<VV> Poor MPG and performance

[djtcz at comcast.net]

original messages 

----- Original Message -----

From: Mark Durham < 62vair at gmail.com > 
Subject: Re: <VV> Poor MPG and performance 

Really? That's good to know. Mark Durham 

Sent from my Windows Phone From: Tony Underwood 
Sent: Saturday, September 17, 2011 10:12 AM 
To: Virtaul Vairs 
Subject: Re: <VV> Poor MPG and performance 
At 11:11 AM 9/17/2011, Mark Durham wrote: 
>Its possible you have the cam retarded 1 tooth . Mark durham 
> 
>Sent from my Windows Phone From: Bob Dunahugh 
>Sent: Saturday, September 17, 2011 5:45 AM 
>To: Virtaul Vairs 
>Subject: <VV> Poor MPG and performance 
> 
> 

If it runs better and mpg improves if you advance the ignition timing 
to about 22 degrees, that will confirm the "off one tooth" cam gear. 



tony.. 
_______________________________________________ 


The valve timing can be checked with the engine assembled. 


I'd do that, and map out the ignition centrifugal (and vacuum) advance before assuming anything about cam installation. 
I'm not all that comfortable assuming cam timing marks are correct. There is a tolerance on the location of the keyway locations on all those components. 
And manufacturing mistakes happen. A friend has developed a good reputation building engines for race cars and specialty cars. A land rover inline was running weakly after being rebuilt with lots of new factory parts. The degree wheel quickly revealed the crank sprocket had the key generated in the wrong location. Re-timing it 6 times to the factor marks would not have fixed that. 


Assembly mistakes happen too. 
A mechanic of a friend of my daughter was recommended because "he works on Corvettes, and has a race bike." He changed the timing belt, and got the exhaust cam timing wrong by a tooth on her INTEGRA 3 times (and left the crank bolt just snug the last, and I do mean LAST time). The key and keyways were lighly battered after just a week or 2 in gentle service) 


The first step for both is confirming the TDC mark on the damper is accurate. 
Down the page ~ 1/3 here. 


http://www.iskycams.com/degreeing.php 
A "positive stop" can be bought or made to work through the spark plug hole on an assembled engine. 
http://www.jerrybramlett.net/images/pic_installation.jpg 
http://www.purgeraptor1.btinternet.co.uk/Pictures/PitStop/poslockstop.jpg 


Dan T