Thru Hull Exhaust on a 1979 Larson All American with 5.0 OMC Stringer

[Spivy30]

I have a 1979 18' Larson All American 5500 with a 5.0L OMC Stringer, well my buddy gave me some stainless thru hull ports off a late model cobalt, I was wondering what it would take to add thru hull exhaust if at all possible

 

[Spivy30]

Thru Hull Exhaust on a 1979 Larson All American with 5.0 OMC Stringer

I do have room to run the exhaust "tubes" to the side

 

[1976 Slickcraft]

Re: Thru Hull Exhaust on a 1979 Larson All American with 5.0 OMC Stringer

I have a 302 Ford stringer that I would love to put thru hull on, but can`t see how it would work with the whole motor tilting with the trim.
Jesse

 

[Bondo]

Re: Thru Hull Exhaust on a 1979 Larson All American with 5.0 OMC Stringer

but can`t see how it would work with the whole motor tilting with the trim.

Ayuh,....

And,... Log-style manifolds aren't very conducive to thru-hulls either....

You need Center-risers to line things up...

 

[Manipulator]

Re: Thru Hull Exhaust on a 1979 Larson All American with 5.0 OMC Stringer

There was a guy on this site that did a great job making his own manifolds and tubes and made it work. This guy obviously was a great welder and made adapters that could pivot so the engine could still raise and lower to adjust the trim. He also made it a captains call (option of going thru-hull or down through the prop with a flick of a switch). No way I could do it like he did. I thought about it but my problem was clearance issues with the swim deck being in the way. what I was going to do is get center riser manifolds and use flexible exhaust hose to the tips. I found a flange that had a rubber seal around the inside that the exhaust tip would slide through. This allowed the engine to raise and lower without kinking the exhaust hose. I never did go through with it due to the swim deck being in the way. The main issue is the motor lifts and lowers on the select trim models. You also need to get center risers like mentioned in order to make it work. I did see a boat that was an Imp Eleganza that had twin GM 350's and the old style log exhaust that was converted to thru-hull. The guy had spacers under the risers to raise them up about 4 inches off the exhaust manifold. Then used flex pipe to route the exhaust to the tips. I just saw a picture of this, it was hard to see what other modifications he made.

 

[mtnrat]

Re: Thru Hull Exhaust on a 1979 Larson All American with 5.0 OMC Stringer

I am a performance nut, but I just cannot see the point of thru hull on such a small engine. More noise with no hp gain. I will only make mods if it results in more performance, better efficiency, or greater longevity. That does none of those. MHO