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Old Hemi Parts
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Powerflite
Posted 2019-01-17 10:58 PM (#576965)
Subject: Old Hemi Parts



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I just got a great deal on this collection of new hemi parts. It includes a full set of brand new 331 10:1 compression pistons, a full set of brand new 392 hemi Mickey Thompson aluminum rods, and a brand new 392 hemi camshaft made to 300D specs.

The rods are about .015" short from standard 392 hemi length. They measure out at 6.942", whereas standard length is supposed to be 6.956". I assume that's to account for the extra thermal expansion of the aluminum vs. the iron. The difference in expansion between 7075 aluminum & cast iron is about 13.1 ppm/C, and assuming that the temperature goes from 20C to 260F or 126C, - a 106C range, that gives a length change of .14% or a final length of 6.952". It's still a little short, but close enough that it is plausibly correct.

The cam is brand new and just what I need to get one of my 392 motors running well. People say that rebuilding old hemi motors is expensive, but I would have to disagree. The reason is because of the wide availability of old speed parts like these that can be obtained very cheaply. I paid around 15% of what this stuff would have cost me if I were to purchase them new. You do have to know what you need, well in advance of when you need it though, because it takes time to find them.



(New Hemi Parts.jpg)



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Attachments New Hemi Parts.jpg (238KB - 45 downloads)
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Powerflite
Posted 2019-01-17 11:14 PM (#576966 - in reply to #576965)
Subject: RE: Old Hemi Parts



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The Jahns pistons are in a 3 7/8" size, according to the box, and 10:1 compression on a Chrysler. I measured the skirts on them to be 3.87" so the box label seems to be correct. But what is odd is that the box says they are STD. Usually that means standard size, but 3.875" bore isn't standard for any hemi motor. The 313 Canadian poly has a standard bore of 3.88, but these definitely have a hemi dome to them, so I seriously doubt they would work in a poly. If I ignore that STD label, these should work in a 60 mil overbore 331, and I am hoping that's what they were intended to be used in. I tried doing a search for the 8-942H TP part number, but came up empty.

The old paperwork on these parts is really neat. I will scan them and include them here for future reference.

Edited by Powerflite 2019-01-18 12:23 AM




(331 Hemi Jahns Pistons.jpg)



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Attachments 331 Hemi Jahns Pistons.jpg (157KB - 42 downloads)
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Powerflite
Posted 2019-01-18 12:05 AM (#576967 - in reply to #576965)
Subject: RE: Old Hemi Parts



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M/T Aluminum rods instruction sheet.



(MT Aluminum Rod Instructions.jpg)



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Attachments MT Aluminum Rod Instructions.jpg (246KB - 39 downloads)
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Powerflite
Posted 2019-01-18 12:07 AM (#576968 - in reply to #576965)
Subject: RE: Old Hemi Parts



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Jahns Pistons Instruction sheet (both sides).



(Jahns Pistons Sticker.jpg)



(Jahns Pistons Instructions pg1.jpg)



(Jahns Pistons Instructions pg2.jpg)



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Attachments Jahns Pistons Sticker.jpg (88KB - 40 downloads)
Attachments Jahns Pistons Instructions pg1.jpg (244KB - 38 downloads)
Attachments Jahns Pistons Instructions pg2.jpg (246KB - 41 downloads)
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ToMopar
Posted 2019-01-18 2:35 AM (#576977 - in reply to #576965)
Subject: RE: Old Hemi Parts



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Powerflite - 2019-01-18 3:58 AM

......People say that rebuilding old hemi motors is expensive, but I would have to disagree.
......it takes time to find them.


Nathan, you're a lucky guy
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57burb
Posted 2019-01-18 5:39 PM (#577005 - in reply to #576977)
Subject: RE: Old Hemi Parts



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Lots of Hemi stuff out there, but the issue is getting someone to sell it. And of course, the price when you do. That's a good score!

