Exhaust conversion Mercruiser 140 3.0

[mattyrich]

Hey, Its me again....

I am in need of some info on the subject of exhaust elbows and and there applications.

I have an older 140 with the straight back exhaust elbow that im planning on dropping into a 91' bayliner set up for a 45'd exhaust elbow. I do have two 45'd exhaust elbows that Im pretty sure will fit my motor, but they are not in the best condition.

I also have some extra rubber tubes/hoses that I may be able to jive around to make a connection. As long it makes a tight seel and doesn't get in the way of anything, does it matter what contraption that i come up with?

Does anybody have any other advice as far as prepping the cooling system(open) before dropping the motor back in the boat? I heard of some people cleaning/soaking the rubber to put some life back into them. what do you think about that?

Thanks again, Matt

 

[mattyrich]

Re: Exhaust conversion Mercruiser 140 3.0

Some pics...

 

[wire2]

Re: Exhaust conversion Mercruiser 140 3.0

....I do have two 45'd exhaust elbows that Im pretty sure will fit my motor, but they are not in the best condition.

I also have some extra rubber tubes/hoses that I may be able to jive around to make a connection. As long it makes a tight seel and doesn't get in the way of anything, does it matter what contraption that i come up with?
....

45? or 90? elbows in 304 stainless sched 10 (thin) pipe are available in 2, 2?, or 3" dia here;
http://vibrantperformance.com/catalog/product_info.php?cPath=1022_1066_1117&products_id=525
$27.95 list for 3", will last for 100 years.
I used ss tube, even thinner and lighter than sched 10 pipe to make my headers. They're ~15 years old now, not the slightest hint of corrosion inside or out. I got a local weld shop that specializes in stainless & aluminum welding to order the elbows & tube for me.

 

[Bondo]

Re: Exhaust conversion Mercruiser 140 3.0

Ayuh,... You have to use the manifolds off the newer motor,...
The older manifolds are Not adaptable...

 

[mattyrich]

Re: Exhaust conversion Mercruiser 140 3.0

so, the 45 degree elbow wont fit on the manifold that i currently have on the motor? it looks like it should line up with no problem? Is that the only solution? thanks, matt

 

[mattyrich]

Re: Exhaust conversion Mercruiser 140 3.0

Ok, so i see what your saying now. yay. guess i need to find a manifold... I dont think that the one i have is any good. looks prett rough. what do you think? cant really see it in this pic. I'll take some more today...

 

[mattyrich]

Re: Exhaust conversion Mercruiser 140 3.0

The manifold that i have off of the 91' motor with mercarb bolt pattern is in pretty bad shape. mating surfaces for the exhaust elbow are wearing thin. I would like to buy a new one. Anybody know if this will bolt to my 1981 head/block FOR SURE? i dont want to buy the wrong part... Thanks, matt

 

[mattyrich]

Re: Exhaust conversion Mercruiser 140 3.0

bump?

 

[Bondo]

Re: Exhaust conversion Mercruiser 140 3.0

bump?

Ayuh,... On 1 of your many threads on this subject,...
It's been stated that Yes, the manifolds interchange with the Head/ Manifold interface, for ALL years of 3.0l/ 2.5ls...

If you run into differences in the head port shape or size, vs. the port shape or size of the manifold,...
Yes, there'll no doubt be a degradation of the Potential hp... But it'll Run...

Ideally, you should be swapping Just the 2 Long Blocks,....
Then, EVERYTHING fits... But even then, there'll be "Gotchas"...

The Mixin' 'n Matchin' you're doing is a, put it together, 'n Try it kinda thing...

 

[mattyrich]

Re: Exhaust conversion Mercruiser 140 3.0

Thanks bond, I know that I have far too many threads posted on here on the same topics, and im sorry for that. I have problems finding straight forward anwers, probably because there is just not one available. Im trying to avoid spending 3-5 hundred bucks on a manifold that may not work. I would just swap the head from the other (91) block but it is in bad shape. looks like it had water intrusion into the head. I think it's seized. the manifold that was on the head of the 91 ( i think it was original to the motor from factor) doesnt actually look like it matches up perfectly. the ports on the manifold are definitely smaller than the ports on the head, and the head has six bolt holes of which only five were being used for that manifold. this leads me to believe that it should work, but i want to be as sure as possible. sorry for the repeated posts. I do appreciate all of your time. good guy. thanks a lot man.