StylishOne

56 engine questions..for those who know LMK

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Trying to learn best, most reasonable $ course to take with an issue. 

My 56 model 72 needs a drive-train. Found a nice running Special w auto donor. Can it be rebored to 9.5 compression, as it's an 8.9 from a Special? They are all 322's but Roadie is  255 horse n Special 233? Were Specials a 2 barrel, n Roadie a 4?  Is this best way to get her moving or should I find a Century, Super, Roadmaster engine to redo? and is that worth it?

Some car guys are suggesting I go modern under the hood, though I always preferred original. 

Suggestions, advice? 

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The block & pistons are the same, but other things are different. Compression was changed by the top end. Some say the heads are different, some say it's different thickness head gaskets. I've tried to find a parts manual to get the definitive info, but as yet I haven't. Yes, a Century or Super will have an identical engine to your Roadmaster. If you have to settle for a Special engine, finding a 4bbl intake is not difficult. Not cheap, but not difficult.

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The shop manual says the low compression Special uses different pistons in section 2-4. All the gaskets are .015" thick. 

Edited by Beemon (see edit history)
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On 11/9/2018 at 11:10 AM, Beemon said:

The shop manual says the low compression Special uses different pistons in section 2-4. All the gaskets are .015" thick. 

 

As I recall, the Syncromesh (lowest compression) Special also gets a different cam. 

 

Buicks.net lists two different castings for ‘56 heads. Reportedly, one has smaller chambers than the other, but I haven’t had the pleasure of having both side by side to compare. 

 

http://www.buicks.net/shop/reference/nailhead_casting_numbers.html

 

For what it’s worth, running the 4bbl on a lower compression configuration  is probably a nice compromise on modern pump gas. 

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A review of a 1960 Parts manual reveals the following regarding a '56 322:

 

There is a cam shaft difference between a 56 Dynaflow and a C.T. (Stick shift) transmission drive train.  There is no cam shaft difference between any engine followed by a Dynaflow transmission.

 

 

1112181616.thumb.jpg.2a6fa00d82e0db6fead056422e60f8e1.jpg

 

Heads are the same regardless of the transmission option.  Also noted this book shows the 55 heads are the same as a 56.

 

1112181615.thumb.jpg.ad78c0aa5a5193b6f82be90be3aec14f.jpg

 

Pistons are different for a Special , and within the Special line, different for a Dynaflow and a CT transmission option. The next two pictures reflect one chart.  I just could not get the top line in with the 56 Piston information.

 

1112181611b.thumb.jpg.9f3d0700c8d60c0372128d4952401558.jpg

 

1112181611a.thumb.jpg.3e56bdbe3a23bc532ae62660b3518907.jpg

 

So,  to answer the OP's  original question, I would wait and look for a 56 322 from any other series than a Special if you really are concerned about the horsepower difference.

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24 minutes ago, JohnD1956 said:

Also noted this book shows the 55 heads are the same as a 56.

Nope.  Yeah, that is what it shows in 1960, but the part number for the 55 cylinder head in the 55 parts book is 1391947.  The 56 pistons had a higher dome and more surface area of the dome than 55 and the 56 heads were opened more on the periphery.  The 56 head will fit and run on a 55, but with lower compression and in 1960 with the cars 5 years old, who cares or notices.

55 heads used with 56 pistons will give higher compression, but will sometime hit the head, especially if aftermarket pistons are used.

The 54, 55 heads were actually developed for the 264, but used on the 322 after some experience with the 53 322 engine.

Russ Martin:  HEADS INFO

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That's a very good point Willie.  My book is from 1960.  It cannot be used to say that these are the original parts, but rather what was considered acceptable as a replacement in 1960.  So there very well could have been different '56 heads, in 1956, for various engines.  

 

But the information posted does seem to indicate that there was differences between engines for Specials,  and engines for the rest of the models.  As to the original question on this thread: Can a Special's engine be rebuilt to meet the specs of the other models engines?  I would say just about anything can be done.  But it seems to me that it would still be better to find an engine from one of the other models to start with.   

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That's what I'd like the proper motor, since a the trannys once they're "auto" are the same, right? 

Still hunting for complete Century- Roadmaster running gear I guess..

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John, your book probably says 55 because done 55s were fitted with "56" engines. If it came with valve cover breathers and the heated carb base manifold, it was a 56 engine. 

 

I bet the low compression pistons in the special were 55 pistons. 

Edited by Beemon (see edit history)

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There is a lot to be said for putting a modern, warrantied crate engine in. However, you likely will need a brain box.
An updated tranny means an OPEN drive line and rear end pumpkin. Kiss the torque tube goodbye.  You will need to then link up the rear end/axle housing with trailing arms. Chev C-10 long trailing arms and axle housing u-bolts work great for this. The torque tube and it's arms cannot  be used in any manner what so ever. If you can find a 61 Invicta pumpkin, it will bolt right up to the rear housing--no kidding--and the '56 axles will slide right in too.

