Head Deck Scratch

[jtb032295]

Hey guys/gals, I just picked up a set of heads and one has a .020-.030 deep scratch that extends into the fire ring.. Any recommendations on the best way to fix it?

Thanks

[user-17438]

Touch her with a tig, resurface. Or if you have the ptv flat mill both heads.

[ProPower engines]

Touch her with a tig, resurface. Or if you have the ptv flat mill both heads.

X2

[MadBill]

It looks like the fire ring contact is well outboard of the chamber edges; maybe you can come up with a smaller diameter gasket that will seal inboard of the gouge.

[SchmidtMotorWorks]

Hey guys/gals, I just picked up a set of heads and one has a .020-.030 deep scratch that extends into the fire ring.. Any recommendations on the best way to fix it?

Thanks

If welding isn't practical for you.

Make a smooth polished round ended punch with a tip about the size of a pencil eraser.
Punch down the metal outside of the scratch until the scratch area bulges up enough to file it down smooth.

[jtb032295]

It looks like the fire ring contact is well outboard of the chamber edges; maybe you can come up with a smaller diameter gasket that will seal inboard of the gouge.

I thought about this... The fire ring mark on the head is from a Felpro 1003 which is for 4.166" bore. I may be able to get something for a 4.060 bore get the fire ring inside of the gouge. I fear it might overhang the chamber on the sides though..

[MadBill]

Using the smallest possible bore is a not widely-known speed secret. The reduced crevice volume has a disproportionate benefit, since the not usefully-burnable mixture is compressed into it by as much as 100X.

[induction apprentice]

Hey guys/gals, I just picked up a set of heads and one has a .020-.030 deep scratch that extends into the fire ring.. Any recommendations on the best way to fix it?

Thanks

If welding isn't practical for you.

Make a smooth polished round ended punch with a tip about the size of a pencil eraser.
Punch down the metal outside of the scratch until the scratch area bulges up enough to file it down smooth.

Go with this if a tig is not available. I do lots of head repair and do this often. You would be surprised how much material you can push back in to the scratch. That coupled with a good file or a minor surface should get you there. As mentioned. A smaller head gasket is also worth looking at.

[midnightbluS10]

Had something similar on the block of my Trailblazer. It was outside of the coolant holes and outer edge of the gasket, luckily. I knocked down the edges with crocus cloth and went with it. No issues after 7 months.

[jtb032295]

Hey guys/gals, I just picked up a set of heads and one has a .020-.030 deep scratch that extends into the fire ring.. Any recommendations on the best way to fix it?

Thanks

If welding isn't practical for you.

Make a smooth polished round ended punch with a tip about the size of a pencil eraser.
Punch down the metal outside of the scratch until the scratch area bulges up enough to file it down smooth.

Go with this if a tig is not available. I do lots of head repair and do this often. You would be surprised how much material you can push back in to the scratch. That coupled with a good file or a minor surface should get you there. As mentioned. A smaller head gasket is also worth looking at.

Thanks for the idea but I'm not sure I follow this one... In order to move the material, won't the punch actually make other indentations in the surface? I guess I'm just not sure where the "filler" material will come from without further damage.

[fdicrasto]

Is the mark a dent or a scratch? If its a dent there will be raised material along the outer edges that can be peened into the indentation with the smooth faced punch mentioned. If material was actually removed the tig might be necessary but the area right near the gasket fire ring looks like a very minimal flat cut should clean it up, .005"-.010" max. No big deal.

[Keith Morganstein]

the area right near the gasket fire ring looks like a very minimal flat cut should clean it up, .005"-.010" max. No big deal.

X2

[PackardV8]

Using the smallest possible bore is a not widely-known speed secret. The reduced crevice volume has a disproportionate benefit, since the not usefully-burnable mixture is compressed into it by as much as 100X.

Bill, agree completely and I work to reduce crevice volume/increase squish/quench on the obsolete stuff as well. However, as is our wont, I'm taking this further OT; recently we were discussing piston top design and how now pistons have high ring groove placement to reduce the crevice volume you referenced.

Then, my machinist brought out a OEM 350" SBC piston from a time period where GM machined an approx 45-degree taper around the circumference, making for a huge crevice volume.
Earlier and later pistons were the traditional flat-top-with-valve-reliefs. What was GM thinking with that beveled edge, as that's been bad science forever?

[MadBill]

I think their theory was that the resulting triangular groove was sufficiently open to allow flame travel, rather than quenching it like the flame arrestor effect of a typical piston crevice. The fact that the design came and went suggests the theory was wrong.

[pdq67]

I installed 4" bore MrG .020" thick steel shims on my 406 fine. Maybe look at installing 283 or 305 head gaskets??

I had my bare block on my engine stand and put my heads on it with my head gaskets, then reached up inside and scribed the gaskets where they overhung the bores and very carefully hand removed the overhang. I used good old, "Indianhead", to seal them and checked torque three times after as many heat cycles. Worked fine.

pdq67