I have an old nos Isky cam for a 392, and a set of Ansen main straps for one too. If I ever build a drag engine I'll put them in there. Good stuff!
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hemidenis
Posted 2019-01-18 7:21 PM (#577009 - in reply to #576965)
Subject: Re: Old Hemi Parts



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Yes, i'm the ones that assured that restoring a HEMI is very expensive. I did one and with many NOS parts, one of them was a complete NOS set of connecting rods that were listed in Gary Goers catalog for about 12 years and nobody care to purchase.

I faxed Gary and he said, "yes I have 16 of them NEW in the box" I purchased all of them, used 8 and sell the other 8 for a fortune on ebay with more than 26 bidders fighting for it. Also found a NOS engine damper, power steering, oil filler cap, crank pulley, bypass hose, oil sump, water pump impeller, main and rod bearings.

Yes parts are there, I'm just waiting to Gary to go back to business and wait if he print more NOS hemi parts on his catalog. Ha!










Edited by hemidenis 2019-01-18 10:57 PM
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wayfarer
Posted 2019-01-21 11:29 AM (#577168 - in reply to #576965)
Subject: Re: Old Hemi Parts



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Nice find!
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Mopar1
Posted 2019-01-23 10:55 AM (#577271 - in reply to #577168)
Subject: Re: Old Hemi Parts



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Some years ago there was a set of NOS Jahn's in the OEM box for a 331. Buyer didn't know what the C/R was, so I took a chance & won them. I found the C/R on the box. 13:1. Sold them to a vintage drag racer in Ca.
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Powerflite
Posted 2019-01-23 2:25 PM (#577277 - in reply to #576965)
Subject: RE: Old Hemi Parts



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Wow 13:1, that's in the Alcohol range. On these, I think I was just as pleased with the old instructions as I am with the parts. These 10:1 331 pistons are gonna be great in the '55 Imperial motor currently installed in my '56 Plymouth.
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ToMopar
Posted 2019-01-24 5:27 AM (#577320 - in reply to #577009)
Subject: Re: Old Hemi Parts



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hemidenis - 2019-01-19 12:21 AM
I'm just waiting to Gary to go back to business and wait if he print more NOS hemi parts on his catalog. Ha!


Denis, do you know if Gary sold that parts to Quirey? Or do he still have those kind of parts.
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Stroller
Posted 2019-01-26 10:30 AM (#577400 - in reply to #576965)
Subject: Re: Old Hemi Parts


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Hm. When I re did my 354 hemi it was not easy but I found Fel Pro Sealed Power jugs and nope were not cheap. Found a guy from the machine shop that new someone whose grand dad was into racing back in the 50-60's and was a mopar nut. Seems that with so many people starting to use the old hemi's there would be more parts re-pops. Folks are getting stuff somewhere.
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mikes2nd
Posted 2019-01-26 12:17 PM (#577409 - in reply to #576965)
Subject: Re: Old Hemi Parts


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i think Quirey bought everything.
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hemidenis
Posted 2019-01-26 9:23 PM (#577428 - in reply to #576965)
Subject: Re: Old Hemi Parts



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yes Tom Gary sold everything.
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Powerflite
Posted 2019-03-11 12:52 PM (#579171 - in reply to #576965)
Subject: RE: Old Hemi Parts



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I compared my stash of 392 hemi pistons that I have. I had always thought that the Jahns pistons that I ran in my '68 Barracuda throughout high school were 10.5:1 compression, and I was told that the Venolia pistons I purchased with my '58 Imperial motor were the same 10.5:1 ratio. I have never verified either of these claims. The Arias pistons have a part number on them and I remember calling them to find out they were 11.2:1. All of this makes me doubt the advertised compression of the stock '58 pistons. The difference in compression height between it and the '57 pistons is very small. I will measure it and do a calculation to see what it comes up with but something seems off here. I realize that the taller forged pistons have larger valve reliefs so it's hard to make a direct comparison without looking at displaced volume, but nevertheless, something is a little odd here.

