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Engine Tick Valve Hitting Piston???

J

jongage

New member
Several years ago I was at shasta lake when I began to hear a "tick" coming from the engine. I stopped running the boat for the weekend, and drove it home. When I pulled the intake manifold I found a lifter with the plunger lodged sideways. So with a little extra money in the bank and a good excuse, I did a full Cam, lifter timing chain, and springs. Bolted it all back together and BAM, the freaking tick was STILL THERE.

Now I removed the cylinder head again and found about a tablespoon of oil on top of the piston and a shiny mark that looks like the exhaust valve is kissing the piston. The mark is uniform on the flat and raised portion on the left. The engine is a new rebuild from a mass rebuild internet place. It was purchased as a "Marine Engine" (Father in-law purchased it before we got married) It has less than 15 hours on it.

I have not run the engine past the break in period of the new cam.
The sound is definatly coming from the exhaust valve.

Can a bad guide cause this problem??
Does anyone know of the proper piston to deck clearance??
Piston.jpg
An help is appriciated before I start spending money
 
What breed of engine is it?

Looks like a bad lot of corrosion to the side, in as much as a car head gasket and not Marine Gasket used.

The "Shiny" mark couldn't be a valve hitting as it is nowhere near where the valve could hit. The Relief cuttings would be showing shiny spots, first.

Bruce.
 
Perhaps he did leave us. Hmmmmm.
But since I typed this out before realizing that..............

It would appear to be that we're looking at either #1 or #8 cylinder.

attachment.php


If we look at this, it would have to be #1 or #8.
SBC_shortblock.jpg


His are single valve relief pistons (good choice BTW for any piston), and appear to be installed correctly.
(see image above)
Note the valve relief cuts.
The cuts are to mirror the valve heads in the event that any valves were to come in near contact with the pistons.
In order to come in contact, the valve would need to stick partially open, or have a valve spring that's not doing it's job..... or a cam follower that is somehow not allowing the valve to fully close at the correct time.

Doubt that he has a high RPM issue with a Marine application.

If the piston deck height was incorrect, there would be other tell tale signs.
This is likely not his issue if he's thinking "valve", IMO.

If the valve is remaining open, he'd certainly have some performance issues.

Side NOTE in the event that all is OK:
These are full dished pistons.
If some reason a cylinder head replacement is in order, be sure to use the 64cc chamber cylinder heads with these pistons.


Now..... as if this wasn't enough, I'll share a quick story with you:
A forum member goes to assemble pistons/rods into their freshly prepped crankshaft and block.
(their machine shop had ordered and installed the new pistons on reconditioned connecting rods)

Upon installation, the boat owner notices that the piston valve reliefs Do NOT form a straight line (if all were to be intersected one piston to the other from one end of the block to the other as per engine centerline).
All piston reliefs were tilted some.
Unlike in this image (if you were able to see all pistons and valve reliefs)
SBC_shortblock.jpg

Apparently the wrong pistons had been ordered and fit to the connecting rods.
After being installed in the block....., when you looked at the engine, it looked as though the pistons were tilted sideways.

This is an example only of BBC
(they were not tilted quite this radically..... and if memory serves me, the tilt was oposite from this)
20826861-921-396-402-bbc-short-block.jpg


I cannot tell from the OP's image if these valve reliefs run parallel with the engine centerline.
Another photo would help in this area.
However, if this one piston's valve reliefs (for some reason) are not parallel to the block centerline..... perhaps this would explain the wierd marking on the one piston.




The point of me telling this story is multi-fold:
  • Apparently there is a piston p/n that fits the SBC 5.7L connecting rod, but with tilted valve reliefs.
  • Apparently this piston p/n also fits the SBC bore.
  • It also meets the deck height requirements for the SBC 5.7L.
  • The 5.7L piston rings fit this piston p/n also.
  • The assembly aslo fits nicely into the block and all connects up.
My questions are:
What's the likihood of one piston being incorrect?
Or... what's the likihood of a piston being mis-machined, and not being caught during inspection?
And what's the likihood of the machine shop not catching this, and going ahead with the complete assembly?

I know...... it's a very long shot at best!


I went back to that thread... but the images are no longer there.
Wish that they would have been..... it was quite interesting to see it.


.
 
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