[Shotimes] Valve lash done.....but car seems weaker now.

[Ron Porter]

In most cases, it's not probably anything that the "butt dyno" can detect.

OTOH, he did say that he set them to the tight side. If they were very loose
to start, the difference "may" be noticeable. It doesn't seem to take more
than a few lbs/ft of torque on these cars to matter. An example are the
underdrive pulleys. These only add a bit of torque throughout the range, and
only maybe 5 HP at the peak, but they can be readily felt throughout the
entire rpm range. From my experience, the "butt dyno" gets more accurate
over time as you get a lot of driving in one particular car.

Or.....it could just be the weather or the gas quality as others have
mentioned.

Ron Porter

-----Original Message-----
From: shotimes-admin@autox.team.net
[mailto:shotimes-admin@autox.team.net]On Behalf Of Donald Mallinson
Sent: Saturday, February 22, 2003 2:27 PM
To: shotimes-admin@autox.team.net
Cc: SHOtimes
Subject: Re: [Shotimes] Valve lash done.....but car seems weaker now.


Ron,

Considering the narrow range of adjustment recommendations
on the SHO shims, wouldn't it be correct to say that while
your explanation of gap and torque is correct, that the
difference would be so small between minimum correct gap and
maximum correct gap, that the torque (or lack of) would be
VERY hard to detect on a "butt" dyno?  Maybe you could pick
it up on a real dyno, but with the loss of power he is
talking about, I don't think you could even come close to
accounting for it in just doing a "towards the tight end"
valve adjustment?

When I did my valves, I just shot for the middle, assuming
it was the ideal from the factory, and they did a pretty
good job.

Don Mallinson

Ron Porter wrote:
> Bruce, just go buy the numbering on the coils, and route to the correct
> cylinder. (1-3 in the rear from pass. to drivers side, 4-6 in the front),
> forgetting about the manual......in this case, the manuals are more
trouble
> then they are worth.
>
> Also, on your loss of power. A wider valve clearance is better for low and
> midrange torque, while dropping high rpm power. A tighter lash is better
for
> the high-rpm power, but can lower the midrange torque. Torque on the SHOI
> motor is rather low, and the car (being rather heavy) is sensitive to
> changes. The feeling of acceleration is primarily the gross torque at a
> given rpm, so I believe that this is the issue. If you would have done a
> dyno run before & after the 60K, you would most probably see a higher peak
> HP, but probably a lower torque curve down in the rpm band.
>
> Ron Porter
>
> -----Original Message-----
> From: shotimes-admin@autox.team.net
> [mailto:shotimes-admin@autox.team.net]On Behalf Of Bruce Malachuk
> Sent: Saturday, February 22, 2003 11:23 AM
> To: SHOtimes
> Subject: Re: [Shotimes] Valve lash done.....but car seems weaker now.
>
>
> I used the helms manual for the plug wires, but I'm gonna check them again
> just to be sure.
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