Every time we tagged a valve on one of our race engines, we ended up having rod bearing troubles on those cylinders shortly after that. I just automatically slipped in new bearings, too. Difference is we were turning 7500-9200 depending on what engine was in the car. With lower RPM's you may not experience those problems. SPark
I have some new info on the bent valve issue and I don't don't know if I should continue on this thread or start another one. someone can let me know , So here is what happened .I pulled one head off and found valve had stuck and hit piston , when I pulled the other head off I found exhaust valve stuck ( couldn't get it out had to cut stem) but it hadn't hit piston. # 5 cyl & # 4 cyl . almost across from each other. That got me to thinking about my carb, it is a quadrajet rebuilt from Jegs 2/3 years ago and hasn't been driven much, I had heard they leak bad when setting around and I always smelled a strong odor of gas,around engine. Sorry for the long post ,But my question is could that gas dripping and being old contributed to the carbon build- up I hope this makes some since to some of you Thanks
A wize man once told me to always add MM oil at every oil change. I do this as well as use Lucas Oil Stabilizer. My Roadster used to sit for months at a time while I worked overseas. I also use MM oil in my fuel to help prevent carb build up with the cheap gas we have now. Also good oil is a must!!! I use Valvoline 20-50 Racing oil. High zinc content and the best friction fighter on the market. I do hope when you get it back together all comes out well for you.
What could of happened is the leaky carb could have filled the cylinders with fuel and when you started the motor it hydraulic ed??
The stuff gets sticky and in cold storage on the warm balmy days plays havoc on metal. Valves can stick at anytime for what seems no reason at all. 100,000 mile go by and you stop at Taco Bell then boom you get a bent valve. Blame it on the burrito. Fresh build and first time out gets a bent valve, or sits mostly and gets a bent valve. Tight, sticky, build up, dry, cold start high rpm, old gas, exotic oil treatment, exotic fuel additives, hard use or just grandmas car ,,,,
I run only non Ethanol fuel in my 2 cars. Costs more but worth the peace of mind. Sent from my iPad using The H.A.M.B. mobile app
carbon doesn't bend valves. hydraulicing doesn't either as both valves are closed. Most likely on the rebuild the guide to valve clearance was not enough. Pull the heads and measure the guides and valves.
these days, that behavior in an otherwise good motor is bad gas. ethanol or not, the formulation is changed. the new stuff oxidizes internally, becomes gummy, sticks valves, bends pushrods, etc. that old gas cannot be used anywhere, not in lawnmowers, nothing. it's gotta be disposed of. it's not gasoline any more. i don't know how old is "old", but it seems to be more than months. over a year? dunno.
Lol ! A valve issue out of the blue! 2 days ago my mower ran great for about 2 hrs till it started raining. All of Last week it ran great after a head gasket change. Mowed for About 8 hrs total in hour or so blocks without any issues. Late Last year and years before it ran great till the head gasket took a shit in the fall. Today the mower won’t start and is blowing raw fuel and popping out of the carburetor. Not sure what went wrong sitting for 2 days. Damn thing woke up in a bad mood and that’s that. Very well could have been some remnants of last years gasoline that went thru it two weeks ago could be something else.
Gas would most likely work it's way down past the rings into the pan if the car sat for long lengths of time. If there wasn't a bunch of hard gummy carbon on the piston heads or around the back side of the exhaust valve heads it wasn't / isn't an old gas issue as that would be seriously obvious. We aren't talking a little bit of granny put putted around town carbon here we are talking hard caked gummy carbon and a lot of it. What do/did the back side of the valves and the valve pockets look like carbon wise?
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