Quote:
Originally Posted by Pete Munroe
Rick, and all.
Oil pickup is now set about 0.40"...(kept getting bad measurements using some sort of putty that was too sticky and elastic to be measurable...found REAL modeling clay at a craft store..made it easy to get repeatable measurements).
Made up a stable TDC fixture that bolts to the block. Used a dial indicator to find TDC consistently...timing pointer is now set pretty close to TDC.
Oil pan is on...used a Jegs rubber pan gasket with grommets.
Let is settle as the end gaskets were slow to pull down...will go around one more time later and add blue locktite when I finally pull up all the bolts tight to the metal grommets.
Today, cleaned up an old head gasket, dug out the head studs, and temporarily set a head on to prepare for claying the valve clearance.
Took two of the old roller lifters apart to remove the springs and set them up as solids for claying the pistons and verifying the valve clearance with the new cam...doubt there will be any problem, but fun (SORT OF!!) to check...set the new cam 2 degrees retarded compared to the old one...ie: straight up...Comp grinds it 4 advanced built in...(I am guessing to accommodate heavy cars)...the Cobra is light and seemed good to shift the power up the rpm band, if only a little. Torque down low has never been a problem.
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With the cam in a comparatively retarded setting who knows where the clearances will end up. New cam lift is minorly less lift and more duration...Again mainly an exercise to do it. Doubt there is anything close.
Need to verify the geometry on the new roller rockers...the ratio is the same but don't want the rocker touching the stud...not quite sure how to do that other than with machinist blue...which I don't have...something will work...
Actually at this point things are finally coming together...
Pete
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Pete,
Your "fixture" for finding true TDC was the positive stop method?
A paperclip works to check clearance between the rocker stud and rocker arm with valve closed and valve open at full lift.
There are many other clearances to check in the valvetrain: rocker arm to pushrod, pushrod to cyl head, rockerarm to retainer, retainer to valve stem seal, spring coil bind at full lift, valve to piston clearance etc.
These days, cams are ground with advance to allow the "lazy engine builder" to fit the cam "dot to dot". The built-in advance allows for timing chain stretch throughout the life of the engine.