I am thinking of building a .0625" oversize 354 motor for my Savoy and so I am thinking of possibly using these stock '58 pistons in it. If they are indeed 10:1 in a 392, then they would equal out to about 9:1 in a 354, and with 331 heads, I would get to about 9.5:1. But if they aren't really that good, I don't want the compression ratio down to less than 9:1, so I would be forced to get custom forged pistons for it. Anyone have a set of 11.5:1 392 pistons in standard size they would like to sell? I would use those Arias pistons in it, but they are .03" oversize so that would be a stretch in the 354. The Venolias are .08" oversize! and all set to go into my '58 motor.



(392 Pistions.jpg)



(392 Pistion Heights.jpg)



Attachments
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Attachments 392 Pistions.jpg (144KB - 23 downloads)
Attachments 392 Pistion Heights.jpg (182KB - 25 downloads)
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58coupe
Posted 2019-03-11 9:33 PM (#579210 - in reply to #576965)
Subject: Re: Old Hemi Parts



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Nathan, are you sure the 58 392 pistons would work OK in a bored out 354? I have a 57 354 poly i am converting to a Hemi and using 331 heads and i also don't want the C.R. too low. Is it still possible to get 354 hemi pistons in at least 9.5 to 1?
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jboymechanic
Posted 2019-03-11 10:00 PM (#579212 - in reply to #576965)
Subject: Re: Old Hemi Parts



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I'm running standard bore 10:1 compression 392 Hemi pistons in my 1956 354 hemi. My block needed at least 0.050 bore to clean the cylinders, easiest piston to source was 392 pistons as they are 0.0625 over standard 354 bore as Nathan said. My car runs beautifully. I'm guessing that I'm at about 9.5:1 compression after having the deck and heads machined true. I have the details written down in a book... somewhere.
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Powerflite
Posted 2019-03-11 10:00 PM (#579213 - in reply to #576965)
Subject: Re: Old Hemi Parts



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The problem is that people offer replacement pistons only. Dumb!! That means that you can only get the compression ratio that was originally offered in the motor back then - which was 9.0:1. I believe that later marine or truck pistons don't help you out either because they were listed at 8.2:1 compression. If you want higher compression pistons you have to get a custom forged piston. With those, you can get any ratio you want, but they cost around $700-$800.

But yes, standard bore 392 pistons work fine in a .0625" overbore 354 motor. But using them makes you lose about 1 compression point when swapping to the 354. You can gain 1/2 a point back by going from 354 heads to 331 heads (or aluminum). So if '58 392 pistons actually give you 10:1 compression, then you can get 9.5:1 compression that way. But you can also get the same compression by using replacement 354 pistons in any size, with the 331 heads. So you aren't gaining anything by boring it out, except potentially being able to use cheap used pistons like these.
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wayfarer
Posted 2019-03-12 8:00 PM (#579261 - in reply to #576965)
Subject: Re: Old Hemi Parts



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The current crop of castings are indeed oem c/r and some do not even make the advertised number. Buyer beware.
The best route is to use a custom forging...no, not inexpensive.
If you can tolerate the lower c/r then hog out the 354 and use std 392 pistons.
I'll suggest that you play with the numbers before buying 392 pistons to be sure that is a viable solution.
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ToMopar
Posted 2019-03-14 7:57 AM (#579308 - in reply to #576965)
Subject: Re: Old Hemi Parts



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Something went wrong on this forum,- look on the date
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Powerflite
Posted 2019-03-14 8:09 PM (#579332 - in reply to #576965)
Subject: RE: Old Hemi Parts



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I compiled data from different piston manufacturers to compare them to each other. I found data on Arias, Ross, and Keith Black. It was kind of annoying that none of them provided compression ratios at the same combustion chamber volumes. The ratios that are published by the manufacturers are enclosed in green. For your information, an uncut 392 head is typically around 110cc, 354 at 105cc, and 331 (& HH aluminum) at 100cc. If you mill them, the volume goes down from there. To create CR numbers at the same combustion chamber volume, I derived the equation at the top of the picture to fill in all the missing blanks.

