Where does the 4.3 GS PCV hook up to vacuum? I am doing a 2 to 4 barrel conversion

[smassey22180]

My newly purchased used intake and carb has arrived and I think everything is going to work out. The only thing not lining up is the PCV hose fitting. On my 2000 2 barrel, it hooks to a fitting on the rear of the carb base plate. The 4 barrel base plate (from a 1997ish) does not have a fitting. The base plate probably can't be tapped in back like my 2 barrel. I could tap a fitting just under the adapter in the manifold but I figured I would ask what the factory did before I started drilling holes.

Also, the 80487 carb needs a rebuild. Holley had a kit 703-66 but it has discontinued it. This 4160 carb does not have a powervalve which seems odd. Any insight on this is appreciated.

thanks

 

[Scott Danforth]

the valve cover breather tubes do not have a PCV valve, and they should connect to the top of the spark arrestor

yes, this spec for volvo doesnt have a power valve

http://boatinfo.no/lib/volvo/manuals/md_fuel/pages/page_l87.swf

My experiend where someone installed the power valve eliminator plug is then the fuel economy sucks because you have to go up 6 jet sizes on the primary side to get it to run at partial throttle. however per the spec, thats how your carb was set up from the factory.

I also find the the marine carb is listed as 500cfm, however the auto version (80487s) is listed as 600 cfm

 

[smassey22180]

Thanks for the info. So GS 4.3 does not have a PCV valve like my 2000 GL 4.3? I currently have a breather on the port VC and PCV valve on starboard. And I was wrong above. My vacuum line hooks to the base plate and not the adapter.

 

[dan t.]

So drill and tap a hole in the adaptor plate and thread in a fitting so that it pulls from both sides equally. I have converted 3 boats that I have owned to pcv systems with no problems at all . In fact once you have had a valve cover rust out from the inside you will soon realise the value of pcv. It is far superior to the passive breather system that most marine engines use. A pcv pulls the moisture laden crankcase fumes out of the engine and pulls fresh air in, the result is a motor that is far cleaner and drier inside than one with a stock passive breather system.

 

[smassey22180]

My adapter plate is not thick enough to tap. It is double walled which also makes it difficult. The base plate of the carb is also too thin. I can tap the side of the manifold but that will not put it evenly in the center. The 4 barrel intake has a crossover unlike the 2 barrel so do you think the a vacuum on the side is good enough. My old 2 barrel intakes use one barrel for each side of the engine. The new 4 barrel does not isolate one side of the carb for that side of the engine.

 

[dan t.]

If the only place to tap in is the side of the plenum I would tap into both sides and "T" the hoses together then hook to the pcv hose. I would not tap into 1 side only, even with a crossover this would lean that side out. In fact I would make sure that the hoses from the sides to the "T" are of equal length so that they draw evenly.

 

[smassey22180]

I was finally able to get a port in the adapter. The double wall was a around an inch thick and did not allow me to simply tap something in. I took a male to male 3/8" hose fitting and ground the barbs off of one side to make is smooth. I was then able to drill out the adapter plate to press in the new fitting.

 

[dan t.]

Glad you figured it out, you wont regret running a pcv, much happier motor