tomcat

Standard port, spread port, 18 degree...can you shed some light on the choices? If you were building a NA 598 with solid roller, 6500 RPM redline, why you would use one style over the other?. How would the possibility of a blower in the future affect your choice?

Thanks,

Tom Robinson

RumRunner

I would think your budget, and goals are going to be your factors. A Big Chief style head is going to make more HP than a conventional head, but it's going to cost a lot more to use. Different pistons, valve train, custom headers, etc. It's all a matter of what you're trying to accomplish. It takes a big HP difference to see a Speed change in a boat. I don't think I've answered your question, but it is a loaded question.

tomcat

Hi Doug:

Bang for the buck is always important. I know the Big Chief style is more money and trouble, but I'm hoping that some of the members have personal experience with this decision.

I know that the Big Chief style makes more HP in drag racing, but what is it's HP advantage in the example marine engine? Whether that extra HP is worth the trouble is up to each individual and application, and I would love to hear about it.

I know it's a loaded question because I look around and see most engine builders sticking with the convential style of head. Opinions on which brand of conventional head is the best are plentiful.

Were you in Miami this year?

RumRunner

Yes, was in Miami for a few days.

Personally if I was building a new engine with a Supercharger, in a brand new application I would go with a Big Chief style head. If I was retrofitting an exisiting boat (already had headers, and acc.) no need to use one, just run a little more boost. Of the guys doing this type of stuff themselves, I think they are doing it in steps, so being able to re-use certain parts until you can upgrade is important.

GPM

If you are building a new motor, it's not that much more money to do the spread port. I believe the large runners and valves limit application. They work very well on 598 plus cid.

Mbam

Tom, been there. Personally I don't think I would run Big Chief again. Yes, potentially more power, but I don't think it's worth the trouble/expense.

On a big inch blower motor you can't get the compression low enough, combustion chamber is too small. Wound up with 65 cc dishes in the pistons, that was another nightmare. Did make 1400 HP on 89 octane though - for a while

Then again, that's just my opinion, been a while since i built an engine.

WETTE VETTE

On my 6500 RPM 598 NA solid roller motor Nickerson recommended 355 Dart CNC ported heads. That is what I am running and I couldn't be happier with the performance.