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PCV observations

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PCV observations

Post #1 by 63falconATX » Tue Feb 18, 2020 12:09 pm

Been tuning and have come to the conclusion the stock PCV might not be right for my hopped up six.

Stock bore and stroke E0 200
Aussie 2v head, stock valves, 1.6:1 rockers
Re-cureved HEI
6/2 headers
Holley 2300 350 cfm
274/274 110 degreed 7.5*
Measured/calculated 8.9:1 cr

We know we have higher manifold vacuum at idle and the PCV spring should allow increased airflow at higher RPMs when vacuum is low.

Simple test, tissue over the breather hole opposite the PCV, tissue pulled in at idle. When RPM is increased the tissue is no longer pulled inward. Over ~2800 RPM it is actually blowing off. It is simply not keeping up with crank case pressure.

This seems wrong to me. I'm thinking the build might need a PCV other than stock?

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Re: PCV observations

Post #2 by xctasy » Tue Feb 18, 2020 2:07 pm

the 300 truck PCV is a good replacement if the the Dual Flow Adjustable PCV Valve from M/E Wagner Performance Products is too expensive.

It does the same thing. Ford EV-98-B Motorcraft PCV Valve #D9ZZ-6A666-A (1980-2001 V8 item)

THE FRENCHTOWN FLYER wrote:You must have a PCV valve if you are going to route crankcase fumes into the intake. The valve acts as a metering device so that at small throttle openings (and high vacuum) there is minimal flow through the valve, and at large throttle openings (low vacuum and high blow-by) there is virtually unrestricted flow through the PCV. If yours does not have one try a Motorcraft # EV-98.

I highly recommend a PCV valve for all street-driven engines.

see Search found 28 matches: pcv valve 300 ford
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FAZER 6Bi (M112 & EEC5) or FAZER 6Ti (GT3582 & EEC5) 425 HP 4.1L/250 I-6
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Re: PCV observations

Post #3 by 63falconATX » Tue Feb 18, 2020 4:34 pm

Thanks for the comment xctacy. Interesting read there. What stands out is how these PCVs we're using are intended for a closed system when mine is anything but... Before I try a $129 adjustable, I'll give the 300 a shot and maybe even a fixed orifice version which is apparently helping a lot of folks in the v8 world with similar issues.

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PCV observations

Post #4 by chad » Tue Feb 18, 2020 5:35 pm

"...we're using are intended for a closed system..."
some "yes", some "no". Depends on yr.

Take a lookat all the online pic of ur vehicle from
mid 60s thru late 70s. You'll see the change (if those pic R of
concourse correct vehicles). The bronk & stang have shot up in resale ask
(bronk got #1 prices this fall, has dropped to #28 now) and some were done in oem fashion
as @ those prices there's more $ for restore & geta leg up on other sellers. PCValves R listed
by yr (correct application) weather U have the rest of the equp (closed) or not (modern cam,
ac housing 'hook up', etc).

Some finishing items on mine (just gota new drivetrain in) R a cold air intake tube (if I can find it'n make up other prts. I put on headers the vehicle never had) and a late '70s closed pvc system w/a '69 250/4.1.

Let us know how U do :thumbup:
"Big thing is only make one change at a time. Change 2 or more things at a time it becomes difficult to figure which change helped or hurt" turbo2256b » 1/16/2017
Chad - '70 LUEB on '77 frame (i.e. PS, D44, trapezoidal BB 9", 4.11), '69 250ci, NV 3550 & DSII, "T" D20/PTO, 2" SL, 1" BL, 4 discs, 33"X15", tool boxes, etc. Seeking: Hydraulic gear motor for Koenig pto. (413) 259-1749

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Re: PCV observations

Post #5 by wsa111 » Sat Feb 22, 2020 8:43 pm

Just use the stock PCV. To keep blowby in check install a Spectre oil breather cap.
Remember at full throttle the PCV see zero vacuum.
All the PCV does is evacuate the crankcase at idle & part throttle driving.
67 mustang,C-4, with mod. 80 hd, custom 500 cfm carb with annular boosters, hooker headers, dual exh.-X pipe, flowmaster mufflers, DSII dist. MSD-6425CL & MSD-Blaster 8252 Coil. Engine 205" .030" over with offset ground crank & 1.65 roller rockers. 9.5 comp., Isky 262 cam.
2003 Ford Lightning daily driver. Recurving Distributors.

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Re: PCV observations

Post #6 by ldm314 » Sun Feb 23, 2020 2:26 am

I like having a PCV valve with a non vented cap. Even my 351C with a big cam that gets 8" at idle has a PCV valve. I did have to find one that had a lighter spring in it that worked with low vacuum.

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