MTFCA Forum

Opened it up and the number three exhaust valve was broken in half. It had two-piece valves. No scoring to the cylinder but there were some small dents in the piston head.

No part of the valve was in the cylinder whatsoever, so it must have blown it out or pulverized it.

Replaced all the exhaust valves for now and will leave the intakes for another day.

Now I have a new problem which I am currently tracing down. The car takes longer to start now. When the #3 plug is grounded out, there is no change in the running of the engine. I checked the communicator to see if #3 wire was touching block. NOPE.

I checked gap on plug. Not a problem.

Checked plug wire. All good.

Checked the travel of the intake valve though the inspection cover. Valve appears to move up and down.

Moved #4 coil to #3 spot. NO CHANGE.

Next I will be removing the coil box and check for carbon trace.

Did you check the clearance after the new valves ?

How to answer that without sounding snarky.

Yes

All of the other plugs when grounded change the running of the engine, EXCEPT for number three, where the problem valve was. But, I changed ALL exhaust valves. I even did the offending valve first.

[quote=Will_Vanderburg post_id=19047 time=1553545122 user_id=295]
How to answer that without sounding snarky.

Yes
[/quote]

Sorry, but you have to rule out things one at a time.
Did you end up just lapping them in with compound ?
I would check compression next, dry then with a little oil in the cylinder.

Will,
You had an engine that started and ran well until the 2 piece valve broke, you replaced only the 2 piece exhaust valves, and now it starts hard and isn't producing power on the cylinder that had the bad valve. First, I would not worry about carbon tracing in the coil box, if it ran well before the valve broke, the valve breaking will not cause carbon tracing...that's a red herring. I suspect you do not have adjustable lifters since you are running the original valves. There is no way your new valve has the right gap with the original worn solid non adjustable lifters. Old lifters wear a divot that you cannot see very well. When you try to measure the valve gap with a feeler gage you are measuring the non worn edge of the tappet, not the bottom of the divot. Your hard start and week cylinder is a result of a incomplete valve job. If you want it to start and run like before, or better, you need to do a proper valve job on all 8 valves. Replace the other 2 piece valves before another one lets loose. My advice is to pull the engine and do a refresh which would include grinding the valve seats, replacing the lifters with adjustable ones, replacing all the 2 piece valves, honing the cylinders, new rings, and inspecting the Babbitt bearings, cam, cylinders, pistons, timing gears, and flywheel magnet screws.

[quote=Humblej post_id=19054 time=1553548576 user_id=163]
Will,
You had an engine that started and ran well until the 2 piece valve broke, you replaced only the 2 piece exhaust valves, and now it starts hard and isn't producing power on the cylinder that had the bad valve. First, I would not worry about carbon tracing in the coil box, if it ran well before the valve broke, the valve breaking will not cause carbon tracing...that's a red herring. I suspect you do not have adjustable lifters since you are running the original valves. There is no way your new valve has the right gap with the original worn solid non adjustable lifters. Old lifters wear a divot that you cannot see very well. When you try to measure the valve gap with a feeler gage you are measuring the non worn edge of the tappet, not the bottom of the divot. Your hard start and week cylinder is a result of a incomplete valve job. If you want it to start and run like before, or better, you need to do a proper valve job on all 8 valves. Replace the other 2 piece valves before another one lets loose. My advice is to pull the engine and do a refresh which would include grinding the valve seats, replacing the lifters with adjustable ones, replacing all the 2 piece valves, honing the cylinders, new rings, and inspecting the Babbitt bearings, cam, cylinders, pistons, timing gears, and flywheel magnet screws.
[/quote]

First of all, there are no divots on my lifters. I know what that looks like. My other engine had those. Second, changing one or four of the valves would effect all of the cylinders not just one.

And third, the last part of your paragraph starting with "If you want...flywheel magnet screws.", is not going to happen. I am not a bottomless well of money. I live on a fixed income that does not cover all my bills. If you are offering your services GRATIS, then I accept. Otherwise, the car will run just like it is until it dies again.

Now, I apologize for being snarky in this post, but really...

Now that I'm remembering sequence of events, I know what the problem is. And will take about 5 mins to fix after I take the head off.

That broken piece of valve that was missing may have gotten under the intake valve and bent it. I would check compression on #3.