Lonely in fiberglass territory

Keeping your powerboat under power is a lot easier with good advice. Post your power systems questions here.

Lonely in fiberglass territory

Postby island time » Sun Oct 22, 2017 6:58 pm

Hi to all that have been following my new engine timing problem.
My engine now resides at a top notch engine builder's shop. This being the slow season for building racing engines he agreed to take on my problem child engine for diagnosis and eventual repair.
That's all that's been going on lately except for a couple of trips to the Islands for some pre-winter R&R.
I posed a question on the Commander forum and got no replies so I thought I'd try it here for some opinions.
As you know I will be replacing the long (12') exhaust hoses with new, in fact I have decided to use 3" copper pipe instead of wet hose...it's actually a little cheaper and I know how nice the wood boat sounds breathing through copper so this engine should sound even better.
So here is the question for your consideration; Should I run the copper pipe downhill all the way so no water sits in them or should I run them uphill to trap water creating that big block old cruiser sound where it has to build up exhaust pressure to force the water out?
Of course this is all for effect at Idle, anything above an idle will force the water out anyway.

Craig
Craig Wilson
Churchville, NY
Alexandria Bay, NY

1968 23' Chris Craft lancer
1971 31' Revelcraft
1988 25' Fourwinns
1972 19' Chris Craft Lancer
1957 18' Chris Craft Sea Skiff
1958 18' Chris Craft Sea Skiff
1968 23' Chris Craft Commander
User avatar
island time
 
Posts: 112
Joined: Mon Sep 28, 2015 9:11 pm

Re: Lonely in fiberglass territory

Postby Greg Wallace » Mon Oct 23, 2017 8:39 am

You should not run any part of your exhaust system higher than manifold outlets to avoid back drain or surge into exhaust ports.
Greg Wallace 23 Custom 22166 former Chris-Craft dealer Russells Point, Oh.
Greg Wallace
 
Posts: 335
Joined: Wed Mar 08, 2006 2:49 pm
Location: Indian Lake, Ohio

Re: Lonely in fiberglass territory

Postby island time » Tue Oct 24, 2017 6:25 am

Ok good point Greg. Thanks.

Craig
Craig Wilson
Churchville, NY
Alexandria Bay, NY

1968 23' Chris Craft lancer
1971 31' Revelcraft
1988 25' Fourwinns
1972 19' Chris Craft Lancer
1957 18' Chris Craft Sea Skiff
1958 18' Chris Craft Sea Skiff
1968 23' Chris Craft Commander
User avatar
island time
 
Posts: 112
Joined: Mon Sep 28, 2015 9:11 pm

Re: Lonely in fiberglass territory

Postby bflaherty » Tue Oct 24, 2017 2:07 pm

In our '69 Cavalier Ski Boat with the original 327Q the wet exhaust hose goes down from engine to hull bottom (actually rests on bottom for about 4 feet) then enters a copper pipe tip that takes it up and out the transom at a rather steep angle. The exhaust tips are just at water level (mush like a classic Century) so they spit water everywhere! This effect makes the boat sound amazing and throaty at the idle but still prevents water from going back into the exhaust manifold and cylinders. The critical height is that the exhaust tips are still about 1.5"-2" below the risers on the back of the manifolds.
Brian Flaherty
1969 Chris-Craft Cavalier 17 Ski Boat "TUPPERWARE"

"You'll never discover great lands, with your feet planted in the sand"
bflaherty
 
Posts: 61
Joined: Tue Feb 19, 2013 3:21 pm
Website: http://munsonboats.com
Location: Bellingham, WA
Facebook: bflaherty3632

Re: Lonely in fiberglass territory

Postby island time » Tue Oct 24, 2017 8:46 pm

Great info Brian,
The sound you mentioned is exactly the reason I asked, it's the effect I wanted. I won't be able to scrutinize the height difference until I get the engine back from the shop and get it reinstalled in the boat but now with this new info I can't wait.

Thanks,

Craig
Craig Wilson
Churchville, NY
Alexandria Bay, NY

1968 23' Chris Craft lancer
1971 31' Revelcraft
1988 25' Fourwinns
1972 19' Chris Craft Lancer
1957 18' Chris Craft Sea Skiff
1958 18' Chris Craft Sea Skiff
1968 23' Chris Craft Commander
User avatar
island time
 
Posts: 112
Joined: Mon Sep 28, 2015 9:11 pm


Return to “%s” Fiberglass - Engines & Powertrain

Who is online

Users browsing this forum: No registered users and 1 guest

cron