Strange noise from engine, need help with identifying it please.

[Coronet1965SWE]

Anyone? It would be good to know if the thicker gasket is the way to go.

 

[SwedCharger67]

It seems the piston has been rocking a little.

Myself I would first explore the possibility to do a bit of grinding in the heads, to establish a proper clearance. Or, taking some material off the edge of the piston.

If none of that's possible, then I guess a thick gasket is the way to go.

 

[Garys1969RR]

Anyone? It would be good to know if the thicker gasket is the way to go.

Since there has been only light contact between piston and cyl head, ( and that was probably causing the strange noise), I think it would be safe to use a .075" thick head gasket. If you were using a .040" thick gasket before, and you were getting light contact, then going to a .075" thick one should get you around .035 clearance, right? That is about the minimum.

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Wow those cometics are expensive! You know since you decked the block, and milled the heads, that is probably what contributed to your problem. And that could be why the original assembler put the pistons with the dish part at the top. Cause the flat part of the head is toward the top or valley side of the head. So the dished area would then give added clearance that way. Did it make the noise when the pistons were in backwards?

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Ok I see now that the noise started after you rotated the pistons 180 degrees. The heads must have been really cut down a lot! A stock open chamber head has the chamber recessed .080 to .100 maybe more. You know, you could put a stock head back on with a .020" gasket, and it shouldn't hit. That would eliminate the need for the expensive cometics. And remember the cometics require a really smooth finish on the mating surface to seal well.

 

[Garys1969RR]

I finally got the video to play. Boy that definitely sounds like metal hitting metal. 1 is real bad. Hope the thicker head gasket, or going to a stock head works.

 

[dvw]

You have quench dome pistons. The factory head is cast. The combustion chamber openings are inaccurate. How do we fix this issue? It doesn't appear that there was hard enough contact to damage the piston ans crush the ring land. Laying the head gasket on the head with dowel pins to align the gasket carefully trim the edge of the head with a die grinder. It is easy but takes a steady hand. You can keep the head gasket mounted to the head as a guide. The depth of the chamber is more than sufficient for these pistons, just clean up the edge.
Doug

 

[Coronet1965SWE]

Thanks for the feedback all. I will take the advice to grind off a little in the heads so i ordered this die grinder: http://www.toolstop.co.uk/makita-gd0800c-high-speed-die-grinder-750w-240v-p4060 wich will hopefully do the job and for the saved money with buying regular headgaskets its almost free

 

[Garys1969RR]

Yes just some around the edges looks like that will help.

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What head gaskets do you plan to use? You were using a .020" compressed thickness, right? Put the head on with no gasket after grinding the edges of the chambers, put in a few bolts to hold it down, then rotate the engine through a couple turns. If no contact then you know you will have at least the thickness of your gasket for clearance. You may want to use a .040 thick one. I would probably use the .020 thick one, as long as I was sure there was adequate clearance.

 

[Coronet1965SWE]

I was using a 0.040" gasket and my plan now is as you say. Grind for clearance and check with the heads on.

The 0.040" gasket puts me at 9.95:1 static compression and 8.06:1 dynamic (if i used the calculators right).
We have both 95 and 98 octane gas here so i think it will work well.