Rebuilding the 322 Nailhead isn't rocket science, but you have to remember that the engine is 60+ yrs old and most mechanics have never seen one. Hot rod shops will take on the project, but you could lose the block to over zealous drilling, grinding, boring etc. Valve guide updates can be the death of nailheads due to the water jacket being easily damaged.  I'm sure every Buick guy will tell you to be super careful in your mechanic selection process.

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You mention you need a drive train but comments are about the engine only. If you also need a new Dynaflow the Roadmaster/Super output shaft and housing is longer than the Century/Special. Not a big job to switch out from your old transmission (if you have one???) to the new transmission but if you don't have an old one get a replacement transmission from the large body series'.

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21 hours ago, Gene Brink said:

You mention you need a drive train but comments are about the engine only. If you also need a new Dynaflow the Roadmaster/Super output shaft and housing is longer than the Century/Special. Not a big job to switch out from your old transmission (if you have one???) to the new transmission but if you don't have an old one get a replacement transmission from the large body series'.

In 1956 all dynaflow transmissions were the same for all models...the earlier cars (54-55) had different lengths depending on the model.

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From what I've observed others to have mentioned over the years of watching these discussions, you pretty much have to duplicate what's correct for the pre-'57 Buicks and their engines, UNLESS you do a large amount of extra work to use the incorrect model year items.  Old-Tank knows the '55 Buicks inside-out and sideways, by observation.  NOT book-larnin', either!  Additionally, some things that might be suspected to not change between model years DID change and need to have coordinating parts to go with them . . . no mix-n-match in so many cases.

 

On the issue of pistons, I've seen a listing for "Export" pistons for Specials.  Something like a 7.5 compression ratio?  IF that matters.

 

The best way to know what's really accurate for the vehicle, with respect to GM-Buick parts, is to have the first edition of the particular model year parts book, which came out in the fall of the year for the new model year just beginning.  It normally used to have a front section of parts that were new for that model year, to allow parts managers to see what new parts they might need to order.  The later editions of the same book, printed after the first of the year didn't have these things.  By the time the later model year books are out, the earlier cars' part listings will reflect part number changes and even part application combinations.

 

As to the noted cylinder heads being superceded into just one part number, that seems a little unusual, to me.  If the 'earlier heads were designed for the 264, I would perceive that the port sizing was good for that engine size.  IF the same head could work well with a 322, then it should be over-sized for the 264 from the start, possibly.  In reality, the smaller ports (IF that is the actual case) of the 264 head would possibly (with the same CR) make a bit more low-end torque response but hinder higher rpm power a bit.  Which might explain why the "smaller" heads were superceded to later work on the larger 322s and nobody noticed.  Back when it was starting to be fashionable to have an OHC motor, in the earlier '80s, a Buick rep was quoted as saying "For our customers, acceleration ends on the other side of the intersection."  No real need for higher rpm power, typically.

 

In the case of the particular model year where all engines were 322s, I suspect the main power differences between the Specials and the other Buick cars, other than the noted camshaft issues with manual transmissions, was due to the 4bbl carburetor, with a little help from the higher compression ratio for the higher-line cars' engine.  BUT you'd probably need at least 1/2 throttle to feel any difference, in normal driving.  IF you could modify the intake manifold to use the larger Rochester 2bbl (the 1.69 throttle bore size which some Pontiacs used back then), it would possibly have as much real air flow capacity as the 4bbl had . . . which would make it an incognito upgrade, of sorts.  Might need a Pontiac air cleaner, which might have some cosmetic differences, though.

 

Just some thoughts,

NTX5467

Edited by NTX5467 (see edit history)

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I thank you for your input..I'm, not a mechanical person. Most engines available today are from Specials, luckily most are autos.

My Roadmaster has been off the road for many, many  years, being separated from its original motor during those years.

So in my view, if I put a 4 barrel carb set up from a Super with a dual exhaust on it on my Special block, that should render me pretty close in punch to the 255 it had to start with?? Still can't find an Air cleaner for 4 barrel tho, (if anyone knows a replacement type that fits lmk.).

Okay guys, who know mechanics really well, whats the verdict?..

 

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If the above information is correct, and the pistons are the only difference between a Special 322 and a Roadmaster/Super 322, I'd have no reservations about using an engine from a Special.  I doubt you'd notice the difference in power, and you may even be able to get away with less expensive gas; however, I'd really go over this thread and do my homework, because it sounds like Buick changed a lot of parts over the course of a couple of model years.  I'd want to truly make sure everything you have will fit together.  Good luck...I enjoy getting a mothballed car running again, even though the process is often rife with frustration.  

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