Getting ready to slap together my engine. I have a set of high compression domed pistons and a set of regular, both with appropriate rings.

What do you guys recommend? Are the domed a BIG improvment over stock or are they too hard on the little engine?

My original cam is in great shape and I was going to run this stock cam. Do I need a hotter cam for the domed psitons?

Lemme know guys, I'm getting this lil booger together!

Patrick,

Domed pistons will give some improvement in performance although not as mush a a Z head. Beings as you have them in hand, I would go ahead and use them. They won't make any improvement in performance on the shelf. Some help is better then none at all. Make sure you have enought clearance at the top.

Be_Zero_Be

My recommendation would be to not "slap the engine together".

Well you know what I mean, not literally slap LOL! I'm an extremeley particular engine rebuilder

The one that bugs me is,"I'll just pop it back in after it is together". It's not a 5 second job.
I would use the regular pistons as the domed will raise the compession you do get a poor shaped combustion chamber and don't gain much power-if any.
Run it that way and get yourself a good high compression head some day. Then you'll really get a power boost.

I have a Z head new sitting in a bubble wrap bag, Big Domed pistons and well at the moment , there isn't a lot in it, Z against Big Domed, choice is yours, the Z or the Domes !
Shame that there is not a ZD head for much bigger compression with Domed Pistons, l'll have one of them thanks.
David

So even the high compression pistons are a gimmick? I'd like to hear more about this.

I just built a 351W with performance aluminum heads and TRW forged pistons for my 67 mustang convertible and I can say that the new pistons definitley have a higher profile than the stock aluminum ones.....which.....is basically what is going on with the domed T pistons.

Patrick, my two cents isn't worth anymore than anyone else; and probably less than a professional engine builder (although you'll be lucky to get anything from them for two cents.) My thoughts are; what kind of a budget are you on? If the budget is tight, I'd use the high compression pistons you have and mill the stock head about one eighth of an inch, checking with a small dab of clay on top of the piston to make sure that you have the necessary clearance. If money is not a big object, I'd follow the advice of others, sell the HC pistons and buy a Z head. A different cam isn't needed unless your cam is excessively worn. If it is, many on this forum claim the new Stipe 250 cam is as good a running cam as the Stipe 280, and maybe better. I have a simular situation coming up, as I don't have a Z head, but I do have a Rajo four valve head and a set of high compression pistons. The Rajo has deep combustion chambers like a stock head, so the only problem that I can see is checking the tops of the pistons for clearance with the intake valves. That's my story, and I'm sticking to it.

The high compression pistons to not help breathing. they just give you more compression. The exhaust is equally compressed in the chamber and must find its way out when the valve opens. With the Z head, the shape of the combustion chamber assists with the exit of the exhaust gasses because the v-shape guides the exhaust out where it should actually go rather than just going around in a circle with no place to go in particular. Wanna race ?