When Stroker Motors Go Bad....

[Jerry Clayton]

was that modeling clay or silly putty????

Scotts right---auto engine machining is discussed in thousands---we recently had an marine engine where the customer gave us a diminsion but misread/mis stated the diminsion and we couldn't come up up with compatible parts for days before we figured out that he had left out a digit.

Jerry

[AK1234]

....causing the valve to hit the Piston ...

[BDR561]

Wayne Partridge Sr.
Newton, KS

His clay was Plat Dou
Here's his last claim:

"Mark, what you see there is some of the blue dow that simply came off with the head and stuck on the valve. In a situation like this the complete valve area would be crushed, not two small holes. I remember the material when I removed it and it was setting in the studio. It had set up and was hard and the complete intake and exhaust ports were almost 200 thousands thick. That cam was not that big, under 700 lift, nor was the rocker ratio over sized. All normal and well below critical standards".

I did see the gauge on the video stating .2100, but again that was not in the relief. The still shot will amaze you all. The video also shows him applying oil on the clay so the material wont stick to the valve!!

[BDR561]

AK1234,

Not a defective valve, unless there was 8 of them. Every Ex. valve had hit it's piston. A/F was perfect and actually running a little rich.

You need to see the video/still shot to see... I do have someone working on that for me so I can post. Now I just need to order the replacement parts and rebuild....

[LMH]

I might have missed it in the thread but how many miles are on the engine when this occured?
Larry

[BDR561]

400 easy miles

[DAVID GAGNARD]

I use Play Doh to check the piston/valve clearance and have had no problems with it.........I always degree the cam first, then bolt on the head with NO gasket and run thru the cycle twice, remove head, check notch in Play Doh.........if the clearance is within specs, then you have extra clearance with the head gasket thickness..........

With all 8 exhaust valves hitting the pistons, it's obvious that the piston to valve clearance was NOT correct from the start and I'm suprised the motor lasted 400 miles.........

If the Pay Doh was all pushed out of the valve notch and you could see the valve after checking the clearance, then your builder screwed up big time!!!!!!!!! the whole purpose of the check is to see that what happened on your motor DOES NOT happen!!!!!!!!!!

The valve springs had nothing to do with the valves hitting the pistons.........

The failure was simply not enough piston to valve clearance on the exhaust valves, something any engine builder should have seen and corrected before going any futher with the assembly of the engine........

David

[LMH]

Originally Posted by BDR561

400 easy miles

400 miles!!! Yep, this is an build problem for sure.
Larry

[CHANMADD]

So much ado about what is obviously like david say's ,poor assembly with not enough clearance,or someone changing rocker ratio's without thinking.

[Excaliber]

You know I love the title of this thread. Kind of like, "When wild cam's attack".

[BDR561]

OK guys...

Here's the still shot. I have about a 30 second video I will post shortly..

[blykins]

What's weird is that the side with the aluminum showing through is the intake side. You would think you would have had problems with the intake valves hitting as well.

It's really hard to distinguish the thicknesses from a 2D picture though.

[BDR561]

That is the intake side (there goes my theory)!! Time to break out the clay and see what the clearance is now, then check the crank key, etc...

[blykins]

What was the seat pressure on the valve springs?

[Excaliber]

Looks like the PlayDoh doesn't lay down well on the piston and some of it stuck to the intake valve, which is the bare metal you see. I think I will stay with clay, seems to leave a better impression and stays put more securely.

[blykins]

There are a lot of variables in this one....I would carefully examine each component....even the timing chain. If something happened and the cam timing retarded enough, it could pull the intake valves away from the piston and shove the exhaust valves down into it.

[DAVID GAGNARD]

Not sure from the pic how or what your builder did with the measurements, but the correct thing to do is whether your using clay or play doh, is to clean the piston top, add the clay/paly doh, lighlty smear motor oil on top of the clay so it won't stick to the valves and rotate the engine over..........then, with a razor blade, cut the clay in the middle of the valve relief and carefully remove one half of it, not disturbing the other half, then take your measurement on the thickness of the half left on the piston at the valve relief.............

You must always use solid lifters for this, regarless of what type of camshaft used in the motor......using hydraulic lifters will not give an accurate reading. Summitt/Jegs sells solid lifters in pairs just for this..

the best I can tell in the pic is the measurement was taken from the flat top of the piston????? if so, this measurement is useless and does not tell you anything about piston to valve clearance.

David

[Jerry Clayton]

Looking at that clay, I don't believe he turned the engine over twice to get all 4 strokes in---the exhaust side looks like it wasn't touched, at least as far as the damage indicates

What bothers me is the use of the term studio in the engine builders comments--they are maybe more interested in lighting than measurements

[Frank Messina]

I apologize if I missed the answer to this, but is the builder going to take care of this for you or has he offered another remedy?
Frank

[Jac Mac]

This is prior to check with heads fitted?, as that is intake pocket that he is checking and no evidence of engine having been cycled thru two turns, only head set in place.

Jac Mac