whats the compression on this 440?

[jg68]

Its a 77 thats been rebuilt, i was using the ross calculator, but they changed it & its not working right for me, or if theres a place that has a simple calculator.

Heres the specs on it if someone can tell me

440- .030 over
pistons are F/Ts with no valve relieves, there .136 below deck
452s, .90cc
3.75 stroke
.039 gasket.

I'm thinking around 8.2.1, am i close..

Thanks

[Challenger340]

Methinks somewhere around 7.9:1

[jg68]

Well i came up with 7.84 on the KB web sight calc., I'm impressed how good this stock low comp. 440 runs in my 3700 slug with no gears to speak of , i could only imagine how well it would do with 9.5.1

[Challenger340]

Yep, it's pretty amazing at times, how well the low-pop 440's would perform, even with high "7"'s for CR.

Not to reminisce too much, but we had a few that would bust mid 13's, with those low CR pistons, with the addition of bowl ported 452 heads, .484" hydraulic cam, street dom intake, 3500 stall & 4.10 gears !

Basically, the "mule" car was well set up, but heavy @ 3700. Very good 60 ft times. We'd stuff in a "terd mill" , just being plain lazy, and CHEAP !

All we did to those short blocks, was a "quicky" inframe rebuild, size the rods with new rod bolts, "chicken ball" the holes, pinfit, and reverse the "low-pop" slugs on the rods !
BEAT 'em to 6000 for a long time, or until a bearing went south. TOO FUNNY ! Especially the part, during street encounters, where we got to tell the Chebby LS 6 Chevelle owners, they just got handed their ass by a $ 100. junkyard engine ! VERY "POOPY PANTS "

Anyways, I'm NOT expounding the virtues of doing crappy rebuilds on low CR motors, just reminiscing, and agreeing that yours probably works great for what it is !

[firefighter3931]

The calc i use shows 7.88:1 plugging in those numbers. Now that is a real smogger ! 

Useing the .020 steel shim it jumps to an impressive 8.13:1 

With the steel shim and an 80cc chamber you're up to 8.74:1 


In reference to a cam for this combo....the xe262 or even the xe256 would be the way to go.


Ron


Ps. Challenger 340's low buck recipe has worked many times in the past...lotsa stall/gear helps to mask the low end deficiencies. 

[dave571]

Could be worse.  I've measured them as far in the hole as .170"