[Flatout'69]

Let me start out by thanking the many helpful posts I've read over the last year or so; I've only just become a member of this forum although I've refferenced this site hundreds of times during the course of my '69 restoration. Now that I'm a member I can personally thank those of you that help me directly! I've been through every component of this car with the exception of the engine. I'd love some insight and recommendations for my upcoming build. My block and heads are fresh out of the machine shop. 400 small block bored .030 over, Dart Iron Eagle Heads (72CC, 200CC Intake Runners). I plan on reusing my Lunati Flat Tappet Cam @ .540/.556. I'm looking for input as to a lower end rotating assembly. It seems Scat and Eagle are the preffered manufacturers; and I'd like an H beam, fully forged assembly. I'm looking for maximum compression to safely run on pump gas and the option for nitrous down the road. My understanding is that the "balanced" kits from both manufacturers are ready to install. Does anyone have any experience with these kits? Anyone with a similar build? On paper a -5cc domed piston kit puts me at 12:1 CR, is this too much to run on 93 octane? Thanks in advance for any insight!

 

[ChevelleFan70]

On paper a -5cc domed piston kit puts me at 12:1 CR, is this too much to run on 93 octane?

Yes.

-Dave

 

[Tom Mobley]

way too much. you need more like 9 - 9.5:1 with iron heads and a street cam. not close. A stock type piston with a 12cc dish is where it's at. Or, you do like some of the others, build something with too much CR, retard the timing till it stops pinging, runs like sh!t and gets 8MPG.

 

[Flatout'69]

Thanks for the reply guys; the internals coming out are aftermarket hypereutectic speed pro with 5.7 rods; ran well at a 10.5 CR (static estimated). I spend more time at the track than I'd expected and would love to see a few tenths off my ET! I thought CR was the way to get there but I don't want to have to run race fuel (I drive it on the street often as well). Is nitrous the way to get me the best of both worlds? I have zero experience with it and frankly it scares me a bit. Is a forged bottom end at a safer, 10:1 CR all I need to support a 150 shot or so? Thanks again guys!

 

[AJS]

You may want to look into a custom ground camshaft. There is some guy on this website that grinds custom cams. i think it is Straubtechnologies. You may be able to run more static compression and have a cam ground to work with your compression on pump gas.

 

[blue_69_malibu]

In all likelihood, you WILL have serious detonation issues. You could drop a full point and still have detonation issues.

With iron heads, 10:1 compression should be your limit....although other people "in the know" may tell you differently....but it won't be their car that runs like crap and crushes all of your hopes and dreams. It happens....more than it should.

Personally, I'd stay in the 9.5 to 9.8 range and end up with a nice running, reliable motor...with real world timing.

Why cut off your nose to spite your face to gain a few tenths....especially if you're a street car? Motors that are constantly broken and run poorly are less fun then getting a root canal w/o novacaine.....every day.

Again, that's just my opinion.