What is Packard V8 block deck height ?

[gary roth]

What is the block deck height - from the centerline of the crankshaft to the block deck - of the 1955-56 320-352-374 CID Packard V8 engine ?

[WCraigH]

I have a note that says it's: 10.610", based on rod length = 6.7182", half stroke = 1.7500" and pin height = 2.1418" for zero deck clearance, but don't take this as an absolute value.

[gary roth]

WCraigH, thanks for the info, Packard V8 specs seem to be mostly fractional, bore spacing is 5.125, block deck height is probably 10.625, this would leave a deck clearance of 0.015, which is about right.

[WCraigH]

Bore spacing is 5.000" [color:"red"]NOT 5.125". I measured my bare Panther block to verify. That 5.125 number is from a website somewhere (I saw it once, but did not bookmark it). Anyway, 5.000 is plenty big, same as Chrysler Hemi.

[55PackardGuy]

Craig,

Absolutely correct. According to the Packard engine specs from their engineering paper on the V8, re-printed in the Summer '91 Packards International, the bore spacing is specified at 5.00"--don't know where that other number came from, but I also remember seeing it somewheres.

[gary roth]

Sorry about the misinfo, I wrote to Packards International and asked them what the Packard V8 bore spacing was, they said 5.125, thank you very much for correcting me ! <img src="http://www.aaca.org/ubbthreads/images/graemlins/blush.gif" alt="" />

[55PackardGuy]

Gary,

They gotta start reading their own magazine! BTW, that Summer '91 issue of PI is available for just a few bucks from the publisher, and has a very thorough writeup on the Packard V8 development and specs. Also, lots more goodies on the '55 and '56 models. <img src="http://www.aaca.org/ubbthreads/images/graemlins/cool.gif" alt="" />

[Guest]

Greetings, All,

When I measure my 352 pistons, I get a piston compression height of 2.070", plus a book spec for .035" minimum piston-to-head clearance, minus a .025" gasket thickness, which by my math, would make the ablsolute block deck height somewhere between 10.55" and 10.566"

thnx, jv.

[gary roth]

Thanks for the input, 56J-PackardV8, the 352 has less compression than the 374, so it stands to reason the 352 has a lower piston compression height than the 374, assuming Packard used the same heads on all three V8 engines.

[Guest imported_PackardV8]

According to the service manual under heading of "Pistons:" "Height Centrline of pin to top" is 2.072 for ALL 1956 engines. The increase in CR for the 374 is probably due to the bore increase or possibly upper ring position or just a specification over embelishment.

[gary roth]

I just got my 55-56 Packard service manual from Kanter. I took an engineering ruler and calculator to Fig 4 - transverse cross section - in the engine section and made measurements. Cam to crank center to center appears to be a dead even 5.00. Block deck height appears to be about 10.69 - if its fractional it would be 10 11/16 - 10.6875. Piston pin height for all Packard V8s is listed at 2.072, con rod length is listed at 6 25/32 for all Packard V8s - the 6.7182 listed elsewhere is apparently a typo and should read 6.78125. With 3.50 stroke for all Packard V8s, half stroke 1.75 + 6.78125 + 2.072 = 10.60325. Apparent block deck height 10.6875 - 10.60325 = 0.08425 deck clearance.

[Guest imported_PackardV8]

" Apparent block deck height 10.6875 - 10.60325 = 0.08425 deck clearance. "

Thats nearly 1/10 inch!!! Isnt that alot??? I have seen very few engines where the top of the piston is not FLUSH with the top of the cylinder.

[gary roth]

PackardV8, I agree with you 100% that the deck clearance is suspiciously high here for an OHV. Flathead Fords ran 3/16, 0.035 is typical of an OHV. Bear in mind that we both know that measuring illustrations in a service manual is no reliable way to get specs. But until a sound source comes along for the last piece of the puzzle - the deck clearance - what else do I have to go by ? <img src="http://www.aaca.org/ubbthreads/images/graemlins/confused.gif" alt="" />

[Guest imported_PackardV8]

lets make sure i'm on the rite track here. When i say deck clearence (in terms of the previous posts) i mean the distance or clearence between the flat crown of the piston and the surface of the block to which the cylinder head mates. Is this what we are talking about here???? I have a 56 352 short block (no heads) that i can measure. But i will be very surprized if it more than .015 and i'm expecting ZERO +- .005

[gary roth]

PackardV8, the deck clearance as you describe it is the same defination I have, if you would measure it I would appreciate that very much.

