The only way to truly know what any specific engine puts out is with a dyno.

Estimating actual horsepower based on a, probably, inaccurate factory rating is probably not a good idea. Only a dyno would give you the facts.

I can verify it past the reading stage. I actually rebuilt engines with the taller pistons. It was a Mopar thing, not a slop thing or an aftermarket thing. I had a daily driver 69 RR that got too cold and froze and blew open the block. I found another block and then we first found out about the pistons when we rebuilt it and only needed to replace one. I will say it is past the myth stage here. Believe as you wish.

Right, but that does not necessarily make it so from the factory.

I'm still waiting for someone that has measured a factory original that is proud. Between the ones I've measured, and people that I trust that have measured them, I have not heard of any being positive. There could be some due to factory tolerance differences, but I have not seen or heard of any. They ranged from very near zero to 0.008" below.

I have run 915 head on a 1.932" CH 68 383.

NHRA Stock specs are what is allowed in teardown. It has nothing to do with factory specs.

I have a 69 383 4Bbl A/C(turquoise, duel exhaust Holley carb)I just had the heads off because of a stuck valve. So I removed the 906's heads and cleaned up top of block for my re-man 1971(346)heads and my pistons are flat top and if they are not positive deck height, then they are so close to positive and you would need measuring equipment to tell the diff, because with my finger and eye, it looks to be above the deck(very small amount)
I do have photos, And the driver head is not torqued down yet, so I could take it off to measure I DO NOT want to but I could.

First time trying to post picture,if it works this photo was taken to show the damage to the top of the piston but also looks like the piston is at or close to top of the stroke.

Again I didn't measure with a dial indicator and .010 is really hard to see with naked eye, but my pistons appear and feel like they are above the deck. I will look for a better photo,as when I took the pictures I was not trying to capture positive deck height.

You can easily tell if the piston top is above the block deck by using anything with a straight edge to slide across the deck to the piston top, if it slides over the piston the piston is NOT sticking up above the block deck If it won't slide over the piston top the piston is above the deck

According to NHRA tech. directors when I started racing NHRA in 1973, Farmer Dismuke and Jim Dale, and the other directors that have served as NHRA Tech directors since them all say that NHRA only uses the engine and car specs. furnished to them from the car makers
Back in the early days of SS and stock Grumpy Jenkins proved to NHRA and probably Plymouth racing division that the piston dome height for the 1963 415 HP M.W. motors was incorrect for the advertised compression ratio. stock was between + .062 and + .065 from TRW, they needed to be + .091 to have the true compression ratio Plymouth and Dodge said they had according to the math. NHRA changed their spec. after that to allow the +.091 dome height on those motors in 1965 or 1966
The only way to get a OEM legal stock piston to measure that was to use a 1964 415 HP piston and mill the top down from +.120 to +.123 to +.091
To much politics in every form of competion

I would have used straight edge if I had thought to document the deck height before I slapped the heads on.
But if I do remove the driver head, I would def measure it with dial indicator to get a very accurate number for everyone.
I have pass side head torqued and valve train just set in place, I was gonna torque driver side and try to button her up today, then I can finish up engine and engine bay paint. We will see what happens when I get my but out to the garage.

This ^^^. You don't need a dial indicator to tell if it's positive deck height. To tell how much, yes.

Well some people on here had asked how much above deck it sat, that's why I mentioned the dial indicator.
As I said on my engine, at TDC it totally appears to be above the deck just a small amount,so small that you would need a dial indicator to measure how much above the deck. And then we would have a measurement to use for future discussions.

I only pulled my heads do to stuck valve, so I did not think to check and measure piston deck height, but as I rotated it to check cylinder walls I noticed pistons looked to be above the deck a small amount.

So I understand you don't HAVE to have a dial indicator to tell if its positive deck height but to have an actual number vs a guess seams like a small bit of useful info.

Also zero deck ht and 0.008 above or below is very hard to see by feel or sight.

Feeler gauges work pretty well .

This.

Um... what?

Pretty sure this is bum info too. I have a 375 hp/440 'cuda from 1970 and it doesn't have any h-pipe either. I was there when we picked it up at the dealer.

H-pipes were on all Hemi cars and A12 cars only is what I always thought.

H-pipes

B-bodies w/HEMI & 440s 1967 'til mid '71

E-bodies w/HEMI

Correct ...don't know why I wasn't thinking about the rest of the B-bodies

I was wrong, My car(69 charger 3834Bbl A/C) does NOT have an H-pipe, It is straight duel exhaust.
I am sorry about that. I guess I have been under way to many Mopars as of late,thats a good and bad thing,LOL.

But now I am Making time for my car, so I should be getting to know it better. I got in late Dec,16, and I have not done very much, but look at it, and sit in it making Vroom, Vroom sounds.

I have a 68 non hp 2bbl short block sitting assembled with new rings and bearings, I can not say for sure that the deck is untouched, but I do have a couple of pistons proud of the deck, they are dished
I will get some pics up soon