what pcv system to use?

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hgprem400
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what pcv system to use?

Post by hgprem400 » Sat Jun 12, 2010 11:27 pm

i would appreciate some feedback on pcv systems. i see different systems being used on engines from 500hp + and wondering if one is better than another. i am building a 406sbc around 620hp mark. i like the old fuel altered look with tall breathers straight out of the covers. do these work as well as a vac-u-pan set up or plumbing covers into a catch can or pcv valve into carb? i am running a tunnel ram if this helps car is only gonna see about 1000 street miles a year, mostly strip car. dont want to use a vac pump. thanks.

Sandman
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Re: what pcv system to use?

Post by Sandman » Fri Aug 27, 2010 5:37 am

I've used PCV valve with vac u pans in streeters. Works pretty well, especially if you make a seperator tank and draw fumes from there.
If you only use vac u pans on a streeter with no PCV, I haven't had much success with it, as your not doing enough revs/exhaust flow to make the vac u pans work at low revs/normal driving.

cjperformance
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Re: what pcv system to use?

Post by cjperformance » Tue Nov 02, 2010 8:38 pm

With a cam like what you will use an off the shelf pcv valve will not operate properly and will cause you tuning/low rpm issues due to the spring tension and valve action in them not suiting low idle intake vac readings. You will be far better off running the big breathers to get the look you want and just running a fixed restriction to the crankcase, this can just be a 1.5 to 2mm restriction which is easy to tune for at low rpm and is plenty of ventilation to draw any condensates out of the crankcase for street use. Just be sure to pull the vac from a spot where you will draw no oil.
OR, just use the breathers and no crankcase ventilation, this just means more frequent oil changes, as plain breathers are not as good at getting moisture vapour or fuel vapours out of the crankcase.
You can modify pcv valves to operate with low vac but for the limited street use you will see, I would not bother with this.
Craig.

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