compression ratio for stock '72 fe360

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jpiercef
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compression ratio for stock '72 fe360

Post by jpiercef »

I have been looking at cams for my truck but need to know my compression ratio before making a final decision. what would the stock compression be for a 72 f250 4x4 with a fe360?
Lee
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Re: compression ratio for stock '72 fe360

Post by Lee »

8.0:1 yielding 196hp, ..... healthy engine gives around 150psi. It's more important that all cylinders be within 10% of each other.
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MadJoe
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Re: compression ratio for stock '72 fe360

Post by MadJoe »

Was it a change in the heads that brought the compression down in 1972? 1971 is 8.4:1 iirc, and a little over 200HP. I was under the impression this drop in compression and HP was managed through retarding the timing to meet emissions regs without having to reengineer the entire engine. Can anyone set me straight?

Barring a huge expense to bring it to 1971 (or earlier) spec, that's the way I'd go. My next plan is to advance the initial timing to 10° to 12° BTDC once I get my hands on a timing light, and then to check total timing and see if I need a recurve.

-Joe
1971 F-350 DRW SWB Stake Body
360 FE
C6 transmission
OEM disc brakes
OEM power steering
Dana 70 4.10 rear end
8ton
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Re: compression ratio for stock '72 fe360

Post by 8ton »

'72 had several changes from what I can tell. Heads changed from c8ae-h with 68-71cc to d2TEaa with 71-76 cc heads.
My all original '72 has c8 heads with 70 cc chambers. Check what you have.
71 hp was a gross rating, 72 was a net rating, iirc.
Supposedly the timing gear and cam pin were retarded, but that may have been a '68 change.
An adjustable timing set will fix this.

Unrelated to year change, but something to think about with your compression is what head gasket is on there. My stock original gasket was a .02 steel shim. The normal felpro replacement is either .041 or .051. This will drop your compression a good bit, as well as adding extra quench distance that the 360 already has too much of.

Bumping the ignition up will help, although my truck pinged on regular, towing with initial set at 10 *. I had a lot of carbon on the pistons though and some leaking valves.
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