge in the exhaust,single ring and stamped aluminum rod.