Use, Fix, or Trash

Reprise

Lifetime VIP Supporter
I'd like opinions on the photos here, if you'd be so kind. Not the image quality, of course - the condition of the head.

This is from a rebuilt set of 317s that I got nearly a year ago (so returning them is a 'ship that's sailed'). When I got them, I chased all the exhaust and spark plug threads on both heads. But I missed these items (and wouldn't have seen one unless I removed the valve). New seats and hat-type seals were installed; valves are original to the head (and in excellent shape), and I swapped out the springs / keepers / locks to LS6 beehives.

Now, over the past few days, I originally thought I'd be stuck with one of the options, and after some thoughts / research, am now thinking the other ones are available, as well. But I'll withhold disclosing my decisions until I see some feedback.

Am planning on using the stock GM MLS gaskets (.051 thickness); am open to other options, but my main concern now is potential leakage through the valve. I put the valves / springs back in and will fill the chambers with a bit of water, to see if there's any leakage. Inexact, but it's all I can do right now, short of either installing the head to the block surface, and checking pressure retention / leakdown then, or taking the head to a shop (and it seems the ones around me are closed for Covid vacation). I don't want to waste a gasket / set of TTY bolts, if I can avoid it.


First, the Intake valve... you'll see a small gouge that extends from outside the seat through to the inner seat

IntakeGouge1.jpgIntakeGouge2.jpg

(The first of the second set of pics below will show the valve in place, as well)

This second group is a scrape on the outer edge of the exhaust seat (in about the 7 o'clock position):

ExhaustScrape1.jpgExhaustScrape2.jpg
ExhaustScrape3.jpg

You can also see some additional scraping outside the valve seat, and on the spark plug boss. I did run a magnet across the surfaces, and it doesn't seem they were repaired with JB Weld or anything (e.g.; not magnetic / ferrous). If they had, I'd know I couldn't use them, as JB Weld wouldn't hold up past 500F.

So... your thoughts?
a) Use as-is (you see no problem at all, and the machine shop that did these apparently didn't, either)

b) Have a shop repair (welding is a possibility, if I can find a shop open)

c) Trash the head and get another one (I've been looking, but most 'rebuilt' options are selling a pair, not one)

Thanks, fellas. I want to do it once and not worry about having to R&R later on.
 

Mounce

Well-Known Member
I'd run it/test it and see. Reuse the factory bolts for the test. Plenty of people reuse the headbolts. Is it proper? No. Does it work? Absolutely. Sloppy mechanics on YouTube/Facebook, etc reuses everything down to the stock paper headgaskets and makes 1000 horsepower boosted regularly.

That gouge in the first complaint is the only thing I can place, never found the issue on the second set of pics.

The first set, I see it but it's not completely across the 'seat' but only the outermost portion of it. Will it cause an issue? I'm honestly not sure, looks like plenty of sealing surface left for NA applications to me but I'm also not a head builder. I'd test it and see.
 

christo829

Well-Known Member
That gouge, I'd just make sure it didn't have a burr that was above the plane of the seat, but it doesn't look like it extends through the entire seating surface. As long as it's smooth, I'd re-use it.
Can't really see what you're referring to in the other images. Run your test, see if it holds up.

Cheers-
Chris
 

Mooseman

Moderator
Lap them and see if the part that's lapped is affected and if they hold water.
 

MRRSM

Lifetime VIP Supporter
...and after Lapping them in... Try re-installing a Spark Plug and the Springs & Keepers for the Valves in one Cylinder Combustion Chamber at a time... and then Pour in some Lacquer Thinner and cover the area with small Plastic Lid over the top to minimize evaporation.

Because Lacquer Thinner has much less surface tension than most other liquids do and thus vaporizes-evaporates so rapidly... if THAT stuff does NOT manage to penetrate in, around and then drain down past the Valves & Seats... then you'll have done a good job with mating the edges of the Valves to the Seats and have Very Good Compression as a result.
 
Last edited:

NJTB

Silver Supporter
What Mooseman said-you could also buy a set of valve seat grinders and do a 3 angle job. That ding on the seat should come right out.
Make sure the 45 degree angle is the same width as before.
 

northcreek

Well-Known Member
I'd go with it,that damage looks to be clearly out of the seat..:twocents:
ps and what they said...
 
