Engine Torque output for straight eight engines

sp&s700

sp&s700

Team Member
Dear Forum
I am looking for engine Torque values for the 320. Im not referring to bolt toruqe at all. All that is listed is engine horse power.
I have looked through all of my service books and the on line pdf service manuals here at Reference, and I could not find any torque engine output ratings. Does anyone here have such info or where I could find such information? In particular interested in the dual carb 320, 1947-1950 320 and the 1952 with 4 barrel.
Thanks
Clint
 
Motor's Auto Repair Manual for 1958 lists the 320.2 from '49 through '51 at 280 ft/lbs @2,000 RPM. For '52, same output, rated at 2,400 RPM. (They wound it up higher, but peak torque didn't change. ) In '52, BHP went up to 170 @ 3,800 from 152 @ 3,600 in '51. Compression ratio went from 7.2:1 to 7.5:1 in '52. TMI?
 
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Stray
Thanks very much no to the TMI. I found one of my books, poorly written, but it is very close to what you are showing. Im surprised that the torque did not go up on the 52 with the 4bbl.
Thanks again
Clint
 
I had another look in the Motor manual, in case I had missed something like a separate listing for the 4 barrel engine. But there is only the one, so it looks like the 4 barrel didn't boost the torque. Is yours a 4 barrel? It would be the pinnacle of Buick's straight 8s, I guess. It's interesting to me that its impressive 280 ft/lbs only edges out the Chevrolet 292 6 cylinder by 5 ft/lbs.
 
Stray Tate said:
I had another look in the Motor manual, in case I had missed something like a separate listing for the 4 barrel engine. But there is only the one, so it looks like the 4 barrel didn't boost the torque. Is yours a 4 barrel? It would be the pinnacle of Buick's straight 8s, I guess. It's interesting to me that its impressive 280 ft/lbs only edges out the Chevrolet 292 6 cylinder by 5 ft/lbs.
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Not really sure why anybody would think that bolting a 4 bbl carb on a otherwise 2 bbl intake manifold would produce more power? The 320 intake is worth about 240 cfm, on a good day, at sea leavel. The 4 bbl carb is worth about 325 cfm. The manifold won't move the extra cfm. Then there's the awful exhaust manifold... If you're going to get more power out of any of the 3 str8's you gotta fix the top end. Alleycat
 
alleycatoo said:
Not really sure why anybody would think that bolting a 4 bbl carb on a otherwise 2 bbl intake manifold would produce more power? The 320 intake is worth about 240 cfm, on a good day, at sea leavel. The 4 bbl carb is worth about 325 cfm. The manifold won't move the extra cfm. Then there's the awful exhaust manifold... If you're going to get more power out of any of the 3 str8's you gotta fix the top end. Alleycat
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Yes, what you said. Although there is the coolness factor attributed to having a four barrel, and the lovely whoosh when the secondaries open...
 
Stray Tate said:
Yes, what you said. Although there is the coolness factor attributed to having a four barrel, and the lovely whoosh when the secondaries open...
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Yup, it's me. Been out of the country for a while. So all my projects got not much more than a lick and a promise during that time. I'm getting back to it and I'll chip in my 2 bits from time to time here. And the 4bbl coolness factor, yeah, that why I'm gonna put 2 of 'em on my 263. What'll it sound like when all 8 barrels whack open? No clue. Alleycat
 
Stray, Thanks for the reply. I'm building a 320 1952, block to go in my 1946 Roadmaster. I have both the dual 2 and 4bll manifolds. The cylinder head has been milled .120" and cams have .020 lift. I'll be putting hydraulic lifters in. I relooked through my books and only one that shows torque figures is "Standard Catalog of Buick" 3rd edition, shop manuals only list Hp. The 52 shop manual states 168hp and not 170hp that seems to be the standard quote. The Standard Catalog of Buick has terrible proofing. Example on page 81 lists 280 @ 2400, yet for 1951 274@200. Yes 200 the other years show 2000 so proofingng reading for the book is not the greatest. As Ben states 280 @ 2000 seems right.
As for the the 4bbl I had one on my 1948 Roadmaster in 1975 .100 removed from head. She had noticeable more power than the 2bbl. Sorry for the late reply
 
