Thread: Low compression?

Having not long got it all back together after doing rings, valve lapping, bearings, gaskets etc, I've ended up with 120psi on each cylinder. Would anyone have any ideas as to why? For it to be across the board like that I'm thinking rings. But if I tell that to the minister of finance I may end up sleeping in the truck for a while. Can't find the invoice from B.O.R but I'm dead certain I bought 20 thou over.

Should I be considering having the heads skimmed?

Wow thanks for the quick responses. I'd like to say I'm certain the rings were 20 thou over, that is what I asked for, however I was in a bit of a rush to get it done, daily driver and all.

The rings were indeed installed correctly, in hindsight I didn't really know if the ring gaps should be staggered, but logic dictated that if the gaps were away from eachother then there'd be more resistance for compression loss, so that's how they went in. It was just logic to me, but I have been wrong before.

All in all, the v8 is running well, maybe the slightest of slight misfires at idle but once you're over 700 rpm it's brilliant, I can only really notice the miss at considerably low rpm, in gear, with the brakes on.

Maybe it is within tolerance, just that I've read several other posts where the minimum compression has been stated as being 130psi, some people (on and off forum) have said it should be as high as 140-150 psi.

Yes it is an 8.13:1 engine, but given that I've never done the maths and that it seems to be drinking petrol (albeit better than before the rebuild) and it occasionally seems to be low on power, I thought the "low" compression was just that little bit too low.

Anyway, thanks again folks, I won't worry about the compression anymore, I'll just take satisfaction in that I've successfully rebuilt a victim of fire.