CVX16SS 140 Mercruiser

[InvalidConflict]

Hey all! So over the weekend in my 1978 CVX16SS, Ran her pretty hard and she did not like that and started knocking...

So this boat we have no idea how many hours are on it so not too surprised something let go. We haven't torn into it to see
what exactly happened. But should know later this week.

My questions right now tho, is there any way to juice these things up a bit? I figure if we are gonna have to rip it apart and rebuild it, we might as well toss a couple more bucks at it and have something even more fun. Not sure how that's possible tho, i love this boat.

Right now, i'm seeing about 37.4mph at 4100rpm. That was about an hour before she started whining. Thoughts?

Any rebuild kits i should be specifically looking at?

Any help greatly appreciated!

[Plugcheck]

Sounds tired, my 16 as would run low 50's with a 19p prop at 4800 rpm.  There was a turbo kit I believe that pushed it to 185 hp, not sure if it was mercruiser or aftermarket.  The 16ss with merc 140 is a great boat when running well,. Good luck with the rebuild.

[Hyperacme]

Brandon ( 75starflight on forum ) did some mod's to his .. He should post with info when he see's this ..

[Jason]

I had my 140 rebuilt in my cv16ss. There really is not much you can do to these. They are pretty much maxed out. I even had a custom made cam for mine with almost no gain in performance. I’ve seen the turbos before as well but I’d be surprised if they help much either. Best I can do is 46.8mph (gps) with a 23p laser II. I think RPM was around 4600. The CVX is a faster hull so there is hope!


CV16SS 140 rebuild
 https://r.tapatalk.com/shareLink/topic?share_fid=82420&share_tid=6073&url=http%3A%2F%2Fforum%2Ecgoamn%2Ecom%2Findex%2Ephp%3Ftopic%3D6073&share_type=t&link_source=app

[Hyperacme]

1975 CV16SS & 1979 CVX16SS
Both weigh 775 lbs. CVX is a little faster ..

[75starflight]

Since Gregg called me out. Lets see if i can remember. 

switched from dished pistons to flattop pistons. Used stock Camshaft. (After doing some research it has the best performance of anything available. My machinist agreed with that also)  Had a cracked head so found a used one that had been extensively worked over(ported and polished, port matched ect) this came from a mini sprint race car.

speeds I am a little blurry on since it has been 6+ years ago but I believe I went from 38mph gps at 4800rpm with a mercruiser 120  and a laser 2 21p to 48.5 mph gps and around 4500 rpm with the same prop. And this is on a 1975 V-179 starflite that weighs around 1000 lbs more than a CV16-ss.

One thing I do regret is going with the flattop pistons as I can only use 91 or higher octane fuel in it which is not real convenient for refueling on the water as it is hard to come by.

[Hyperacme]

4 & 6 cylinder info ..
https://inlinersinternational.org/

[demian5]

I rebuilt mine stock after the exhaust valve on #1 let go. I put in a stock replacement cam for the 140. It runs great and I don't think I need more than 40 ish MPH really (4500 with 19P). If I was wanting more perf I would get something with a v8.

But that's just me, and I have the same boat.

[InvalidConflict]

Awesome stuff here guys, thanks! We'll be ripping it apart later this week and plan pretty much at the moment is to just go back all stock. I do want to be able to get the trim switch redone and put on the throttle if that's possible. Three button trim is a pain.

[Plugcheck]

I used a two button model and just spliced it in the red/blue/green wires.  A quick tab bent from aluminum and I mounted it to the throttle.  Huge difference playing with trim while on plane.