440 build suggestions needed

[JerseyJoe]

Hey Ron,
  I re, re-joined over here to continue the discussion...
I appreciate the info you've shared with me on this and admire your knowledge, but let me throw this out and see what sticks:
       After discussing with my machinist zero-deck versus the .017 below deck of the Ross pistons in the stroker kit, he explained that after I mock up the assembly the "average height" of the piston needs to be determined. For those that don't know what this is, with the piston in the bore the amount of movent or "wobble" of opposing edges of the piston is measured and divided by 2.
       This is done to determine how close to zero deck to mill the block to avoid piston to cylinder head contact (this is where the head gasket discussion comes in). So is there an allowable below-deck height without sacrificing much power?
       My guy feels that the desirable quench zone is somewhere between that .017 and zero deck (with the flat tops and a closed chamber), on a race engine he may have the pistons nearly "kiss" the cylinder head with a zero decked piston but feels it may only be worth single-digit horsepwer gains.
       So, what's my point? I think my machinist is trying to find the happy medium with running pump gas. A zero deck with the eddy 84 cc's, flat tops with 8cc's of valve reliefs, and a .039 head gasket yields 10.95 to 1 CR. If I can't make that work I know I have higher octane gas nearby.
        Not trying to dispute you, I want to explore the possibilities so I only build this motor once!  

[firefighter3931]

Hey Joe, those are valid questions 

(1) piston rock won't be an issue with the correct piston to wall clearance. The finish hone will keep the clearances where they're supposed to be. As long as the piston clearance isn't excessive, piston rock is a non issue.

(2) The crank needs to be checked for indexing before any block machining is done. This will establish that each piston is rising the same amount in every cylinder. Sometimes there needs to be some correction on the crank to create uniformity within all the cylinders...this needs to be checked out by the machinist.

(3) ideal quench occurs between .040 and .060 piston to head clearance. The closer to .040 the better with diminishing returns the closer you get to .060 and no quench effect beyond that. With a steel rod engine you don't need to worry about the pistons hitting the heads. Aluminum rods require looser piston to head clearance due to the thermal expansion of the aluminum rods.

(4) why is quench important; basicly it forces the mix up into the chamber for a better , more complete burn. The added bonus of quench is it helps to fight predetonation on pump gas engines. With aluminum heads the tight quench (.040) flattop piston/closed chamber head combo with 10.5:1 static compression works very well and is a "proven combination". Some people try to push the envelope and end up not being very happy with the outcome.

Here's something to consider: I consulted on a build awhile back which was your basic 493 stroker combo, allmost identical to yours. Ross flattop pistons, closed chamber e-heads etc...My opinion at the time was that it wouldn't run on pump gas with that high of compression. The engine builder felt that they'd be able to bleed off enough cylinder pressure with a big cam to make it pump gas friendly. Well the bottom line is that it won't run on pump gas. They have to back off the timing to 28* or it pings like crazy. Retarding the timing kills the power so rather than do that they now mix in race fuel. The guy is now sorry that he didn't listen and told me the hassle of mixing fuel wasn't worth the extra trouble of having done things right in the first place. He wanted to use off the shelf parts and was too impatient to wait for a set of custom pistons....and it came back to bite him. Diamond now carries an off the shelf 12cc dished piston that is perfect for the 493 stroker with 84cc closed chamber e-heads. 

It boils down to convenience; do you want a pump gas or a combination pump/race gas combo....that's the question you need to ask yourself when putting this engine together. The 3/4-1 point difference in compression isn't going to make a whole lot of difference power-wise but it becomes a pain in the a$$ when your constantly mixing in race gas to make it run properly. That is why the dished piston at zero deck was recommended for Steve's build. He'll be able to run full advance and use pump fuel. 

Well, that's my opinion on it...don't know if it helps you or not with this build. I do know that when it comes time to build my own stroker, it'll be a dished piston at zero deck dialed in at 10.5:1 static compression with .040 quench and a closed chamber head.

Ron

[JerseyJoe]

Ron,
So I figure I'm on the loose side of usable quench with the stock deck height
Playing with head gasket thickness and deck height (which you can't put back!) may be an option unless it gets more expensive than just getting different pistons

I'm second-guessing the 11:1 setup now so I'll figure this out before bringing it up again , thanks for your help, Ron

[Steve P.]

  I just had to bring this back to the front page. It's a very good read and covers a ton of Q & A's. 

[375instroke]

I prefer to keep things simple on street motors....no little wheels to come off the lifters, less moving parts to break. Nothing is simpler than a solid flat tappet.    Softer valvespring rates and less hassle....at least inmo. If i was building a drag only motor, a roller cam would be the ticket....but i like to street drive my cars...so no roller cam for me.    I'd prefer a long lasting reliable build over a go for the throat combo that will eat itself to pieces in a shorter amount of time....it's a philosophical choice i guess.

The new Challenger runs low 13s with a roller cam and a lifetime warranty.  The new GT500 runs 12.8 with a roller cam and a 5yr/60,000mile warranty.  I guess retrofit rollers are marketed to really high performance applications, but are there rollers for a big block Mopar that would last a long time and give better performance than a flat tappet cam?  I'm worrying about the reduction of ZDDP in new engine oils and the rash of flat cam lobes I'm hearing about.

[JerseyJoe]

I prefer to keep things simple on street motors....no little wheels to come off the lifters, less moving parts to break. Nothing is simpler than a solid flat tappet.    Softer valvespring rates and less hassle....at least inmo. If i was building a drag only motor, a roller cam would be the ticket....but i like to street drive my cars...so no roller cam for me.    I'd prefer a long lasting reliable build over a go for the throat combo that will eat itself to pieces in a shorter amount of time....it's a philosophical choice i guess.

The new Challenger runs low 13s with a roller cam and a lifetime warranty.  The new GT500 runs 12.8 with a roller cam and a 5yr/60,000mile warranty.  I guess retrofit rollers are marketed to really high performance applications, but are there rollers for a big block Mopar that would last a long time and give better performance than a flat tappet cam?  I'm worrying about the reduction of ZDDP in new engine oils and the rash of flat cam lobes I'm hearing about.

    Glad to see this one resurface...
My 493" build stalled for a long time (babies and minivans and jobs, etc...) but I'm back on it with a new set of Stealth heads. Took 'em to my machinist and he recommended swapping a few pieces but I still feel like I got a good deal on a good head for my motor.
I agree on the flat tappet cam, simple and effective, but it's all up to preference.

BTW, 375, I just bought a new Caravan and was reading up on my liftime powertrain warranty... the SRT8's aren't covered! I doubt the rollers are the reason but more what you would do with their help 

[gman]

its now a 504  ci  motor   9-4-1 compress,,  180 psi compress at cyl
my prob is when i get to a hill motor starts to ping and knock ,its a 70 charger
  727 tr   323  gear,   ran fine on dyno, i put in 93non etha ,plus lucas   oc boost
still pings,,time  was at 34 total deg,,,  any idea on a solution,,,, on  dyno  best run
was 565lb    torq   450 h

[heyoldguy]

its now a 504  ci  motor   9-4-1 compress,,  180 psi compress at cyl
my prob is when i get to a hill motor starts to ping and knock ,its a 70 charger
  727 tr   323  gear,   ran fine on dyno, i put in 93non etha ,plus lucas   oc boost
still pings,,time  was at 34 total deg,,,  any idea on a solution,,,, on  dyno  best run
was 565lb    torq   450 h

450hp/565tq from a 504.......hmmm. At what rpm? What cam are you running in the engine?