64 thunderbird heads

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Aug 25, 2002 | 07:39 PM

dhickey

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64 thunderbird heads

I picked up some heads (C4AE) this weekend that I believe are from a 64 t-bird. Can anybody verify exactly what they came from ? The numbers aside from C4AE are 6090G, 25, and DIF ? The compression ratio for these heads was 10.1:1 to the best of my knowledge, however they were decked .006, anybody know how much that will change the compression ratio? I was told by the guy I bought them from that even with 93 octane they will ping unless I get a thick head gasket to decrease the compression ratio. So my question to anybody that knows is, why is it that my vw which has 10:1 compression can run 87 octane and not ping at all...and a 390 with 10.1 will ping even with 93 and a rich mixture? Also, what size are the combustion chambers for these heads compared to C7AE, C8AE, and D2TEAA?

Aug 26, 2002 | 09:23 AM

mlf72f250

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64 thunderbird heads

Lots of things can affect tendency to knock:
1) Compression ratio (you already got that one)
2) Air fuel ratio
3) EGR (some EGR actually helps to supress knock)
4) Bore diameter (that's one reason why 6 inch bore aviation engines need 100LL)
5) Spark timing
6) Manifold pressure
7) Air and water temperature
8) Turbulence (created by swirl or tumble)
9) Aluminum vs. cast iron heads
10) Centrality of spark plug and number of spark plugs per cylinder
11) Cylinder to cylinder differences in air-fuel mixture, temperature, compression ratio, PCV, etc., because you first hear the most sensitive cylinder.
12) Sharp edges or deposits in the combustion chamber.

I'm sure I've missed a few.

Your VW probably has port fuelk onjection givinbg better air fuel control between cylinders. It probably has better turbulence, smaller bore diameter, higher operating RPM, aluminum heads, and there's a chance it has a knock sensor.

Aug 26, 2002 | 11:05 AM

William

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64 thunderbird heads

C4AE and C4AE-G are 64-65 352CI and 390CI Heads. They have 71.2-74.2 CC combustion chambers. Combustion ratio is determined by the volume of the cylinder, the stroke, type of pistons and the volume of the cylinder head. Using these heads should not be a problem, unless they have been milled to excess. To check the CC of your heads set them combustion chamber up, perfectly level with a spark plug installed. Fill the combustion chamber with light oil, and run a square over it to eliminate surface tension. Draw out the oil with a syringe and measure it. This procedure will give you the head CC, or come fairly close. Hopefully someone here will be able to do the math on compression ratios for us?
William in Atlanta

Aug 26, 2002 | 03:33 PM

dhickey

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64 thunderbird heads

Thanks for the insight guys. Do you know the combustion chamber size of D2TEAA heads? I was thinking of picking up How to Rebuild Your Big Block Ford by Steve Christ. Does anybody have any other suggestions on books that have stuff like combustion chamber size of heads etc? So you think I'll be all set running 10.1 compression with 93 octane? I just wanna be able to run pump gas without it pinging.

Aug 26, 2002 | 09:56 PM

mlf72f250

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64 thunderbird heads

Here's a link to help you through the compression ratio math (if you need it)...
http://www.geocities.com/marsha89129/DETERMINING_COMPRESSION_RATIO.doc

Aug 27, 2002 | 07:04 AM

William

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From: Sun River St. George

64 thunderbird heads

D2TEAA are 72-76 std. 360, 390,428 w/o AIR with 68.1-71.1 cc. 10-1 compression ratio is a little higher than I am comfortable with. I am building for 9.5-1 or a little less and I will run it a little rich, or retarded timing a tad and use thicker head gaskets if it pings. Don't think I'll have a problem but we'll see. The link dosn't work?Profanity Removed
William in Atlanta

Aug 27, 2002 | 08:21 PM

mlf72f250

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64 thunderbird heads

[updated:LAST EDITED ON 27-Aug-02 AT 09:45 PM (EST)]William: Thanks for the feedback on that link. I had just copied and pasted it, but now it doesn't work for me either.

Here's a link to the guy's main page:
http://www.geocities.com/marsha89129/

I went to the bottom of that and clicked on the compression ratio link. Then, within the compression ratio page, there is a link to a comp ratio calculator.

I just checked the new link and it seems to work.

--Matt