<VV> splitting the block over a tooth

[djtcz at comcast.net]

Before I undertake heroic measures to adjust cam timing I confirm the actual valve timing events.  Actually I  confirm the cam/valve timing events on most engines I  assemble.
1 - confirm damper tdc mark with a dial indicator or positive stop.
2 - provide degree markings with damper tape (bought or made using circumference = Pi X Diameter)  or by installing a degree wheel (paper versions downloadable all over the internet - here's a pretty good one )
http://www.savetheledges.org/test/AVS/images/tech/CrankDegreeWheel.png ) .
3 - using a dial indicator or a valve retainer rotate  crank and note when #1 intake valve opens and closes.
4 - brag to friends that cam is "degreed and installed straight up, advanced 2 degrees, or whatever"

Blind faith in factory marks as good enough is >>usually<< justified, however....
- Last year a "pro" bike racer installed my daughter's Integra cams 1 tooth off 3 times in a row.
- Not too long ago a friend who does high end engine assembly for a local shop found a factory OEM Land Rover timing gear with its mark machined a tooth or so off.

In each case "degreeing" found the problem right away.

http://www.iskycams.com/camshaft.php

--
Dan Timberlake

-------------- Original message -------------- 

Message: 5
Date: Mon, 22 May 2006 08:56:03 -0700 (PDT)
From: Smitty Smith <vairologist at verizon.net>
Subject: <VV> Smittys Carb
To: virtualvairs at corvair.org
Message-ID: <20060522155603.47743.qmail at web84010.mail.dcn.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1

Smitty says:  OK guys, this appears to be the story.  But before I take the 
engine out and break it down to split the block I would like to have some 
knowlgable person verify the accuracy of the timing index mark on the rear 
engine casting.  How accurate is it?  Half tooth, one tooth, or right on?  This 
is important because that accuracy is what I am basing the next week's work on.  
  Finally got my honeydos out of the way this morning and very carefully moved 
the damper timing mark to TDC for cyl # 2.  This placed the little zero on the 
cam gear at the block split line on the bottom of the engine.  Only problem is 
that it is not at the split line but about one tooth off.  So based on the 
accuracy of the timing index mark and the location of the zero I can only assume 
that in spite of my best efforts, I did indeed index the cam and crank wrong.  
If I did, this is the first time in 30-35 years to do that.  I remember like it 
was this morning looking at the match up of the timing marks with a flashlight 
when I put the block together.  Maybe it is time to quit this crap