Leave the pcv valve on or take it out pros and cons

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SWAMPHUNTER45
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Re: Leave the pcv valve on or take it out pros and cons

Post by SWAMPHUNTER45 » Tue Feb 06, 2018 4:15 pm

ZZ4 is 355hp @ 5250
Drive is 2:1 belt spinning WW Falcons

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kwanjangnihm
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Re: Leave the pcv valve on or take it out pros and cons

Post by kwanjangnihm » Tue Feb 06, 2018 7:37 pm

I had to read this thread a few times, but finally have a visual of how a CM pcv valve works!! :toothy7: :stirpot:

Image
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Re: Leave the pcv valve on or take it out pros and cons

Post by One Eyed Gator » Wed Feb 07, 2018 8:37 am

FYI on the vacuum cap use the silicon caps. The black rubber caps will not last. I also put a small zip-tie around the cap.

BTW Loudmouse what is the name of your shop?

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Re: Leave the pcv valve on or take it out pros and cons

Post by Basin_Runner355 » Wed Feb 07, 2018 10:29 am

Well upon checking other things yesterday i come to learn that i have a head gasket leak and I’m getting fluid on my #3 cylinder so I’ll be tearing it all down and getting my heads Reworked and fixing that issue before i make any adjustments. Always someting with a airboat.
14ft diamond back mild zz4 355sbc pushin 450 hp 450 TQ 2:1 belt drive reduction with a 3 blade sensenich 78Jw series

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Re: Leave the pcv valve on or take it out pros and cons

Post by Basin_Runner355 » Wed Feb 07, 2018 10:30 am

358E02BC-47CD-4896-959C-7D81CA6DAFDA.jpeg
Spark plugs
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Re: Leave the pcv valve on or take it out pros and cons

Post by loudmouse » Wed Feb 07, 2018 11:19 am

@kwan, there is another 50+ pics of a pcv setup but they do not depict GM's way after the late 80's. Nor did the sbc come with a aftermarket holley carb.

Looking at ur plugs that engine has some severe tune issues that need to be corrected.

The Holley carb was NEVER designed to operate with a vacuum leak (vented pcv) as it's design is for performance use no pcv. The large port on the back of the base plate, (intended for the brake booster) SEALED, can be used for pcv if the system is sealed! If it's used in a vented pcv, the metering of the fuel must be reprogrammed by changing the air bleeds and corrected jetting. This I also do but not for a pcv but for a carb operating on an engine with very little vacuum(high overlap cams) to achieve a linear afr throughout the rpm.

Now to the head gasket, its very unfortunate that this had to happen but I see it all too often. 4 causes of blown head gaskets are operating the engine out of tune with a high load (prop), operating the engine hot, electrolysis from improper grounding and not maintaining a proper mixture of anifreeze to stop the corrosion inside the engine. Good luck with the repair and remember if the engine is allowed to operate under the same paramiters again the end result will also be the same!
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Re: Leave the pcv valve on or take it out pros and cons

Post by Basin_Runner355 » Wed Feb 07, 2018 11:43 am

I wil try my best to get it right so it doesn’t happen again. When i got motor it had the green coolant i put the orange dexcool since that is suposed to be for engines with Aluminum head. I will get with about the tuning of the carb once i get the head gasket squared away and i know I’ll have a fresh set of valves that are seating properly. Hope I’m not down to long got a big ride in a few weeks.
14ft diamond back mild zz4 355sbc pushin 450 hp 450 TQ 2:1 belt drive reduction with a 3 blade sensenich 78Jw series

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Re: Leave the pcv valve on or take it out pros and cons

Post by Basin_Runner355 » Wed Feb 07, 2018 11:50 am

I have to get the head gasket and all that fixed before i worry about the carb i haven’t rsnnit since that last guy i told you about put his touches on it but loudmouse i will be intouch oncd i get the internsls right again
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Re: Leave the pcv valve on or take it out pros and cons

Post by Basin_Runner355 » Tue Feb 27, 2018 12:32 pm

Well come to find out i fried the #3 piston and rings. My plan of attack right now it to just short block the motor out it back stock and use my old block to build a new one for later on down the road gonna get it bored and all that good stuff and build it bullet proof from the ground up. All forged internals the whole 9 yards so I’ll be asking for parts and what not in the near future.
14ft diamond back mild zz4 355sbc pushin 450 hp 450 TQ 2:1 belt drive reduction with a 3 blade sensenich 78Jw series

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Re: Leave the pcv valve on or take it out pros and cons

Post by Striker543 » Mon Jul 02, 2018 1:49 pm

Do you guys have a catch can system you recommend? I just bought a boat with a 406 sbc that is building pressure and forcing the dipstick to pop up a little. It currently has a line from one valve cover going to the base of the carb and the other valve cover has a breather with a line going to a mount that faces the mouth of the hose against the carb air filter.

