Can I raise the compression on my 440?

[The_Handier_Man1]

From: Buzz  (Original Message)
Sent: 7/19/2002 12:48 AM

     I noticed that after 1972, the 440 got lowered in compression  and consequently lowered in horsepower by 100Hsp! Can I get the heads milled to get the higher compression?...or, is there something else to consider?  Buzz

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     I'm no MH expert, but Mopars are something I have a bit of knowledge about. From what I read in another thread the 72 440 is about 8.5:1 compression. That pretty low. Milling the heads to get that up to 10:1 would probably still allow the use or pump premium (depends on if you can get 92 or 93 octane). The biggest problem you are overlooking is that milling the heads also lowers the intake ports. Now you have to correct at the intake manifold. Real pain to get the geometry correct again, but not something that can't be done. The better choice to raise compression is new pistons. That way you get a nice set of forged pistons vice the cast ones you have now. They don't expand as much so you get to run tighter bore clearance and that makes more power too.     toster

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     I don't reallty know this for sure, but I'm guessing the compression numbers you are looking at are car engines. The truck engine probably didn't loose any compression, since it was only 8.5:1 and the car's had it lowered from 10.25:1 for emissions. Like I said though I don't know this for a fact.
     Try a set of small primary headers, K&N air filter and Flowmaster mufflers before you do anything! I went from 17MPG freeway to 21MPG freeway on my Jeep with just the muffler change.

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    The lowered compression ratios was for lower nitrous oxide levels, along with the egr systems. My impression is that running a higher compression ratio is going to run the valves and the exhaust manifold a little hotter, put more stress on the head gaskets, that you might worry about the proper advance curve and carburetor jetting, and why the manufacturer didn't use the higher compression in the first place.   denison