Ghetto Oven Head Test

Clatter · Post by **Clatter** » Tue Jul 24, 2007 10:58 am

Sooooo, I have a couple of sets of 1.7 heads...

They are Q and J heads.
One came from a 412 and the other from a 914.
Both cars showed less than 100K on the odo, and the motors appeared to have never been taken apart before.
Pulling the valves out, and looking at them, they _seem_ fine.
Can I put them in the oven, bare, seats down, to test them?
If none of the seats fall out, they are *less* likely to be bad, right?
This would adversely affect the heat treat?
Is it only if seats are to be replaced would this be done?
Temp?

Just another dumb idea from the dumb idea department!

raygreenwood · Post by **raygreenwood** » Tue Jul 24, 2007 12:51 pm

If they have 100k on them....just change the seats. Its worth the piece of mind. The thing the "ghetto" oven does not have...is valve pounding, heat cycling and vibration. It will be a good tell-tale on the worst heads. But on a borderline head.....you may be just inside of "fine" at 100K...but by 130K...it could be "drop" time. Ray

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Tue Jul 24, 2007 5:21 pm

I'll bet that those heads will lose a seat if you keep them at 420F with the heads flipped face down n the oven...
the "Q" head more than likely won't lose a seat.

Kelley · Post by **Kelley** » Sun Jul 29, 2007 9:58 am

How long would you leave the heads in the oven? Until the seats fall out, or is there a specific heat/time limit you look for when checking seats and for plug hole cracks?

Clatter · Post by **Clatter** » Mon Jul 30, 2007 12:28 pm

So....

420F...
Face down...
For 45 minutes...
Or until golden brown!

Cool!
I'm going to try it.

If all the seats stay in,
then it's getting the 'ol 3-angle,
and the keepers ground for good measure.

Keep it cool,
and an eye on the valve adjustment,
and RUN IT!

Clatter · Post by **Clatter** » Wed Aug 22, 2007 12:14 pm

Yes! Time!
Please!
How long is long enough?

Probably ought to take them up to temp, and then that's it, right?
Don't want to anneal them, if they are going to get re-used as-is...
Right?

I'm about ready to try this, just to see.
I'll keep everyone posted...
Anyone have any ideas?

davebuckholts · Post by **davebuckholts** » Wed Aug 22, 2007 12:26 pm

Throw some brownies inthere while you're at it.

Clatter · Post by **Clatter** » Fri Aug 29, 2008 12:55 pm

OK so i FINALLY did it!

Both the "Q" and "J" heads went into the oven.
425 degrees for 1 hour.
And *none* of the seats fell out(!)

Does this mean I have a good set of cores?
Do I need to put them in longer?

If there are no cracks, or stripped plugs,
Then we have some good cores here for sure,

Right

Class 11 streeter · Post by **Class 11 streeter** » Fri Aug 29, 2008 1:15 pm

Either spend the money to change them, or run them as is and hope for the best.

I have a 1.7 going together myself and the non-Q 1.7 heads were cleaned up and put back together. If I drop a seat it's an excuse to put some real power in there!

Now, that said, Karma being what it is I will probably be driving this pokey 1.7 around forever.......

NextGen · Post by **NextGen** » Fri Aug 29, 2008 5:09 pm

Class 11, Yep that is the problem with T-4's the things don't die especially if in a light car like a bug. Mine is just running and running since 1989. You have to go for it when you build it. Problem was I had no idea how mine was going to run. No internet and very few guys this side of the Atlantic had T-4's in bugs.

Last night I changed the oil and it looks like new. Oh well!! But I must admit my engine was a brand new never run training engine. So it can go for 200k easy. After all how many brand new never run T-4's went into a bug. There are no records to check, must were rebuilds.

dawie · Post by **dawie** » Sat Aug 30, 2008 5:59 am

Also tried the oven test once. Left the heads in the oven for an hour at 200 deg celsius, (around 400 deg fahrenheit), then quickly tried to turn the seats clockwise and anti-clockwise,using a pair of pliers. One seat could turn about ten degrees in each direction. Then put it back in oven at 160 deg celsius,(320 f?). Then tried again with pliers an it was stuck solid.

If they dont drop out from gravity,they could still be loose with just a ridge keeping them there.

type3 · Post by **type3** » Sun Aug 31, 2008 12:09 pm

raygreenwood wrote:If they have 100k on them....just change the seats. Its worth the piece of mind.

Seconded. It just makes sense to change them.

Clatter · Post by **Clatter** » Mon Sep 01, 2008 10:49 pm

I guess the real intent of this test wasn't that clear...

Last couple of times i sent in cores for a re-seat, was told that the cores were no good.

Now, with no cracks, and never flycut, no stripped studs...
Perhaps the "Ghetto Oven Head Test" would be a way of semi-verifying that the cores were good?

Could I remember Len saying that sometimes when he has core heads in the oven, the seats fall out on their own?
And then, afterward, he uses them, with new seats and all, of course...

That must mean that, if the heads are otherwise good, if the seats stay in, they must be good cores....

If good head builders will re-seat a set of heads that the seats fall clear out of... Then heads that keep their seats are probably OK.

Right?

Being able to verify that the heat-treat has not been taken out of the head by overheating at some point would be nice to know too...
I don't have a Rockwell tester, but do have an oven...

How else to tell if a set of heads is junk???

dstar5000 · Post by **dstar5000** » Mon Sep 01, 2008 11:04 pm

Clatter wrote:How else to tell if a set of heads is junk???

IF they haven't been recently rebuilt by a T4 head guy, consider them junk.

Don

type3 · Post by **type3** » Tue Sep 02, 2008 2:12 am

Clatter wrote:Last couple of times i sent in cores for a re-seat, was told that the cores were no good.

I guess it depends why the cores were no good. What you say has some logic to it, but these are ally heads and can welded until kingdom come. Maybe it was a cost effectiveness thing? Although it'd be up to you to decide what you wanted to spend and not the person doing the heads.