I know this has been well discussed but I think you'll find my situation pretty unique. I'll include as much detail as I can, but for starters, I've got a 2000 Formula, 60K miles, 3000 stall vigilante that's been in the drivetrain for about 50K miles, and a built 4L60E trans.

I just got word from the shop where I've had my car serviced for eight years that I've got bent valves on cylinders 5 & 7. #5 showed no compression, and #7 showed I think he said 90%. I've never bounced the engine off the rev limiter, never overheated it, and as far as I know, there's nothing wrong with timing.

Not too long ago I was discussing engine miss-fires here with a couple of people, but since I didn't have any problems with performance, I swept that under the rug. Well, about 3 - 4 months later an event occured that alarmed me. One morning when I started the car, the motor stumbled so bad it stalled. After I restarted it, the motor was still stumbling but after about 1 minute it smoothed out. I made a mental note of this but continued on. A couple of weeks later, it happened again but this time it happened while I was driving in town at about 40 mph. The car stalled, but after restarting it again, it idled smoothly, so on I went again ignoring this. Well, a couple of weeks later I was driving about 65 mph on Central, and all of a sudden the engined started what I'll call motor boating; definatelly not running on all 8, but then it would smooth out again without me lifting off the gas. In other words, this problem has been intermittent up until now. This past Saturday night, while on Central again, I let it downshift while I was passing another car and it started motor boating again, but this time it became permanent. So this is where I am now. Can someone tell me how only 2 cylinders could have bent valves, how this problem could have at one time been an intermittent one, and why wouldn't I also have bent pushrods? I'm going to further interrogate the tech's involved when I get there later, but there was no mention of timing chain or push rod problems. Also, I would suspect that the rev limiter would prevent valve float, correct? Thanks.

 

Have the valvesprings checked on those cylinders. I'm willing to bet they lost tension and allowed the valves to float even at low RPM. I'm guessing the engine is bone stock otherwise? Stock valvesprings are marginal even with a stock cam.

 

Thanks for the advise dude. Yes, the engine has stock internals, and I looked at the damage when I got there earlier today. Sure enough, there's one shiny little half-moon scored into #5's piston from the intake valve, so I guess they were right. #7's valve was bent too, but apparently not enough to mark the piston. I talked to the tech and he told me the valve springs will be checked for proper tension, but the bottom line for me is to just get the car back into proper running order so I can be on my merry, albiet pennyless way.

No joke... the craziest **** ONLY happens to me.

 

im sure there are several people in the for sale section selling the better 'yellow' LS6 springs, it would be a nice cheap upgrade on a stock cam, or if you plan on camming in the near future go with patriot dual golds

 

And rich ive got a set of used 918's that would work for you...Id let em got for cheap. Stronger then the ls6 stuff but I wouldnt use them on a cam over 550 lift. They are not strong enough for that size cam. They have about 40K on them. I spring tested them on a bench tester and they have enough pressure to be a replacement for as big as an LS6 cam. None broken. Just wore out to control a large lift cam. Stock would be absolutely fine.

 

Sent ya a PM Fletch!