I hope this does not seem too retarded a question. I was wondering if anyone out there knew what the realistic RPM redline is on a 1957 or early 261 inline six cylinder motor is. My motor was rebuilt stock and the only modification is the Pertronix electronic ignition conversion. I run the original 3 speed stick and original 3.36 rear gearing. I do not plan on thrashing this beautiful car but once in awhile i like to run it out because it always amazes me how this motor can really haul. George.
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1957 Pontiac Pathfinder Deluxe sedan restored 261 six
1974 Chevrolet Caprice Estate wagon low mileage original 400 V-8
Yep the 261 engines are really goog torque producing engines. If the 57 was originally a standard trans the rear diff is 3:55. The autos were 3:23. I did a lot of street racing in the early 70's with my 55 with the 261 and I surprised a lot of people. The 55 was faster than the 57 because of the rear gears and the 55 was a little lighter. I never ran a tack so I just shifted when it felt like it was not pulling anymore.
The 55 I have now I do not beat it up but I still let it go once in a while in first and second gear but I only granny shift it and I do not pull any hole shots. I am afraid to damage the trans or rear diff.
Al, my neighbour has a 57 Chevy Sedan Delivery, was a 6 stick but has a 355 V8 & we put an orginal 3spd back in it. I spun the rear wheel & counted the D/shaft turns & I think this might have 4:11's out back?? Could this be thats it's commercial?? Haven't got it on the road yet, but told him he may want to change that once he starts driving it. Pete
-- Edited by dualquadpete on Saturday 14th of August 2010 07:52:50 PM
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Some times I wake up GRUMPY, but today I let her sleep in !!!!!!!!BLACKSTOCK Ont.
4:11 was the gears offered in 55-56 with the 3 speed overdrive. It could have also been ordered by the dealer or dealer installed in 57. An SD being a delivery or work vehicle could of also been modified by an owner at some time.
Maximum HP is at 4000 rpm, maximum torque is at 2000 rpm (reference: Racer Brown article in May 1955 Hot Rod magazine), it is the torque which gets you moving quickly, there are indications that a well-built 261 can go to 5000 rpm but why on earth would you want to do that when it would be well out of ooomph well before then, and risk hurting the motor? As a practical matter on the street you might go as high as 3500 but Al's method (shift when you feel it not pulling anymore) is what I would do. Given the low torque curve, when mine was (for a short time) running, I never went over 3000 on my Sun tach and I could hear the motor starting to strain then.
Dave
-- Edited by davelacourse on Sunday 15th of August 2010 09:00:32 AM
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1956 Pontiac Pathfinder 2dr sedan, 496 - dyno'd 545 hp, stick shift, 4.11 posi - Hot Rod
Thanks for the reply folks. Yes i actually did think it might have been a 3.55 because it was in 55 and 56. I thought that both the standard stick and powerglide cars were both 3.36 in 57 with with that new change in 57. I do not claim to be any expert and there is always room to learn. I have always shifted by the seat of my pants and i was just curious about going the other way. I am 51 years of age and over the years at car shows i have spoken to many older guys who say the same thing that the 261 gave many a V-8 a run for the money. I thought maybe some of these stories were just deluded fantasies but now i think a good number of them were true. Thanks again for all the input folks, its always appreciated. George.
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1957 Pontiac Pathfinder Deluxe sedan restored 261 six
1974 Chevrolet Caprice Estate wagon low mileage original 400 V-8
I've had 6 old Chevy's with 235's, and the '59 Chevy 261 in my present '53 Chevy is the first 261 I've had. My last '54 Chevy truck I put 90,000 miles on as my daily driver. All the 235's I've had LOVED running at relatively low rpm's. Since the 261 is very much based on the 235 I feel it's limitations are similar.
My '54 Chevy truck, with the 235, loved running at 67 mph on the U.S. Interstate's. It didn't much like going 70, but 67 was it's sweet spot. I had 3.55 gears in the rear end of that truck. I did get it up to 95 a few times, but I felt I was pushing it's limitations to do so--I always felt a little nervous to do so.
Now that said, I've read plenty of articles and stories about 235's & 261's producing higher H.P. (at corresponding higher rpm's) with full-on race cams, double or triple carbs, fancy ignitions, etc. etc., but most guys are not going to put a full-race cam in their cars today. Me included. I want a little more power than the normal 235, and I want dependability. Running it out till it stops pulling is a good strategy, in my opinion.
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1953 Chevy convertible with a 261 inline six-banger.
Too check what rear end ratio you have jack up 1 rear wheel and put car in natural. Mark a spot on drive shaft and mark the wheel jacked up, now turn the wheel 2 full turns and count the turns of drive shaft. If the drive shaft turns 3 1/4 turns you have a 3:23 if it turns 3 1/2 turns you have a 3:55 and if it goes 4 1/8 you have a 4:11 ETC. With a posi rear you jack up both wheels and turn 1 full turn and count drive shaft the same way. BOSSY.
I know for a fact that if you do a 3500 clutch drop on one of these motors and the car hooks up real good, it will split the three speed into two pieces and the rear half will fly onto the ground. On a positive note, you WILL get a standing ovation from all the people watching this performance. Do not ask how I know this....... :(
1956 Pontiac Pathfinder 2dr sedan, 496 - dyno'd 545 hp, stick shift, 4.11 posi - Hot Rod