Home Leakdown Test

[jjone20]

So, I built a leak down tester using a diagram I found somewhere. Seems reasonable, holds 100 lbs on both gauges when not plugged in. I have a 74 I bought cheap and pulled the engine out to see what was going on. Numbers are REAL bad - 0% on three cylinders. Low on the rest. My questions are:

1. Is the engine worth more as a core, or in pieces?

2. If I wanted to fix it (not afraid of a challenge, just $$$), would the most likely culprit be timing chains? And the associated damage, like valves, pistons, etc?

3. It turns, so the crank and case are prolly salvageable?

4. Is it reasonable to use my own gauge, or a waste of time?

Thanks

[gregwils]

1. It depends on the condition of the pieces and the type of motor. Mag cases are not particularly desirable, even less if it hasn't had appropriate updates.
2. Timing chains are cheap and are not a source of low leak down, more likely the rings, valves and guides, etc. You won't know until you tear it down. Buy Wayne's rebuild book and read it cover to cover before you do anything.
3. The crank turning is not an indication of condition or re-usability.
4. No disrespect, but have you done leak downs on other engines? 0% leak down isn't achievable, but 3-5% leak down is good. Before I tore into an engine with a home-made leak down tester, I would verify it produces accurate readings.