Crash,
If/when the 948 goes back into a car, I'm doing the later timing cover mod.
I noticed it on Speckman's Bugeye at Road America and I thought that's
what he'd done to his 948. I later came to find he was a running a
cheatin' dog 1275 (sorry Gar - couldn't resist). Nory's explanation of the
valve's function is great. As stated, at higher speeds the vacuum is less,
and if you want to get fancy Vizard talks about plumbing crank vent into
the exhaust manifold with (VERY IMPORTANT) an anti-backfire valve installed
(available most local stores). Vizard calls it an "Evacu-sump" or
something. I call it an ejector. This would work great for your
high-revver, I'd think. I spoke to David Anton at APT (Vizard's company)
about having him put in a boss on an Long Center Branch manifold for me to
screw in an AN or pipe fitting, and he felt it wouldn't be too effective on
a stock (or slightly modified) engine due to low exhaust speeds. He gave
me a price of $25 to do the mod to the header I was buying for me (you need
to have a stub protruding into the exhaust, and it is at an unusual angle,
not just angled in the direction of flow as you might think). I chose not
to go for it, and the PCV setup described earlier works great. I have a
friend (The Engine Nazi) who races a 428 Cobra Jet Mustang and he has run
the "Evacu-sump" setup for 20 years with good success. 'Course he's making
600 hp... Anyway, you might try to contact Anton at APT to get his
feelings on the usefulness on a 948. I would think at 7 grand your engine
is going to make enough exhaust velocity! I will get you his e-mail later
today - I have it at work.
Ron
----------
> From: David Ramsey <dwramsey@worldnet.att.net>
> To: spridgets@autox.team.net
> Subject: PCV for 948cc
> Date: Thursday, November 05, 1998 2:28 AM
>
> All this talk about PCV has got me thinking about my 948cc bad dog motor
that has always leaked. This PCV sounds like the ticket. I have a 1098
side cover with the can, and somewhere I have a later intake manifold with
the PCV inlet ( guess I'll need to hog it out like the old one ala Vizard
). What I want is a 1275 timing chain cover with the can so I can pull
vacuum from both it and the side cover. Anybody got one they want to trade?
Has anybody tried this yet, on a high revving motor ( red line at 7000 rpm
)?
> Crash
>
|