OK, need some serious help fast

[vande97]

well here is the story, the other night i lost compression in one of my cyl , i popped the tappet cover off and found a rocker laying off to the side. the rocker bolt was ver loose , so i put it back together and nothing still not firing, one weird thing i found is that i culd spinn the valve spring around with hardly any effort , so i thought hmmm, maybe a bad spring so i replaced the spring and still no luck, the spring i took off looked a little more compressed then the new one. the car is not smoking and there is no gas or antifreez in the oil, the spark plug is firing so i know its not that, also i dont think it is a ring because it is not smoking at all, and i dont think it is a hole in piston because there is no gas in oil, i dont think it is head gasket because no trace of water in oil, so now i am stumped!!, and it would seem that if the valve was bent and hung open that i would not be able to turn the valve spring at all, I AM REALLY PISSED, this is a brand new motor with less then 1,500 miles on it

mods if you need to know
-306
-mild cam (total lift 498)
-stock heads milled and ported
- forged pistons, 10.5/1 compression
i can give more info if needed!

thanks alot guys!!!!

[Idhomustang]

Could be a couple of things wrong, you need to run a leak down test and see if you have a burn't valve or bad rings. You can by a leakdown tester from many sources. I think Jegs sells them or even Summit. Maybe even a speciality tool supply store might have one.
Pull the exhaust manifold on the side that you are expecting trouble on and the valve cover. Pull the plug and rolled end over so that the cylinder in question has both intake and exhaust valves closed then add air. If it doesn't hold air, you have a valve problem if it does hold air go to the next one.
What did the pushrod look like? Bent broken?
You should have already called your engine builder, and break the bad news to him/her. They may not want you to screw with it at all, doing so might void the warranty.
But, it does sound like a valve train problem maybe several, bent valve, stuck valve, bent pushrod, just to name a few, maybe worse. Not having antifreeze in the oil, is just one of many things that might have happend the same could be said for gas in the oil.
I would call your engine builder, it sounds like something was wrong on his end espically if you have a loose rocker arm, did you assemble or did they? These should have torqued down to the proper spec.

Mac

[PKRWUD]

Just curious, have you cranked the engine over with the valve cover removed to verify that the valves are opening and closing? Is the installed spring height the same as the others? If you don't have a leakdown tester, but you do have compressed air, bring the piston to TDC on the compression stroke, remove the valve from the hose in your compression tester, insert the hose into the spark plug hole, and attach it to the compressor. Slowly add air. Now, listen for leaking air. Listen at the TB, the exhaust pipe, the oil filler tube and the radiator (at the radiator, look for bubbles). This will tell you where the air is going.

Take care,
-Chris

[vande97]

yes i have checked to make sure valve is opening and shutting , o dont have access to air but , i took the upper off and turned the motor over and i felt air coming up threw the intake runner, so i think it is a bent vlave, i am ripping the head off this weekend to really find out what happend ,

thanks for the advice!!

vande

[2FastLX]

I shaved my heads .030 and installed an F303 cam. When we checked the piston to valve clearence it was like .090 on the intake side. For you to have 10.5:1 compression you must have milled your heads a little more than I did. If you went like .045 or so with a .498 lift cam I'd say floating a valve in that engine would be pretty scary, and you'd be very close to smacking the pistons. Your pistons are notched right?