77 440 vs 70 440

[Davidrad]

I'm thinking about diving into the world of the BB. I know the later 440s CR went to crap. How did Chrysler lower the CRs by so much? Is it a deck height thing, open heads? I'd like to get that missing power back. The 440 I'm thinking about messing with is a police pursuit 77.

 

[Glenwood]

The pistons in both engines may be both flattops but the distance from the wrist pin to the piston tops are different to lower the compression in the late 70's RBs.

 

[Chilsam]

I've read where the later blocks are beefier also...

 

[Davidrad]

So the connecting rods are shorter?

 

[Chilsam]

So the connecting rods are shorter?

No rods are the same ...wrist pin location in piston is diff....lowers the top of piston in bore

 

[IQ52]

I think you will find that the missing power is mostly in the camshaft but raising the compression certainly won't hurt.

 

[Mike67]

Heads went from a closed to open chamber as well.

 

[Cranky]

It's called piston compression height. The top of the piston is not as high in the later engine. Not real sure about stock pistons but in many aftermarket pistons, the top is thicker to raise compression or thinner to lower it.

 

[MiradaMegaCab]

Low CR + Boost=

 

[Chilsam]

I think you will find that the missing power is mostly in the camshaft but raising the compression certainly won't hurt.

yep lift,duration & timing...

 

[Glenwood]

Heads went from a closed to open chamber as well.

I thought the last RB closed chamber head was 67? My stock 70 440 had open chamber 906 heads on it anyway.

 

[dukeboy_318]

http://www.440source.com/blockinfo.htm

enjoy

I'm thinking about diving into the world of the BB. I know the later 440s CR went to crap. How did Chrysler lower the CRs by so much? Is it a deck height thing, open heads? I'd like to get that missing power back. The 440 I'm thinking about messing with is a police pursuit 77.

I've read where the later blocks are beefier also...

 

[Daves69]

Adding cast crank and forged.

 

[Mike67]

I thought the last RB closed chamber head was 67? My stock 70 440 had open chamber 906 heads on it anyway.

I was just referring to the way the factory lowered the cr, not necessarily to the year.

 

[Glenwood]

I was just referring to the way the factory lowered the cr, not necessarily to the year.

That's what I thought. I wasn't sure if I had my facts wrong.

 

[Photon440]

I think you will find that the missing power is mostly in the camshaft but raising the compression certainly won't hurt.

I believe the camshaft was the same from the late 60's until the end of production. The only change there was a 4 degree retard to cam timing.

 

[RT K_line]

The distance from the top ring land to the top of the piston changes too. At least on my 6 pack engine there was at least a 1/8 inch more height compared to a standard 440 piston. It's been a while so it might be more or less but I remember it was definitely noticeable. If you plan on a rebuild then you can order pistons with the compression you want for your combo. Good luck with the build.

 

[Cranky]

I've read where the later blocks are beefier also...

That's pretty much a myth. One change in the block around 68 (or for 68) was added ribs on the outside of the block. I've read a few different reasons what they were actually did but from what I've seen, they really didn't do a whole lot.

 

[MarPar]

That's pretty much a myth. One change in the block around 68 (or for 68) was added ribs on the outside of the block. I've read a few different reasons what they were actually did but from what I've seen, they really didn't do a whole lot.

I heard the earlier blocks (pre-74) had more nickel in them making them stronger. but what the f*** do I know?! lol

 

[Photon440]

I've read where the later blocks are beefier also...

Interesting article from Source. http://www.440source.com/blockinfo.htm According to their measurements (photos included) the '76 and later blocks have thicker main bearing saddle supports. Later blocks also weigh in a little heavier. Thicker mounting lugs starting in '75 as well.