The easiest way I can explain a leak down test other than the percentage of leakage is that it will let you hear what is leaking. If you hear air coming out of the carb it is intake valves. Out the tailpipe exhaust valves and thru the crankcase breather its rings.
Mike
Thanks for the inputs. I did start the motor a year ago (after weeks of pre-prep and Marvel Mystery Oil) and it showed 72 pounds of oil pressure, 18 inches of vacuum, no smoke, no blow-by and had a very pleasant rumble from the glass packs (which are now gone). If this is the same block that was in it when I owned it in 1970 then the engine has been blueprinted and balanced by Iskendarian and is a SCJ in a CJ block (LeMans rods).
When I drop the pan, I can tell.
There is no difference between a CJ block, an SCJ block, a 428 cop car block, or the block used in granny’s '68 Colony Park station wagon. All used identical 428 blocks.
You are correct but there is a difference INSIDE the motor, which is why I am dropping the oil pan to see! In 1970, or so, I bottomed the car in a big dip and ended up replacing the oil pan. While I was looking up into the crankshaft and rod cap area, I seem to recall that the rod caps were allen screws and that each rod had a hand-painted number on it in blue paint. The number, as I recall, was 612. Additionally, I remember reading somewhere, years and years ago, that the 612 number represented the gram weight of the rods used in a Super CJ. When I bought the car in 1970 I was told that the engine was a Super CJ (even though it does not have the SCJ harmonic balancer) which tells me that they had the engine balanced and blueprinted and built for racing. I bought the car as a “demonstrator” with 2400 miles on the clock. Those 2400 miles were largely 1/4 mile at a time either at Lions Dragway in SoCal or Fontana Dragway, near San Bernardino, CA.
LeMans rods are quite a bit heavier. Around 900 grams each.
Correction, the cap screws were 12-point, not allen as I mentioned before; but remember that I was 22 years old at that time and I have not seen it in 50 years.
Chuck.