pin height

[gtxrt]

1967 440 350 hp, piston pin height, 1.99 or 2.00 any one know which one . thanks

 

[69Bee]

No such thing as "Pin Height". What exactly are you looking for?

 

[gtxrt]

lol. compression height. no such thing as ft lbs of torque either but everyone know what it is

 

[BSB67]

If it is the same piston as the 375 hp, it’s 2.00.

 

[Lefty71]

If it is the same piston as the 375 hp, it’s 2.00.

In '70, they dished the piston top somewhat to lower the compression. I'm not certain on a '67.

 

[R413]

1967 440 pistons were all flat tops, even the standard 350 horsepower,

 

[Curiousyellow71]

All 67 should be about 1.99ish and a flat top.. About .080-.090 down. There is a forged sealed power equivalent.
They also used that same piston in the 70 440s and some 350hp 68's...but 68-69 is suppose to have a taller piston 2.04-2.03ish. I think it's more then 2.00 and around .030-.40 down??? It's replacement was discontinued 30 years ago.

71 has a dish. The block would've been dated '70 but in a 71 car.
And I have learned you never know what ma mopar did...

 

[gtxrt]

they are flat tops and there .094 in the hole

 

[33 IMP]

Forged flattop Sixpack replacements were 2.06, still down the hole a bit.
(Theoretically. 023, assuming blueprint deck height, which it won't be, lol).

 

[Curiousyellow71]

The old 440 domed trw/sealed power L2295 had a compression height of 2.029. It was a compression height that doesn't make much sense for a custom 440 piston.
why did TRW do a dome so far down the deck
we always had to deck the block .055 or so to get the pistons closer to 0 deck.
The best reasoning we came up with is trw used the ch of the 68-69 375hp engines and then added the dome and the valve reliefs.. just a theory any way
but if that were the case...
67 replacement would be 1.99
68-69 375hp 2.029

 

[33 IMP]

Got a set of 2295s in my current engine in my 62. With 906 heads and a comp gasket, barely 10 1/2 to one. Missed the "11 1/2 to one" by quite a bit! Got a set of Arias 12 1/2 to 1 that aren't even 11 1/2 in a maxwedge too.
In both cases, I'd rather have the compression they really are, than blueprint to spec.

 

[PRHeads]

My first 440, that I built in 1981........ used some Sealed Power forged pistons.
The correct part number for the 68-69 motor.
In a block that was just decked to clean/square, they were down the hole .055 +/-
They were 2.030ch.

When I needed a replacement because of a galled up pin bore, that piston had long been discontinued.
However...... the 6bbl piston actually provides the same CR.
The added CH and the valve pockets are basically a wash.
The ring height was the same too(same distance from pin c/l).
Within a couple grams in weight as well.

The “heavy” part of the 70 and later 6bbl rotating assy(requiring external balance) was the rods.

 

[BSB67]

The 1967 375 hp piston is 2.00, actually 2.004. This is not a guess or an estimate, it’s a measurement of an original piston that was sitting on my workbench. They sat 0.080 to 0.085 below the deck.

PRH is correct on the 68-69 piston. My Speed Pro NHRA approved forged piston measures 2.03 and some change.

 

[33 IMP]

The 1967 375 hp piston is 2.00, actually 2.004. This is not a guess or an estimate, it’s a measurement of an original piston that was sitting on my workbench. They sat 0.080 to 0.085 below the deck.

PRH is correct on the 68-69 piston. My Speed Pro NHRA approved forged piston measures 2.03 and some change.

I have the original untouched (at least to my knowledge) A12 motor out for freshening. There is a 511 in it for now. I will document everything I find when I pull it apart. (Real compression ratio, head gasket, chamber size etc.)

 

[gtxrt]

The 1967 375 hp piston is 2.00, actually 2.004. This is not a guess or an estimate, it’s a measurement of an original piston that was sitting on my workbench. They sat 0.080 to 0.085 below the deck.

PRH is correct on the 68-69 piston. My Speed Pro NHRA approved forged piston measures 2.03 and some change.

i have an extra .010 in the hole so pin height is 1.99 or block is an extra .010 longer

 

[Curiousyellow71]

i have an extra .010 in the hole so pin height is 1.99 or block is an extra .010 longer

Usually you will have to measure more then one hole....and average...stock they usually weren't real square..not uncommon to be. 010 to .015 off. Can vary end to end and bank to bank.

 

[BSB67]

I have the original untouched (at least to my knowledge) A12 motor out for freshening. There is a 511 in it for now. I will document everything I find when I pull it apart. (Real compression ratio, head gasket, chamber size etc.)

Great! And valve relief volume.

I wish I had recorded my measurements from the 1970s of head combustion chamber volumes. It is generally accepted that the 906 head volume is 90-92 based on measurement conducted today. I not sure that this is what they were originally.

 

[BSB67]

i have an extra .010 in the hole so pin height is 1.99 or block is an extra .010 longer

If the motor had a rebuild with a new/replacement piston anytime in its history, it is likely a 1.99. I'm not aware of a 2.00 piston being available other than maybe from Mopar back when they still had their OEM replacement stuff on the shelf.

What Yellow71 states is what I have seen as well. If there was an operation that the factory was not consistent on, it was deck milling. I've seen 0.013 difference from front to back on the same side, and 0.015 from side to side. You cannot determine a pistons CH with certainty by a deck CD measurement alone.

 

[gtxrt]

these are the new race-tech pistons. 2.070 pin height. 12 cc dish. we decked 7 thousand off the block. looks like either ending up with .008 or .018 in the hole . hoping for .018 in hole for less compression

 

[PRHeads]

The way I understand it is, the 1969 A12 engines had the same pistons and rods as the 375hp 440.
The big rods and tall pistons didn’t show up until 1970.