440 compression boost

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NoahSewal

NoahSewal

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I've got a completely stock 1975 440 that I've torn apart. The factory compression ratio is terrible on these being close to 8.0. I was wondering what pistons are out there that will get me as close to 0 deck as possible. What's the disadvantage of having a heavier piston/pin?
 
Forged replacement 440 Sixpack pistons are supposed to be .020 in the hole. Somewhere around 9.5 to one. Maybe 10 to one with 75 cc aluminum heads.
 
There are many off the shelf pistons that will get you compression with what i'll assume is an 88cc chamber head, one of which is a KB hyper piston. I've used them with an 88cc 906 head and yielded 10.5:1. Those heads were blueprinted as well. Surprisingly the chambers didn't vary as much as you'd think for factory junk.

When you get looking at a set of pitons with rings you are pushing towards 1,000, then the cost of building this engine, only to put stock heads one it? This makes no sense. I mean, maybe, if you could literally do it all yourself, which very few can. I'd be more inclined to get your self a stroker kit for 88cc heads. Then you are only looking at a potential heads change down the road which you can do yourself in the car.
 
Heavy parts are no problem in an rv or tractor motor, rpm limited. For a high performance street engine, lighter parts reduce the loads on the crank, rods and rod bolts at higher rpm. Build as light as budget will allow.
 
NoahSewal said:
Not sure on heads yet. i'd like to either go closed chamber 915 or aluminum heads. it's gonna be a street/strip car
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You have to pick the heads before you pick the pistons, or you have know the chamber CC.

If you are going to spend money on a set of heads there really isn't any reason to use cast iron heads. It's not very hard to approach the cost of an entry level aluminum head when rebuilding a stock head.
 
NoahSewal said:
I've got a completely stock 1975 440 that I've torn apart. The factory compression ratio is terrible on these being close to 8.0. I was wondering what pistons are out there that will get me as close to 0 deck as possible. What's the disadvantage of having a heavier piston/pin?
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Check out some of the low compression builds.
it's possible to make decent power with lower compression and then keeping iron heads ain't bad, if they will flow well enough.
 
roccodart440 said:
You have to pick the heads before you pick the pistons, or you have know the chamber CC.

If you are going to spend money on a set of heads there really isn't any reason to use cast iron heads. It's not very hard to approach the cost of an entry level aluminum head when rebuilding a stock head.
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what's the best entry level head you would recommend for my 440? link? do you think the pistons UEM-KB237-060. would be good for my build?
 
Are you planning on the stock cast steel crank? The ultimate decider is going to be your budget. What
octane fuel are planning on running?
 
Garrett Ellison said:
Are you planning on the stock cast steel crank? The ultimate decider is going to be your budget. What
octane fuel are planning on running?
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yes im using the stock cast crank. the budget is going to be somewhere around 2,500 give or take depending on if i get heads or what. i'll use any pump gas
 
roccodart440 said:
You have to pick the heads before you pick the pistons, or you have know the chamber CC.

If you are going to spend money on a set of heads there really isn't any reason to use cast iron heads. It's not very hard to approach the cost of an entry level aluminum head when rebuilding a stock head.
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^This. My dad went down the 915 path and once they were redone he could have bough new RPM or Stealth Heads and he had to fight several leaks with the exhaust studs.

Same with Rods. Scat I Beams are strong, light, and about the same cost as remand stockers and ARP rod bolts.
 
NoahSewal said:
what's the best entry level head you would recommend for my 440? link? do you think the pistons UEM-KB237-060. would be good for my build?
Click to expand...

440Source Stealth heads. I'm building a 440 for my D200 which will see moderate towing duty and decided to go with those heads because at $1200 a PAIR, I could easily spend just as much or more to have the original 346 iron heads machined and all new hardware put in. And I'd still have heavy iron heads that hardly flow enough air for a 440 cubic inch engine. Hell the ported Edelbrock RPMs on the 360 SBM in my Duster probably flow 40 cfm more than the best unported iron BB head which is a joke. 440Source claims the Stealths flow 280-290 cfm OOTB.

I listed my 346 heads on bacefook marketplace a couple weeks ago and have gotten zero interest; nobody wants to mess with iron heads anymore since decent aftermarket aluminum ones are so affordable.
 
Let’s do a reality check before going too far.

For the budgeted $2500....... what is the complete list of parts and services you’re hoping to fill with that money?
 
Wait, you mentioned boost in the thread title, but not in the thread??

Lame.
 
NoahSewal said:
what's the best entry level head you would recommend for my 440? link? do you think the pistons UEM-KB237-060. would be good for my build?
Click to expand...

I only have experience with the Performer RPM heads. I've used them several times with good results.

I've used KB hyper pistons, but have also used forged. I think the KB pistons are fine as long as you aren't using FI or NO2.
 
604B1duster said:
CNC-Motorsports | Performance Auto Parts and Engines
I use this to find stuff
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You’d probably want this
upload_2022-3-30_21-43-45.png
 
3.75 /2 =1.875 + 6.76 + 2.067 = 10.702
Have you block bored .030, take .010 of the decks and you’ll be in business
 
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Shown above is our BRAND NEW 5140 forged steel stock replacement AND performance rods. These rods use a 7/16" capscrew, a premium design borrowed from our high end H beam style rods, which is much stronger than the older factory style "bolt with a nut on the end of it." Finally, a rod that works great for stock replacement press fit pin applications as well as high performance engines at an incredibly reasonable price. Forget about reusing 40 year old stock rods! We now have an option that is many times stronger for considerably less money! The beam shape and size on these rods is modeled after the famous (and super strong) 426 Hemi rods. These rods use a non-bushed small end for factory size 1.094" press fit applications. Length is factory RB at 6.76." Both the big and small end housing bore are finished to precision tolerances on AMERICAN MADE Sunnen Power stroke honing equipment. One other important fact to remember is that metal has what is known as a fatigue life. Everyone has bent a paper clip back and forth so many times until it breaks. Once it breaks, it has reached enough "cycles" to get beyond the limits of it's fatigue life. Connecting rods are also made of metal and also have a fatigue life. Every time the piston fires, the rod is compressed and every time the crankshaft turns back around, it drags the piston back down from TDC. This causes the rod to expand and contract, or "cycle" just like bending the paper clip back and forth. The only difference is that the rod is much stronger than a paper clip (unless maybe you're talking about Ford rods) and it's being cycled millions of times as the engine is running. The more cycles on the rod, the weaker it will become, and the closer to failure your engine will be. These rods are BRAND NEW, so they will always be starting with ZERO cycles on them. That alone is worth a huge amount of strength. After forty years and thousands upon thousands of miles, do we really know how many millions and millions of cycles those old factory rods have on them? With the cost of cleaning, magnafluxing, resizing, buying new bolts, etc, etc with a set of stock rods, going with our new aftermarket version is a no brainer!!
 
What are your plans for the engine? Will it be an everyday street driver? If so, no need for close to 10:1. YOU HAVE 440 cubes at your disposal. It's gonna have pavement peeling torque regardless, as long as you build for the compression ratio you use. You'll be sorry sitting in traffic in the summer with heat soak when all it can do is spark knock and rattle. There are other ways to make one haul *** besides compression. Keep in mind the general rule of thumb is for every 1 compression point raised, your return is only about 3% all else equal. If it's a street only car, my recommendation is to work with the stock compression ratio and build the rest of the engine to match.
 
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