Quick! Help Needed! Heads...CAN they or can they NOT be re-surfaced?!?!

[Jeffu]

Sorry but I kind of have a urgent situation here.

A week or so ago I dropped my heads off for general reconditioning at a very reputable machine shop here in town. Prior to this, the shop owner confirmed with me that the Volvo specs for the B27 B28 engine were in his system. I also provided some photocopied pages from my DMC manual and Volvo manual as they pertained to the valves, springs etc.

Today, I just got a call from the machine shop saying my cylinder heads were ready to be picked up. When I asked how they turned out the shop said great! When I asked if there was any warpage they said well we had to re-surface them. I said....uhhh, you did?? I said all of the literature I have states that they MUST not be re-surfaced and have to be replaced if the warpage is out of spec. The machinist tells me, "we have all specs listed out in our machine and we resurfaced within those specs. I am happy to go over them with you when you come to pick them up."

So can they or can they not be re-surfaced?? I plan on going over to the shop on my lunch break but I certainly don't want to pay for them and take them out of the shop until I absolutely know they will be "ok". Let's say the shop owner shows me his CNC machine, how will I know and how can I dispute it?? Granted, I did drop off those photocopies of the manual so I might have grounds for argument there if needed. But, perhaps being 30 years later, because of newer CNC machines, maybe they can be shaved down, I don't know? Anyone???

[dmc6960]

Do you have an exact number for how much was taken off? Thats really important. The deck height sets the timing on the camshafts. When more material is removed, it retards the timing a little bit. With today's machines its possible to completely resurface the heads with hardly taking anything off. When mine were first redone (before I decided to go "all out"), they were shaved about 0.30mm. This amount would be fine to reassemble an otherwise un-modified engine. Go more than 0.5mm though, and your probably going to be slightly affecting the engine operation. You can counteract this by a few different methods. You could modify the camshaft mounts to manually time them, probably very difficult. Another option which is also some good $$ is Ed Uding's camshafts from DMCEurope. They are specifically designed to take into account specifically a 1mm decking of the heads and not need anything special to time them.

[Jeffu]

Do you have an exact number for how much was taken off? Thats really important. The deck height sets the timing on the camshafts. When more material is removed, it retards the timing a little bit. With today's machines its possible to completely resurface the heads with hardly taking anything off. When mine were first redone (before I decided to go "all out"), they were shaved about 0.30mm. This amount would be fine to reassemble an otherwise un-modified engine. Go more than 0.5mm though, and your probably going to be slightly affecting the engine operation. You can counteract this by a few different methods. You could modify the camshaft mounts to manually time them, probably very difficult. Another option which is also some good $$ is Ed Uding's camshafts from DMCEurope. They are specifically designed to take into account specifically a 1mm decking of the heads and not need anything special to time them.

Thanks for the quick response Jim! No, I don't know yet how much was taken off. I can certainly have them provide that to me. I can tell you that I am modifying the engine a bit. I removed my old BAE turbo kit and I just purchased a set of modified cams from DMC. I am also going with an upgraded exhaust system. Other than those two items, everything else is stock. However, I do not know any of the particulars on the DMC cams vs Ed's cams and how they both would pertain to resurfacing of the deck? I guess the key will be to see how much was taken off of the surface.
Thanks again for your help!

[Jeffu]

Do you have an exact number for how much was taken off? Thats really important.

One was taken down to .006" and the other .009"

[Delorean Industries]

One was taken down to .006" and the other .009"

you are fine with that.

[Jeffu]

you are fine with that.

Thanks Josh! That makes me feel a whole lot better. That's what I love about this forum. People like me can tap into the experience of you and others that have "been there before". Thanks again!

[David T]

You may also notice it difficult to get the bolts started for the intake manifold too. Just enlarge the bolt holes in the intake manifold a little. I hope they left the appropriate amount if surface roughness, it is necessary so the head gaskets do not tend to move around. You do not want the surface to be shiny, that's too smooth. You might want to check the valve timing with a dial indicator and a degree wheel when you are done. BTW, milling heads is an old "Hot Rodder's" trick to increase the compression ratio to get a little more HP. On an interference motor you would put some modeling clay on top of the piston to make sure the valves do not get too close to the pistons.
David Teitelbaum

[Ron]

No one makes a shim or thicker gaskets to compensate for resurfacing...seems the guys across the pond would have had this covered a long time ago???

[TTait]

Thanks Josh! That makes me feel a whole lot better. That's what I love about this forum. People like me can tap into the experience of you and others that have "been there before". Thanks again!

I've been there before - similar numbers no issue except than there was a slight gap at the valve cover as the top of the heads no longer perfectly aligned with the top of the timing chain cover... Had to use a bit of gasket maker to get a good seal there. Congrats on your refurbished heads...

Tom

PS - I have a good place in the San Fernando Valley that redid mine some years back. PM me for a referral if needed.

[Jeffu]

I hope they left the appropriate amount if surface roughness, it is necessary so the head gaskets do not tend to move around. You do not want the surface to be shiny, that's too smooth.

Yes, there is some roughness there. Thanks for you input!

[Jeffu]

No one makes a shim or thicker gaskets to compensate for resurfacing...seems the guys across the pond would have had this covered a long time ago???

Ron, you sure would have thought so? Odd...

[Jeffu]

I've been there before - similar numbers no issue except than there was a slight gap at the valve cover as the top of the heads no longer perfectly aligned with the top of the timing chain cover... Had to use a bit of gasket maker to get a good seal there. Congrats on your refurbished heads...

Tom

PS - I have a good place in the San Fernando Valley that redid mine some years back. PM me for a referral if needed.

Yes, I am anticipating a bit more RTV sealant will be needed. Shouldn't be too much trouble. Thanks again!

[ramblinmike]

No one makes a shim or thicker gaskets to compensate for resurfacing...seems the guys across the pond would have had this covered a long time ago???

Maybe the liners' tendency to move makes a thicker head gasket impossible. I wonder if the gasket material could let the liners move.