We just finished putting the TA 107 "window rattler" cam in my friend Larry's 455 motor. When cranking over with the exhaust and mufflers on, didn't hear anything unusual. After cam was broke in, he took the exhaust off to run just open headers. When cranking you hear a noise that sounds like a loose spark plug on a single cylinder. This noise is heard coming from the right side header at the collector. What would cause this?? motor is .030 over 455 with compression ratio at approx. 10.25. Pistons are what appear to be hypereutectic with the valve notches. When engine is running, it sounds (sounded) great. We ran it at Milan dragway last night and ran consistent 11.50 to 11.60. On the sixth pass ran a 11.73 with a rod or something coming out the side of the pan. This was the final run of the eliminations, he was running me, he won (I broke out). The car is a 1970 Skylark Post Race Car. My car is also a 1970 Skylark. Two Buicks in the finals of the company (GM) raceday at Milan. Anyway, the question is, do you think the noise should have been an indication of a problem or could it be normal? We were not sure if it could just be valve overlap allowing compression leak into exhaust? Any ideas, we won't be able to get the engine out and apart for inspection until monday. Thanks for any thoughts.
All rod and mains were torqued to spec. Even went back over all 8 rods to verify torque was @ 45 ft lbs. 110 ft lbs on mains. The noise was not a "Knock" it was just an air sound like head gasket leak or loose spark plug, except the noise was coming out the header. Thanks again.
just going by what I read here is sounds like compression was leaking out the exhaust some how. could have been: burnt exhaust valve, stuck exhaust valve from anything being bent valve to a bad lifter, cracked head, leaking head gasket, cracked block. uzzled: which rod (number or side) made the hole in the oil pan?
He pulled the right head off since it was number 8 cylinder that beat up the spark plug. Piston was completely gone, as was the rod. Could also see that number 7 rod was gone. New cam was broken just in front of the last few lobes in the rear. Also when the left head was pulled, number 7 piston had a hole in it and also noticed both exhaust valves from number 7 and 8 were bent. Also the engine had piston parts even in the intake manifold. Oil pump seems to be seized and the MSD distributor gear was sheered. What a mess. Do you think it could have been the hypereutectic piston in number eight that broke to start the failure? We are confident that we had the assembly correct and didn't see anything unusual when putting back together. Oh yeah, we had a rev limiter chip for 6000 rpm and shift point were 5600 and 5800, and usually went through top end at 5500-5600. Anyway we are going to try to get another engine in the car so he can make it to Salem this weekend. Thanks for your replies.