Alleycatoo
Ive read youre older posts with much interest.
As to the 4bbl not making power, I have no experience yet with the dual twos, but if I get my 1946 Roadmaster running I will be putting on the dual 2 set up once vehicle is dialed in with the 4bbl.
I have a question for you. Did you cut down the skirts on the stock pistons? If so how much and what weights were you running for the pistons and pins?
 
sp&s700 said:
Stray, Thanks for the reply. I'm building a 320 1952, block to go in my 1946 Roadmaster. I have both the dual 2 and 4bll manifolds. The cylinder head has been milled .120" and cams have .020 lift. I'll be putting hydraulic lifters in. I relooked through my books and only one that shows torque figures is "Standard Catalog of Buick" 3rd edition, shop manuals only list Hp. The 52 shop manual states 168hp and not 170hp that seems to be the standard quote. The Standard Catalog of Buick has terrible proofing. Example on page 81 lists 280 @ 2400, yet for 1951 274@200. Yes 200 the other years show 2000 so proofingng reading for the book is not the greatest. As Ben states 280 @ 2000 seems right.
As for the the 4bbl I had one on my 1948 Roadmaster in 1975 .100 removed from head. She had noticeable more power than the 2bbl. Sorry for the late reply
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That 320 sounds like a fun project. The dual 2 and 4 barrel carb setups each have their theoretical advantages and disadvantages, coolness being a common advantage. The dual 2 setup (which I've never seen) has the complexity of linkage and syncing not a problem for the 4 barrel, (also never laid eyes on,) and a reputation for heavy drinking, and the 4 barrel has the same disadvantage as the single 2 barrel, that the remote cylinders get a leaner mixture than the near ones. Or so I'm told. Does the choke operate on both 2 barrels? I'm surprised to read that the valve lift is only .020", my Chev 6 being .050". Are you using stock Buick hydraulic lifters? I've taken advertised power and torque figures with a grain of salt ever since reading, long ago, someone's comment that "5 horsepower were added at the stroke of a pen."
 
Pistons. Yup worked 'em over plenty. I've got a original set of .010 over 248 pistons. I took off .625 off the bottom, cleaned and polished the top, and then, sent them out for moly coating. It's still a very long piston. Plenty stable. I ended up with a piston weight of 380 grams, including the pin. I did'ent use the 4th oil control 1 piece ring. So, total weight, likely a fuzz under 400g. 320 piston is exactly like a 248 piston, just bigger. The original buick piston is a suprisingly good piston and any oversize originals are likely long gone. Any new replacement is going to be much heavier. You won't get any where close to 400g but a lot can come out. Much more can't be done. There are a number of features in the stock piston I don't like. At the top of the piston there's a little machined groove, a " heat dam". Does not work. Fills with carbon and other junk. Under the ring pack is a slot on both sides. 'Post to be a "expansion slot". Does not work. Pistons this small don't have much, that is on the piston pin hole side, NONE! So, if you get your engine above a certain power level, what it is, I don't know, the piston top will break off between the "expansion slots" and park the top of the piston at the top of the bore. Power will fall off. And the piston is still very long. And the 4th ring. There's no fixing these features in a already made piston. So, you gotta make your own piston. Or get 'em made. I got Egge to cast me up a bunch of blanks. I made my own. Still a long piston but everything else is fixed. As a side note, Buick fixed everything with the piston in the 263. They knew all about it in the 1930's! And the piston making guys keep copying that old crapy piston.

