Math question.
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Joined: Jul 2001
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From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Re: Math question. (DollaGreen)
Can someone tell me what my compression ratio would be with a 64cc head, .039 gasket and everything else stock for my 73 L48...Thanks!
Melting Slicks
Joined: Dec 2000
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From: Union Ontario
Re: Math question. (GrandSportC3)
I would say probably 76 CC...... but there are a lot more variables..... chances are the pistons have been change in the past 29 years. Whcih means the pistons might not be the right compression height and might have a different CC dish or dome.
Thread Starter
Pro
Joined: Apr 2001
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From: Waukesha WI
Re: Math question. (MikeC)
Im fairly sure that the pistons were orig. The heads are 76cc and the plate reads 8.5:1. Im guessing that my new setup will be about 9.5:1ish wanted someone to confirm and if possible give me the exact number.
Thanks!
Thanks!
Race Director
Joined: Mar 2001
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From: Living in the Hartland
Re: Math question. (DollaGreen)
I believe it to be about 9.3 to 1. I did the calc because I was thinking of putting my 64 cc heads on my LM1 which is 8.5 to 1 with 76cc heads. Look at some new short blocks for sale through parts warehouses and they state the comp with the the 2 diff cc heads.
Drifting
Joined: Oct 2000
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From: Shawano WI
Re: Math question. (DollaGreen)
Your original setup should have been 76cc heads .016 steel shim head gasket, -.010 piston to deck height, -15cc piston volume (4 valve relief), which would give you a CR of 8.44-1
With 64cc head and a .039 head gasket and everything else the same you will have a CR of 9.04-1
If you use the 64cc heads but still use a .016 steel shim head gasket your CR will be 9.49-1
With 64cc head and a .039 head gasket and everything else the same you will have a CR of 9.04-1
If you use the 64cc heads but still use a .016 steel shim head gasket your CR will be 9.49-1
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Drifting
Joined: Oct 2000
Posts: 1,823
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From: Shawano WI
Re: Math question. (Cookwithvette)
Steel shim was stock?
Did it have blocked and partially blocked water passageways?
Did it have blocked and partially blocked water passageways?
If you are asking if the holes in the head gasket are smaller than the holes in the top row of the block, then the answer is yes. All head gaskets, either steel or composite have smaller holes in the gasket than the block. The holes in the block are much larger than needed as they are part of the core release. The head gasket used the correct sized holes to regulate and force water to areas that need it.
[Modified by Pete79L82, 5:57 PM 6/11/2002]
Thread Starter
Pro
Joined: Apr 2001
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From: Waukesha WI
Re: Math question. (Pete79L82)
I had a .039 ordered, but I think I am going to switch to the .016. Might as well take advantage of the extra compression right??? There is no down side to this is there?
[Modified by DollaGreen, 6:43 PM 6/11/2002]
[Modified by DollaGreen, 6:43 PM 6/11/2002]
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From: Living in the Hartland
Re: Math question. (DollaGreen)
You might have to run a grade or two higher on the gas. I run 87 inn my 8.5 to 1 with no detonation. Extra octane above your detonation level does nothing but cost you extra. I would run premium (93 octane)in it to start then progressively work your way down untill you get some detonation then back to the last grade with no detonation. You might also find that diff brands run different in your car. It's trial and error, but isn't most everything.
BTW I re-checked my math on comp level and it is closer to 9.4 everything else being equal.
BTW I re-checked my math on comp level and it is closer to 9.4 everything else being equal.
