Bent Intake Valve

dpson

dpson

Senior Member
Since changing engines in the Model A last summer from one in a running chassis there has been a clicking sound coming from the front of the engine that sounded like a valve out of adjustment. Unfortunately this engine doesn't have adjustable valves so it meant pulling the head and replacing the valve with a longer one. Once the head was off and things cleaned up the intake valve on the #2 cylinder was looked funny and when it was pulled was found to be bent, even though the engine seemed to run pretty well. There are a series of marks on one side of the valve edge almost like it was gripped with a large set of pliers, but no marks on the other side. The split valve guide(s) were also cracked at the top. The head, piston exhaust valve and valve seat all look good. Any idea what happened?

My plan is to replace the valve, grind it in, adjust the clearance and put the head back on and see how it runs. Thoughts or suggestions?
 
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That usually happens when the valves are over the pistons and something is dropped like a screw.


Check the carb for anything missing or the air cleaner bracket.


What ever it was spent some time in there beating up the valve and seat.


John
 
Depending on what tools were used to pry the head loose, it may have been bent at that time. I also see some recessed valve seats.
 
Tom Wesenberg said:
Depending on what tools were used to pry the head loose, it may have been bent at that time. I also see some recessed valve seats.
Click to expand...

At first I thought that I might have bent the valve pulling the head, but was very careful not to pry on the valve side of the block due to chances of cracking something. I used a flat putty knife all around the block to open up the head gasket and may have hit the valve, but it's hard to believe it would have been hard enough to bend the stem, it seems pretty tough. Plus there is evidence that the valve was damaged before the head was removed as the valve stem has wear and a small ridge where it was rubbing on the valve guide, so this was done some time ago. I also was wondering if some disgruntled previous owner may have purposely bent the valve when the engine and chassis was sold. You never know.

Also, I noticed the recessed valve seats, but am going to live with them for what limited use this car will get during my ownership.
 
I had a bent valve on a supposedly rebuilt Model T engine one time, methinks the engine had been rolled over and/or stood upside down causing the valve to bend. For the uninitiated, Model T engines don't use head studs, just cap screws.
 
Measured the valve clearances using the method in Les Andrews Handbook. Here are the results: #1-.052, #2-.025, #3-bent removed, #4-.015, #5-.014, #6-.013, #7-.015, #8-.015.

As can be seen valve #1 was badly out of spec and the end had been ground down so much that they had to insert a filler strip to keep the keeper off the tappet. A real hack job, no idea why they ground or cut off so much of the end of the valve. Valve #2 is also out of spec but not as bad. While I thought the bent valve #3 was the source of the tappet noise it now appear valve #1 is the culprit. Still considering options.
 
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