Merc 4.3L Exhaust Manifold Conversion, 1-piece to 2-piece?

[vzett]

There have been a few threads on this, but not much conclusive information. My 1-piece manifolds/risers are due for replacement and I'd really rather go to the 2-piece system as the cheapest I've found the 1-piece sets are $543.00 for each side + shipping. <br /><br />The major concern is y-pipe compatibility. mercruiserparts.com lists seperate part numbers for the y-pipes for 1-piece vs. 2-piece, but the drawings don't show what the difference would be. <br /><br />Has anyone actually done the conversion?<br /><br />Thanks,<br />Virgil

 

[garycinn]

Re: Merc 4.3L Exhaust Manifold Conversion, 1-piece to 2-piece?

Virgil,<br /><br />Are you going to get the Dennis Moore manifolds and elbows?<br /><br /> http://www.mooreperformance.org/Three.html

 

[vzett]

Re: Merc 4.3L Exhaust Manifold Conversion, 1-piece to 2-piece?

At present, I'm fishing for options. Mercruiser did confirm that the 1-piece and 2-piece y-pipes are different.<br /><br />Going to 2-piece would thus cost me about $1350 in parts with the new y-pipe and not include the cost of pulling the engine (no minor job for my Chaparral Cuddy given lack of overhead access to the rear of the engine). <br /><br />I hadn't considered going through-hull, but this would still require the engine pull, plus more modifications to the transom.<br /><br />If I decide to pull the engine, what else should I do while it's out? The engine is 8 years old with low <200 hours, but runs fine. <br /><br />Thanks,<br />Zett

 

[tommays]

Re: Merc 4.3L Exhaust Manifold Conversion, 1-piece to 2-piece?

if you stay with the orginal maniolds do you need to pull the motor i cant see any inprovement that a 2 piece system would make that would be worth the time and money of pulling the motor 8 years is a pretty good life for manifolds<br /><br />if you start doing things to and engine that has 200 hrs and runs well your just looking for problems that arent there IMHP<br /><br />when the manifolds are being changed i would replace the exaust shutters in the y-pipe<br /><br /> you are being very smart to replace the manifolds before they damage the motor most people wait until they fail and ruin the motor<br /><br />tommays

 

[vzett]

Re: Merc 4.3L Exhaust Manifold Conversion, 1-piece to 2-piece?

I've pretty well decided to stick with the 1-piece manifolds as long as they are available and the engine doesn't need some other major work.<br /><br />I agree doing the shutters is probably a good idea as they are relatively inexpensive. Is there any trick to getting them out easily?