Brad Christy

Knot 4 Me,

My bad....

This is correct.... Mostly.

The 496, in fact, never had forged pistons. They have always been those damned hypereutectic cast pistons. Not your grandpa's cast aluminum, but cast all the same. Certainly the weak link in the engine, I'd guess.

As I understand it, there was a transition around '01-'02 when Merc started using the cast crank and rods across the board in the 496s. Prior to that, both were forged in the HO models and cast in the base engine. My guess is they ran through the parts already on the shelf after the spec change. I have an engine built in '01. I called Merc. They keep build sheets for all their engines. According to the service tech that ran my serial numbers, both crank and rods are forged.

Thanks. Brad.
(937)545-8991

Brad Christy

My guess it's either due to hull design or aesthetics. Our Rinker 236 Sport Cuddy had them. I always thought they were cool when I saw them on other boats. Then I owned one. It didn't take me long to not really like them anymore. They sound weird, and the blast the boat you're tied to with exhaust water when you fire up.

I had aspirations of rerouting our exhaust. My intention was to make a couple of stainless cap plates that would cover the old side exhaust holes. But I didn't think there was really anywhere convenient to run the exhaust through the transom without having them stick out from under the swimdeck or remain submerged at idle. I opted aginst it.

Hopefully, if Dragracer moves forward with the repower, he can make a reroute of the exhaust work better than it wouldn't have on our Rinker.

Thanks. Brad.
(937)545-8991

Brad Christy

Boomer,

Bite your tongue....

Thanks. Brad.
(937)545-8991

liquidlounge

All of the Volvo big blocks have been running an H-pipe in the exhaust for a long time and they sound fantastic with side exhaust or through the transom.. They H pipe was initially added to control reversion on the 454/502 (Mags) as VP doesn't employ the Merc type flappers in their Y-pipe. A side benefit of this H pipe was a great sounding exhaust note/tone. I have often wondered what the limits are of the H-pipe set up in regards to reversion. In somewhat non- technical reasoning, could it be that evening out (or essentially doubling) of exhaust pulses of each exhaust pipe, as an H-pipe is said to do, make a short riser equal to or superior to your basic extended performance risers?

Dragracer_Art

Yeah I didn't want to get into an argument here... but mine honestly sounds pretty decent through the side exits. I wish I could hear a little more cam though.
If I had a choice... the exhaust would exit out the transom... but there just isn't enough real estate back there to poke more holes in the boat. The extended V-plane transom offset/step prohibits it because there is very little flat surface back there. I had same issue with previous Chaparral 2330.

The "H-pipe" on mine is just a large crossover hose at the exhaust diverters. Never saw anything like this on a Mercruiser.
This is exactly how it left Chaparral in 2007. My boat was pretty well-optioned when new and has remained untouched.

SB

Vacuum break.
Is the hose connected to these ?

articfriends

If you like to "party" you'll just put some boost to it, run it a little on rich side to ward off detonation, don't let all these negative Nancy's talk you out of it, the bottom end will be ok until its NOT!

Dragracer_Art

Does not appear to be. Looks like they are joined by a simple nipple/tube that is part of the Corsa kit.

Dragracer_Art

In latest news... I just dropped $2k on a closed cooling system. It's only a half system and doesn't touch the manifolds... but at least the engine wont have scummy water running through it and it wont freeze over the winter.

https://www.hardin-marine.com/p-1003...lf-system.aspx


Next will be a better set of manifolds with dry joints. Still shopping for the right system. Looking at Stainless Marine and Dana. Cannot swing $8k+ on CMI stuff. $3500 dry joint manifolds will suffice.
I never liked the VP and Mercruiser wet joints. Almost lost my last (merc) motor because of previous owners maintenance neglect. Had water in several cylinders one day after running on muffs in the driveway. Figured it out the next day when the motor was hydrolocked. Pulled all plugs, spun it over to push water out and fogged all cylinders. Resurfaced manifolds/risers and replaced gaskets and it was good as new. Motor wasnt hurt and still ran strong.

Brad Christy

Dragracer,

I also wonder about the 90DEG bends in the exhaust routing that is usually implemented with side exhaust. I would think they would induce backpressure that would be unwanted for a higher performance engine. We had them in our Rinker, and I often wondered if they weren't holding the engine back some.

Thanks. Brad.
(937)545-8991