Head damaged by detonation

[Coyotemutt]

I believe I had an oil cooling issue that reduced lubrication of the #2 exhaust valve until it began to stick open and ruined the mixture at freeway speed. The space between the valves was partially eroded but not cracked.

I'm not even going to ask if it can be run this way. Anyone know of a good shop that can weld it up, install new seats, and check the valve guides for around 200 dollars?

20200808_213024.jpg

Lucky me, the piston didn't hit the valve or anything. The rings seized in the ring lands though. I'll have to measure that when I get them unstuck but I suspect the ring lands were compressed by detonation.

[buguy]

Not trying to derail you, but a new set of heads is not far off from that. https://aapistons.com/collections/cylin ... ad-35-5x32

[Coyotemutt]

Not trying to derail you, but a new set of heads is not far off from that. https://aapistons.com/collections/cylin ... ad-35-5x32

Those heads would be a huge step backward on this build. The heads pictured are 050 Rassers from MOFOCO.

[buguy]

Oh damn. Yeah you want to hold on to those. Maybe send it back to Roy since he built it?

[madmike]

that aint $hit, I'd run it,, but do ask Roy ,he'll probably laff
what fuel u running when this happened?
if the valve hung open you'd have some piston damage and a bent valve
check carb on that side for crap in the float bowl,
find/make a W/I system to cure the destination issues

[Coyotemutt]

that aint $hit, I'd run it,, but do ask Roy ,he'll probably laff
what fuel u running when this happened?
if the valve hung open you'd have some piston damage and a bent valve
check carb on that side for crap in the float bowl,
find/make a W/I system to cure the destination issues

I lucked out HARD on this one. When I pulled off the road the valve was still stuck open. But somehow,, no piston contact.

Honestly, I run a modest cam. .478 lift if I recall correctly.

Edit: 92 Octane pump gas. Forgot to answer that, sorry!

[buguy]

What compression ratio? And do you have a wideband?

[Coyotemutt]

What compression ratio? And do you have a wideband?

Compression is 8.2:1 static. I havent figured out up to do a dynamic calculation yet.

I do run a wideband. When I first started slapping this together I didnt have any pipe to build a downpipe after the turbo so I stuck the wideband in the pressure side. I'm planning to move it to the outlet side before putting it back together though. Now that I have a muffler built for it.

[buguy]

Oh yeah i remember seeing it now. 8.2:1 isn't bad.

[madmike]

not enough octane for any kind of decent boost, in 3rd & 4th , race fuel would of prevented the det. or w/i which I highly recommend
check for a plugged up pushrod 'not getting enuff oil' on that side of the head ,,was this on the 1/2 side?

[Coyotemutt]

not enough octane for any kind of decent boost, in 3rd & 4th , race fuel would of prevented the det. or w/i which I highly recommend
check for a plugged up pushrod 'not getting enuff oil' on that side of the head ,,was this on the 1/2 side?

Indeed it was the 1-2 side. That's also where the turbo drains.

If I can manage to swing these repairs cheaply enough, I'll probably be able to budget for an intercooler of some kind.

I should go get a picture of the neighboring chamber. It looks textbook perfect. Nice brown exhaust valve, black intake, thin layer of black all around the chamber. Plug has a light brown dusting and no signs of detonation.

I seriously think all was well and then the valve stuck and it just went to hell in milliseconds.

[woodsbuggy1]

Not sure where you are located but I send everything to Brothers in California they have always done a great job for me. Hopefully they are willing to work on Mofoco heads, some shops won't. I am in Indiana and still ship all my VW machine work to Brothers they do things right.
Good Luck
Kenric

[Schweg]

I’m not sure brothers is still up and running looking on TOS seems like they aren’t answering calls and emails.


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[Coyotemutt]

I'm going to try just running it with the damage. I pulled the valves and the seating surface is still well defined. The damage doesn't even go down 1/10th of the supported area of the seat. I could see that roughness leading to hot spots though so I'm absolutely going to have to turn down the boost, retard the timing, add an intercooler, or add water injection.

Or maybe more than just one of those!

[buguy]

Could always fill the chambers with something and see if anything leaks through.