What RA would you say this is?

[Acuratechva]

So decided to try a faster and cheaper head shop....and got finish like i have never seen before. Having some concerns with leaks, have no desire to see the customer come back.

Any Machinists here that can comment on this finish?

And this is the finish i am used to, but those guys take over a week to get anything done. Two weeks on the last set actually

 

[gte718p]

If you can run your fingernail along the surface and feel the ridges I wouldn't run it. If you can't feel it, then it is cosmetic and I would run it.

In reality the gasket will seal up pretty good ridges, but I don't see any reason to risk it.

 

[Acuratechva]

I agree, the gasket is suppose to compress anyway and is going to take form of the surface...to an extent but still.


Oh the nail definitely buzzes over the surface

 

[bullnerd]

Looks like the tool was dull to me.

I'm not sure if Id be worried about the finish, but is it flat?

Theres some marks towards the back of that one picture, looks like the cutter hesitated for bit?

 

[purplezr2]

I agree, the gasket is suppose to compress anyway and is going to take form of the surface...to an extent but still.


Oh the nail definitely buzzes over the surface

Heck no, I would not run it.

 

[zkling]

Looks like it was not rigid enough setup or too heavy of a cut/feed.

 

[jask]

Not to stress you out but have you measured that? The stock EJ25 head is 127.5mm with a .3mm max cut... That looks way overcut. And given the history of that head/ gasket I would not accept that finish.

Edit: warp limit is .035mm. I was looking at the first pic again and that dark line on bottom ( upperr right in the 3rd pic ) sure looks like a crack.

 

[Acuratechva]

I think thats just a rag streak. Cant remember what it is in metric but they took 5 thou off, 12 being the service limit. In any case youre absolutely right.

If you look close it almost seems the finish is smother on one side of the head... Had a feeling you guys would say that, mother-fucker! Why cant anyone do **** right first time around.

 

[Capt Chrysler]

I'm not up on this cylinder head. But, back in the day with aluminum Mopar heads, you wanted them glass smooth. As the head really moved during warm up. A rough surface bite into the gasket. Then the gasket would fail sooner.

Maybe this is why this shop could get you right in?

Also, don't let them belt sander it smooth. ( if they have one in the shop )

Good Luck

Capt. Chrysler

 

[Jim Johnstone]

For you car guys, is a milled finish typical for heads or are they ever surface ground?

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[NUTTSGT]

Did your shop ask you what type of head gasket you were going to use ? My aluminum heads have a similar finish but the guy knows I'll be running Cometics.

 

[68 Coupe]

I have had this happen before, only worse! I was in a hurry and took it to a "reputable" machine shop that had been around for years. Everyone said they were good, but they mostly worked on old V8 engines and I brought in a head from a 4 cylinder that was running a good amount of boost. When I picked up the head the finish looked horrible, grooves down the whole thing and burrs along the edges and was dirtier than when I dropped it off. While listening to them argue that the finish was acceptable, I heard a nasty noise and chatter from the machine that was loaded with another head, it was running at about 3-4 times the speed of other shops, and looked to be an older macine with little to no maintenance. To top it off, they even lost a lifter (which I noticed after getting back) and then tried to say it wasn't there when I dropped it off, and there was no finding it in that place. They refused to return any money (which was higher than most places) and wouldn't admit anything was wrong.

I then took it to a shop that I had dealt with before, they thought there was enough left to try salvaging the head. It took longer than the first place, but when I picked it up it had been steam cleaned and "visually" inspected before machining, and they took 3 very light passes to clean up the previous shops shoddy work. The finish was excellent, and the head was saved, and for $20 LESS than the bad shop. I ended up running a slightly thicker MLS gasket and it worked out great!

 

[ilovevocs]

If you want a quick fix I would lap it on a surface plate using a figure 8 motion.


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[3 Gun Shooter]

The top head was cut on a rotary broach like a Van Norman 870, bottom head was surfaced on a grinder. With the newer heads especial aluminum head you need to grind them or if you use a broach needs to have a very slow feed rate. The older broaches only had one or two feed rates.

 

[Brettholmes89]

Looks like the feed was too fast.
If I were you I'd wait be bit extra and have the job done right.

 

[moriboy]

It's hard to tell from the pic, but it looks like it's a least a 250 RA finish, maybe worse. I think it needs to be smoother to seal properly.


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[kkroger]

Looks like a typical broach or shaper cut, doesn't matter the gasket will seal it. looks like you are used to a "Ground" finish instead of a machined finish. Use good gaskets and it won't mean anything, factory finish is a linear shaped finish not a "Milled" finish. That is probably a "125 RA" by comparator... RA being R Average, RZ or R Max are more meaningful... the Surface Profilometer MAHR Federal at my old LAB calibrated on a 125 Finish Sample...

 

[Al Borland]

Not good. Look at the third picture above the chamber on the right. there is a lip running from the long oval hole to the triangular one. Also, that picture shows the line Jask was concerned about. (Upper right by the head bolt) It looks like the outline/shadow of the old head gasket.
Zooming on the picture, there is a whole lotta texture going on there.

 

[Acuratechva]

Looks like a typical broach or shaper cut, doesn't matter the gasket will seal it. looks like you are used to a "Ground" finish instead of a machined finish. Use good gaskets and it won't mean anything, factory finish is a linear shaped finish not a "Milled" finish. That is probably a "125 RA" by comparator... RA being R Average, RZ or R Max are more meaningful... the Surface Profilometer MAHR Federal at my old LAB calibrated on a 125 Finish Sample...

This is what my regular machinist said, its funny too, i bring him the head and he goes" yeah i got a another set of heads from that shop for same issue" . Right at that point i **** myself ... lightly, but Seth assured me it will be fine. I know pictures make it look worse than it is, especially light angle.

Am i taking the short cut next time? Hell No, emotional toll not worth it. On the good side customer states car is bone dry 10k, lots of driving.

I learned my lesson, that shop can have all the flywheels they want lol, i'll take the heads elsewhere.

 

[SteveH-CO]

I presume you will be using only the latest revision of the Subaru MLS head gasket? I found that the Fel Pro EJ-25 gasket kit contained genuine Subaru head gaskets, but that was a few years ago.

 

[Acuratechva]

Never have, never will. I dont bother with any aftermarket head gaskets, ever.