SuperMX, a lot of the car guys are running the stop-leak pellets and powders to seal up the seapage. Seems to work well for them - GM even sells a version of this for use on some of their newer vehicles that have aluminum heads / cast iron block. However, with open cooling on a boat, you don't have any easy way to circulate this stuff and bring it up to temp. I guess you could run the engine on a start-up cart with a radiator before it is installed in the boat, but not many of us have this luxury.

I guess the key is getting it to seal the first time. I have seen some threads saying that the teflon paste sealants, including the ARP stuff, have a tendency to wash out and don't work that well, although there also seems to be people using this stuff with success. I may look closely at "The Right Stuff" as indicated by others. Leaky head studs are another worry that I can do without for this build!

OK, here's the plan. I talked to Bob Madara - he likes to use the Hylomar sealant - waiting to get the exact PN from him as they make several formulations, but if I was to take a guess at this point I would expect it to be the hylomar pl32 aerograde. I think Permatex makes a sealant that they also call "Hylomar", but have seen several remarks indicating it is not as good as the "real" Hylomar.

Planning to THOROUGHLY clean the head stud threads with a good solvent and then follow that up with a wire wheel on the threads. Will run a chase through the head bolt threads in the block and follow up with brake cleaner and plenty of air.

I'll install the studs with a liberal dose of the Hylomar, and then immediately drop the heads on and torque them to spec. I will plan to come back the next day and loosen them 1/8 turn and retorque to value.

I would like to rig up some type of regulated pressure test with water before I ever start the mill. I figure about 28 PSI will be more than enough to ensure that I have no leaks.

Am I leaving anything out?

Then again, I might just punt and go back with a set of new ARP bolts, but that will cost me another Benjamin and then some.

Yes, it is. Its funny, when you search the net, you'll be hard pressed to find anyone who's had leaks using it, leak lok, or even stuff like ultra grey on head studs. But, any of the specific thread sealers, like ARP Teflon, permatex, Loctite, pretty much any of the "thread sealers'' you'll get pages of guys with leaks who used that stuff.

which blocks require and which don't? I get conflicting answers on this subj all the time

if the threaded hole goes into the water jacket it needs to be sealed.

i use the standard that comes in a grey tube.

Have always used the Hylomar sealant and never had a leaker , you can order it online .

permatex makes a product specifically for this called high performance thread sealant google it

Found some excellent info about the Hylomar product. Apparently Universal Blue and the PL32 AeroGrade are essentially the same formulation. Grainger carries the Universal Blue = stuff's expensive - about $20 for a 4 oz tube!

Hylomar Universal Blue gasket and jointing compound, non-setting sealant, Hylomar gasket jointing compounds , PL32/H ( heavy) , PL/HC (heavy), PL32/M (medium) hylomar universal blue

I solve my stud leaking with the moroso ceramic treatment, i do it in the boat with a home made close cooling systeme, without enought cooling but the product have do is job. I have run the engine at idle 3x 15 min and let it warm up to 210 f.