I am posting this for a friend with a TT that runs very rough. A few of us have surmised that a valve job or compression issue is the factor.
He removed the head today and found this scene underneath. Why is the number 1 piston so clean compared to 2,4 and 3? What factors cause this please?
No 1 not firing it's washed clean with raw gas
I am not a model T expert, but have worked around cars my whole life. That looks like a coolant leak into Cyl #1. A leaky head gasket / cracked head or block at cyl #1 could do that. The coolant coming into the cyl sorta steam cleans it. There are some people that remove carbon buildup by slowly trickling water into a carb while the engine is running. In this case only cyl #1 was seeing the water.
Others with more model T experience please chime in.
Looks like it was running a little rich, turn the mixture clockwise once you get it ruining again
I like to do a compression test, first dry and then with oil. It will tell a good deal about the state of the motor, but too late for that now..
Clearly a valve job is necessary, it may need piston work but tough to tell from the info supplied.
My inexpensive recommendation is to do the valves, stick the head back on with a new gasket and copper seal and give it a try. If it works great, if not it has not cost too much, just the $20 gasket and a few hours work.
(Message edited by Tony_bowker on July 12, 2016)
#1 was washed clean by something - most likely coolant from a leaking head gasket like Joe suggests. Check the drivers side area of the head gasket - maybe something can be seen, maybe not - he needs a new one anyway.
Coolant leak. Should have done the comp test before pulling the head. Would have given you a much better idea as to the rings and valves condition. I'll tell you something you don't want to hear BUT: If you re-install the head & gasket (no fancy torqueing needed) and take a dry then wet comp test you'd be WAY WAY better off diagnosis wise than you are now. Which is totally guessing.
Just a swag at another problem, looks like the head gasket is on backwards. Dan
Coolant leak into #1.
Dan's right, head gasket is on backwards, may or may not be the problem.
Number 1 was steam cleaned! the gasket was leaking water into the cylinder.
Have I just been 'lucky'??? Obviously, I don't see something in the photo to tell me the gasket was backwards. Help me to understand.
Looks like modern valves and 0.040" oversize aluminum pistons. My guess is rings and valves are good. Looks like a new head gasket is in order. Clean the block and head surfaces and put a straight edge to them. If you see light between the straight edge and the surface see what clearance is there with a feeler gage. If its 0.005 or 0.006" or less then put it back together. If it's more let us on the forum know. The water channels in the block are different front and rear. When the head gasket is installed it should match. If it runs OK after you have it back together you are done. If not then a wet and dry compression test is in order.
The water channel connections between the engine block and the head has different sizes, the rear one is larger than the front one since Ford had to make it easier for the coolant to make a detour around the rear of the engine instead of going straight for the upper outlet towards the radiator. The gasket holes are thus also different size and the rust on the deck plane tells that the gasket has been turned upside down with the larger rear hole in the front. Thus a large risk that was the cause for the coolant leak towards the piston.
I didn't catch that.... When doing a job such as gaskets, I've also tried to rely on 'some common sense'. Maybe it takes longer, but seems to work out better in the long run. Thanks again!!
Good catch Erik I was just typing that and thought I should read first the replies.
I agree coolest leak
Do the valve job can't hurt and button it back up after flipping the gasket and seat with copper coat
A small water leak will clean up a cylinder in a hurry, Don.
Are the other pistons .040 oversize too?