[Shotimes] Re: Vacuum Specs

[George Fourchy]

On Wed, 21 May 2003 13:25:56 -0400, Bruce Malachuk wrote:

> but does anyone
>have the vacuum specs for a SHO at idle, and then all the specs for diferent
>maladies that can befall a car?

Back in the old days, the general concensus was that 21 inches at idle was a healthy
engine.  Fifteen or 16 steady was retarded timing, and 12-15 wobbling back and forth
was a leaking valve.  There were more examples of a bad engine, but those were the
basic ones I used.  These were basically stock, mild engines.  My '65 289 4bbl
w/hydraulic lifters (225 hp) 'only' had 18 inches at idle, but got 25+ mpg with 18
inches indicated on the gauge at 70 mph.  The Boss idles at 10, due to the large
overlap on the special propane cam, but rises to about 17 or 18 inches at 3500-4000
rpm, which is 90 mph (4000).  When it was new and 'stock', it idled at 15 inches. 
My '69 Country Squire, with a 429 2bbl premium fuel engine idled at 21 inches, and
cruised at 70 mph at 21 inches.  

George