Interpreting Compression Test Results

Cylinder 4.. In case the picturs are in the wrong order, the number on the piston (1,2,3,4) represents the cylinder.

Notice how clean the pistons are.. I did not wipe them down.. That is how they looked when the head came off.
 

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Is EX-4 the valve that has the chunk missing you referred to in post 15?
 

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Your engine is at maximum bore, sleeving is the next step with your cylinders,an expensive process.Your .011-.012 is larger than ford spec at .002 or the modern 'acceptable' spec of .005..Id do a valve job but wouldn't touch the cylinders,at the most I would do is a light glaze break and re ring,but I don't think its necessary from the readings.The high compression head will accelerate the wear already evident in the bore,that piston clearance will grow over time,faster than a stock head..that being said,how long it will last is arbitrary,but my advice is to run it and see,many pull the trigger and rebuild an engine with many useful miles left on it.
 
I started disassembling the valves and got #1 valves out. The valve springs free height are both 3-9/32" tall +-, and the new springs are 2-15/16" tall. Searches on the web tell me that 2-15/16" is correct. Maybe these are flathead v-8 springs?
 

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#1 exhaust valve and the ace of spades have alot in common. You can see where the seat made contact with the valve at one time, but it is not showing signs of recent contact.. Or it is burnt bad.
 

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The #1 intake valve looks a bit better. You can see where it contacted the seat all the way around the valve. My calipers show the contact line varies from .030 " tp about .050" wide.. I like a wider contact area, but atleast this seat was making some contact all the way around.

As info, i did check the lash before removing the valves. The intake was 13 thou and the exhaust was 15 thou.
 

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.012 is not true number on your pistons. they are smaller on the top. You need to measure them at the bottom of skirt 090 degrees from the wrist pin.
 
Stage1gs said:
The #1 intake valve looks a bit better. You can see where it contacted the seat all the way around the valve. My calipers show the contact line varies from .030 " tp about .050" wide.. I like a wider contact area, but atleast this seat was making some contact all the way around.

As info, i did check the lash before removing the valves. The intake was 13 thou and the exhaust was 15 thou.
Click to expand...

you are burning oil, check you valve guides.
 
Stage1gs said:
I started disassembling the valves and got #1 valves out. The valve springs free height are both 3-9/32" tall +-, and the new springs are 2-15/16" tall. Searches on the web tell me that 2-15/16" is correct. Maybe these are flathead v-8 springs?
Click to expand...

Offhand I would say that spring looks like a Model T spring.
Have you checked both old and new springs for pressure? (57-64 lbs at 2&1/4")
 
I am using the modern valves and guides from Snyders, this saves hammering or pressing the guides in, and using spacers for the valve springs.
 

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I spun the engine over with the head off and valves 2 and 6 stuck open. I aimed a flashlight in the intake. / exhaust port of each valve when the valve was in the closed position, and found that a couple tappets had "self adjusted" preventing the valves from completely closing. I am in the process of installing the modern valve kit shown in #34 and have 6 of the 8 valves completed. The seats are cleaning up nicely. I am lapping until I get a .090" wide wear pattern on the seat, one valve took a while but I finally got it.

Question - when installing the one piece guide that looks like the original guide, is there a sealer that should be applied around the guide, or do you put them in dry? Once I cleaned the valve guide bore they pushed in with just a bit of resistance.

I measured the lower skirt of each piston at 90 degrees to the wrist pin. The engine is .125 over and thr bore is 4.00". All 4 pistons came in between 3.996 and 3.998.
 
Stage1gs said:
I spun the engine over with the head off and valves 2 and 6 stuck open. I aimed a flashlight in the intake. / exhaust port of each valve when the valve was in the closed position, and found that a couple tappets had "self adjusted" preventing the valves from completely closing.
Click to expand...

Interesting that you got such good compression readings - I would question the accuracy of your compression gauge.
 
I would install the guides dry.Id venture to say all your diagnostics done with the compression gauge are unreliable. Whats the visual conditions of the piston bores?
 
The bores all look pretty good. No real scars are visible other than the occasional streak down the pistons. I honed them and put new rings in.
 
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