[Guest imported_PackardV8]

ed roth rote:

"What is the block deck height - from the centerline of the crankshaft to the block deck - of the 1955-56 320-352-374 CID Packard V8 engine ? "

I took a direct measurement using a machinist square: 10-21/32. My measurement will be off a little unless someone wants to send me scrap REAR main bearing shells and a piece of tubing or round stock 2.5 inches in diameter at least 6" long. U probably see how i got my measurement above without explaination. The piece of tubing i used was not real desireable but its all i could find and i dont have any rear bearing shells

[Guest imported_PackardV8]

Deck clearence from 5672-1834 115K+ miles : 0.023 - 0.025 MAX! I measured only one cylinder using 6" machinist rule and feeler gauge pack. All carbon was cleaned away. I'm surprised its that much. If i remember rite the head gasket is .025.

[gary roth]

From my 56 Lincoln shop manual : 368 CID crank main journal is 2.6239, block main bearing bore is 2.8164, difference is 0.1925, half that is 0.09625. From my 58 Lincoln shop manual : 430 CID crank main journal is 2.8998, block main bearing bore is 3.0926, difference is 0.1928, half that is 0.0964. Note the 0.09625 and 0.0964 include some clearance, so a typical main bearing shell is probably about 3/32 thick. If thats a bare block you took the block deck ht from, you could measure the block main bearing bore, take half of that, and add that to the main bearing bore to deck surface measurement. Thanks, PackardV8.

[Guest imported_PackardV8]

Roth wrote:

"If thats a bare block you took the block deck ht from, you could measure the block main bearing bore, take half of that, and add ...?

Well yeah, BUT the problem is setting up the measuring equipment to do this acccuratly for say even +/- .010 inch on that large of a span. We are talking about a measurement of about 10 inces and none of my precision tools go that big. Even if one has a precision depth gauge of 10" capaicty there is still a problem in that the mains are not reasonably well in line with any part of the bore to use the tool.

What is needed is a piece of round stock that will precisely fit thru two of the mains and then measure down thru the bore to the round stock. I believe a pieced of 2.5 inch tailpipe stock would probably be close enuf for any precision needed to meet production variances.

Yes i have 3hree BARE blocks. But no bearings and no 2-1/2 tailpipe stock thus long enuf to span two mains.

What kind of precision are we looking for anyway??? I'm guessing that production (not print spec) probably varied by at least +/- 0.005 inch on deck height.

[Guest imported_PackardV8]

Post deleted by PackardV8

[WCraigH]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">(snip)What is needed is a piece of round stock that will precisely fit thru two of the mains and then measure down thru the bore to the round stock. I believe a pieced of 2.5 inch tailpipe stock would probably be close enuf for any precision needed to meet production variances.(snip)</div></div>

OR, a Tool & Die quality microflat table with matching QA height measurement tools. That's what my old racing partner used to own. One time we got a "finished" machined block back from one of the "famous" engine builders (I believe it was Keith Black) in SoCal, but because it was a Pontiac (Packard would also applicable), I guess they let one of their "junior" machinist do the machining. As measured on the above Aerospace-quality equipment, the deck height was not only off side-to-side, but also varied from front to rear by more than 0.010"! We sent it back to that shop with a "Hughes AeroSpace QA" big red rejection tag on it! Needless to say, it came back correct the next time and so did anything else we subsequently sent to them.

Unfortunately, I don't have access to that kind of measuring equipment anymore...I'm in the same boat as PackardV8 nowadays. But, it does give one pause about what kind of aftermarket machine work that is being done, especially when one doesn't have the measurement tools to really check it properly. I'd trust the original Packard machining above anything else.

[Guest imported_PackardV8]

Craig wrote:

"We sent it back to that shop with a "Hughes AeroSpace QA" big red rejection tag on it! Needless to say, it came back correct the next time and so did anything else we subsequently sent to them."

Yep, one of the most bragged slogans of the business world is "know your customer". TRANSLATED: know what u can get away with. This is especialy true of the classic car and especialy classic MC world. It never ceases to amaze me how some so-called mid level managers are such lemmings when it comes to understanding that concept.

