My 1971 Road runner

[Runcharger]

Likely a head gasket by the looks of the one plug, especially if you caught it right away. And yeah it's been running rich.

 

[71Beeper]

I agree the plugs are dark in color. The carb is a Holley 800cfm. That was the carb used when it was on the dyno. The primary jets in it are 72's - I'll jet it down to 68's.

 

[71Beeper]

Well, a bit of time has gone by. There was a period of time where I didn't want to look at the car as I was just deflated over what had happened.
But pick myself up and get my *** back in the garage to figure out what happened.
So, lets dig into the engine.
Off with the valve covers.

More milkshake....
Next, pull the intake.

No damage there. I pulled out each lifter to look at the face and am happy to report everything is good.
Next, pull the passenger side head.

Hmmm #6 cylinder & number 4 look cleaner than the other two.
Here's the head.

Next, inspect the bore for damage.
Cylinder #2

Cylinder #4

Cylinder #6

And cylinder #8

No visible damage and the head gasket showed no signs of damage.

 

[71Beeper]

Next, pull the drivers side head.

Cylinder #5 looks cleaner than the rest.
Here's the head.

Checked the bores and they were as clean as the passenger side.

So, I took the heads up to my engine guy (the same place that did the dyno work).
No sooner did I unload the heads from the trunk of my car and carry them in and put them on the bench does he find the issue....

And this is before any pressure testing or magnafluxing has been done, which he will still do.

I hope that can be repaired & he finds no more holes....

 

[T2R9]

Wow. That's a pretty big hole. Surprised they did not catch it during the machine work. Maybe a casting flaw that did not show till it was run again??

Get at it again, you got this!

 

[Nxcoupe]

Next, pull the drivers side head.
View attachment 1770139
Cylinder #5 looks cleaner than the rest.
Here's the head.
View attachment 1770140
Checked the bores and they were as clean as the passenger side.

So, I took the heads up to my engine guy (the same place that did the dyno work).
No sooner did I unload the heads from the trunk of my car and carry them in and put them on the bench does he find the issue....
View attachment 1770141View attachment 1770142
And this is before any pressure testing or magnafluxing has been done, which he will still do.

I hope that can be repaired & he finds no more holes....

I have been building engines for close to 50 years and I have never seen that before. Thanks for sharing, glad everything else looks ok.

 

[72 Satellite]

Next, pull the drivers side head.
View attachment 1770139
Cylinder #5 looks cleaner than the rest.
Here's the head.
View attachment 1770140
Checked the bores and they were as clean as the passenger side.

So, I took the heads up to my engine guy (the same place that did the dyno work).
No sooner did I unload the heads from the trunk of my car and carry them in and put them on the bench does he find the issue....
View attachment 1770141View attachment 1770142
And this is before any pressure testing or magnafluxing has been done, which he will still do.

I hope that can be repaired & he finds no more holes....

Thanks for detailing your issues and Troubleshooting steps so well here, along with the good quality pics!

 

[71Beeper]

I thought I'd better dig back into my old photos of when I first got these heads freshened up and serviced - must have been prior to 2005.
Holy Crap!
I can see the flaw.

Second one in from the right, just below the exhaust valve.

 

[T2R9]

Yup pretty visible. Did they say if it can be fixed or do you need to find a new one?

 

[71Beeper]

No response yet as he is going to the PRI show this weekend.