Renewing 1980 CC Inboard Questions

[ranintothedockagain]

Rebuilding the 350 in my 1980 Chris Craft 251. This is a 25' inboard, reverse rotation 275 hp 350, Raw Water Cooled and Paragon Trans.

The (rusty) manifolds I took off were the log style units with the big hump at the rear. I've seen this
style boat with center rise manifolds and that seems to be the way to go.

I have 4" flex pipes going through mufflers to the stern that I plan to extend to reach the center rise manifold.

Here are my questions on this....How to determine 3 or 4" riser ? Just go with what fits under the deck ?

What style center rise manifold to use ? I see mercruser style kits on ebay for 350's in the $475.00 range ?

Is it ok to extend the exhaust pipes using couplers and clamps - or should I plan to use new pipe ?

With a raw water cooled system and one (trans) cooler - where can I find a layout or diagram - showing thermostat housing, etc ?

And - How can I install senders for both a temp guage and a temp alarm on a 350 block ?

Thanks !

 

[bondo]

I have 4" flex pipes going through mufflers to the stern that I plan to extend to reach the center rise manifold.

Here are my questions on this....How to determine 3 or 4" riser ? Just go with what fits under the deck ?

Ayuh,.... If ya got 4" pipes now, ya probably oughta stay with 4"....

You'll need whatever elbows, 'n pipes, 'n couplers it takes to go from log risers to yer center risers....

The differences between Merc style, 'n others is usually the accessory mounting holes...
Donno what ya need, so, You'll have to decide..

With a raw water cooled system and one (trans) cooler - where can I find a layout or diagram - showing thermostat housing, etc ?

And - How can I install senders for both a temp guage and a temp alarm on a 350 block ?

We don't know what yer T-stat housing looks like Now, so it's hard to say how ya gotta plumb it...
The Temp sensors go into the drillings in the T-stat housing...

 

[RicardoMarine]

Here are my questions on this.... How to determine 3 or 4" riser ? Just go with what fits under the deck ?

What style center rise manifold to use ? I see mercruser style kits on ebay for 350's in the $475.00 range ?

Is it ok to extend the exhaust pipes using couplers and clamps - or should I plan to use new pipe ?

With a raw water cooled system and one (trans) cooler - where can I find a layout or diagram - showing thermostat housing, etc ?

And - How can I install senders for both a temp guage and a temp alarm on a 350 block ?

If you need riser height, let your hatch clearance determine the max height of your risers and/or riser spacers.

Extending rubber couplers (Marine exhaust hose) should be OK. There will be both soft wall and wire re-enforced hose to choose from.
Double band clamp these, or use single SS Marine style T bolt clamps.

Keep in mind that any exhaust manifold for a Merc with an A drive, or OMC with a Cobra drive, will have the thread bosses cast into it for an ESA or SA system.
If you want a nice clean look, you'll want to avoid these manifolds.
Then consider that there will be several riser outlet diameters and down angles.

Post a few photos of your existing Chris Craft engine, exhaust and sea water pump.
The plumbing may change slightly with the center rise exhaust.

As for the temp and over-temp alarm senders, if the intake manifold front cross-over is ported on both sides, the second port can house the over-temp switch.