Chrysler Big Block redline??

[Sir Dodge alot]

As the title says I'd like to know what the redline is for Chrysler BB's in particular the 361, I suppose a 383 is close enough candidate as reference.
Recently I have completed my Pushbutton A727 rebuild & installed a Transgo TF-2 kit with a 2000 stall converter from Hughes performance converters.
Rear gear is 2.76

The motor is stock with potentially a 256/256 cam.
It does have a forged crank which I hope the crank being forged raises the max RPM threshold.

The WOT at 2nd gear will shift just past 4800?/5000? RPM, but I tend to let off at around 4800.
I'm afraid of potentially blowing the motor if it does hit 5000 RPM.

Is 5000 RPM a "safe" WOT shift? Are Chrysler big blocks even capable of hitting 5000 with no unseen unfortunate events to occur?

Thanks for your input.

 

[Davea Lux]

As the title says I'd like to know what the redline is for Chrysler BB's in particular the 361, I suppose a 383 is close enough candidate as reference.
Recently I have completed my Pushbutton A727 rebuild & installed a Transgo TF-2 kit with a 2000 stall converter from Hughes performance converters.
Rear gear is 2.76

The motor is stock with potentially a 256/256 cam.
It does have a forged crank which I hope the crank being forged raises the max RPM threshold.

The WOT at 2nd gear will shift just past 4800?/5000? RPM, but I tend to let off at around 4800.
I'm afraid of potentially blowing the motor if it does hit 5000 RPM.

Is 5000 RPM a "safe" WOT shift? Are Chrysler big blocks even capable of hitting 5000 with no unseen unfortunate events to occur?

Thanks for your input.

Is the engine a well used original, or has it been rebuilt? You can get away with 5k on a fresh engine but there is not really any good reason to rev it that high for street use. You should also be running high performance valve springs, the factory buffered units would be fine for street use. Are you running dual exhaust? Your high end potential is limited with the stock exhaust. I would suggest since i do not know much about what else has been done to your engine that you set up a dyno appointment and set the shift points where ever your engine hits peak torque.

Dave

 

[Sir Dodge alot]

Is the engine a well used original, or has it been rebuilt? You can get away with 5k on a fresh engine but there is not really any good reason to rev it that high for street use. You should also be running high performance valve springs, the factory buffered units would be fine for street use. Are you running dual exhaust? Your high end potential is limited with the stock exhaust. I would suggest since i do not know much about what else has been done to your engine that you set up a dyno appointment and set the shift points where ever your engine hits peak torque.

Dave

Hi Dave, thank you for the swift response.

Regrettably the odometer stopped working 3 owners ago with it reading 94K miles.
But if I had to guess a mileage, it's probably somewhere around 120K miles since I drove the car back and forth to college as my daily.

But the engine is very much original and stock, aside from it's life started as a 2 barrel WWC Stromberg carburetor, it now has a #2806301 (1969 4 barrel intake manifold) that has been gasket matched. The head are the 516 small exhaust valve heads.
And a Carter AVS, And J spark plugs.
Step up rod springs to a lighter set to keep fuel economy up at cruise.
HEI style cap, (non HEI ignition, stock single point ignition)
8.8? MM plug wires.
Stock distributor single point with lighter weight springs.
Initial timing at around 15/17 BTDC
Timing chain replaced for a double roller timing chain to replace the stock worn one.

Some minor induction modifications.
And some other "hot" speed tricks I learned from old timers.

It's a single exhaust system with cast log manifolds.
The shifting is factory also, no modifications to the governor. But I do recall before I installed the new TC the trans shifted from WOT at around 4200 RPM?

But truthfully as you say, the top end performance is limited for sure, just the occasional straight road WOT romp.

I'll see if I can get some valve springs, something like the "beehive" shaped ones?? I've heard those are pretty good?

Just some optimization with factory parts before I even think about throwing some "serious" performance parts at it.
This is mostly a cruiser, so I'm probably barking up at the wrong tree...

Sorry if there was a ton of unnecessary information.

Thank you.

 

[Toolmanmike]

As the title says I'd like to know what the redline is for Chrysler BB's in particular the 361, I suppose a 383 is close enough candidate as reference.
Recently I have completed my Pushbutton A727 rebuild & installed a Transgo TF-2 kit with a 2000 stall converter from Hughes performance converters.
Rear gear is 2.76

The motor is stock with potentially a 256/256 cam.
It does have a forged crank which I hope the crank being forged raises the max RPM threshold.