You can use the equation to predict the change in CR if you use a different piston dome volume too, to see how the Ross numbers would predict what the Arias piston CR would be. By doing this, the Ross pistons seem to be assuming a thicker head gasket because it's numbers are consistently lower than the others, but the Arias & Keith Black numbers agree with each other pretty well. Notice that using the Keith Black pistons in a standard 392 head results in a best case 9.5 CR. If you use a thicker head gasket like Ross, you will end up with 9.2 CR. But these are typically advertised as being 10:1 and are based off the same design as the Egge aftermarket and stock '58 Chrysler pistons.

This tells me that if I use Egge or KB 392 pistons in a 354, that I would likely be getting around 9:1 (or less!) with 331 heads unless I cut them, and deck the motor to increase it. One unknown here, though is the stock Chrysler piston dome volume. If the stock valve reliefs are significantly smaller on the stock pistons, then maybe that could bump up the CR a bit from the reproduction versions. I will try to measure that on my motor to get a good estimate to compare it here. But it looks like Chrysler may have over-estimated their compression ratios on these motors. We'll see when I measure it out.

Edited by Powerflite 2019-03-15 12:02 AM




(Piston CR Comparison.jpg)



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Attachments Piston CR Comparison.jpg (146KB - 21 downloads)
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Powerflite
Posted 2019-03-14 11:45 PM (#579359 - in reply to #576965)
Subject: Re: Old Hemi Parts



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Using the Deck Height of a 392 hemi at 10.877" and the above information, you can calculate the Deck Clearance and resulting compression ratios directly. It is:
Deck Clearance = Deck Height - Stroke/2 - Rod Length - Compression Height.
You get:
Arias: .017" Deck Clearance, gives advertised results with .023" gasket thickness
Ross: .022" Deck Clearance, gives advertised results with .033" gasket thickness
Keith Black: .032" Deck Clearance, gives advertised results with .010" gasket thickness!!

Looks like the Ross numbers are the only ones that make sense with realistic gasket thickness. If you use the same .033" gasket that Ross uses,
the Arias CR with a 110cc head results in a ratio of 9.82.
The Keith Black results in a ratio of 9.04! That's a long ways off the advertised value!
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wayfarer
Posted 2019-03-15 12:17 PM (#579378 - in reply to #576965)
Subject: Re: Old Hemi Parts



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I have yet to find a 'shelf' piston that makes advertised c/r in whatever application it is made for. Strictly speaking EarlyHemi here.
Egge is probably the worst but, for a reason. Egge bought all of the molds for the Hemi stuff from 'X' after 'X' bought the entire Hy-Duty operation simply to add to their
sbc production capacity . They basically discarded all other production. Egge then decided, I assume, that having both 57 and 58 pistons was not needed so they now only make one.
It is further assumed that they either just called the 57 10:1 or they made changes to the 58 molds for some reason. Although they make a decent piston it is not even close to 10:1.
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Mopar1
Posted 2019-03-15 2:51 PM (#579383 - in reply to #579378)
Subject: Re: Old Hemi Parts



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From what I've seen the OEM numbers are optimistic on low deck engines.
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Mopar1
Posted 2019-03-15 2:52 PM (#579384 - in reply to #579308)
Subject: Re: Old Hemi Parts



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ToMopar - 2019-03-14 6:57 AM

Something went wrong on this forum,- look on the date
Jan. 17, 2019????
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Shep
Posted 2019-03-15 4:18 PM (#579390 - in reply to #579384)
Subject: Re: Old Hemi Parts



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Without ccing the combustion chamber for a volume reading, the specs are nominal at best.
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Powerflite
Posted 2019-03-15 5:01 PM (#579395 - in reply to #576965)
Subject: Re: Old Hemi Parts



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I know that the specs will change with different volume, but the numbers should at least match what they advertise, and they should use a gasket thickness that is most common in doing so. The fact that those Keith Black numbers are a 1/2 point off is completely unacceptable in my book. Add to this the perception that they are 10:1 replacement pistons, with a whole point of compression off, makes it even worse.
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