So I looked at some past threads and it sounds like this is a common problem. Mine is driving me crazy as I am about to go with my third set of head gaskets. I have a newer reproduction hemi block and an original set of 64 Race Hemi heads. Both block and heads have been machined two years ago. The first head gasket I used was the MP steel shim gasket. I used copper spray and Permatex 2A around the oil drain holes and water passages. ARP studs torqued to 80 lb ft torque per instructions. Leaked right away on front driver side and a small amount on passenger side rear. The leak at the front was pretty bad, but I kept engine running to break in the cam. Pulled it apart and swapped to a multi-layer fel-pro. Used Hylomar Blue around oil and coolant holes. We use Hylomar on our turbomachinary at work and it seems to work well even under pressurized oil passages. Still leaks, but not real bad.

So now, I have a pair of Cometic gaskets and another tube of Hylomar. But I have read that sealant is not necessary. Or should I get Permatex Ultra Copper Silicone or Right Stuff as I have read recommended in other posts.

I have also checked to make sure the dowel pin isn't holding the head off. I looked into the passages with a flashlight and the one that leaks appears to have a slight offeset between the head and block. Not quite 1/16" (drain back holes are 7/16" diameter), but the others are also off slightly, so not sure if that is a cause. I doubt it since I made sure to spread the sealant out over 1/4" away from hole.

Any other suggestions? I WANT to drive the car this year for change. Its been two years. If this doesn't work, I will be very disappointed as I have always wanted a cross ram Hemi.

Thanks in advance.

Also Check Read # 652....

https://books.google.com/books?id=9Rs2c6...lem&f=false

Should fix the head gasket problem..... Scroll down.....
http://www.arruzzahighperformance.com/Parts/Parts.html

I've always used steel shim sealed around oil returns with hylomar as you tried.

I would just tube the return holes in the heads extending them into the block.

I'm thinking about the arruzza head gaskets. I know the valve covers are different. I had to make my own gaskets there. I have the right valve covers. The leaks are definitely where the head and block meet at the corners.

Had the same problem yrs ago. I went with cometics. Separated the gaskets, copper coated all 6 surfaces. I put ultra-gray silicone around all water & oil holes. Torqued head & let silicone cure for 24 hrs. Worked for me.

I had this problem MP iron block / MP alum. head combination with Fel Pros. I switched and used the Aruzza gaskets and silicone as added insurance. I think it was Ultra black, IIRC. could have been Ultra gray. The Right Stuff sets up too quick IMHO.This did stop the leaking.
Currently using Cometics with Hylomar on the drain-backs and water passages.
Mark

BTW Aruzza gaskets max @ 4.320.bore

I have had two Hemi engines over the years do this. Both factory blocks. The Arruza head gasket does the trick.

I am not sure the Arruza gaskets will handle this. Nor the Cometics. It appears that the return home in the block is drilled incorrectly. You can see where the embossing on gasket barely surrounded the hole. It look like there embossing actually squished into the hole allowing oil seep around. Its about 1/16" to 1/8" off. I did add sealant but must not have been enough. I am not sure what options I have now. Anything requiring drilling will leave possibility of chips in the pan. External return in that corner? Another gasket with even more sealant? Looking for additional ideas. I am not happy with this adventure.

Orings?

I have a hemi going together,with the short block done and heads going on in a week or so using cometic gaskets,block was decked,should I use sealant