Re: TPI Vacuum at idle

[gabe <gellett@earthlink.net>]

Thanks, I thought that was awfully low for a stock engine (except dual exhaust,
and no cat or air pump).

Next question:

What to look for other than a severe vacuum leak which if it had, would probably
have to be under the intake manifold (I fixed one when I installed the engine
less than a year ago, #8 was sucking coolant and air).  Last time I checked it
had descent compression, measured near 160psi on all 8.

I think this is where my low end power is going, & also causing the ECM troubles
(surging idle sometimes, poor cold running, poor response off idle, rough
running in the low end).  Do these motors (non roller) have a history of the
cams going flat?

Gabe

Mike Frels wrote:

> At 06:29 PM 1/24/2000 -0600, you wrote:
> >I seem to remember mine pulling around 20" or so. I can check if you want.
> >14" sounds low, although I do have the 87auto no-lift cam.
>
> My '86 auto cammed TPI pulls 22 inches of vacuum. To me 14 sounds low. The
> rule I had always gone by was 13 inches should be minimum for driveability.
>
> Mike
>
> > > Hey, anyone know off hand what a stock '85 TPI auto 305's idle vacuum
> > > should be?  Keep in mind that it has the same cam as the later model 5
> > > speeds (little longer duration & more lift than the auto's of 86 up)
> > >
> > > Mine is at 14"@ about 575RPM.  I think this may be causing some off idle
> > > derivability issues for the ECM...
>
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