I have a 73 440 I'm going to install some 440 Source heads on. It has a stock rebuild from the previous owner using the original pistons. I know these were low compression (anybody know what it was?). My concern is the original gasket was .020 thickness while the one I'm going to install is .039 crush depth, further lowering the compression. I'd like to actually increase the compression over the stock numbers. Something around 8.5 or 9:1. It appears the cc of the new heads is close to the stock ones. Can anybody recommend how much to mill the new heads to achieve this ratio? Plus the Performer RPM intake will need to milled too to fit properly. Need the numbers for that too. Thanks

figures vary but compression would be around 8 to 1 maybe lower for a 73 stock 440 unless its considered a hp 440, but i think they were gone by 73 . to get the compression ratio you want you need to mill those heads to around 75 cc which would be 50 or 60 thou. off . the intake would need milling .060 to .072 to fit right.

If you bolted those heads on stock and with tha t .039 gaskets you'd be at about 7.8 compression. Mill the heads down to 75 cc and be at about 8.3, switch to a .020 gasket and be at about 8.6. I know 440source says their heads will mill safely to 75cc. There is a formula telling you how much to mill the intake flange on the heads per thou of head milling, I don't know what it is though.

cut the 2 surfaces of the head

dont cut the intake,it will then be fore that engine only and will not fit another unless the heads have been milled the same amount

kills the resale of intake in the future if its milled

I find there are too many downsides to head milling. A clean up is ok but to raise compression ratios due to low piston heights it's a bunch of cutting for little gain.

Intake bolts hard to line up, valley pan not fitting properly which equals oil sucked into intake ports and will usually create pushrod length problems.

My choice would be to buy new pistons.

the formula for head milling is to remove .0125 off the intake face for every .010 removed from head surface. i think that spec came from dick landy. but i would also think about new pistons.

.0123 is stated by Direct Conection books.

.042 of head will reduce 1cc volume as far keeping on open chamber section.

Yeah pistons is better but 400 doesn't have too much options off the shelf. So mill is a handly solution to help. 440s have lot of options though

Even better, aftermarket heads too

depending on what you want to get of course will be entering on troubles or not

I've been debating on milling the heads since eventually I plan on pulling the engine. I was just doing a cam, head swap with the engine in the car to boost the power. Right now it has a Mopar RV cam and it's pathetic on power output. I've been considering the head milling because with the thicker gasket, decreasing the compression even more seems like going the wrong direction. I was eventually planning on pulling the engine in a couple years for a proper rebuild with a stroker crank. Right now it's getting a Comp XE268 cam, 440 Source heads, Performer RPM intake and 1.6 rockers. I'm just considering my options at this point.

oops. double checked that spec. should be .0123 off intake face per every .010 milled from head/deck surface. not .0125

One thing not to forget although you mill .050 off the head you are using a .019 thicker head gasket so you intake side milling should be based on .031??
Just my we been doing it this way for years and has worked well for us??

What they said, I would not cut/mill anything instead I'd either bolt it together w an .020" or thicker if need be gasket or I'm wondering if it would it be possible/practical to pull the pan/rods/pistons & R&R the pistons with some higher CR ones and balance them to the orig piston/pin/rings weight and ball hone the block plus that'd give you fresh rings but as I am typing I realized that the KB's MIGHT be much different in weight than the oe's but not sure if the diff would be enough to badly screw up your bobweight. I'm a firm believer in running what you have in the car now & maximizing it as opposed to what might come about in the future but the CR in the low 8's or even likely in the low 7's is really going to be a problem (change the cam to build some psi).

The cam going in is fairly short duration. 224 intake and 230 exhaust at .050. Hell, maybe I'll just bolt it together and see what happens. If it doesn't work, then I'll pull the motor and swap out pistons. Just checking the 440 Source site, they list the chambers as 80cc, vs. whatever the stock heads are which I think average around 88cc. Oh why can't I leave anything alone?

He's probably got enough of a ridge in his cylinders that they'd be rough on rings with a higher CR piston.

I agree, milling heads is more trouble that it's worth. Save the money towards your engine rebuild later on down the road.

Also your stock heads were more like 90cc with a .020 gasket. The source heads have been cc'd by others to be more like 86cc. 86cc with a .039 gasket will give you the same CR as stock 90cc with ah .020 gasket. No loss, no gain there. I've got a 76 440 with stock smogger pistons, I put in a new set of rings, bolted on a set of 440source heads, headers, lunati voodoo 60303 cam and (temporarily) a stock intake and thermoquad. It runs well and puts out good torq considering I threw it together out of parts I had laying around.

I just redid my Jensen's engine, it was a rebuilt 440 .030 when I bought it, I took a peek and noticed the cam was .250 lift, .375 at the valves. New cam, but puny in a crazy way.
I pulled the heads, the pistons were aftermarket, I milled my heads .030" and used a Felpro gasket, which didn't raise my compression much, but it didn't LOWER the commpression with thicker gaskets either....
I went with a 270H Comp Cam, I have 9.35 to 1 measured compression, and I did a bit of headwork while I had it apart. It idles strong and smooth (ish), has good free response, but I won't know what it goes like until spring when I get it on the road.....

It's a factory 1974 440 HP engine with a steel crank. Weird?

I've cut iron stock heads .030" and used Felpro gaskets for years, the intake bolts up, compression doesn't get worse, but milling nowadays costs a lot more than milling used to- I paid $100 a head when I used to pay $40 a pair...