The WOT at 2nd gear will shift just past 4800?/5000? RPM, but I tend to let off at around 4800.
I'm afraid of potentially blowing the motor if it does hit 5000 RPM.

Is 5000 RPM a "safe" WOT shift? Are Chrysler big blocks even capable of hitting 5000 with no unseen unfortunate events to occur?

Thanks for your input.

THose stock 440's make plenty of power at lower rpm. You don't need to twist it to 5000 to get there. 3500-4000 would be plenty.

 

[496 polara]

It's a single exhaust system

This will be the limiting factor (among others). I would imagine that cam is done by 4000rpm , 4500 max. It may rev higher but won't be making any more power than peak which has likely already occurred. That being said it won't hurt a thing motor wise. Set 5000rpm as your ceiling and you will be fine.

 

[Just Carbs]

I don't know about max rpm, but I can tell you that we run twin 440s at 4200 rpm full throttle for hours at a time in the big fishing boats.

 

[Lefty71]

The bottom end of a good or new 361/383 will happily do 5k. A motor in crappy condition with a half clogged oil pickup will spin a rod bearing!

If it makes power to 5k, id do it....if the powers falling off by 5k, then dont.....cuz its not doing anything for you at that point.

 

[CBODY67]

I would say that 5Krpms is "nothing to be worried about, period. As long as the engine makes no lower-area knocks or noises. With proper cam, induction, and exhaust, 6K is in its capabilities. Many of the NASCAR RB motors were running 7K for their races, as were the higher-level drag race motors. So the B/RB architecture is fine with those higher rpms than 5K rpms.

For an "as-produced" engine, it might do good to hit 5500rpm at WOT . . . with enough distance to get there with your axle ratio. Being that the factory 4bbl power peak was closer to 4600rpm or so. As to limiting factors, everything behind the exhaust valve on the car. Plus the stock cam's power range.

Chrysler normally set their automatic upshift speeds in the 4200-4400 rpm range, back then. A shift kit normally does not affect that, unless you get some new springs for the governor with the kit and they are installed.

Beehive valve springs were designed to keep the valve springs out of "coil bind" at high valve lifts, like over .500" lift, which your stock can is nowhere near at about .430" valve lift.

Without a good aftermarket tach installed, figure about 11mph/1000 rpm for 1st gear, 18mph/1000 rpm for 2nd gear, and 27mph/1000 rpm for 3rd gear, as general numbers. Then check the WOT 1-2 shift point and 2-3 WOT shift point against those loose figures (for your axle ratio and suspected tire size) to see where the engine speed might be at those road speeds. One night, I found out that our '66 Newport Town Sedan 383 2bbl would run 88mph in manual second gear at WOT. Took it a while to get there, though. 2.76 rear axle ratio and H78x14 tires. Which equated to its rated peak horsepower rpm. In high gear, available power vs wind resistance might knock it down to 115 or so, at best, although a 90mph cruise was just past the rated power torque peak rpm.

Have you replaced the timing chain yet? Or is it still the stock one? Just curious.

Enjoy!
CBODY67

 

[MEV]

I cant tell, but it looks like about 6000 in this video if you zoom in. It has a hemi govenor in the trans, i think i got it from A1

 

[Sir Dodge alot]

I would say that 5Krpms is "nothing to be worried about, period. As long as the engine makes no lower-area knocks or noises. With proper cam, induction, and exhaust, 6K is in its capabilities. Many of the NASCAR RB motors were running 7K for their races, as were the higher-level drag race motors. So the B/RB architecture is fine with those higher rpms than 5K rpms.

For an "as-produced" engine, it might do good to hit 5500rpm at WOT . . . with enough distance to get there with your axle ratio. Being that the factory 4bbl power peak was closer to 4600rpm or so. As to limiting factors, everything behind the exhaust valve on the car. Plus the stock cam's power range.

Chrysler normally set their automatic upshift speeds in the 4200-4400 rpm range, back then. A shift kit normally does not affect that, unless you get some new springs for the governor with the kit and they are installed.

Beehive valve springs were designed to keep the valve springs out of "coil bind" at high valve lifts, like over .500" lift, which your stock can is nowhere near at about .430" valve lift.

Without a good aftermarket tach installed, figure about 11mph/1000 rpm for 1st gear, 18mph/1000 rpm for 2nd gear, and 27mph/1000 rpm for 3rd gear, as general numbers. Then check the WOT 1-2 shift point and 2-3 WOT shift point against those loose figures (for your axle ratio and suspected tire size) to see where the engine speed might be at those road speeds. One night, I found out that our '66 Newport Town Sedan 383 2bbl would run 88mph in manual second gear at WOT. Took it a while to get there, though. 2.76 rear axle ratio and H78x14 tires. Which equated to its rated peak horsepower rpm. In high gear, available power vs wind resistance might knock it down to 115 or so, at best, although a 90mph cruise was just past the rated power torque peak rpm.

