offthefront,

I agree with Patriot. Forget the exhaust tips!---unless of course your bent on having them. Buying 4-tips and then having them welded on is going to cost you more $$$, time and aggrivation (probably A LOT MORE) when all you need to do is have the tailpipe extended 6 inches or so out from the transom---problem solved. Don't make this any harder on yourself than you have to. I am quite sure just having the existing tailpipes extended will be the easiest and most cost effective way of correcting your exhaust situation.

I also agree with RedDog382 about Bob at Lake Precision Welding. A couple years ago my cousin and I both needed tailpipe work done. Mine was a straight pipe application like yours---a no brainer, but my cousin had GIL exhaust manifolds and tailpipes that he bought second hand that were too short and didn't have the correct angle for his application. He called Bob, took some measurements, drew up a diagram and sent all 4 tailpipes into Bob's shop. In addition to needing to have the pipes extended, he ended up needing about 3 angle welds on each pipe to get the correct angle and length to make them fit in and through the existing holes in the transom of his boat. When we got them back my cousin and I looked at each other like "how are these going to fit with all the angle welds?"---but he went to bolt them on and ALL 4 tailpipes fit perfectly through each existing transom hole! The real kicker is that Bob was extremely reasonable with his pricing---especially for what he did on my cousin's stuff!---at least he was with the both of us and he didn't know us from Adam! We just took some measurements, drew up some diagrams, sent him our tailpipe stuff and delt with him over the phone.

Lake Precision Welding, Inc.
7710 Crile Rd. Unit F
Concord, OH 44077
Ph: 440-639-1444 (ask for "Bob")

Cmi, End Of Story.

I'll check with him Monday ... .. thanks

Gona Crank new motor Monday ....

This is what I did to install my system last winter. I had TRS dry pipes that I shortened, changed to wet and added 2 angles to fit my existing holes. I made all the cuts with a 14" cut off saw. Then brought the pipes to local welding shop to have them MIG welded. I then polished the pipes back to new.
After I cut the pipes I heated the inner pipe and drove a triangle piece of steel into the pipe to expand the inner out the the wall of the outer pipe. leaving gaps for the cooling water to enter the exhaust stream.
The worked great!

Payton ...looks great ..about the triangle .. did you just drive it into the end of the heated inner pipe and then remove it after pushing the walls out ? or is a triangel with a hole to allow the exhaust thru?

Not so fast! CMI's are very nice, but they will be problematic in the 311. Due to the Silent Thunder, the holes through the transom are higher than the standard Bravo holes, therefore there is no downward angle in the tailpipes. This will cause problems with reversion unlees you go to a dry system or dump the water out way past the transom. Trust me, I battled this problem for a couple years in my 311!

Mike,

Are you putting your Silent Thunder platform back on? I was always concerned about the heat from the exhaust burning or melting the fiberglass if the exhaust was not "wet" (cool) enough as it entered the platform. On my 382, I have some rubber collars with stainless flanges with screws to secure them to the outside of the transom. The pipes slip through them and create a seal. Wish I could send you pics, but no digital camera.

Red Dog, I noticed that the rubber exhaust hose does not have much drop on my 311. Why isn't there a problem with reversion with the stock Merc exhaust units flowing ultimately into the Silent Thunder box?

1.) Cam profiles in the stock motors are pretty mild and not known for reversion.

2.) Are you sure the problems with your engines/valves are not due to reversion?! I think it's unlikely, but I haven't been able to keep up with your postings on the engine/valve problems.

Chris