Milling cylinder heads
 

How much can comfortably be milled off the deck of our cylinder heads without causing any issues? I'm replacing all the gaskets on my 5.9 and figured it would be a prime time to shave them down a little bit. The engine has 168,000 on it so it won't hurt anyways. I'm not doing a cam swap, although I would like to but it's just not in the budget. Ideally I would like to give a slight bump in compression.

I'm thinking if I could get away with 0.020-0.030" I would do that. Also if I mill that off the deck I have to mill it off the intake mounting surface as well right?

In all reality, you can't get away with milling them at all. The deck castings were already far to thin when they were brand new.... If you are pulling the heads, instead of wasting money on them, you should simply replace them with better heads. Odessa/Clearwater cylinder heads off of Ebay are NEW castings, with thicker decks. Much better than stock.

I had a feeling you'd say that lol. I am aware of the new heads but would prefer not to spend the money on them. The engine ran great before so I suppose I could always just put it back together with new gaskets and run it.

I would recommend that before I would suggest milling the heads. :) If you wanna bump compression, go with a thinner head gasket.

Any chance you have a part number for a thinner gasket? I was otherwise just going to purchase a felpro head gasket set from advance auto since it includes all the intake gaskets I need as well. Worst case senario I just check the heads for flatness, clean them up and bolt them back on. I plan on putting a tuner on the truck once it's finished so that should help open it up some anyways.

Personally I would go with a better head. PIE has a fully assembled set of iron rams with 2.02" int valves for $1500. http://bhpconcepts.com/newPIE/prodde...nstealthlevel1

You can get regular EQ heads cheaper.

No, I don't have part numbers, but, I bet Fel Pro would be able to help you out. Might give em a call, or email, and see what they have to say.

Yes you can. But take it from someone who put a set of standard EQ's on and regretted not getting the 2.02" int with porting and regretted it later.

Not trying to be pessimistic here but I had a set of heads checked out by the local machine shop and he had yet to see a set of factory heads that at least one was cracked and/or had a repaired crack. He also said that because of where they crack you usually don't see any issues.

So at how many miles do the heads crack ? I just scored a 01 5.9 from work that has blown head gaskets but has only 171,000 miles on it !

I think they came pre-cracked from the factory. :D

I cleaned the heads up and for ****s and giggles had them magnafluxed. No cracks anywhere!

That's absolutely amazing. :D

I have a 5.9 as well and have kicked around this idea also, but, everything ive read and heard about the stock heads is not good, there so prone to cracking i wouldnt trust them down the road, even if there ok now.
Im thinking about buying the EQ heads as bare castings (much cheaper) then have them assembled down the road as more funds become available, this way i can do my own gasket matcing and bowl cleanup as well, while there bare castings...

You leave those off the truck and mount them over your fireplace like the trophy they are. In all seriousness if they are fine you could get away with a little porting and milling. I looked up flow charts and they are on par with chevy vortec heads which every chevy guy thinks are the best iron head ever concieved, maybe divine intervention even. Until you mention hemi or ls heads that is :icon_crackup: Sorry off topic. If it wasn't for the cracking the heads aren't terrible. Its the intake manifold that really kills flow from the it seems experimenting I have done.

If I wanted to make decent power out of this engine I would throw in a strong cam, some EQ heads and a good tune. I'm really just building a cruiser that will weigh about half or even less then the truck the engine came out of. Coupled with a set of 4.56 gears and a 31" rear tire I'm confident this there will be plenty of pickup for my needs. If I had the spare $$$ in my budget I would spring for the said upgrades but it's just not there. The heads are not cracked and the engine ran good before being pulled so it'll run good again.

In that case, don't cut the decks unless you NEED to. A bit of porting/gasket matching certainly won't hurt you. :)

I just checked to make sure the decks were flat, which they are and went through each port and smoothed them out a little bit.

I would look at head gaskets from Mr. Gasket. I'm using the 5805G steel-core graphite gasket for my build. It's .038" compressed, while the stock Fel-Pro is I think .055" (someone correct me if I'm wrong). The bore diameter is 4.140" while the stocker is 4.180". So both those will increase your compression a little. I think they even make a gasket that's .032 compressed thickness. And about the same price as the Fel-Pro.

The composite/rubberized gaskets act as insulators. An added bonus of the steel/graphite construction is these gaskets transmit heat so fast you'd think they were pure copper. I think that's probably a very good thing with regard to heat being actively transferred from the heads to the block through the gasket and not solely via the cooling system.