Have you replaced the timing chain yet? Or is it still the stock one? Just curious.

Enjoy!
CBODY67

Yes, the timing chain has been replaced to a double roller set from the manufacturer Cloyes.

It's got an Auto meter tachometer #2300, same gauge as the one in the video @MEV posted.

 

[Sir Dodge alot]

Thank you to all who have chipped in, very reassuring that the engine has got more RPM potential.

Up up and away! (Knock on wood)


Thank you very much!:
@Davea Lux @MEV @CBODY67 @Lefty71 @Just Carbs @496 polara @Toolmanmike @

 

[Sir Dodge alot]

I cant tell, but it looks like about 6000 in this video if you zoom in. It has a hemi govenor in the trans, i think i got it from A1

HA you beat that Honda Del Sol like he was standing still. Great footage much appreciated.
Shows that B/RB motors can do the RPM's.

 

[Sir Dodge alot]

The bottom end of a good or new 361/383 will happily do 5k. A motor in crappy condition with a half clogged oil pickup will spin a rod bearing!

If it makes power to 5k, id do it....if the powers falling off by 5k, then dont.....cuz its not doing anything for you at that point.

I have been changing the oil sooner than the regular mileage intervals, maybe every 2000 miles?

 

[Sir Dodge alot]

This will be the limiting factor (among others). I would imagine that cam is done by 4000rpm , 4500 max. It may rev higher but won't be making any more power than peak which has likely already occurred. That being said it won't hurt a thing motor wise. Set 5000rpm as your ceiling and you will be fine.

Gotcha, 5K RPM, time for the old Italian tune up!

 

[68PK21 440.6bbl]

Just a quick image from Nicks Garage's Dyno Pulls, granted most of what I watch are 440 builds and I've been always waiting for him to do a full 6.5k rpm pull as argumentatively can't be done on a BB Mopar but has been disproved with the 6.5k 440-6bbl/pack & Hemi rallye tach. Most I've seen Nick pull a 440 is to 6.2k, even the Hemi's he has been restricted by the customer(s) to 5.5k on the 'vintage' blocks as if he blows it up on the dyno he owns it.

1971 Plymouth HEMI Cuda 6.5k Tach

(edit) better picture quality


.

 

[Sir Dodge alot]

Just a quick image from Nicks Garage's Dyno Pulls, granted most of what I watch are 440 builds and I've been always waiting for him to do a full 6.5k rpm pull as argumentatively can't be done on a BB Mopar but has been disproved with the 6.5k 440-6bbl/pack & Hemi rallye tach. Most I've seen Nick pull a 440 is to 6.2k, even the Hemi's he has been restricted by the customer(s) to 5.5k on the 'vintage' blocks as if he blows it up on the dyno he owns it.

View attachment 671640


1971 Plymouth HEMI Cuda 6.5k Tach

View attachment 671651


(edit) better picture quality


.

Appreciate the pictures and the information, feels like I have the front row seats at Nick's!

6.2K... yup, I don't think I'm brave enough to go that high!
(Even if the engine is capable of getting there)

 

[Sir Dodge alot]

THose stock 440's make plenty of power at lower rpm. You don't need to twist it to 5000 to get there. 3500-4000 would be plenty.

Sounds good, was curious what the stock components would handle.

 

[Sir Dodge alot]

This was before I installed a Tach and just before I rebuilt the transmission.

But I could have been hitting 5000 RPM in one of the shots.

The intake ducting is not final in this video FYI.

 

[57fury440]

I've had quite a few Mopar big blocks over the years. None were stock and all of them would easily do 6,500 RPM. It all depends on the set up as in cam, lifters, heads, intake, exhaust. It is not necessary to rev these motors that high because of the big amounts of torque they make. I would think that getting 5,000 RPM from a 2 barrel, single exhaust 361 is doing good. If it was mine and it is an old motor I wouldn't push it that high.

 

[CBODY67]

Neat video. Hope you get an air cleaner on it soon as the DFW atmosphere can get gritty.

Be careful with over-tightening the secondary air valve spring. On the 9801 TQuad, seeking to do the same things you seek to, I managed to tighten it enough that it broke. Not good.

Take care,
CBODY67