Nonetheless, fairly accurate measuring can be improvised using some basic precision tools such as mics, with drill rods and bearing balls etc. Its just a matter of how large they can span. Most of my large precision measuring tools stop at about 6". OR they are at least close enuf to set up roller bearing rod journals on Indian and HD engines.

[55PackardGuy]

According to the Engineering Paper on the Packard V8, which appears in Summer '91 issue of PI, the Quench Area between the piston and head at Top Dead Center has .045" clearance. See attached drawing.

[Guest imported_PackardV8]

You're right. i double checked my documentation and it is .045. I deleted my erroneous post.

[55PackardGuy]

Now if they only had a deck height measurment for the block... it seems they give everything else but. <img src="http://www.aaca.org/ubbthreads/images/graemlins/frown.gif" alt="" />

[gary roth]

Accurate to the nearest 1/32 would be plenty accurate for my purposes. You said earlier that you made a measurement of 10-21/32 not including the bearing shell. Well, if the bearing shell is 3/32 thick, does that mean that the block deck height is 10.75 ? Book specs for stroke, con rod, pin ht + your deck clearance measurement = about 10.625 block deck height. Im just trying to find out if deck ht is 10.625 or 10.75 probably one or the other. Would prefer to go by direct measurement of block, the iron doesnt lie, book could be wrong.

[Guest imported_PackardV8]

Go with the 10.625 for now. (someone else made that calculation - i did not double check his math). The 10-21/32 i came up with sould be taken AS-IS without adding or subtracting for anything. The descrepency between my measurement and the mathematical computation is due to the lack of precision of the cylindrical slug i improvised thru the main bearing to take the measurement with. I installed the slug in the block and rear main bearing cap withOUT the bearing shells because i do not have any shells. It should make no difference if the measurement is made with shells or without shells other than the 1/2- diameter measurement that would be taken into account for subtracting.

[gary roth]

Thank you, PackardV8, for your help. Like the old Packard slogan goes : " Ask the man who owns one " - Ive done a lot of that lately - and I really appreciate all of your help. <img src="http://www.aaca.org/ubbthreads/images/graemlins/crazy.gif" alt="" />

[Guest imported_PackardV8]

Gary Roth: click on the attachemnt in the very FIRST post of the following link to see one of my mock-up toys for taking measurements and other testing.

http://www.aaca.org/ubbthreads/showflat....amp;amp;fpart=1

[Guest]

Gary,

Interesting debate on the deck height and now the rod length. The 1956 Studebaker Shop Manual, the Packard Serviceman's Training Book and the 1956 Hot Rod Magazine technical article list rod length as 6 23/32" and/or 6.71875". The 1955 Society of Automotive Engineer's Technical Paper, written by Packard engineers, shows 6.781", which would equate to 6 25/32", but I have not seen this fractional figure published.

I just measured with a 1/100" steel ruler. The distance from the piston pin to the centerline of the rod is 6.300". Taking 1/2 of the pin diameter of .980" = .49". Adding the two gives us 6.79" or confirming the 6.78125" as the rod length.

Hard to believe that typo survived the type proof reading normal in those days.

Now, deck height: I just measured with the same 1/100" steel rule and got 9.39" to the bearing surface + 1/2 the 2.499" main bearing diameter (1.2495")+ .001" bearing clearance per side and we have 1.6405". Given Packard Engineering's penchant for fractions, they probably drew it at 10 5/8".

thnx, jv.

thnx, jv.

[gary roth]

Thank you, 56J-PackardV8, for shedding more light on this topic. It seems Packard wasnt the only one with a fondness for fractions - many of the flatheads, and even some early OHVs from other makes are largely fractional specs.

[gary roth]

Thank you, 55PackardGuy, for the quench spec. That was the last piece of the puzzle. The illustration you posted made it crystal clear.

[55PackardGuy]

Glad it helped! <img src="http://www.aaca.org/ubbthreads/images/graemlins/smile.gif" alt="" />

[55PackardGuy]

That's easy:

For information on Packard Motor Car Company®

please contact:

Roy Gullickson

Packard Motor Car Company®

P.O. Box 5506

Goodyear, AZ 85338

Phone: 623 853-0681

Fax: 623 853-0682

Email: packard@futureone

I've actually e-mailed this fellow, and sent him a copy of the discussion thread about "what makes a Packard" with all the neat ideas about specs and styling. He answered me once, but never took me up on the invitation to visit us on-line.

The web site address is www.packardmotorcar.com