blackcloud03

I was just wondering if i turned the crankshaft to put my new piston in did it effect my timing? just put it in yesterday and working on puting everything back together.

dieselfreak21

It shouldn't have unless you moved the tone ring. Especially if the cam and gears are still in place. The computer reads both to detemine where it is at and adjust accordingly.

blackcloud03

ok thanks and if i torque the rocker arms do i need to still check the valves cause i did take the head to a machine shop put new valves and liners? thanks in advanced

classicpuller

If you have taken you head apart, which would include taking the rocker arms off anyways to replace valves.... You absolutely need to adjust you valve lash via the rocker arms, and then put a few miles/heat cycles on the motor and then check it again to see if any rockers came loose. You can destroy pushrods and sometimes more if they come loose. I have a gas pulling truck and I went one pull too long before checking the lash again, it was too late, lost 6 push rods because they slid past the rocker arm and twisted. Also lost a vertical bar roller lifter and the camshaft because one of the rods hit the bar on the lifter set, broke it and the lifter turned in its bore scoring the cam terribly... As you can see, its a chain reaction type thing. Also, as long as you didnt have the shop take any material off of the deck of the head, you shouldn't need to check the piston to valve clearance if all the valvetrain is stock replacements.

CP

blackcloud03

ok i will work on doing that anything else yall think i need to do before i crank it up? just replace the main bearings and #1 piston that i had melted. thanks

Nsomniac05

How do you check the clearance between the valves and the piston? Train a mouse to go in the injector hole with a feeler gauge?

classicpuller

While the head is off the motor take a piece of playdoh (about 1/4" thick) and place it on the #1 piston making sure to cover the areas where the valves would be come close to. Take the head and smear a little bit of oil on the valves. Reinstall the head with the old head gasket and torque to spec. Reinstall lifters, pushrods, rocker arms and make sure to set correct valve lash. Rotate the motor several times so that the valves (intake and exhaust) open and close twice or so... This will leave impressions in the clay. Disassemble head off the block. You will see the clay still stuck to the piston (hopefully, lol)... If it was too thick initially it will stick to the valve and get stuck in the valve guide, you have to start over (took me 5 times the first time i did this).

Initial looks at the clay... If anywhere in the clay to see a bare spot (the top of the piston), you have interference guarenteed. Remove the clay and use a pair of calipers to measure the thickness where the valve impressions are. You can also cut the clay in half to get a more accurate reading. Be careful not to crush the clay with the calipers. Most engine builders will tell you a minimum of 0.100" is the required piston to valve clearance. This allows for timing chain slack and also any cam variances between different lobes on different cyliders.

Sorry for the book, lol.

CP