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Sorry more head questions.
https://slantsix.org/forum/viewtopic.php?t=33430		 Page 2 of 2
Author:  runvs_826 [ Thu Jan 22, 2009 12:56 pm ]
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Shave it, if you ping on pump gas I will send you a new head in exchange. I told the shop the same thing, they rolled their eyes and took the head. I picked it up the next day from a different guy and asked if the job was done to spec. He said, "Of course"
Well, I don't know if they truley shaved it or not cause it runs fine on 87 octane which tells me probably less than 9.0:1. If your investing this much into the head a higher compression ratio is a must, but on that same note. Investing this much into the head warrants an hour measuring the cc's of the head and putting it into a calculator.
Author:  Doc [ Thu Jan 22, 2009 2:02 pm ]
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Quote:
Somewhat off topic- how do you CC a head? I assume you get a piece of plexi and a gradated syringe (in CCs of course) and see how much water it takes to fill each combustion chamber? If you find discrepancies, how do you correct them? :?:
Yes, a plastic plate with a couple of holes (entrance and a vent hole) along with a syringe. I use alcohol mixed with a little ATF to give the fluid a red tint.
Here is my set-up being used to check a piston dish.
The same process is used on a cylinder head chamber.
It is good to check all the chambers to see if a angled milling cut is needed. (cc increase as you go "down the line")

If one or two chambers have less volume, you need to grind material out to even them up to the others.
DD

Image
Author:  Reed [ Thu Jan 22, 2009 3:22 pm ]
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Thanks Doc!
Author:  sandy in BC [ Thu Jan 22, 2009 3:29 pm ]
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http://www.slantsix.org/forum/viewtopic ... ht=cc+head
Author:  Reed [ Thu Jan 22, 2009 3:48 pm ]
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Thanks Sandy! I have a new bookmark!
Author:  Mike_64_Valiant [ Thu Jan 22, 2009 3:55 pm ]
Post subject:  update
I stoped buy the shop today and they have shaved .045 off the head so far and he started some heavy porting. He CCed the head before doing anything and he said they where all sitting at 57.5cc's. He is holding off on taking more off the head until I pull my other head from the car and measure the piston deck hight. I figure do this the right way but as far as decking the block I agree alot can be gained this way but this bottom end is not coming out of the car. When I build the bottom end we can take more off. I will keep you all posted on the updates. Thanks for all the replies.
Author:  Mike_64_Valiant [ Sun Jan 25, 2009 3:47 pm ]
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I pulled the whole motor and the head. I measure the deck hight and the pistons sit .167 to .174 in the hole. None of them measured the same. Is that a problem? The bore is 3.400. How can I figure out my compression ratio?
Author:  emsvitil [ Mon Jan 26, 2009 7:18 pm ]
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The difference down the hole amounts to about 1cc.

Try this out:


http://www.rbracing-rsr.com/compstaticcalc.html
Author:  runvs_826 [ Mon Jan 26, 2009 10:39 pm ]
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I got exactly 8:1 compression ratio with my math. So, your call but I would creep it up a little bit more.
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