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Original Message
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| RE: top end oil restrictors for Edelbrock heads |
| By Geoff McNew - 10/20/2003 3:20:26 PM; IP 66.52.140.130 |
I spoke with a Marcus Lim, then Mike Rochon and he forwarded my email to their engineer, a "Jim" somebody. Edelbrock says the drain holes on their head should now be 7/16" ID at the top of rocker valley (mine apparently didn't get drilled full diameter all the way thru - looks like the bit stopped short by about 1/10" and left a smaller diameter shoulder - this I can fix with a hand drill without removing the heads or head bolts). Also, Edelbrock is going to start tapping the oil feed to the rocker so it can take a little set screw with a drilled orifice. (I've got a set of 0.090" ID tube restrictors coming from Gessford, BTW. Gessford also says they prefer the Victor Renz over the Felpro 1247 intake gasket.)
Here's the last email communication from Edelbrock:
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From: Mike Rochon <MRochon@edelbrock.com>
To: "'lonewolf@netwiz.net'" <lonewolf@netwiz.net>
Date: Fri, 17 Oct 2003 11:20:53 -0700
Subject: FW: FE heads - oil restrictors & drain holes
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Geoff,
I forwarded you e-mail to the engineer on this head. This is what he
responded. I hope this helps you.
Hi Mike,
This the only complaint I have heard about Fe oil drain-backs I changed the
oil drains. The current configuration is easier to manufacture and works
better. The hole size where the drain breaks into the cylinder head rocker
valley is 7/16" diameter not 11/32", this oil drain size is typically
sufficient. I looked at heads that we are currently manufacturing to check
that they were machined correctly and I saw no problems. I reject the guys
complaint that he cannot restrict the oil because the he cannot use a Holley
carburetor jet in the passage. The passage can easily be tapped for a
1/4-20 setscrew that can be drilled with their desired orifice size. If the
guy is hesitant installing the restrictors in an assembled engine. I would
tap the oil passage with a greased tap and then I would flush-out any
remaining chips in the passage by pulling the distributor and spinning the
oil pump. Catch the oil and chips that come out of the passage with a rag,
then install the restrictor. To solve the oil restrictor complaint I think I
will add the 1/4-20 tapping to the FE head and instructions in the
installation instructions on how to make and install the restrictors.
Jim
-----Original Message-----
From: Geoff McNew [mailto:lonewolf@netwiz.net]
Sent: Thursday, October 16, 2003 9:04 PM
To: mlin@edelbrock.com
Cc: mrochon@edelbrock.com
Subject: FE heads - oil restrictors & drain holes
Too much oil in the valve covers is one of the trusty old FE engine's very
few problems. Finding the balance between too much and too little oil can
be tricky, given all the variables such as pump volume/pressure.
Fortunately, Ford factory heads have a large enough drilling in the passage
under the rocker stand to accept a standard Holley jet, or a fabricated
bushing with 0.060"-0.090" orifice is also commonly used to restrict flow
to the rocker shaft. The Edelbrock head has like a 3/16" drilling - too
small for a jet. It could be a nice feature if Edelbrock started relieving
the drilling and tapping it for a jet, BTW. But, as is, the 3/16" drilling
puts too much oil up top...way too much for the small oil drain holes and
only gravity for help.
I spoke with your Mike Rochon earlier today, and he explained Edelbrock
changed the oil drainback hole design on the FE head once. In fact, I've
corresponded with a customer who had your old design. I have the current
design and the Felpro 1247 intake gasket seems to work fine, but the drain
hole is still inadequate. The head bolt goes through the oil drain, like
with a factory head, but the hole diameter is smaller. Smaller still is the
drain hole diameter "upstream" - something like 11/32". So, all the oil
build up in the valve cover at elevated RPM's submerges the rear most valve
springs (first); after about 1,500 miles with some wear on the valve seals,
they start letting enough oil by and you get smoke out the pipes under
vacuum/trailing throttle, plus very oilly #4 and/or #8 spark plugs.
I guess I could drill out the drain holes a tad? But how much? It'd be
kinda tough to relieve these drain holes with the engine assembled and in
the car. I'm a little affraid to remove even one head bolt to allow a drill
bit, as if the idea of catching the shavings wasn't bad enough.
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