OP
OP
Reprise

Reprise

Lifetime VIP Supporter
Thanks to all who replied. My own replies to selected questions are at the end of this post.


Decision: I'm going to use them.

What I did... First, found a YT vid on checking for leakage. A fairly simple process...

- Thread a spark plug into the cylinder (as an aside, I was pretty surprised to see the narrow clearance / tolerance between the plug boss in the head, and the plug electrode - no more than 1/16th in., I'd estimate.)

- Turn the head upside down, and with springs / valves in place, fill the CC 'bowl' with water

- Test #1 - Take compressed air, and blow it into the intake & exhaust ports.
Look to see if any air bubbles escape from the valve seats.

- Test #2 - With the bowl still full of water, check to see if any water leaks down into the I/E ports.


Test #1 came out fine. Not one bubble.

Test #2 also came out OK. I had filled with water to the tippy-top of the bowl, flush with the flat surface of the head. Came back several hours later, and found the water level still at where I had filled it. Also checked inside the ports - no wetness / leakage.

I originally thought I'd have to replace the head, for sure. In retrospect...I'm glad I didn't just jump and pursue that option.
The one bad thing was that I thought the heads had a 'proper' 3 angle cut. It appears they do not
(manufacturers use a 45 degree cut on valves by default; while I had looked at the valves and saw three defined angles, in what appeared to be the proper proportions, @NJTB 's reply made me revisit this, and his inference appears correct - the seats are 'factory' cuts, nothing more)

Would I like a 3 angle? Yeah, I would. But if I wait until a shop opens up, it'll be *next* year before I'm picking this up again (I won't touch them myself, as I don't know what I'm doing).

Originally, I was going to take the existing heads off the engine and sell them. But now, I may recondition them & prep them for a full engine rebuild (then sell these, once complete).

Responses:

The first set, I see it but it's not completely across the 'seat' but only the outermost portion of it. Will it cause an issue? I'm honestly not sure, looks like plenty of sealing surface left for NA applications to me but I'm also not a head builder.
I'll apologize in advance for my ignorance... you mention 'for NA applications' -- if I were to add FI in the future, using the same cam I'm putting in now -- you think I'd have issues? Or were you assuming I'd put a high-lift cam in, if I went turbo / blower ?

The one I'm planning to put in on this build would probably be called a 'stage 2' - 212/216, .0520 / .0524 lift - not a race cam, by any means. While I might replace the cam a second time (doubtful, TBH), it would be another Stage 2 type, if I did.

I'd run it/test it and see. Reuse the factory bolts for the test. Plenty of people reuse the headbolts. Is it proper? No. Does it work? Absolutely. Sloppy mechanics on YouTube/Facebook, etc reuses everything down to the stock paper headgaskets and makes 1000 horsepower boosted regularly.
Oh, I know people do it... and I've heard about 'Sloppy' having rods grenade his blocks, etc. Don't know that I'd want a 'sloppy rebuild'...lol.
Another guy I've watched is A23Bravo (?) - he re-uses parts, too, but (IMO), he's got a little more going on upstairs than the 'Sloppy' guy. But his stuff has broken too (he builds for HP / RPM, and runs his motors at the strip)

That gouge, I'd just make sure it didn't have a burr that was above the plane of the seat, but it doesn't look like it extends through the entire seating surface. As long as it's smooth, I'd re-use it.
It is smooth. I had checked before creating the thread; just forgot to mention it. Thx for bringing it up.
 

Mounce

Well-Known Member
I'll apologize in advance for my ignorance... you mention 'for NA applications' -- if I were to add FI in the future, using the same cam I'm putting in now -- you think I'd have issues? Or were you assuming I'd put a high-lift cam in, if I went turbo / blower ?
I was just saying for a standard driver I don't see that causing an issue. Pushing 15 pounds of boost and running her pretty hard? I'd probably get that fixed.
 
OP
OP
Reprise

Reprise

Lifetime VIP Supporter
Ah, ok. Given the intended app, I might run 15lb, but the only time I'd be into it would be going uphill with the trailer. Well, at least at first, anyway... LOL
 

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