How to inspect a cylinder head?

[Spoolin4Ever]

I bought a head from J&C Enterprises Cylinder Heads dudes off ebay in West Virginia. I t hasn't arrived yet but I noticed today after i already paid (of course), there was a couple complaints from DSMr's.

So I want to know how to inspect the head? I want to know how much has been taken off the bottom/shaved, I want to know the springs, and what else? And how do I test/measure the said and other things?

Anyone heard anything about J&C lately?

 

[JacksonAuto]

I would first measure the thickness of the head. At each corner, measure the distance from the valve cover rail to the deck surface. Compare this to the book spec to tell how much it's been milled. Do a search for this on the forums here because I know BogusSVO has a nice thread with photos of this process.

I also like to lay a machinists straight edge along the cam bores and see if a .002-.004" feeler gage fits between it and the cam bores at any point. If so, this indicates that the head is warped/bowed badly and the cams will not spin freely.

Look for galling of the cam journals which would indicate a poor oil supply.

I would never trust the springs on a head with an unknown history. Pull them off and at least install a set of stock replacement springs. Chances are pretty good that the head came off of a high mileage engine and the springs are worn out.

If you plan on just cleaning the head and installing it, I would also check the valves to see if they're sealing. Fill the chambers with washer solvent or spray soapy water on them and then blow compressed air on the back side of the valve. If you see bubbles, the valves aren't sealed. If you have a vacuum pump you could do the same test but most people dont.

If you want to go as far as disassembling the whole head to be sure of what you've got, I would also pressure test the head. You'll have to find a machine shop to do this.

If it were my head, I would take the whole thing apart, clean it, check the guides, do everything I listed above, do a stock valve job, mill it and put it back together with new seals and springs. That way you know exactly what you've got.

 

[TexasTurbo]

Be careful about listening to complaints on line from DSM owners. I am one too, but from my experience many of them are really cheap and like to complain about things like ebay exhaust manifolds cracking when a quality one costs 5 times as much as the ebay one.

You get what you pay for. I wouldn't do any business concerning a cylinder head with anyone that I cannot walk into their shop and talk to. I'm not suggesting that you've made any mistake by using these people, i'm just suggesting that you should be a bit more skeptical about complaints from people that like to cut corners.

Obviously, i'm not saying every DSM'r is this way but I've seen quite a few that are.

 

[TSIfreek]

I would first measure the thickness of the head. At each corner, measure the distance from the valve cover rail to the deck surface. Compare this to the book spec to tell how much it's been milled. Do a search for this on the forums here because I know BogusSVO has a nice thread with photos of this process.

I also like to lay a machinists straight edge along the cam bores and see if a .002-.004" feeler gage fits between it and the cam bores at any point. If so, this indicates that the head is warped/bowed badly and the cams will not spin freely.

Look for galling of the cam journals which would indicate a poor oil supply.

I would never trust the springs on a head with an unknown history. Pull them off and at least install a set of stock replacement springs. Chances are pretty good that the head came off of a high mileage engine and the springs are worn out.

If you plan on just cleaning the head and installing it, I would also check the valves to see if they're sealing. Fill the chambers with washer solvent or spray soapy water on them and then blow compressed air on the back side of the valve. If you see bubbles, the valves aren't sealed. If you have a vacuum pump you could do the same test but most people dont.

If you want to go as far as disassembling the whole head to be sure of what you've got, I would also pressure test the head. You'll have to find a machine shop to do this.

If it were my head, I would take the whole thing apart, clean it, check the guides, do everything I listed above, do a stock valve job, mill it and put it back together with new seals and springs. That way you know exactly what you've got.