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I'm in the process of rebuilding my 327 it's a standard 327 with flat pistons with 4 recesses for the valves, I bought a new camshaft for it : http://www.compcams.com/Company/CC/c...x?csid=80&sb=2
and have upgraded to Lunati roller rockers with 1.5 standard ratio
But now when I have pressure on the lifters and try to spin it it hits the pistons on the exhaust valve...
I have comp cams timing chain and if I advance the cam with 4 degree's could that solve the problem?
Last edited by stingraymaniac; Jul 24, 2017 at 03:38 PM.
That's a pretty mild lift cam, shouldn't have problems with a .490" lift.
You may have over - adjusted the valve lash when trying to get zero lash, or you may have installed the cam and timing chain incorrectly.
Try backing the lash off until you can get a .002 feeler gauge between the valve stem and the rocker, and see if that change allows you to rotate the engine over. If you use checking springs on the valves, you can rotate the engine over in small increments and determine what piston to valve clearance you have. Should have around .050" as a minimum.
I don't think advancing the cam that small amount will solve your issue if it's assembled correctly and hitting the valve.
Once you are sure that the engine is at #1 TDC the following valves/rockers can be adjusted:
exhaust - #1, #3, #4, #8
intake - #1, #2, #5, #7
First you must find "zero" lash. This step takes all slack out of the lifter-rod-rocker assembly. This is accomplished by grasping the rod and "jiggling" it so it clanks between the valve and the rocker arm. Tighten down the retaining nut ( by hand if possible) until the push rod can no longer "clank" between the valve and the rocker. THIS IS ZERO LASH! (I do NOT suggest "spinning" the push rod because the pushrod can/will continue to spin after 0 lash is reached !) As soon as 0 lash is reached, turn the rocker arm nut down 1/2 to 3/4's (max 1 full turn) of a turn in 1/4 turn increments. A 1/4 turn increment is recommended to set the lifter pre-load.
Rotate the crank 360 degrees and set the other half of the valves
exhaust - #2, #5, #6, #7
intake - #3, #4, #6, #8
For some reason, setting the lash on hydraulic lifters sees to trip people up. Videos like this, add to the confusion.
What "jim 2527" posted, is the easiest way to do it. Get cylinder #1 at top dead center, adjust 8 of the valves, rotate the engine one full revolution "clockwise" when facing the engine, and set the remaining valves, and you should be good to go.
Personally, I don't care for the "spin the pushrod until you feel some drag" method, for detecting "zero lash", because if you lubed both ends of the pushrod with assembly lube before installing it, the lube can easily cut the friction to the point where you won't feel any drag until you've already begun to compress the lifter.
With a new build, if you haven't installed the intake manifold, you can very easily watch the lifter, as you snug up the adjusting nut on the rocker arm. As soon as it looks like the plunger of the lifter moves, you're at "zero lash". At that point, turn the adjusting nut approximately 1/2 turn further, and you're set.
If you've done this, and your engine still won't rotate, possibly you dropped something in one of the ports, and didn't realize it.....
EDIT..............this is a "long shot", but I just thought of this. You didn't, by any chance, use one of those piston stop tools, that you install in the spark plug hole, when degreeing the camshaft, and forget to remove it, did you?
Last edited by leadfoot4; Jul 24, 2017 at 06:12 PM.
I've had timing chain kits that have the dimple at the top of the cam sprocket when at TDC....really confused me. With the gears the way they are in the pic, are the cam lobes on cylinder #1 on their base circle when the piston is at TDC?....
I've had timing chain kits that have the dimple at the top of the cam sprocket when at TDC....really confused me. With the gears the way they are in the pic, are the cam lobes on cylinder #1 on their base circle when the piston is at TDC?....
In that position #6 is at TDC compression. Need to turn crank 360* to get #1 to TDC compression.
Right now I have all the rockers of and just adjusting the number 1 cylinder and it still locks the engine when I adjust to zero lash, spins freely when you adjust like 1- 2 mm lash but then when you get into tolerance it locks up.. ?
Camshaft problems..
