[Shotimes] +20 cam valve noise

[bmalach1@nycap.rr.com]

Hmm sounds like about waht I'm seeing. if the valves were set at nominal
to looser end of the specs the amount of opening up that I'm seeing
sounds like it would be normal. I set all mine on my own personal car to
.006 on the intake secondaries, nominal to low end of spec on the intake
primaries (didn't obsess over the long runners), and then nominal to
tighter end of the exhaust all the way around. Mine are quiet, but I'm
planning on addding in a set of adjustable sprockets and DFL coating my
cams, so I'll be pulling them out/checking the shims. 

The person that installed them floated some ideas of collapsed valve
springs ect. Needless to say this scared the new owner of this car.

Thanks for the details Mike.

Bruce

----- Original Message -----
From: Mike Bruce <shoitoff@verizon.net>
Date: Monday, October 31, 2005 4:34 pm
Subject: [Shotimes] +20 cam valve noise

> Bruce,
> 
> I did the install on my own set of +20 cams, and chose to set my 
> gaps at .006" and .010" for intake and exhaust.  As soon as I had 
> the car running, I notice more valvetrain noise than normal.  After 
> 2000 miles, I checked the valves to see where the gaps had moved 
> and found that they had opened up .002-.003".  They were all still 
> in spec and making as much noise as when installed, but I chose to 
> tighten them back up to the lower limit.
> 
> 
> My belief is thatv you should check your gaps after a couple 
> thousand miles just to be safe.  The extra valve noise, I think, 
> comes from the change in profile over the stock lobe.  The longer 
> distance from the base circle to the lobe tip would have more 
> impact than stock.  The tip of the cam lobe hits the shim like a 
> hammer hits a nail.  Think of two hammers with different length 
> handles. The "+20" hammer would hit the nail, or shim in this case, 
> with more force.  
> 
> Mike
> 
> ------
> 
> anyone want to confirm for me that when cams are 25% to 50% out of 
> spec on the valve lash they will sound like a sewing machine? Got a 
> friends car in the garage that makes a racket, and I'm finding 
> intake valves in the .008 to .013 range and exhaust valves in the 
> .011 to .016 range. These were a SHOnut +20 set of cams installed 
> by a trusted New England SHO mechanic, so I know they were 
> installed right. 
> 
> I thinks I need to look at my own cams and see if they have opened 
> up in my car. 
> 
> Before I go tearing into this engine to reshim the motor I wanted 
> to make sure I wasn't missing anything else.
> 
> So, outta spec valves sound like a sewing machine? Anyone. I've 
> only seen a few cars with a valve or two just barely outta spec, 
> and never heard these kinds of noises.
> 
> Thanks
> 
> Bruce
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