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Discussion Starter #1
Maybe I'm getting worried over nothing...

My 289 setup will have 10.25:1 CR

My Cam is 284/284 adv 218/218 @.05 w/ 110 lsa .488/.488 lift

.045 quench

Polished 65' Cast Iron Cylinder Heads with 1.94/1.60 valves

Running with an automatic - looking for good mid-range power (street use mostly)

Will be running 91 octane gas

Starting to think I should have picked a cam with a little more duration (thought my CR would be more like 9.5:1 when I picked it out)

Planning on assembling the thing tonight... unless I'm going to have problems!

Advise appreciated!!! (or reassurance
)
 

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10.25 compression may be a bit much for 91 octane. But, I bet it would be just fine if you stuck a small jug of octane booster in the take with the 91 octane, you should be just fine!
Good luck!
Matt
 

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Your going to be borderline at best. I was running 93 with booster on a 10.5 to 1 and it did fine until summer hit. Hot and muggy days would get it to ping. I just swapped to Alum heads and it does fine on just 93. Sometimes you get lucky sometimes you don't. I've also got the timing a little high, but thats where she wants it.
 

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Your problem lies in your camshaft and not your static compression!!With the right cam timing you can run a static compression motor of 12 to 1 with the right camshaft and not even worry about detonation!!PLEASE talk to some of your RACING machine shops around you or talk to a CAM specialist!! Lobe separation,lobe centerline,cam overlap is what effects detonation!!!Hope this helps,because I've done this already!!!
 

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Discussion Starter #5
Thanks all..

Cams are voodoo science... ugghhhh

Well... I put the short block together tonight, so I guess I'll see how she runs and change out the cam if I need to later!

I haven't put the heads on yet. Debating on whether or not I'm going to take them in and have a little more deshrouding done to get my CR down to 10:1 I'd need to remove 2cc's is all. Can .25 really make that much difference though???

I love this stuff

 
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