Compression

[DodgeFreak]

Does anyone know the stock compression ratio on a 77-78 440 police intercepter motor?? also what is the cheapest way to reach 10.5:1 compresion from what ever its at now?  or will i ahve to rebuild the whole motor and and buy new pistons??

[Robb]

http://www.allpar.com/squads/engines.html

looks alot like the same as for RV compression ?   I read somewhere that the cam was changed for the cop car but otherwise the shortblock guts remaines the same including cast crank.  Heads will be 452's with extra cooling.  8.2CR   

440-3 is sometimes the designation for these motors.  Not alot of info out there, but quite abit on RV sites if you google long enough.

My 440 is a '78 factory shortblock (only had 15,000 miles on it) and I put in a nice Engle dual pattern cam and rebuilt the 452 heads and factory HP manifolds.  It has alot of power, but Im sure theres more to be had.   Closed Chamber 915 heads should make it jump a point to around 9.2CR which you clould plan ahead for.  I kept the 452's on mine beacuse of the hot-hot-hot weather I have here in AZ.

Sounds like a good candidate for a 500 Stroker if you want/need to rebuild the bottom end

[Follicly Challenged]

Some of the 77-78 440's, when an "actual" cc measurement was done of the downfill volume and heads, were more like 7.8-7.9:1 compression ratio !

"popcorn fart"

Not that compression is the "be all end all", lots of those motors will make relatively decent power "down there" when properly prepped and tuned, as Robb stated.

"Whoa up" there DodgeFreak, 10.5:1 on an iron head is a little too high for pump fuel, but nonetheless, to get there, you'll be rebuilding and changing Pistons, but for a number of reasons.

I dunno how to put a link to a thread, or I would, but, if you keep perusing this section, there are already a coupla good threads on exactly what you're doing, read on.

[71383bee]

 

Aside from smaller chamber heads there isn't that much you can do.  Let's just say that more compressions makes life easier when building power.

Changing pistons and/or decking the block is proabably the best way to get it.  However, like stated above you can definately improve the motor now with a better cam, intake, carb, etc so if your budget is tight and you can trust the short block then there's some gains to be made by swaping some parts.

[Chryco Psycho]

basically use a set of 2355 speed pro pistons
 I agree if you CC the engine you are probably closer to 7.8:1
a short duration cam with good lift can fool the engine into making decent power without pistons
 

[DodgeFreak]

What would be a good short duration cam with good lift be?? recommend me a cam wise one   

[Chryco Psycho]

Engle K54  depending where you wnat the powerband
www.englecams.com