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Re: Leave the pcv valve on or take it out pros and cons

Post by Striker543 » Mon Jul 02, 2018 2:43 pm

My setup is the same as the diagram posted above

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Re: Leave the pcv valve on or take it out pros and cons

Post by JAMES » Mon Jul 02, 2018 5:50 pm

I like them the motor needs and has to vent some way this is the cheapest source jmo . No vent u will develop leaks
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Re: Leave the pcv valve on or take it out pros and cons

Post by Hotdog » Mon Jul 02, 2018 5:55 pm

I have a 434 with 13.2 compression. I run open breathers one on each side about 6 inches tall and I have no problems with oil seeping out of them

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Re: Leave the pcv valve on or take it out pros and cons

Post by Dying_breed » Sun May 12, 2019 10:11 pm

I know this is old, I read this post researching in regards to my motor staying wet with oil @ the breather on my valve cover. So on my SBC DD, I'm running a pcv valve on one valve cover, an a filter/breather on the other valve cover. This setup is incorrect by what I'm reading here... Correct.? I like my boat clean and absolutely cannot stand the oil spray on my motor, prop and rudder. The boat runs good, imo but I smelled oil after running hard in a shitty situation one day, seen the wet breather and noticed after repeatedly cleaning it, it stays wet with oil. So all that being said, is this pcv setup my culprit???

SWAMPHUNTER45
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Re: Leave the pcv valve on or take it out pros and cons

Post by SWAMPHUNTER45 » Mon May 13, 2019 7:26 am

An engine with positive crankcase ventilation will stay cleaner and live longer. The Branch engines have a filtered breather on one valve cover and a PVC breather on the other that is drawing air through the engine venting out the bad gasses and blow by.

Had you changed valve covers or the grommets and breathers ?

If your getting oil being pushed up a filtered breather it is generally either excessive blow by in a worn engine or a breather location on the valve cover where a pressure spray if directed or thrown up. There is a baffled grommet that corrects the issue if caused by spray. It has a standard look but extends downward slightly and has a shielded opening in it's bottom. $2 fix

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Re: Leave the pcv valve on or take it out pros and cons

Post by flcracker9 » Mon May 13, 2019 7:38 am

kwanjangnihm wrote:I had to read this thread a few times, but finally have a visual of how a CM pcv valve works!! :toothy7: :stirpot:

Image

Kwan, you're killing me! I think this one went over a few peoples heads lol
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Re: Leave the pcv valve on or take it out pros and cons

Post by Deano » Mon May 13, 2019 9:37 am

kwanjangnihm wrote:I had to read this thread a few times, but finally have a visual of how a CM pcv valve works!! :toothy7: :stirpot:
Image
flcracker9 wrote:Kwan, you're killing me! I think this one went over a few peoples heads lol
Kwan, I'm not so sure that you have this figured out as well as you think you do. I understand you AC guys don't have as much experience with some things as the CM guys, but if you continue your research, I think you will find that your diagram shows that internal plug installed backwards.

It's my understanding it should be installed such that the string is toward the outboard end. As you conceptualize
the theory, realize it's sole purpose is to facilitate said plug's removal prior to the next system flush. :toothy7:
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Re: Leave the pcv valve on or take it out pros and cons

Post by loudmouse » Mon May 13, 2019 9:52 am

If a filtered vent or any vent is used on one valve cover and pcv on the other connected to a engine vacuum source 2 things happen (1) the vacuum source can't pull the inside of an engine to a vacuum state. This constant vacuum prevents oil from escaping seals and gaskets. (2) The carburetor was NOT calibrated for this constant leak of air( btw enters below the venturi and is not metered with fuel) and causes a lean condition in most applications. Most often showing up on rapid throttle opening with a stumble, lazyness in acceleration and/or hot running cylinders that cause excessive run on at shut down.
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Re: Leave the pcv valve on or take it out pros and cons

Post by SWAMPHUNTER45 » Mon May 13, 2019 11:43 am

What's next?

HP vs Torque
Sensenich vs Whirlwind
CM vs Aircraft
Synthetic vs Dinosour

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Re: Leave the pcv valve on or take it out pros and cons

Post by Deano » Mon May 13, 2019 12:33 pm

SWAMPHUNTER45 wrote:What's next?

HP vs Torque
Sensenich vs Whirlwind
CM vs Aircraft
Synthetic vs Dinosour
Carb vs Fuel Injection
Aluminum vs Fiberglass
Full Deck vs Open
Front vs Rear Driver
Cable vs Crows foot
Full Cage vs Pancake
Stainless vs Aluminum
Polymer vs QuickSteelFrogSlickFlexSpit

Blonde vs Brunette

When PROPERLY done, time has shown they will ALL work.
. . . provided we deliberately exclude the libtard majority holding the House hostage.
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but it is not the path to knowledge; it has no place in the endeavor of science."
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Re: Leave the pcv valve on or take it out pros and cons

Post by loudmouse » Mon May 13, 2019 12:52 pm

Yes they can. But for those that are not mechanically inclined to adjust (Tune) the engine to make up for the lean condition cause by their simple pcv vented set-up, a closed system is more desirable for 95% of all cm airboats. Hell, you can run. vents in both valve covers and if you have a good set of VC with proper baffles would be fine. BUT if you bought the economy covers or the engine in a lot of blow by state, the volume of blowby would put oil out both sides through the filters.
Fuel injected engines this does not apply in the respect for adjusting the carb but will require the tune to be altered for fuel if using engine vacuum with a vented cover.
15' Alumitech deckover LSX TT Oxbox 84" JX 4-blade
Gas required Water optional :dontknow:
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