Does anyone have the part number on 1971 440 HP pistons? I am led to believe these pistons resulted in 9.7:1 ratio. Also anybody know who makes/brand a piston with similar compression height/specs in a .030 over?
1971 440 HP Pistons
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BLK 68 R/T
Well-Known Member
I think the closest thing you’ll find these days are the ones from Icon or KB. Look for something at the 2.067” piston height, zero deck your block for good quench.
Curiousyellow71
Well-Known Member
I think the correct piston was also used in 67 and 70. In 70 I think the compression was 9.7 and lowered to 9.5:1 with the introduction of the 346 head in 71. The piston available that are the closest are speedpro L2266F. In reality the compression will be lower then advertised unless you blueprint the engine. The pistons will be quite a ways down the deck (.090ish), slightly shorter compression height then the oem piston which was done to keep the compression similiar once the engine is bored.
The 350hp 440 in 71 used the similar piston but with a dish. I can verify that, I have one.
The 350hp 440 in 71 used the similar piston but with a dish. I can verify that, I have one.
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BLK 68 R/T
Well-Known Member
And unfortunately .090” in the hole will equal about a 7.5:1 maybe 8.0:1 compression, dog of an engine.
Curiousyellow71
Well-Known Member
It is better then the late 440's that are near .140 down. 2266 is about 8.75:1 if you use a typical head gasket, and you can get it in the 9's with some machining and thinner head gaskets..or just get a better piston. There are several better then a 2266.
BLK 68 R/T
Well-Known Member
I would strongly suggest you pick a piston that will get you as close to zero deck as possible. And then get your block machined to actually get to zero deck. That combined with today’s head gaskets, which are much thicker than the factory ones, will give you a strong performing engine. As long as the rest of the engine is built accordingly as well.
RemCharger
Well-Known Member
BSB67
Well-Known Member
What you are asking for is different than what you want.
Do you want a 1971 OEM type piston. Or do you want 9.7:1 CR?
If you want 1971 piston, the SpeedPro 2266 will be it.
If you want 9.7:1 CR in a factory like piston the 2355 will be it.
These are both factory-like heavy pistons, but forged, not cast. Piston and pin will go about 1075 - 1100 grams.
There are several other manufacturers that have pistons in you desired CR range that are lighter.
lewtot184
Well-Known Member
Chasing zero deck with open chamber heads will create pump gas problems. If you don't care about pump gas do whatever you want. I know that I couldn't get the 440 in my 69 r/t to run consistently on pump gas with the stock 2.03 pin height piston and open chamber heads.
My intent, first and foremost is to get educated here, thus as a novice, please bear with me. I have a '73 stock 440 HP. I want to leave it stock in external appearance but would like to get more power out of it, similar to a stock '71 440, thus without going to a different head, my most effective options would be pistons and cam (I think). I am thinking about replacing the thermo-quad with a Holley Sniper EFI and eventually going to an overdive automatic trans. My intent is to have a great highway crusier not a drag car and I could probably just rebuild the engine in stock '73 form and get that. However, it is a 440 and without getting to radical I'd like to get more out of it than the stock '73 version offered. I know they changed how they rated horsepower starting in 1972 thus I don't know how far apart a '71 vs. '73 are if they rated horsepower the same way on both engines. I do know the compression ratio is different amoung other things. Thanks for any feedback.
I wouldn’t overthink it and go with quench domed KB Hyper pistons without doubts
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lewtot184
Well-Known Member
I agree. The kb184 piston will give 10:1 performance plus pump gas capability, but they must be installed per the instructions. They are designed specifically for the open chamber head. It's really not difficult at all. If this gives you heartburn than just do the 22
66 piston with .020" steel shim gasket. Don't over cam! Some pocket port head work with some ferrea 5000 series valves will help. I'd keep the thermoquad.
I actually suggested the higher CR one, KB236… the link I posted.
lewtot184
Well-Known Member
I thought they quit making the 236,....? Wouldn't be pump gas friendly if that was the goal.
BLK 68 R/T
Well-Known Member
20 years ago, the shop I worked at had a 70 challenger. The 440 was rebuilt with the 2355 “six pack” pistons and zero decked. We used a Hughes engines cam, think it was their old line made by Engle? Anyways the specs were .504/.515” lift and somewhere in the low/mid 230’s @.050 duration. Rest of the engine was completely stock original. No issues with premium pump gas and had tons of power.
I have a stroked 400 (“451”) with around 10.2 CR on iron heads and so far so good no huge problems with pump gas… except just quite often some pinging but the quench is not correct (working on that). I hope that will be the problem once quench is corrected.
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I don't know what quality gas is available in Florida, (93?, 91 clear?, 91 10%) but in california I would not build a cruiser motor at more than nine to one comp. 8.5 to 1, for a shot at running on 87.
Quench is nice, I like to have it, but if it uses a quench dome (good) and doesn't have a corresponding dish (or a HUGE valve relief trough) to get to 9 to 1 or less, I don't want em.
A performance street engine gets an entirely different formula recommendation.
I buy forged pistons exclusively, but for a driver/cruiser, a hypereutechtic piston is the proper choice, imo. So... KB piston.
I believe Icon forged, and KB hypers are both made by the same company.
Quench is nice, I like to have it, but if it uses a quench dome (good) and doesn't have a corresponding dish (or a HUGE valve relief trough) to get to 9 to 1 or less, I don't want em.
A performance street engine gets an entirely different formula recommendation.
I buy forged pistons exclusively, but for a driver/cruiser, a hypereutechtic piston is the proper choice, imo. So... KB piston.
I believe Icon forged, and KB hypers are both made by the same company.
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Yes, Kb, Icon and Silvolite are all made/offered by UAM.
But not Icon from the shelf on stock stroke for 440… not at least on their website.
Silvolite offers them thought… 1.912 and 1.969 CR for flat tops and 2.023 for dished
But not Icon from the shelf on stock stroke for 440… not at least on their website.
Silvolite offers them thought… 1.912 and 1.969 CR for flat tops and 2.023 for dished
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I think here is a good compilation of options for our engines. Dunno if they are missing some:
Mopar Performance 383 400 440 Parts Big Block Mopar Engine Parts B RB
Mopar Performance 383 400 440 Parts Big Block Mopar Engine Parts B RB
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