When Stroker Motors Go Bad....

[Jac Mac]

Originally Posted by BDR561

Jac Mac,

I just got done watching the video of him degreeing in the cam and checking the valve clearance... Degree was done correct and right on... The clearancing is another issue... He used Play Dough, The CC checker springs and torqued the head to 10lbs!!

After running through the cycle he pulls the head and I can see how the valve has pushed the play dough out and I can see the piston top right where the damage is on the pistons. I'm assuming with the correct torque of the head and heat expansion would account for the rest!!!

In my book, it FAILED and was not correctly clearanced

If he has done exactly as you state above; IE checked the valve lash clearance before turning through two cycles and the exhaust valve has then squished all the playdough/plasticine out to the point of visible piston alloy, AND then made no effort to remedy the problem by recutting the set of pistons in the ex valve pocket area to acheive the reqd clearance then your builder has some explaining to do.
The 0.210" you mention is irrelevant as it would be in a non critical area, the exhaust valve should have in the region of 0.100"+ clearance in the now 'marked' area of the pistons.
Rather than plasticine I prefer to do this check without head gaskets fitted & with a dial gauge against the valve retainer & light checking springs. It is then quite simple to turn the crank thru 5° at a time and check the +/- readings on the dialgauge by pushing the valve into piston contact via the rocker arm.---by doing it sans head gasket you also assure radial clearance of the valve head to pocket sidewall due to the valve inclination.

One further thing--you can see that the valves are not concentric in the valve notches , so no attempt has been made to recut the pockets to address the problem, all of those exh valves will be bent.

Jac Mac