Head Resurfacing

[bosshasr]

So I took the head off my '81 XS-H to my local engine machine shop to get the threads for my exhaust studs helicoiled since they were completely mangled. I got it back this weekend and the pictures below shows what I received. To me it looks like someone smashed it in a vice while they were working on it since the bite marks match each other from cylinder side to rockerbox side.

I would like to get this resurfaced (obviously at a different shop) but haven't been able to find anything about how much can be removed before I would run into interference problems. I will be running a rephased crank with JE 700 pistons and my stock cam that was machined to match by Hugh. I will be putting new valves and guides in but nothing oversized.

As far as the bite marks on the rockerbox side, I'm guessing there isn't much that can do about it other than a little more sealant since removing material from that side would mess with the fit of the camshaft. Please correct me if I am wrong.

 

[fredintoon]

Hi bosshasr,
that's just too bad, eh? And it's not as though vise soft jaws were expensive either.
Me, I'd go back to the shop and publically gift a set to the machinist who left the marks.
But a fix?
The dents will help by holding more sealing compound, it's the ridges that gotta go.
The least material removal will be cleaning up the casting surfaces with coarse followed by medium and fine grades of grinding paste on a big lapping table.

 

[angus67]

on the cam side, yes will be ok after ridges of the dents were gone. no pressure on that side like there is on the piston side. I had my shop just skim enuf to ensure flatness.
it may be enuf. Forget the gift. always inspect thoroughly before leaving any shop with a serviced part.

 

[cycleranger]

I'd go back to the shop and publically gift a set to the machinist who left the marks.

I'd gift him a bill for the repair work...
Seriously, there is zero excuse for that damage.

 

[fredintoon]

I'd gift him a bill for the repair work...
Seriously, there is zero excuse for that damage.

Hi cycleranger,
there's never an excuse but there's usually a reason.
Whether it was the tech's incompetence or his supervisor's pressure
to get the job done quick instead of right, who knows?
That's why I suggested a PUBLIC soft-jaw presentation.
In front of supervision and co-workers.
Humiliation is the best revenge.

 

[650Skull]

Go back to them and show them what has been done and tell them you are going to bill them for a new/secondhand head. If they fix it by skimming the head it has been altered and not for the better

Even if you skim the head you there are going to be repercussions down the line, not un-surmountable but could involve cost or a fair bit of labor on your time if you can do
it. Timing and compression changes, and Hughs cam could be a problem as well.

Do not pay for someone else s mistake. If you are on time restraints then you will have to decide to eat it or chill and take the time to get things done right

 

[fredintoon]

I'm with Skull here,
if those damaged surfaces have enough material skimmed off them to clean off those visejaw marks you will most likely be into all manner of time and expense downstream to get everything OK again.
If the ol' lapping plate fix and it's minimal material removal don't restore the surfaces good enough to seal perhaps you are better off with a replacement head.
Making enough fuss that the shop will pay for one is most likely not worth the effort.

 

[bosshasr]

I guess I'm confused. As long as I dont touch the rockerbox side how would shaving the cylinder side affect timing ireparably. I have everything completely torn down and have to reset the timing with a new cam chain anyway. Sorry if this is a dumb question.

Side note: I was already trying to figure out if I could run this w/o a base gasket which, near as I can tell would have the same affect as shaving the head other than costing money.

 

[fredintoon]

Hi bosshasr,
the top and bottom halves of the head grip the cam bearings between them so if one of those surfaces has material removed from it the hole where the cam bearing fits ain't a perfect circle no more.
Tightening that interface too much squeezes the bearings out of round.
Tightening it just enough leaves a gap for the oil to leak out of.
OTOH, skimming the head where it fits onto the barrels/fitting a thinner head gasket/omitting the cylinder base gasket or any combination thereof will move the camshaft centerline and the crankshaft centerline closer together.
This effs up the timing just enough that moving the timing chain one link won't fix it.
If you gotta skim the head to make it seal onto the barrels, fit a thicker head gasket to compensate.
If you want a larger compression ratio, best you fit lumpy pistons.

 

[bosshasr]

Now I got it. I'd have to re-time the cam by degreeing the cam sprocket if I wanted to machine the head. Unfortunately I don't think I have the room to take much of anything off based on grizld1's post in this thread.

http://www.xs650.com/forum/showthread.php?t=5923

I guess I have to decide if I just want to get a new head or try my luck and just get the high spots taken off. Thanks for all the help guys.

 

[650Skull]

Looking at the pic again................How does someone who would do, or let a worker do, such a thing as to clamp a head in a vice. professionals! ......No.

Frustrates me when i hear someone advise, "Not worth the hassle" Your decision but if you let them get away with it, then they keep doing it, and if they have the attitude that people won't chase them up because it would be to much of a hassle for them, then they need a lesson.

Most firms are on face book these days or the owner is possibly. That is a recourse that can be used to get them to compensate you. No business is going to like a pic of that head as an example of their fine workmanship posted on their Facebook page.

 

[jaybird51]

As someone who has worked in an engine machine shop what they did is a sin. Since the marks are hot near the fire ring part of the head sealing surface an easy fix would be to take a very fine machine file and draw file the marks till you see that you are even with the head. Make sure you keep the file flat with the head surface and go slow.draw filing. The same will work with the cam surface.If you want a deluxe fix Devcon makes and epoxy for aluminum that will fill in the marks below the surface. Tough stuff. Have fixed heads cracks on 800 HP racing engines with the stuff. Follow directions for prep and mix. Let dry and file off excess and you should good to go.

 

[bosshasr]

Wish I had seen this a couple hours sooner. I might have actually tried that.

I sourced a new matching head and rockerbox on eBay and my soda blasting guy gave me a good price so I should be back where I started for $115. Taking the old head back to the shop this weekend to try and get that cost recouped. He fully acknowledged it was put in a vice and defended it when I called him this morning. Offered to deck it for me but with how little clearance room I have to work with I'm not taking the chance.

 

[jaybird51]

Decking the head on these motors is tricky as with all overhead cam motors. You can get into clearance problems with the pistons and it can affect cam chain and cam timing. I would not let him deck the head or rocker surface. Get your money back and bring it home fix it up for a spare, The expoxy is not very expensive. sorry I did not respond sooner, you could have saved yourself some money. Good luck. You need any advice just holler

 

[Jack]

I wouldn't bother decking the head for those vise marks, spray head gasket with either copper gasket , as for the rocker box or head surface apply some good old JB weld,not guick weld,let it dry ,sand it flush and be done with it. Simple and stupid mistake by a rookie. The head is still usable.

 

[grizld1]

Ah, good sense at last! Boss, Jack is the go-to guy for head work, do what he tells you: knock down the high spots, fill the low spots, and forget the drama.