Intro and two part question
 

Hello everyone. I've been lurking on this board for quite some time learning lots of valuable info. My beast is nothing like a fountain, donzi, formula but I'm still looking to push some more power for cruising/fun. Here's my set up:

89 Maxum 2300 open bow
stock 7.4 bravo.

I'm replacing it with:
stroked 498
070 over flat top probe srs pistons
scat forged I beam rods
scat forged crank
bow tie aluminum heads
ultradyne hydr roller 601/601 @ 230*238* duration
Pretty much new block, heads, rotating, intake, carb, the rest will come off my current 454

Questions:
1. I just received a set of 496 take off aluminum manifolds with stainless risers. The risers have connecting water hoses in front and rear coming up from the manifolds. How do I set these up with current thermo assembly? Do I run the hose from thermo to riser and plug the manifold?

2. What is the benefit of Quick and Quiet II? I understand open thru hull and prop but does this lower the dc level due to open prop. I can't afford choice right now but I don't want to scream too loud so i'm thinking of some baffles/mufflers in the tips. Should I leave y pipe or go straight thru with silencers?

I currently boat what's left of Lake Mead. All opinions welcome.

Fixx
 

those manifolds need to be plumed like they are from the factory..
and don't take them apart,those gaskets are like 40-60 bucks a piece..
their should be a fitting on the bottom of the manifold, out from the thermostat housing to the fitting on the bottom of the manifold,if you have a 4 port housing you need to either get a y connector and connect 2 hoses in to one or replace the thermostat housing with this one..

http://cgi.ebay.com/ebaymotors/ws/eB...d=370319170134

whats the LSA on that cam..

Here's the info on the cam:

284*/292*
230*/238*
112* LSA
108* ICL
.3533"/.3533" lobe
.601"/.601" valve w/1.7 rockers
The HR14 is the master lobe number for the intake
The HR15 is the master lobe number for the exhaust
The I/T 5266 is the serial number

The thermo housing in the link has the same # of hoses going to exhaust as stock. I'll just get a y connector for the riser hose.

Fixx
 

so your saying ou have a 4 port thermostat housing? the 2 front ports(starboard),the biggrt of the 2 goes to the circulation pump,smaller one (port side) goes to the sea pum. the rear 2 go to the bottom of the manifold..

is this what you have?

No, 4 hoses leaving thermo housing. 2 hoses to bottom of manifolds and 2 hoses directly into the risers. Stock set up for 1989 7.4l 330hp.

With those cam specs and stock 496HO exhaust, it is almost guaranteed that you will have water reversion.

If reversion is an issue then I'll have to fab some extensions and have my machinist weld them on to the inner riser tube. How far should I make the extensions?

What is the most practical application to fight reversion in my situation?

Should I weld and extenstion to the inner exhaust pipe so the water isn't introduced until the end?

Or, is it as simple as plugging the hose holes on the outside and inside bends of the riser along with one of the manifold's holes and run one hose from manifold and connect to end of exhaust?

I drew a pic showing both scenarios but I can't attach.

For reversion. Buy the correct exhaust.

Awesome answer to my question, :angry-smiley-038: I'm trying to find out how to combat reversion with 496ho manifolds. Any useful opinions appreciated.

Getting a cam bigger than the 454/502mag cam is a waste with those heads anyway. The 7.4 has peanut port heads and they won't flow enough to support more than a stock mag cam.

I'm not reusing my stock heads. I already have the exhaust along with aluminum bow tie heads with large oval ports.

Ooops, Just reread and saw that.

I have never heard of anybody modifying the stock 496 exhaust. It s better than the old cast iron stuff, but you will still be choking your engine with it. You will be better off using a set of performance exhaust and will make more power.

Griff, thanks for the replies. To put it frankly, I can't afford a high performace aftermarket exhaust right now. I'm still piecing together the motor. I came accross the 496 manifolds at a third of the cost of hi perf. I'm now worried about reversion as you mentioned so I'm trying to find the most practical way to use what I have to prevent it. That's why I'm inquiring about modifying the stock 496 mani's.

Good luck with the build. I really don't know of any way to modify the 496 riser to dump water farther back. By the time you pay for any fabrication and welding, you will most likely find that its not cost effective.

For now, I would use a mild cam and then when your budget allows, upgrade the exhaust and cam later.