I'm sure some have read my posts from a few weeks ago about me getting a 440 and what I have planned for the future and whatnot. At the same time some of ya might be getting tired of all my lame engine questions but anyways...

So, its a 1974 440, forged crank, out of a motorhome. It has the 213 heads which I plan on replacing. I removed one of the heads and calculated a CR of about 7.8:1. I wasn't expecting to be at that low of number being a steel crank, but the pistons are .150" in the hole I'd like to shoot for somewhere near 9:1 CR without doing a rebuild of the bottom end. As it sits, there is barely any cylinder ridge, so the bottom end in theory is good.

When I calculated the CR I guessed the 213 heads to be about 90cc being open chambered. If I were to put on a pair of 915 heads, being about a 74 cc or so combustion chamber, that should raise me to around 8.8 CR which would be close enough.

Would that be the easiest way to get me up in compression or is there something else that could be done?

915's are a good add-on .. but I would even cut-those another 60.

The head gasket surface... Cutting it reduces chamber volume... But cutting .060 may require shorter pushrods I believe on the closed chamber heads 1cc = .006 so cutting .060 will reduce chamber volume by 10cc...

Now I just have to find a good set of 915 heads. Sounds like a plan.

FWIW, those 915 heads will be more like 80cc where the open chamber heads are 90cc like you already know. To get compression up you have to mill the hell out of the head surface and run shorter pushrods. Then you still have a terrible combustion area design with a tiny chamber and a piston a mile in the hole.

Hmm... I guess I just bite the bullet and do a rebuild to get compression where I'd like it, down in the 7's seems like it'll be a pig.

get new pistons what will get 0.10-0.20 down the hole and done... then if you want, get closed chambers heads or cut your actual ones.

even earlier stock replacement pistons will be good enough and cheaper, and will get you around 050-070 down the hole

THE BIG DEAL on post 72 engines is JUST THE PISTON COMPRESION HEIGHT, period.

You could use Brodix B-1 b/s heads, they have 65cc chambers.

whats the bore on the engine ?

type Mopar 440 pistons on the ebay and you'll find several GOOD AND CHEAP options for good used ones. In the long ( and also short ) even with some mechanic shop job if you can't, will be less headache try to get the right pistons than mill, heads and still be that DOWN IN THE HOLE. VERY DISSAPOINTING IF YOU ASK ME spend that money and still not get what you want

easier and cheaper get the .100-.150 piston raised AT ONCE keeping 90 cc heads, than be able to cut .060 from heads to get around 82cc and still will be .150 down

Stock 4.320" bore

Your best bet is rebuild it, otherwise it will be doggy trust me, I'd get the TRW forged 2355 sixpack pistons, with a thin head gasket & those 91cc heads, you'll be closer to 10.1, more or less around 9.7.1, it'll run very good with a nice cam & bolt-ons.

By doing that, I would need to have the rotating assembly rebalanced, correct?

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