what is the difference between a billet head and a milled stock head? can you go higher on your compression with the billet head?

 

Here is what I understand. The billet gives you options of different domes for different compression ratios. The billet uses a compressed O ring to seal out the water passages. The billet transfers heat and water better.

 

Yeah what fish said.[img]i/expressions/face-icon-small-tongue.gif[/img]

 

Yep, what he said[img]i/expressions/face-icon-small-happy.gif[/img]

The HPD head also gives you the option of running a girdle kit to help keep the cylinder squished down and from cracking on the front 2 base bolts.

Without a head gasket you have metal to metal contact and that transfers the heat better.

 

Is the o-ring setup pretty reliable against coolant leaks?

 

Im gona speak from my own personal experience here... dont mill the stock head unless you girdle it.
my 2c.

 

I have never had any problems with the o-rings leaking.You need to use some grease to hold them in place ,when you install the head.

 

I agree with what everone has said. I did have mine leak one time, it was blowing coolant out the overflow, but the orings had been in a long time. Changed them out and never had another problem.

 

how often do you have to change the o-rings. i'm not real fond of pulling the plastic and the gas tank to get at it. it would be nice if they started making these things with the gas tank out of the way so you can just pop open a door in the plastic and there's the head. haaaaagghh, fat chance of that huh, that would mean a hour of labor money lost.

 

If the surface is clean and the head is torqued, then o'rings should go at least a couple of years. the more compression and more rpms it turns the less life you will get out of them.

Dont use regular automotive grease to hold them in place. Petroleum will eat away at the rubber. The only preferred grease to use is di-electric grease. Not only is it a rubber lubricant, it also promotes heat transfer. I buy a small can, about 8-10oz with a tip like cheeze whiz. Just push it over to one side and it will ooze out a little. The can costs about $8 but will last a long time. That is also great for lubing up new seals and protecting anything rubber.