tick on fresh rebuild!!!

That is scary on the piston to valve clearance comment from the machine shop. Do you have access to a boroscope?
 
Put up your jump to conclusion mat. Go through possible scenarios in your head and then figure out what test could be done to check each possible scenario.


For the piston to valve, .120" sounds kind of high. Find exact TDC and go through that again. Again you are checking at TDCE not TDCC. THe valves have to be at overlap to check it. Roll the engine(after you check the lash) in a right hand rotation. Exh. valve will open then start to close then intake will start to barely open. Paue there, that is almost exact TDC. Loosen the Rocker adjusting nuts, put a dial indicator on the intake valve retainer and then screw down on the adjuster until the valve hit the piston, take not of your travel. This is your piston to valve clearance.

Lash could be loose or tight........ Recheck lash

Piston could be kissing the head........ bore scope could verify this.

You could have a dead hole....compression check.

If the rod bearing is going, sometimes putting a dial indicator on the piston as it coomes up will find that depending on the severity.

I have seen the lifter bore get messed up which made this sound due to the lifter sticking at different rpm.

Valve job is another thing that you might check. Compression check will also help find this. If you have low compression in a certain hole, add oil to the cylinder, if the compression comes up it is in the rings or piston, if it does not it is in the head.

Although it does not happen often, the cam could have an issue. Although if it was the cam, it would show itself at any rpm.

Two things to remember, if it is put together right it has no choice but to work, and KISS

Good luck
 
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Todays findings-
piston to valve clearance #1 intake done exactly like zach said. .193
#3intake .205 #3 exhaust .143

Piston protrusion .040

intake valve depth .045

Lifter seem to move freely, havent pulled cam yet to look at lobes

piston.jpg

piston2.jpg

valve2.jpg

valves.jpg
 
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Looks to me the valve kissing, I can read the the piston info on the valve.
 
I think you just not doing it right, Piston protrusion .040
is tight should be .023-.027 valves should be around .050 deep is this the same cylinder as the galling rocker ?
 
Head and block were resurfaced, machine shop said they took about .004 off both. Im telling you ive followed instructions to a T. Set lash, rotate clockwise, exhaust valve opens then starts to close. intake opens .002 with dial sittin on retainer. losen nut and turn down till hits piston take reading.............
 
At the very least then the gasket should have been .010 changing the piston protrusion to .030. you need more room. I don't believe your machine shop. Sorry looks like you have had a ruff time of it.
 
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Jpscustoms said:
Heres my findings today, one rocker with some wear, the exhaust valve seals not seated, and machine shop forgot to check piston protrusion and said they think the piston is tapping the head.

rocker.jpg

ped2.jpg

ped.jpg

engine.jpg

valve.jpg
Click to expand...

What color paint is that on the engine?
 
The only way that the valve could kiss the piston, if you have plenty of room just baring the engine over, is if you have lost a rod bearing. That will make the clearances totally different while the engine is running. Especially since it is only on number 1 cylinder. I think that is the issue, or rather that is the only logical explanation for why only one piston would touch. It almost looks like the piston has made contact with the head on #1 as well. But, if the block was cut at an angle, you would not have so much Pto V clearance just barring the engine over.

I am sorry to be the bearer of bad news, and I hope it is something else. It is all pointing to that in my mind. Either that or the head was cut so crooked that #1 sticks out higher than the rest of the pistons.
 
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Hamilton Cams said:
The only way that the valve could kiss the piston, if you have plenty of room just baring the engine over, is if you have lost a rod bearing. That will make the clearances totally different while the engine is running. Especially since it is only on number 1 cylinder. I think that is the issue, or rather that is the only logical explanation for why only one piston would touch. It almost looks like the piston has made contact with the head on #1 as well. But, if the block was cut at an angle, you would not have so much Pto V clearance just barring the engine over.

I am sorry to be the bearer of bad news, and I hope it is something else. It is all pointing to that in my mind. Either that or the head was cut so crooked that #1 sticks out higher than the rest of the pistons.
Click to expand...

I do agree that could be an issue since the smaller crankcase ventilation could starve the bottom end of oil pumping it all to the top of engine. Check the head surface for square and then tear into engine!
 
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