Thread: How much compression?

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Building a daily driver to replace the little 327. I am replacing it with some displacement! It is a 85 C-30 454 motor. It has small oval port heads with standard small valves. Three angle valve job with Comp 911-16 roller cam valve springs. The block was bored 0.060 over and the crank was ground 10/10. The block is ready to go back together. I plan to use the Comp XR276HR roller cam. Since I have to buy new pistons, I would like more compression but want good manners with pump gas for daily driving.
Looking at Speed Pro pistons, I can get flat top, +10cc, +21cc, and +32cc dome pistons. The heads were 0.005 decked along with the block so I am not sure of how much deck clearance there is. I have a standard Fel Pro engine overhaul gasket set.
My 327 has 10:1 compression and I am happy with it for 65,000 miles.
What compression should I have for this big block and be happier for the next 65,000 miles?
Thanks for the help.

The 10CC pistons should give about 8.8-1 compression with a 118cc chamber.

That compression will be 89 octane friendly and make decent power.

My +.030 BB made 542HP with 9-1 compression and runs fine on 89.

Thanks for that reply.
How about a 21 cc dome that is around 9.5
Is that street and 89 octane friendly?

You can be street friendly, but will probably require 93 Octane and watch the total advance.

Aluminum heads would allow 10.5-1, but with iron heads I would go no higher than 9.5

Well thanks for the reply. Geezer what is your secret build combination? What carb, intake, cam, heads, etc. you are running that made so much horsepower? Did you have the engine dyno tested to know that is makes 542Hhp?
I got to know that build! Thanks,

It's a +.030 454 based on an 85 4 bolt block.

Scat steel crank and I beam rods with K-B pistons. I used a Comp Cams hydraulic roller with Lunati roller lifters, and stainless roller rockers. Cam specs are 232 at .050 with .578 lift.

The heads are Gen VI rectangular ports with the proper springs and 10 degree locks.

The intake is a Holley single plane with a Holley 750 carb.

The engine has headers and 2 1/2" mandrel bent exhaust system.

It made the power on a dyno and through the mufflers.

The compression ratio is 9-1 and it made the power on 89 octane

I use an MSD dist and 6A box.

Pretty basic stuff.

As a footnote, a lot of the parts were purchased off Craigs List and E-bay.

It was not real expensive to build (about $4500.00)

I see that is Comp XR290HR cam, I am going to use the XR276HR cam. My bottom end is all stock. Comp recommends 9:1 compression with the 276 cam. With a 10cc dome I get 8.8 and 21cc dome I get 9.6 on the calculator.
What is your base timing, mechicancal, and total timing set at? How much vacuum do you have at idle?
You have been a big help, thanks!

I set total timing only and it's at 36 degrees. 14-16 inches at idle.

Good luck with your build.

Thank you for your responses!