440 Piston Recommendations

[weim55]

Recently picked up a 1971 440 with 346 heads. .040 rebuild with very few miles that after teardown looks absolutely beautiful to bottom. Engine has only one issue I can’t deal with: Low mechanical compression.
I have not cc’d the heads yet but the variety of sources that I have found show it should be close to 90cc. Cast flattops .095 below the deck + .040 fel pros show 8.46 to 1 in the calculator.

Edelbrock performer and Comp XE268
Are the only modifications.
224-230@.050 .477-.480 on 110lsa

The reason compression is so critical is I live at high altitude (6,000-7,000)
Learned a long time ago high compression is absolutely mandatory at this altitude if you want to create decent vacuum and cylinder pressure for snappy off idle torque.

I would like to get some pistons that will put me right at about 10.5. Doing research I don’t think a flattop will get me there even at zero deck. I did not dig any further to see if there’s a small dome I should be looking for for the 440.

Thoughts?

Steve weim55 Colorado

 

[detmatt]

Good luck on your search for pistons. I would just call my engine guy to have him source them for me so I have no suggestions but I’ll tell you that I recently had to buy pistons for a .030 over 440 and it was slim pickings as far as anything readily available.
I’d ditch those 346s in favor of some closed chamber heads and maybe have them milled down a couple of thousandths.

 

[Trace 300 Hurst]

Is the engine apart? If so I'm sure you know that you could deck the block (and intake rails) to get those pistons up from that very deep 0.95.

If it's still together, you should have some C/R choices with aftermarket heads. And use a steel shim head gasket (0.20) with several thin coats of copper spray (fully dried) instead of that fatso blue gasket.

Or do both. 10.5-.75 sounds about right for your elevation. It sounds like you know what you're doing, so you know that your CC work is key.

 

[weim55]

The engine is completely disassembled. I’ve tossed around cutting the decks, cutting the heads, thin head gaskets……

Quick, easy and cheap: .017 steel shim head gaskets, .020 cut off the heads will only get me to 9.1 CR

I’m trying to avoid mission creep and do this on the cheap. Yes, the open chamber 346 heads Are not great to build compression or combustion efficiency but they are newly machined, healthy and ready to go.
Entertained Stealth aluminum heads for the small chamber, but I’m only going to lose 10cc And that will raise me only about .5 CR + very expensive $$ at about $2K w/shipping and gaskets.

In a perfect world, I would like to find a set of .040 pistons That I can set the clearance drop in and go with no other changes and achieve at least 10.0 CR. Seems there would be enough people rebuilding HP 440s w/ stock open chamber heads To create demand for the piston I’m looking for(?)

Another consideration that I’m unfamiliar with on the Big Block Mopar: using the open chamber head is it common to run a piston with positive deck height? I wasn’t sure if the chamber was completely open to the diameter of the piston?

Steve weim55 Colorado

 

[Trace 300 Hurst]

Thanks for further explaining your situation and considerations for your engine. Mission creep......yeah.

I have never seen positive-deck pistons in anything other that full-on race engines, but then again I haven't seen everything.

I betcha @Big_John has some useful advice. He knows these things.....

 

[Big_John]

Thanks for further explaining your situation and considerations for your engine. Mission creep......yeah.

I have never seen positive-deck pistons in anything other that full-on race engines, but then again I haven't seen everything.

I betcha @Big_John has some useful advice. He knows these things.....

I really don't have much to say on it these days. I've seen octane numbers dropping on the ethanol free gas around here, so my thoughts are on keeping compression down a little rather than up.

The '70 six pack engine had a zero deck piston, compared to .017" for the 4 bbl version (or the '69 six pack) The '70 six pack pistons had valve notches and the increased deck height to make up for that.

@mr gtx came up with a good combo of closed chamber heads and pistons. He might be the guy to ask.

 

[FinFury]

I think that kb184 is the only reasonable priced option with at least some dome. Keith Black Pistons KB184-040 Fits BB Chrysler 440 Dome 3.5cc Bore 4.360

 

[Big_John]

Some discussion in this thread. 440 TNT rebuild

Pay attention to Mr GTX's posts. I've driven that car and it's pretty impressive.

 

[weim55]

I think that kb184 is the only reasonable priced option with at least some dome. Keith Black Pistons KB184-040 Fits BB Chrysler 440 Dome 3.5cc Bore 4.360

KB 184 is the closest that I have found to meet my needs as well.
Always good to have a second opinion, thanks for posting.

Steve weim55 Colorado

 

[weim55]

race tech auto tech pistons they are the same company will custom make anything you want. the 906 heads are closer to 86 cc should be the same as 346 heads either way mill the head to 85 cc. gasket .038 compressed. get the pin heights to zero deck height for the pistons. with a -3 cc valve notches. that should give you about 10.30 compression with a nice .038 quench distance. can get away with no dome that gets in the way of flame travel. that is what I would do but everybody thinks differently.

I agree with your thinking: try to stay with the efficiency of a flat top piston by cutting the deck and heads To arrive at the optimal 10.5 I’m looking for.
If this 440 was what I would call a ‘serious’ build I would flip the money $$ and take it to that level and more.
The price for the Stealth heads his worth every penny for the additional flow, better chamber, and weight reduction. I would love to go there.

