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Re: [Fot] Cranks

To: "Kramer, Robert" <RKramer@rdoequipment.com>
Subject: Re: [Fot] Cranks
From: Larry Young <cartravel@pobox.com>
Date: Tue, 30 Jan 2007 09:08:40 -0600
Skat makes a Chevy rod in stock TR4 length (6.25 in) with a 2.1 crankpin 
($459 with ARP 2000 bolts at www.flatlanderracing.com).  This is a good 
choice if you want a stock length rod.  Early SBC's used a 2.0 crankpin, 
and there is a special bearing for using a 2.1 rod on a 2.0 crank.  So 
you can use a stock crank and have it turned down to 2.0 or if it's a 
billet have it made with 2.1 crankpins.  The only change needed to the 
piston is to change the wrist pin diameter to .927 (stock TR4 is 0.875).

I like the rods for the current Ford 5.4L engine.  The crankpin diameter 
is the same as a Triumph, 2.086 in.  It is 6.657 in long, so the piston 
compression height must be reduced by 0.407 to about 1.59. This should 
make for a shorter skirt and ligher weight piston.  The wrist pin 
diameter is 0.865.  If you are custom ordering pistons from Wiseco, 
there should not be any additional charge for the pistons.

For those that really want to be "out there", there is a Skat 7 inch rod 
with 2.0 crankpin made for the old Ford flathead V8.  These rods are 
very lightweight compared to the modern V8 rods. The compression height 
would go to about 1.25 inches.

When shopping for rods you have to check the width of the bottom 
compared to the bore.  If it is too wide, you'd have to install the 
pistons from the bottom. The Skat SBC rods are about 0.030 wider than an 
87mm bore, but it is not a problem to remove a small amount of 
material.  I believe the 5.4L Ford rods will go through an 87mm bore 
with no problems.

What is the view of the various clubs on these issues?  I believe CVAR 
doesn't even sanction billet cranks, but I believe they may be changing 
that rule.  I think longer than stock rods are also a no-no, but then 
again, who tears down engines.

Larry Young



Kramer, Robert wrote:

>It would be great if someone that knows what is needed could coordinate
>a piston and rod order, spliting sets of V8 rods etc. I talked to a
>machinist that seemed to think a 6 cyl. Chevy rod was preferable but I
>don't remember the details.
>
>Bob Kramer
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