1978 140 Exhaust

[flabum]

Hello, new to the forums here.

I have a 1978 140 bubbleback. The exhaust stuffers are deformed and broken. The engine seems to have been rebuilt not too long ago and these were overlooked or considered not a problem. The parts manual does not show these stuffers to be sold seperately. Does anyone here know where I can locate new or used stuffers? I know that the replacements will have to be machined to fit and I have that capability.

Thanks

 

[Dhadley]

Re: 1978 140 Exhaust

Welcome!!

OK, here's the deal. Yes, those are (or were) available seperately. I'll find the part number for you if you decide to repalce them. This is a bad news - good news deal.

Bad news -- they're very expensive. And when you buy new ones they're much to "fat" to fit in. You'll have to disassemble the block and have them installed and then mill the back of the block. Then reassemble, etc.

Good news - you don't need them! Take out what's left and go fishing. Not only is it no big deal, the motor will actually breathe better with them out.

They were melted / twisted because the motor wasn't set up right. It was being lugged, had the wrong spark plugs or someone was using the wrong octane fuel.

Take out what's left, set the motor up at 5800 with a normal load, use fresh 87 octane, good oil and Champion plugs. It'll be fine. as long as the compression is good now. A lot of times the rings on the starboard side coke up abd break if the motor was being lugged for very long.

 

[flabum]

Re: 1978 140 Exhaust

Thanks for the reply,

If it's not too much trouble, I'd like those part numbers. I will see if they are still available. i hate putting things back together without all the parts 8)

 

[Dhadley]

Re: 1978 140 Exhaust

392000

If the motor is propped out at about 5600 or so you'll gain about 100 rpm by leaving them out. The higher the set up rpm the more you'll gain. Try it sometime, you'll be plesantly suprised.

 

[flabum]

Re: 1978 140 Exhaust

It's bad enough that the heads were shaved a bit to get past the 30 years of corrosion thereby raising the compression, now you want me to open up my exhaust for more r's :devil: while I'm at it.... does land and Sea still make the turbo kits for theses engines? d

All kidding aside.... thanks for your help... will do some $$ research and see if the new blocks are worth it or even available...... thanks again.

 

[Dhadley]

Re: 1978 140 Exhaust

The 78 heads were pretty tight without being cut. If they've been cut more than .010, be careful. If you decide to get different heads get a set from as late a model as you can. The later ones are more suited to today's fuel.

 

[Theoutdoorsman]

Re: 1978 140 Exhaust

Can someone post a photo of these "exhaust stuffers". I have an idea , but I'm not 100% certain I understand what your talking about here. Sorry to but in. I'm just curious. Thanks......... ALAN

 

[Dhadley]

Re: 1978 140 Exhaust

They're in the "bubble back" (the exhaust plates between the heads are not flat but have a "bubble" shape) crossflow motors. The whole idea was to create a "tuned" exhaust. Under the plates there are 2 pieces that bolt in the exhaust chamber to create a header of sorts. The idea was to give the exhaust a smoother path to exit thru.

It works on the 235 style V6's. If you take them out of a 235 it'll lose 50 to 100 rpm. On a V4 if you leave them out it'll gain some.

They get melted and burned looking if the motor was being lugged. Lugging creates excess combustion heat and will distort them and eventually burn a section away.

 

[Dhadley]

Re: 1978 140 Exhaust

Alan, is your motor a 100 or a 140?

 

[flabum]

Re: 1978 140 Exhaust

how do you post a pic here?

 

[OBJ]

Re: 1978 140 Exhaust

The link below will help you with that flabum.


http://forums.iboats.com/bbBoard.cgi?a=viewthread;fid=37;gtid=1179789

 

[flabum]

Re: 1978 140 Exhaust

try again....

 

[Theoutdoorsman]

Re: 1978 140 Exhaust

Dhadley......It's a '79 model 140hp.
Flabum.......Thanks for the pic. I suspected this is what you were referring to.

Sorry to interupt your thread gentlemen. Are there any negative side affects to removing them and leaving them out? Of course, this is assuming your not lugging the engine. My filler blocks weren't damaged like that upon disassembly, but the coking looked to be about the same.

 

[Dhadley]

Re: 1978 140 Exhaust

We haven't seen any effects other than the rpm gain. We stumbled on that on a commercial guy's motor one time. He needed his powerhead rebuilt and to no one's surprise the stuffers were melted and burned. He had no $$ for new ones so we left them out.

Knowing he wouldn't break the motor in right we put his powerhead on the motor on our ski boat. The ski boat had the same V4 "bubble back" type motor so we knew where the r's were at. Well, the commercial guy's motor turned about 100 rpm more. We were at 5800, the rebuilt motor was at 5900 (maybe it was 5900 & 6000, don't remember exactly). Now, if anything the ski motor should have turned more because it had Boyesen reeds.

The commercial guy picks up his powerhead and we put ours back on. Sure enough, we were about 100 less. OK, pop the stuffers out and we gained the 100 or so.

Later on we took the stuffers and cut them horizontaly so the upper cylinder on each side had to go thru the manifold and the bottom cylinder on each side could go straight down and out. Each cylinder's exhaust was completely seperate until it met (basically) at the adaptor plate. No change compared to leaving them out. So much for "it looked good on paper".

Down the road we raced a V4 crossflow and left the stuffers out. At 6800-6900 (with them in) we picked up 200 rpm by taking them out. Eventually we got it to turn 7400 (with stock porting). We found out there's a ton of untapped power in a crossflow intake system.