Was a nice motor...pulled out 25 yrs ago....118 cam stock 70 455....ran mid 11s. Orig motor only 40K on it. Put back in car and fired right up...but didn't sound right. Did comp test and 2-4-6 ZERO comp. Just pulled head and all looks good. Cylinder walls still have crosshatch from 1970. Broken rings? Flat cam lobes? rockers were moving normally tho.... Blown head gasket? But look good to me.... I'm puzzled.....
I guess I'll soak them with SeaFoam. It didn't start running real bad until I got on it some. Not too smart since gas was 2 yrs old...
See if any rockers have lots of lash. Maybe valves not fully seating? I never do the "tap the stems with a hammer", after watching a buddy do that and the keepers popped of and the valve went "shloop, thunk". Hope it's rings and they loosen up. Odd it's only on the even side...
I would say stuck rings from sitting. It would be worth having a quick look inside. Likely you can clean everything up and reassemble. It sounds like it was a great motor. Greg
Seems strange to have zero.... I guess I'll lap the valves and put head back on. I'm worried that maybe some rings broke but I don't see any scoring on the cylinder walls. Did trick I saw at a Buick dealer a long time ago...pulled head with intake still on.
Should have used the trick in the Chassis manual. Inject oil into the low cylinders, and repeat compression test. If compression comes up, worn rings.
Yeah Larry, you're right. If low I might have done that but with zero I figured stuck valves or major ring issue. Seemed strange that as soon as I opened the secondaries it started running like crap. Barely got it back to garage. Probably should have tried my other compression tester, too....
Too late now, but you should have aired-up the affected cylinders w/ shop air with the rockers backed off to see where the wind went. Did you do a compression test on all of the cylinders, or just 2,4,6, stop and and pull the head? Never mind the oil “trick”. Why in the world would you waste time doing that when the compression test result is zero? Heck, I can count the times on one hand in 40 years that I’ve done that “test”. Some people read too many books and don’t have enough time under the hood.
Even with stuck,bad,or worn out rings you're going to have more than zero compression. I wonder if the valves froze in the guides
Yeah, pull the rockers and pump full of air. Too late now but it would have answered a few questions. Before disassembling the heads lay a straight edge across the valves and see if you have any sunk seats. I'm assuming you already looked the head gasket over.
Valves stuck open? That would definitely account for zero compression. Would there be rocker noise from all that extra lash?
Zero compression is broken pistons, blown head gsket or burnt valves.. it is possible that one is stuck open on chunk of carbon, but 3.. ? not likely. At this point of disassembly, flip the heads over, level the decks, and fill the chambers with rubbing alky.. that will show your leaking valve.
I had a set of heads that Mike Z did me years ago.......they were fresh.......2nd pass had 7 valve lock up. Several holes dead.....Mike fixed the heads just sucked it cost the long tow to KY, but not the last time I had and engine failure away from home....lol
Really Bob? I know rings aren't likely the problem with 0 compression. Bruce and some others mentioned rings as a possible cause. I simply suggested the oil trick mentioned in the Chassis manual. It would have been a quick and easy test, if for no other reason, to eliminate that cause in Bruce's mind. Why do you have to be insulting?
Never mind guys.... I'm an idiot. Tested the compression gauge on another motor and ZERO. Tried my other one and good. Seems the damn relief on tester failed. And....the reason why it started running like crap after I hit it is that I was running out of gas!!! Fuel gauge not working.....I had dumped 4 gallons in but with carb tuning etc I used more than I thought. I'll slap another steel shim head gasket on it and see what happens. And it gets a free quicky valve job by way of lapping.....
