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I'm thinking these numbers are what you can creep up on but not go over. In other words, what they will allow. The good and bad thing about the 69-383 height, good for compression,bad because the valve hits when using the spec 440 cam.

My math goes to the ratio of the piston depths or CD that were posted to the piston CH that I listed. I intentionally stayed away from the whole deck height discussion. But without that clarification, my comment was indeed unclear.

I have my original set of 67s. They are 2.00 and some change. 2.003" I think. My 68-69 (have we decided if 70 is the same?) pistons are 2.034", I think. I need to go out measure again, and write these down, as it seems to come up a few times a year.

There's the problem.


Don't use old pistons. You can make plenty of power with low compression. Save your pennies until you can do a proper build.

I wouldn't necessarily use unknown old pistons but I will use inspected old pistons in good shape. Pennies aren't a problem I keep them in the trunks of my AAR, GTS, RTs and several other cars for traction. As much as my cheap nature and a desire to build some things like we use to have to at 16, anyone can go to the Summit website and order pretty much any part of an engine or a car for that matter, it's more fun in my view to build something with minimal investment and in many cases used parts. I have built more than I can count, some blue printed in excess and some thrown together at the track on borrowed parts and a wing and a prayer.

Agreed, that is my understanding of NHRA specs back when I knew some drag racers

Compression height is measured from the center of pin and my 70 standard pistons are under 2 inches and are the same as the TRW L2266 (69). All those measurements I did before are from the pin center.

I measured a '72 440 short block I have.

.155 down in the hole.

I brought it home from the junk yard years ago, threw some new gaskets, the bigger summit brand cam, a new timing chain in it, and ran it in my Diplomat for years.

Had about $600 in it and it ran great. Only reason I even pulled it out was it sounded like it was knocking. Turned out the clutch fork pivot had bent and the fork was rattling around.
Bearings still look great and there's no ridge in the cylinder after years of thrashing it. Its probably gonna end up going in my Newport sometime this summer.

Right, measured from the pin centerline. The actual original replacement piston for 68-69 is not the TRW L2266. That is what they will let you use today for NHRA and allowing block machining to the compression height. This is because this is the only piston available that is close, I suspect. The original 68-69 NHRA replacement piston was the the L2286 (I have these as well). These were discontinued in the late 1980s. I did just measure my 67 original piston, 2.002" although the mic, piston and pin were about 25°F.

The pennies comment was a generic thing. It wasn't intended as an insult to you personal finances.

Pulling engines isn't much fun. Get the most value for your time. Do it once and do it right. I'd much rather drive my car with complete peace of mind than to have a set of used pistons in a half-assed engine build popping into my head.

Proper pistons are relatively inexpensive and I'd rather spend my time doing something other than a second engine rebuild.

So far, and I know this is how to jynx yourself, I have been fortunate enough not to have to go back into any of my engines in a short length of time other than an intake gasket I cant seem to get right on the AAR for whatever reason. I drive my stuff all over the east coast so I'm either confidence in builds or ignorance is bliss as they say (I also carry AAA Premium and have friends in most state I travel in). People/racers/builders use used stuff all the time, I'm not necessarily making an argument for it I'm just saying you cant through the baby out with the bath water. I have opening up a many a engine to inspect it and came out with only new gaskets, some maybe just got rings, bearings and gaskets and I'm not alone in it. I believe you recently suffered a failure on an engine, my bet is you aren't gonna replace the pistons if they inspect good, so you are going to build/reassemble an engine with used pistons.

As for pulling engines being fun, it's all fun to some and even though no one really enjoys doing anything on a car twice, I'm gonna tinker on something for several hours most any given day when I'm home so it don't bug me. I really have to but admittedly I've taken some chances that haven't worked out but rarely have I had a failure when I paid attention and truly inspected an item. It helps that I do it all myself and it will only cost me time if I miss my guess. I enjoy building junkyard cars as much if not more than full restoration, I only have $2000 in my 69 RT and drove it to PA and back last year with minimal drama, it's an absolute hoot to drive.

I guess point it, old parts can be fine if thoroughly inspected and really present no more risk than a new part, at least the old part was made in America at a time when there was some thought given to quality.

Someone building an engine to compete in the class is going to build to the max allowed if they want to be competitive otherwise why bother.

The 68-69 383HP road runner/superbee engine and the 375HP 440 Magnum used the exact same cam.

I used the deck height to drive home that NHRA spec and ACTUAL specs are not the same ... You had the actual piston CH , which are not available in the aftermarket currently , and haven't been for quite some time , if at all ...

"The 68-69 383HP road runner/superbee engine and the 375HP 440 Magnum used the exact same cam."

But, the stocker cam used in the 440, can't be used in the 69 383 because it hits the piston in the allowable blue print specs. So the cam has to be less duration, IF they let us notch the piston we could use the better 440 cam.

How can the 440 cam be different if it's a same cam in both engines from the factory ???

Yes I know that duration is not a checked spec and the deeper in the hole piston of the 69 440 allows more duration with the same lift.

I've said it before , and I'm sure I might have borrowed it from someone ... there is little that is STOCK in NHRA STOCK

Not sure what you're interpreting when reading what I write, I've only talked about NHRA stocker camshafts in NHRA Stock class cars, nothing about factory camshafts. These cams have stock lifts but ungodly duration ( the reason it hits in a 383) Did read today in the old DC book with Larry Shepard, the 69 383 was listed at .021 above deck the rest where below. This was probably given to NHRA for whatever reason back in the day. For STOCK class racing only.

My engine will be getting new pistons. I'll go completely through it to raise the compression and get the most out of it.


I don't like combining used pistons in used bores they've never met.
To me it seems similar to mixing used lifters on a used cam.

I get your point but I like to live dangerously.