440 Piston Choices

[CrewCabCoronet]

Hi all,

im sure you've seen this thread ad nausem but im working on building a .030 over 440 for my coronet sedan. definitely going to be a street cruiser. Stock 1969 forged crank and resized LY rods. right now i am torn between using the old standby Speed Pro L2235f "six pack" pistons or the SRP forged series. both have similar compression heights to get my compression around 9.5-1 for pump gas. I know the speed pro's have been used reliably for years but i have heard that their production is now overseas. if im going to pay 450 bucks for pistons id rather pay 100 more for usa made, this is my first time building a big block so id like to know if the SRPs are worth the extra cost on a mild street build. im more concerned about the extra balancing costs associated with the lighter slugs.

 

[mentor70]

my shop charges around 160$ for balancing.
i just suck it up as a normal part of the job. i dont think any off the shelf piston today is close enough to just drop in.
I used the Kieth Black Icons on my latest 440 they worked out real nice.
i balance all rotating assemblies i build, its worth the extra money.

 

[CrewCabCoronet]

The plan was to have it balanced regardless of piston choice but looking at it again it seems my original thinking wasn't exactly sound. obviously it would be less effort to shave weight off the crank with a lighter piston than to add with a reportedly heavy one like the SP. I saw the KB Icon's on Mancini Racing, at first glance they are almost the same piston as the SRPs with compression heights, dome volumes and cost having pretty negligible differences.

 

[mentor70]

I got mine through 440source, i don't know how Mancini sells them, but at 440source the rings are extra...so like 550$ and then another 130$ or so..the only thing i didn't like was the wrist pins. I ended up buying some H 13 tool steel pins from Trend Performance

 

[lewtot184]

in my opinion piston choice depends on the combustion chamber and fuel to be used. i like the icon pistons and use them. i also prefer the kb hyper 184's for open chamber iron heads and have used them several times.

 

[CrewCabCoronet]

I have a set of 452s that i was planning on using that are in pretty good shape. Definitely trying to make this thing run on pump gas as best as possible. are the KB 184s the quench dome design?

 

[mentor70]

I built a KB 184 with 452 combo 20 yrs ago, ran awesome. Ran it exclusively on 85 oct with no drama.
The only bitch I had was my machine shop had piston clearance a little too large, and the engine had piston slap when it was cold.

 

[lewtot184]

I have a set of 452s that i was planning on using that are in pretty good shape. Definitely trying to make this thing run on pump gas as best as possible. are the KB 184s the quench dome design?

they are quench domes and will yield around 9.3:1 with iron heads and steel shim gasket (.039 fel-pro type gaskets can be used but will require additional head milling); perfect for pump gas. 452's do have a combustion chamber issue. usually one chamber on the end of each head will be deeper than the other three were the quench dome fits. '906's are a little friendlier. none of it is rocket science, just some math and measuring. 184's have straight pins like all high performance pistons and may make some noise cold, no big deal. follow the instructions and they'll give long life and will perform as well as a 10:1 non-quench engine. these are the only pistons i'd consider for open chamber iron heads and pump gas.

 

[lewtot184]

I built a KB 184 with 452 combo 20 yrs ago, ran awesome. Ran it exclusively on 85 oct with no drama.
The only bitch I had was my machine shop had piston clearance a little too large, and the engine had piston slap when it was cold.

i've found that the "know it all" machine shop people can't read the instruction sheet or think they know more than the design engineers.

 

[CrewCabCoronet]

Thats right around where i would like my CR to be. as far as the combustion chamber issue, would i have to have material cut from the domes?

 

[lewtot184]

Thats right around where i would like my CR to be. as far as the combustion chamber issue, would i have to have material cut from the domes?

no need to touch the domes. you may need to work the chambers where the dome fits into to even the depths out. seems to be a '452 only problem.

 

[mentor70]

as i recall Hughes engines had a fixture to equalize the chambers.

 

[CrewCabCoronet]

shouldn't be too bad then. ive heard good things about the KBs as long as you stay within their ring gap requirements and they are well within my budget. I appreciate your inputs.

 

[CrewCabCoronet]

I built a KB 184 with 452 combo 20 yrs ago, ran awesome. Ran it exclusively on 85 oct with no drama.
The only bitch I had was my machine shop had piston clearance a little too large, and the engine had piston slap when it was cold.

Just out of curiosity do you remember what cam you had in that motor?

 

[mentor70]

i used a Mopar 509 cam in that engine, i would not to it again...

the engine combo was a bit off with that cam, i only had 145 lbs of cylinder pressure with that cam, i really needed around 170. i could have milled the cylinder heads more or ran a smaller cam.

if i were doing that engine again today, id run either a Comp cam XE 268 or equivalent Lunati Voodoo grind for a hydraulic option.

 

[CrewCabCoronet]

thanks again

 

[lewtot184]

i would caution to not over cam at 9.3:1. the most cam i've used with those pistons is an engle k65 solid, 238@.050"-.510 lift. if the '452's haven't been modified properly big cams and high lifts may be a waste.