My only real goal is to attain 300H engine performance for my ‘62 300 Sport. A piston swap to the KB domes will achieve 10.0CR. Add the cam and intake I listed above and the horsepower should easily be there to match the dual quad 413 even with stock exhaust manifolds. (it won’t have the cool factor, however!)
A stock appearing very drivable combination that should up the fun factor of the car considerably over the stock 383.

Thanks for taking the time to reply,

Steve weim55 Colorado

 

[weim55]

how do they meet your needs ? the piston .080 thousand or more in the hole, the thicker rings costing 8 hp or the 9.4 compression. maybe because they weigh 200 grams more per piston so the engine can rev slower and put more weight on the bearings.

The specs in KB catalog show the compression height at 2.057, should work out to about .024 in the hole. With a 440 source stainless steel shim gasket @ .017 That calculates to 10.0 CR. Not quite the goal, but I would call that good enough. I would much prefer the thinner rings but for the car this is going in, i’m willing to sacrifice that 20 horsepower. I have not compared side-by-side weights, but I would be very surprised if KB were heavier than the stock cast flat top. I’ll check into it and let you know.

Thanks for the reply

Steve weim55 Colorado

 

[mr gtx]

thought you said kb 184-40 shows 1.992 pin height. what part # are you looking at.

 

[mr gtx]

I rode in a 300H there not very fast low 16 second 1/4 mile times. if I raced a 300H with my 67 Newport it would 2 seconds or 20 car lenghts behide my Newport with my 2.94 gears vs the 3.23 gears of the 300H.

 

[mr gtx]

the KB are about 80 grams lighter than the stock pistons

 

[CBODY67]

I looked about 440 pistons several years ago. At that time, the only thing that would be close to OEM compression were forged pistons. All that was available in cast pistons were the generic 440 one size fits all items. The NOS Chrysler Parts 440 I bought on factory close-out sale in the earlier 1980s, the pistons were .125" in the hole at TDC.

You DO know that if you angle mill Chrysler B/RB 906-style heads, that the resultant compression chambers suddenly look surprisingly like Chevy small block V-8 heads? With angle milling, you can increase compression ratio quicker, but also will need to mill the intake port side too (or the intake manifold to match how the angle-milled heads sits on the block).

IF the block is not together, a great time to get a line hone check and decking done. Which will ensure that "blueprint specs" are happening.

A year or so ago, "Nick's Garage" did some 300H engines. Seems like one was a 440 and the other one was a 413? Impressive results with a stock 2x4 inline intake! You might check those YouTube videos out.

CBODY67

 

[mr gtx]

A year or so ago, "Nick's Garage" did some 300H engines. Seems like one was a 440 and the other one was a 413? Impressive results with a stock 2x4 inline intake! You might check those YouTube

never did a 300H that I recall was a 1963J with the long ram intakes.

 

[CBODY67]

Perhaps it was a J rather than an H. I remember the HUGE exhaust manifolds that matched the "over the valve cover" ram intake system. Plus the old late '50s-vintage 2x4bbl intake that pulled down over 500lbs/ft of torque! But, as normal with Nick, few specifics at to the cam, pistons, and such.

 

[weim55]

thought you said kb 184-40 shows 1.992 pin height. what part # are you looking at.

Digging a little deeper, I found an Icon flat top w/ highest CH so far @ 2.067,
Part# IC968. 9.9CR w/ .017 gaskets and 90cc head chamber.
This weekend I will measure head chamber volume and the compression height of the current pistons. Hoping I will get lucky and the chamber volume will be less than 90 cc.

Here are the specs I found on the KB 236:

Steve weim55 Colorado

 

[weim55]

I rode in a 300H there not very fast low 16 second 1/4 mile times. if I raced a 300H with my 67 Newport it would 2 seconds or 20 car lenghts behide my Newport with my 2.94 gears vs the 3.23 gears of the 300H.

I have never driven or worked on a 300H so its performance is a bit of a guess on my part. Using a bar for something I do have experience with:
Overall performance similar to a stock well tuned 383 automatic 68-70 Road Runner would suit me fine. That’s actually a pretty high bar for that 440 in my 4200lb. Chrysler.
The original 383 that is in the car right now runs fantastic and is quiet and smooth - but it’s an absolute dog. Need some performance to go with that 300 badge on the car

Steve weim55 Colorado

 

[weim55]

Perhaps it was a J rather than an H. I remember the HUGE exhaust manifolds that matched the "over the valve cover" ram intake system. Plus the old late '50s-vintage 2x4bbl intake that pulled down over 500lbs/ft of torque! But, as normal with Nick, few specifics at to the cam, pistons, and such.

Nicks Garage test of the 300J cross ram 413 is the best I have ever seen with that induction set up. Yes, MONSTER mid range torque from that 413. EXACTLY what it was engineered to accomplish! Horsepower fell off dramatically @ high RPM (4500rpm+ if I remember correctly) , But that would not have been a priority for the road going Chrysler letter cars of the era.

Steve weim55 Colorado