Add a PCV system ?

[Rod Holder]

Hey,<br />Crazy thought, would there be any benefit to adding a PCV system to a 1977 Merc 470 ?<br /> (470 bashers please be kind )<br /><br />I was hoping for a 25 HP increase , or would be happy with a healthier engine.<br /><br />Whatcha think ?

 

[Don S]

Re: Add a PCV system ?

Mannnnnn, I want some of whatever that is you're smokin' <br />Don't you think that Mercruiser would have put in a PCV system if it would have given 25hp for free?

 

[Rod Holder]

Re: Add a PCV system ?

No really, I'm serious (well, except for the HP gain part)<br /><br />Would a four banger benifet from a PCV ? I would think it would be better to draw the blowby directly into the intake manifold, rather than "pushed" out towards the spark arrestor.<br /><br />Any PCVoligists out there ?

 

[Bondo]

Re: Add a PCV system ?

Well,....... <br />I've read where a Positive Vaccum on the Crankcase,.. <br />Might Increase the HorsePower on a Top Fuel Dragster by 1%......................<br /><br />But,....... A 1% Increase on a 1600hp motor is alittle Different than a 1% Increase on a 165hp motor...........<br /><br />And,.. I Doubt you'd see the 1%.........<br /><br />I'd Think that trying to live with a 470,.........<br />Would keep you occupied enough to Not have Time, To Even Think About something like This.................

 

[Bt Doctur]

Re: Add a PCV system ?

except for the fact that your running at a high throttle setting most of the time and theres little or no vacumn being pulled.If it would work ,Mercruiser would have done it already.

 

[Rod Holder]

Re: Add a PCV system ?

Maybe I'll table the PCV idea for now. I need to see how well the 6-71 blower setup will work first.<br /><br />Gotta think outside the box (I'm actually trying to blow it up so I can throw in a smallblock) <br /><br />RH

 

[Don S]

Re: Add a PCV system ?

A 6-71 blower on a 470 engine, come on, why not just pull it out and sell it to someone that can use it instead of going to all that expense and time just to blow it up.<br />You do realize that the drive is not the right ratio for a V8 don't you? How about the exhaust tube for the 470, you have one for a V8 to fit that transome shield?<br />Seems to me you don't realize that boats are different in how they operated compared to automotive.

 

[I/O WALDO]

Re: Add a PCV system ?

I putta 6-71 on MY 470 and MAN!, picked up 45MPH & halfed the gph!

 

[Rod Holder]

Re: Add a PCV system ?

Sweet results Waldo !<br /><br />I was just about to do the same (wink wink) but I did a lekdown test to find the source of excessive oil vapor from valve cover breather and turns out #2 cyl rings are toast. <br /><br />The good new is that I confirmed that the pistons are Sealed Power made for 460 Ford so finding rings will be easy. The bad news is that when I did the end gaps 120 hours ago, I was not aware of the need for the upper gap to be wider than merc spec for those particular pistons. May or may not be the problem. Will know soon.<br /><br />RH

 

[I/O WALDO]

Re: Add a PCV system ?

Those engines are famous for leakin GREEN water into the oil through the seal behind the cam- drivin circulating pump and the ft.-o- the cam.Justa note.Can create vapor,knott blowby.

 

[Buttanic]

Re: Add a PCV system ?

A PCV valve on a sealed engine ( no vented valve covers) will help to prevent oil seepage past seals and gaskets. I doesn't take a lot of vacuum to do this. I had a 85 Chevy with the 6.2 diesel which had a vacuum pump to operate the A/C and heater controls and also pull 6" of vacuum on the crankcase. It started leaking oil big time past the rear crankshaft seal. I thought I had a bad seal until I found a split in the vacuum hose to the crankcase, replaced the hose and the leak went away. Most marine engines will pull 6"+ at cruise. Sure will help to keeep the bilge clean.

 

[Bondo]

Re: Add a PCV system ?

Buttanic,........<br /><br />Read Waldo's post just above your's,+ Tell Me,... Truthfully,............<br /><br />Would You want to be Pulling ANY Vacuum on a 470,..??..................

 

[Buttanic]

Re: Add a PCV system ?

I am not familar with a 470 so I couldn't answer that but in general a PCV valve on a sealed engine will greatly aid in preventing oil leaks. Most later automotive engines are sealed and you see very few oil leaks now days compared to past years. Of course the engine has to be healthy. Although the vacuum may pull a bit more coolant than would be forced by cooling system pressure alone the heat and vacuum may scavange more water vapor out of the crankcase than just heat and an atmosheric vent would.