The dual carbs: They are so good that the head becomes the restriction but DON'T set them up bone stock. The horsepower thing. I've measured everything in the str8, from start to finish they changed nothing but the power kept going up! I'm confused! Where did that power come from? Alleycat
 
alleycatoo said:
Yup, it's me. Been out of the country for a while. So all my projects got not much more than a lick and a promise during that time. I'm getting back to it and I'll chip in my 2 bits from time to time here. And the 4bbl coolness factor, yeah, that why I'm gonna put 2 of 'em on my 263. What'll it sound like when all 8 barrels whack open? No clue. Alleycat
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You could probably hear the ching ching at the gas pump cash register from quite a distance.
 
Stray thanks for the reply. Here is a pic of manifold and the carb carter upside down. The other is a dual 2 for the 320 intake port to port with the 4bbl. if this picture post I'll post others. Lets see what happens.
Alleycat if this works I'll post some piston pics so I under stand the area you talk about that collects carbon. And thanks for info on cutting skit down.
Clint
 

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Stray Tate said:
That 320 sounds like a fun project. The dual 2 and 4 barrel carb setups each have their theoretical advantages and disadvantages, coolness being a common advantage. The dual 2 setup (which I've never seen) has the complexity of linkage and syncing not a problem for the 4 barrel, (also never laid eyes on,) and a reputation for heavy drinking, and the 4 barrel has the same disadvantage as the single 2 barrel, that the remote cylinders get a leaner mixture than the near ones. Or so I'm told. Does the choke operate on both 2 barrels? I'm surprised to read that the valve lift is only .020", my Chev 6 being .050". Are you using stock Buick hydraulic lifters? I've taken advertised power and torque figures with a grain of salt ever since reading, long ago, someone's comment that "5 horsepower were added at the stroke of a pen."
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Ok should find the Cam spec for the buicks 248 and 320. I took 2 of my 320 cams to Oregon Cam grinding they added .020 to the lift. As to the 4bbl carb my other posts should show that the choke is on the front barrels. The back 2 have a lock out on the linkage so at about 3/4? throttle linkage is unlocked. There is a second set of flaps that are weighted, waiting for the air volume to move them open. Not unlike modern 4bbl and much like the rear carb on the stock 41 42 buicks dual twos which basically pioneered this idea.
 

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sp&s700 said:
Ok should find the Cam spec for the buicks 248 and 320. I took 2 of my 320 cams to Oregon Cam grinding they added .020 to the lift. As to the 4bbl carb my other posts should show that the choke is on the front barrels. The back 2 have a lock out on the linkage so at about 3/4? throttle linkage is unlocked. There is a second set of flaps that are weighted, waiting for the air volume to move them open. Not unlike modern 4bbl and much like the rear carb on the stock 41 42 buicks dual twos which basically pioneered this idea.
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Ummm...Well..Not exactly. Ching ching of bad gas mileage. In my 50 with about the most built up 248 that I could do at the time and running the original dynaflow, I get 19 mpg. The power is quite good. In fact, hard to complain about. I am now building the most all out, take no prisoners 263 with the 56 twin turbine dyna behind it that I can think of. Why? Just to find out what I can get out of the most advanced str8 made in this country. Mileage? Someplace in the 20's.
Cams. I've had 4 or 5 cams ground over the years. One at Comp the others at Delta in Tacoma. One mostly stock cam is mostly the same as any other stock cam. However 1 cam that Scott at Delta ground for me years ago was like "Holy Cow", 248 did'ent much like it but the engine was not much past stock. .421 lift intake, .370 exhaust [not much past stock] 223 duration in, 219 ex. But! Way faster lift than stock, 20 degrees ahead lift wise than same place on stock grind. Bit much for 248 but 263 at 272 will probably like it. We'll see.
Clint, I see that you don't have the dual exhausts on the dual 2's. Gotta have 'em. Or fab up headers of some sort, even better.
Carbs. For some unknown reason the guys at Buick seamed to be deathly afeared of any cfm going through the engine, thus, blockers of some sort on the carbs. Nuts! No cfm=no power. On the dual 2's you want to run the carter 1 3/16" 2bbl, 4 bolt base. Forget any of the 3 bolt base carbs, old early carbs . Won't work. Run 'em tandem, not progressive. Engine'll run like a scalded dog. Alleycat
 
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