New (used) muffler.. which way is up?

[Outrageous]

Originally Posted by ct9amr

Try the exhaust turn downs outside the hull before the muffler deal. I removed the flappers and put on 45 degree units and pointed it under water while running slow.

This was a huge improvment and I never isntalled mufflers after that.
At WOT the turn down are above water sot here is no restriction.

Check out fish the classi for lots of ideas on making yours managable.
A lot of people end of putting sound deadoning inside the engine cover as well.

What is fish the classi? I like the idea of low backpressure that equals HP and fuel economy. Can you post some pictures of your set up? I would like quiet too. Thanks, Steve

[ct9amr]

fishtheclassic.net is the shamrock forum. Lots of good ideas from guys who deal with inboards. The group is great.

I don't have a picture of my setup since I sold the boat a few years ago.
I bought some silicone connections that I clamped onto my exhaust after removing the flapper. They are pictured below, but you need to get them long enough so they are under water while under way.



I also looked at something like this but it seemed like I a lot of work to accomplish the same thing.

[deepsushi]

Finally got to run the boat with the new muffler installed. Made a huge difference in the noise level and was much more pleasant while trolling and while underway running we could easily talk at normal conversation levels.

Had a little snafu with the original used muffler as when I hooked it up the muffler leaked due to the inlet tubes having multiple cracks hairline cracks. Most likely someone over tightened the exhaust clamps and cracked them. Fortunately, another NOS muffler appeared on Ebay and I bought that one. The new muffler had the original sticker on it with "this side up" marked on it which confirmed that I was correct with my my original guess as top.

[Outrageous]

Originally Posted by deepsushi

Finally got to run the boat with the new muffler installed. Made a huge difference in the noise level and was much more pleasant while trolling and while underway running we could easily talk at normal conversation levels.

Had a little snafu with the original used muffler as when I hooked it up the muffler leaked due to the inlet tubes having multiple cracks hairline cracks. Most likely someone over tightened the exhaust clamps and cracked them. Fortunately, another NOS muffler appeared on Ebay and I bought that one. The new muffler had the original sticker on it with "this side up" marked on it which confirmed that I was correct with my my original guess as top.

So how did it work after running for the season? Any issues? Hope you caught some fish!

[deepsushi]

Originally Posted by Outrageous

So how did it work after running for the season? Any issues? Hope you caught some fish!

The new muffler worked out well and I really noticed the reduced noise from the muffler. No issues at all and the motor ran fine with it.

Had a problem with the motor in the midst of the season and it would stumble and bog at anything over 2600 RPMS. Took me about three weekends to diagnose and the problem was resolved after I rebuilt (my first) quadrajet carb. In the midst of troubleshooting my engine the distributor decided to die as well so at one point I was diagnosing two issues at the same time which made for some real WTF moments!

Unfortunately, my engine problems coincided with our local inshore bluefin bite and once I fixed my issues the fish had moved down Cape! Other than that did a lot of bass / blues and bottom fishing with the kids. We have had a pretty great late summer and early fall with the false albies.

Biggest improvement I made was I increased my prop to a 17 X 17 from the crappy 16 X 15. I picked up almost 3 knots of speed at cruise and now am able to run 20 -22 knots at 2950 rpm which makes the fuel burn drop significantly down to around 10-11 gallons an hour. On the old prop I had to run it up to 3150 to get that cruise speed. Now if push it up to that RPM I get a pretty consistent 25 knot cruise. Only downside is the bigger prop does create a fair amount of prop rumble that is definitely noticeable.

[Outrageous]

Glad to hear you got it dialed in. How much clearance do you have in the tunnel with the 17"? nice performance numbers.. Those qjets aren't as bad to rebuild after you do it a few times and get the hang of them. Too bad about the timing it would figure that it would happen during prime fishing..

[deepsushi]

I forget the exact clearance with the 17 prop but I remember measuring it at one point and it falls within the recommended 10-15% of prop diameter. The prop does have a rumble to it now but at this point the performance gains are well worth the increased noise. The prop I used was an old school Federal equipoise. I would bet that one of the newer CNC props made by ACME or a Michigan DJX would probably perform as well in a 16" diameter.

Quadrajet rebuild was a lot easier than I thought it would be. There are some excellent videos on youtube that I used to guide me. Only part that was a challenge was figuring out the float height / installation. First time I installed it I put it on and the float must of stuck as gas started pouring out of the carb. Took it off tore it back apart and adjusted the float and then I was good to go.

[Outrageous]

deep,

Thanks for the info on the prop. Checked out the YouTube thing as well. Great resource for DYI. If you need any tech support or info check out Quadrajetparts.com. Best source I have found for parts and info on these carbs. If you need any BBC parts let me know I have a bunch.