Question about block decking

[ajmorell]

Curious to know a couple of things

1-If you had your deck blocked, how much did you have taken off?

2-How much would you be willing to take off/can you take off before you start worrying about valve interference?

[IH 392]

1) There is sufficient material to take it 0 (in a 4.0) if you do the hear ONLY take enough to make it flat, NO more.
2) I don't believe there is cam on this planet that provides enough lift to get the valves any where near the pistons in a AMC/Jeep straight six?

[PolloLoco]

I'm concerned about this too. I have KB945 pistons on the way and they have a 11.38cc dish, and I'd be willing to bet that it's very shallow. If I were to deck the block to zero and shave the head to increase compression ratio (I'm the crazy guy with E85 on my mind) with a COMP 68-231-4, .462/.485 intake/exhaust, then I should be fine? What if I went to 1.7 ratio roller rockers? Then I'd be pushing .491/.515. Is there still suffucient clearnace?

How extreme would one have to go before running into trouble?
What is ideal clearance? I've read 0.09 to 0.10 for race engines and 0.07 is good enough for street engines. We're building torque-beasts here, not high-revving by any means, can we get away with less clearance?

I hope that I'm not hijacking, just playing devil's advocate here.

[RAPTORFAN85]

There should still be plenty of clearance. There was almost 1/4 of an inch (.250) valve clearance left with my build with .475 lift, .010 plained head and zero deck. I don't think valve clearance should ever be a problem on a 4.0.

Polloloco, how deep are your pistons dished? Mine are probably a little deeper but you should be fine.

[ajmorell]

Good to hear. I just wanted to make sure there wasn't going to be issues with decking the block 0.030" or so.

[seanyb505]

I had my by block decked .045" and the head .015". Right now ex lift is .465, I dont have any issues.