Return to the home page...

Go Back   Moyer Marine Atomic 4 Community - Home of the Afourians > Discussion Topics > Exhaust System

Reply
 
Thread Tools Display Modes
  #1   IP: 162.129.242.40
Old 08-25-2009, 03:03 PM
Dlane Dlane is offline
Member
 
Join Date: Aug 2009
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
Custom Hot Side

I’ve never paid much attention to our boat’s exhaust system. Okay, so that’s not really true. The circa 1969 system that came with the Contest 30 was a water jacket type that worked fine until the low point of the water jacket became crusted in rust and scale—then started leaking into the engine compartment.

The old system was replaced with an aluminum water lift muffler, fed by a hot section that was the usual assemblage of hardware-store plumbing, wrapped in some magical stuff to keep the heat in. As the years passed I came to expect that somehow, the connection between exhaust and manifold would become rusted and full of scale—freezing the bolts in place so that nothing could get them out without breaking the heads off. In fact, when I brought the engine to Don Moyer for a rebuild many years ago I had to remove the manifold to get the exhaust out of the boat.

Having been raw water cooled for 30+ years, Don commented that the block was pretty thin is several places, so I went with fresh water cooling. The rebuild involved minimal torque on the head and manifold nuts for that reason, but it has held up beautifully. Except, of course for the rust and scale at the exhaust flange, which, as you might guess, I didn’t pay much attention to.

…until July of this year when the engine started sounding funny. We were just setting out on a two-week cruise. It turns out that the rust and scale was hiding the fact that the pipe exiting the mounting flange had worn paper thin, and had rusted through to where only about 20% of the circumference was still connected. Fortunately, we were in Chestertown on the Chesapeake, and Don said he was coming there anyway, so we scrounged through a local hardware store and bought enough stuff to splint the system. Happily it lasted out the cruise, but the next steps were not so clear.

Don had observed that since the actual muffler was well aft of the exit of the hot section, the exhaust hose connecting the two had something of a saddle-back shape to it before heading down to the muffler inlet. Water could puddle in the bend of the hose, and if the boat was jostled enough at the dock, some of that could back into the manifold--causing (you guessed it) rust and scale around the exhaust flange. Certainly something was not right. Don had installed a stud at the lower flange hole, and the associated nut had eroded away to what, frankly, looked like a glob of snot.

I figured there would be trouble getting the old exhaust off, and managed to prove it in the time--honored way by first trying penetrating oil, then applying heat, then breaking the head off of the upper flange bolt. I gave up on the rest of it, took the manifold off (with the now broken end of the exhaust still attached) and went to my local machine shop. When I got there I noticed a fair amount of rust and scale at the aft end of the manifold, so I asked them to clean it up and advise me if the manifold had enough meat left to use.

Their comment about the manifold being more like Swiss cheese was a pretty good description of the situation. Turns out the rust and scale couldn’t differentiate between the manifold and the exhaust plumbing. The only difference was that there seemed to be enough rust and scale to keep the manifold functioning for the cruise, while the same amount of the stuff totally failed to hold the exhaust together. I guess they just don’t make rust and scale the way they used to.

I ordered a replacement manifold, and then tried to figure out what to do for a new hot section. The hardware store plumbing parts were heavy, and I didn’t want to unnecessarily stress the manifold studs. Also, I wanted a system that would never rust, and that would have the muffler inlet directly below where water enters the system. In short, I wanted to get out of the rust and scale business.

I contacted a racecar fabricator named Mitch Piper (http://www.pipermotorsport.com). Mitch said he could make something up for me, so I drew up a plan and sent him an exhaust flange so he could order parts. The shop is near Dulles Airport, so I went down there on a Friday morning. Two and a half hours later I left with a new exhaust system made of thin-walled 304 stainless.

Even though I had done my best with the measurements, I had gone under the assumption that the flange would be square on the end of the outlet tube. The downward tilt of the rear of the engine, combined with the length of the tube put the aft end about 4” low, and 3 ½ inches inboard of the muffler. I called Mitch and drove back to the shop a week later. It’s only about an hour and 20 minutes from Baltimore, as long as you avoid rush hour traffic.

