Packard Forum Index » V-8 (1955-56)

ok. I'm starting a seperate thread on V8 pistons. EVERYONE is welcome to chime in anyway they want to. After all, this is a discussion group and NOT a sunday school class.

Here is a quote from another well known Packard V8 builder.

"1. The International Harvester truck diesels are the closest in the book, offered in a 4.00" and 4.110" bore sizes. These pistons w/pins weight TWICEas much as a Packard piston w/pin. This doubling of the reciprocating weight would make it practically impossible to balance the crankshaft. If it could be balanced by milling out the counterweights and filling them with Mallory metal, the combined reciprocating/rotating weight would then overstress the crankpins and break the crankshaft.
2. The IH piston pins are 1.1101" in diameter. This is .1297" larger than the Packard pin. The machine work cost to bore and hone eight rods to size is considerable. The rod small end could possibly be bored out to that oversize, but strength would be unknown.
3. Diesels don't turn fast, so the inertia of heavy pistons isn't a problem. The weight of the diesel piston would literally pull the Packard rod apart at anything above 3,000 RPMs."

The above quote appears here:
packardinfo.com/xoops/html/modules/newbb/viewtopic.php?topic_id=1281&start=60

RE: FIRST POST of this thread.

Lets consider point 3 from the above quote FIRST.

The claim is that weight is a factor. ok. I agree. BUT, if someone suddenly offered up FORGED pistons then how much heavier would a FORGED piston be than the stock Packard piston????? And everyuone would suddenly smile and say "oh yes, oh yes Forged pistons for my Hi-po engine, God has sent me a blessing" And they would never mention weight gain.

The wall and crown of the Harvester piston is probably at least twice as thick as the OEM packard piston. SO, the Harvester piston could be cam ground to size for the Packard engine loosing probably half of the the wall thickness AND THUS THE WEIGHT.

Don't worry, i'm not finished with the possibility of this piston yet.

Quote:

1. Quote: Modern forged racing pistons/pins of the same diameter are LIGHTER than the OEM Packard cast pistons/pins.
2. Quote: Yes, but the compression height of the IH piston is already too low to be of use in a Packard, so taking anything off the top is not possible. I only used it a weight example because the bore diameter is the same.
3.Quote: cam grinding is used to finish the outside skirt contour. It is NOT a weight removal operation or process.

FWIW, there's NO way to use a diesel piston, but here's a way to make a Ford big truck gas engine piston fit the Packard:

1. Custom mill the top and inside of the piston to fit.
2. Rod small ends have to be machined for pressed pins.
3. The Ford truck pistons are a lot heavier than the Packard, so the rods have to be extensively machined to lighten them and the engine has to be re-balanced.
4. Now that I have done with the learning curve, there is some cost advantage over custom forged pistons, plus the cast pistons can be fitted with .0025" bore clearance, where forged pistons need at least .005". Thus, the cast pistons will be quieter, use less oil and have less blowby and should last longer in normal operation.

I have one 352" engine bored .070" over for 364" about ready to go in my Studebaker truck and have Ford pistons and rings on the shelf to do two more engines.

thnx, jack vines

Jack writes:
"Yes, but the compression height of the IH piston is already too low to be of use in a Packard, so taking anything off the top is not possible."

Thank you. This ends the harvester Diesel piston analysis for me.

I'm guessing Carillo or some other rod manufacturer will make a set of Packard V8 rods for about $1600 retail.

BUT, make the rods longerand the big end of the rod like a Packard rod and the small end of the rod to suit a 350 Chevy piston.

MAYBE change the big end of the rod slightly to accept some more commonly available rod bearing that is close to the original packard bearing.

YES, the rod will get longer. YES the rod will get heavier. So what??? many builders are going to rebalance anyway. They are trying to pick a set from various engines to get them all to match.

The new rods will be carillo rods (or some other custom manufacturer) which means THEY WON'T break and they will all match. What do u want???

IQuote:


And it is a good idea why to spend $1600 for custom rods instead of $800 for custom pistons?

FWIW, I built a Packard 3/16" stroker using a $2500 billet crankshaft, custom Oliver 7.25" rods which cost $1500 and the pistons were $800. However, custom pistons are the bargain of the bunch. I'm getting ready to have six sets of 4.155" forged pistons run up. Anyone have his $800 ready?

thnx, jack vines

JV writes:
" custom Oliver 7.25" rods which cost $1500 and..."

Packard pin height = 2.072, 350 Chev = 1.56.
Packard rod = 6-25/32 long.

According to my calculations the 350 SBC pistons could be used with rods 7-9/32 long. That's 1/32 inch longer than your Olivers. What i don't know yet is pin hieght of a 400 Chevy piston nor how common the 400 pistons are.
It would be great to have ONE rod like your Olivers to work with both pistons in 352 and 374 Packard V8's.

Apparently my guess worok on pricing the rods was not too far off. Last time i bought Corrillos was about 12 years ago.

To answer your question:

IIRC the $800 pistons comming available is only in SETS????? What if u only need ONE piston??? Have to buy a set to get it????? Rings extra??? Pin issues???? What if u get into an engine that has only ONE oversize or some varied oversizes. Not everyone is so picky and mite only need ONE piston for one overbore. MoPar did it in production among others. What oversizes available on the Packard pistons????? Std. thru .030 over???? Chev's avaialable up thru .060 maybe even .125 over????

The Chev pistons are relatively dirt cheap, plentiful and definately have stood the test of time.

IIRC someone indicated a few months ago some concern about Packard rods, something about 3hree different rods found in an engine and trying to pic a matching set from 4our different engines, varied weight of rods, replacement rod inserts from china-rica, rings and pins extra, oversize pins etc etc etc.

Custom rods could use a readily available bearing shell???

So, $800 for pistons, $100 for inserts made in Istanbul and desperate search for OEM rods,rings and pins extra, oversize pins and balancing and so-forth adds up to what???? $1000 ?????

For another $500 - $600 why not have the Oliver rods and readily available pistons at a cheap price and KNOWN inserts??? AND THE rods WILL NOT BREAK under even severe service.

Jack i'll try to find my info on the pontiac rods i mention in the other post. they were, best as i rember a littel longer so chrysler bb pistons could be used and around 400$ for the set.

Based on rudimentary research the SBC 350 and SBC 400 pistons BOTH have the same compression height of 1.54 inch. So (when used in a Packard V8)one (custom)rod fits both.

NOTE: There seems to be variations in compression height of the 350 and maybe the 400 pistons depending on year of engine and maybe other engine model criteria. I've found 1.54 and 1.56 for the 350 .