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Discussion Starter #1
Hello,
its been awhile glad to be back. Im confused on my compression ration with my dooe-r heads, Listed are the stats of the motor.

Bore & Stroke 4.44 x 4.145 =513
Deck Height .045
Gasket thickness .042
Piston to head quench.045
Head cc 72.6
Piston Volume -12.7 that is a negavtive symbol.
Gasket volume cc 11.2
this is all have for numbers.The pistons are Wisco no part number.
I run 93 octane. When i try to throw a couple of gallons of 110 in him he heats up quite a bit. Not over heat , but a difference from the 93. Thanks for the help
 

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Too high for pump premium even with an obnoxious cam.


Compression Ratio Calculator
ENTER YOUR DATA CALCULATED DATA
Cylinder Head Volume (cc)
72.6
Cylinder Head Vol (cubic in.) 4.429
Piston Head Volume (cc)
12.7
Piston Head Vol (cubic in.) 0.775
Gasket Thickness (in.)
.042
Swept Volume (cubic in.) 64.177
Gasket Bore (in.)
4.5
T.D.C. Volume (cubic in.) 5.918
Cylinder Bore Diameter (in.)
4.44
Gasket Volume (cubic in.) 0.668
Deck Clearance (in.)
Note: Neg. number above deck, Pos. number below deck
.003
Deck Volume (cubic in.) 0.046
Stroke (in.)
4.145
STATIC COMPRESSION RATIO 11.844



What is your initial and total ignition timing?


SJ
used 2b RHP



:D
 

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Discussion Starter #3
Thanks for the response. I run it locked out @ 34. I was thinking about putting in springs and bushings to have initial timing. I was also thinking of going with aluminum heads. The CJ heads aren’t indigenous to a 56 ford anyway. I bought this car from another fellow and this is how he set it up. Why does it heat up when I run 110 in him compared to 93....thank you.
 

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Discussion Starter #4
Here is my combo Mad Porter: along with the CJ heads I have a victor intake and old Barry Grant 850 dp carb and Lunati flat tappet cam 245-255 @ .050 .620 lift.

Maybe I should do a cranking compression test. What is the limit these days for cranking compression on pump gas.
 

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Here is my combo Mad Porter: along with the CJ heads I have a victor intake and old Barry Grant 850 dp carb and Lunati flat tappet cam 245-255 @ .050 .620 lift.

Maybe I should do a cranking compression test. What is the limit these days for cranking compression on pump gas.

With iron heads typically 170 to 180 psi after 5 to 6 needle pulses.

Running hotter with higher octane fuel can simply be a matter of the total timing not being enough for the fuel.



SJ
used 2b RHP



:D
 

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Thanks for the response. I run it locked out @ 34. I was thinking about putting in springs and bushings to have initial timing.


/\ That would be silly




alum heads

/\ that would help, maybe use a 1099 fel pro larger cc gasket as well,also would help
 

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Too high for pump premium even with an obnoxious cam.


Compression Ratio Calculator
ENTER YOUR DATA CALCULATED DATA
Cylinder Head Volume (cc)
72.6
Cylinder Head Vol (cubic in.) 4.429
Piston Head Volume (cc)
12.7
Piston Head Vol (cubic in.) 0.775
Gasket Thickness (in.)
.042
Swept Volume (cubic in.) 64.177
Gasket Bore (in.)
4.5
T.D.C. Volume (cubic in.) 5.918
Cylinder Bore Diameter (in.)
4.44
Gasket Volume (cubic in.) 0.668
Deck Clearance (in.)
Note: Neg. number above deck, Pos. number below deck
.003
Deck Volume (cubic in.) 0.046
Stroke (in.)
4.145
STATIC COMPRESSION RATIO 11.844



What is your initial and total ignition timing?


SJ
used 2b RHP



:D
Too high? Scott, I thought you have mentioned running compression that high with pump gas and being more concerned about dynamic compression? OR is it too high due to the iron heads? If he were using P51s (or another aluminum head with modern chambers) it wouldn't be an issue?
 

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Too high? Scott, I thought you have mentioned running compression that high with pump gas and being more concerned about dynamic compression? OR is it too high due to the iron heads? If he were using P51s (or another aluminum head with modern chambers) it wouldn't be an issue?

The issue is with iron heads and the antiquated chamber.

AFR, SCJ and P-51 / SR heads will easily deal with 11 to 1 static. I've been doing that with the LTD for over 7 years.

We have a couple of really obnoxious street combos out there with 11.7 to 1 static at 830+ HP.

Dynamic is an issue when loaded at lower RPM below 100% VE.

At some point a well thought out street combo can reach or slightly exceed 100% VE and at that point actual static c/r is into play.


SJ
used 2b RHP


:D
 
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