I told Mitch what I wanted and after staring at it for a bit he decided that the only way to do it right was to weld the existing pipe to the work table, so it would be stable enough to gauge the changes. I had no idea what he was thinking, so I nodded and watched him go to work. First, he took a spare piece of box section he probably uses for chassis parts and tack welded it upright on the worktable. This gave him a flat vertical plane to work with. Then he supported the exhaust on a 1” piece of metal, and tack welded the flange to the flat side of the box section. Then he cut the exhaust pipe off of the flange, used a 4” piece of metal to gauge the additional height needed, and drew a mark on the table 3 ½ inches to the side.

It took him several steps to grind the end of the severed tube to the correct angle. Once he was happy with it, he re-welded the pipe to the flange, cut the spot welds, and off I went. Later that evening I bolted the new pipe to the manifold and was thrilled to see that it was perfect.

The next step was the exhaust wrap. If you have never messed with this stuff, I suggest wearing old clothes. They say to wet it (but not to soak it) when you do the wrapping. It tends to drip light brown colored stuff and to be a little floppy, but once dry it firms up. Expect about 20 minutes of thin smoke rising from it the first time you run the engine.

I had been concerned that a stainless steel pipe would be noisier than the old version, but I don’t hear a difference with the engine running. The pipe is relatively light weight and easy to maneuver from the flange end, so bolting it to the manifold was easy.

The bad news about the custom stainless exhaust approach is that Mitch’s shop rate is $90/hour, and the stainless bits and pieces are a bit pricey. Mitch charged me for two hours plus parts for the initial assembly, and another half hour for the modifications. Not counting gas and coffee I have a bit over $300 in the project. At first I was thinking I was a bit nuts to put that amount into the exhaust. I could have functionally duplicated it out of plumbing parts for about half that price.

However, for the $150 difference (which won’t even buy a race tire these days) I’ve got a custom piece made exactly to measure. Besides, there is something rewarding about working to an ideal, as opposed to simply getting by. We can just call it the “cool” factor. And, with luck, I won’t ever have to pay attention to the exhaust system again--except maybe to grin when I look at it.
Attached Images
 
Reply With Quote
  #2   IP: 64.231.100.246
Old 08-25-2009, 07:19 PM
67c&ccorv's Avatar
67c&ccorv 67c&ccorv is offline
Afourian MVP
 
Join Date: Dec 2008
Location: London, ON
Posts: 1,559
Thanks: 4
Thanked 9 Times in 9 Posts
Very nice!
Reply With Quote
  #3   IP: 68.6.86.125
Old 08-25-2009, 08:52 PM
superdave474 superdave474 is offline
Senior Member
 
Join Date: Jun 2007
Posts: 55
Thanks: 0
Thanked 0 Times in 0 Posts
very sweet looking exhaust. I agree that working towards an ideal is much more satisfying than doing the minimum. I'd rather take a bit more time and effort and end up with a quality product. Good work.
David
Reply With Quote
  #4   IP: 69.251.147.56
Old 08-25-2009, 10:09 PM
Dlane Dlane is offline
Member
 
Join Date: Aug 2009
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
Smile

Thanks, guys.
Reply With Quote
  #5   IP: 206.125.176.3
Old 08-26-2009, 11:24 AM
sastanley's Avatar
sastanley sastanley is offline
Afourian MVP
 
Join Date: Sep 2008
Location: Solomons, MD
Posts: 7,016
Thanks: 1,134
Thanked 600 Times in 442 Posts
I think I'd call that a 'custom stainless header'.

Souping up the A-4...nice work indeed!!!
__________________
-Shawn
"Holiday" - '89 Alura 35 #109
"Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!)
http://www.moyermarine.com/forums/signaturepics/sigpic3231_6.gif
Reply With Quote
  #6   IP: 24.108.89.186
Old 08-27-2009, 12:28 AM
Easy Rider's Avatar
Easy Rider Easy Rider is offline
Afourian MVP
 
Join Date: Feb 2007
Location: British Columbia
Posts: 139
Thanks: 231
Thanked 30 Times in 20 Posts
Nice. Quality only hurts once
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Replacing side plate, head gasket Kemp Dawson Cooling System 2 05-15-2008 07:37 AM
side plate bolt dimensions m_galligan Cooling System 0 07-30-2007 01:03 AM
Metal Side of Seals? NewburyportWags Cooling System 3 04-13-2007 08:40 AM
Water Jacket Side Plate Leak 1973 Ericson Cooling System 5 11-09-2005 10:43 PM


All times are GMT -4. The time now is 04:26 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2024, vBulletin Solutions, Inc.


Universal® is a registered trademark of Westerbeke Corporation

Copyright © 2004-2024 Moyer Marine Inc.

All Rights Reserved