Max safe cruising rpm for 360la?

[Dry Heat]

Just got my 69 Dart back together. I have a fresh 360la with ported iron heads, .501 lift square intake/exhaust comp hydraulic cam, .060 kb pistons, stock stroke, fully balanced, stock rods, arp studs throughout. Built 727tf. Msd electronics.
This is mostly a strip car. I test drove it for the first time today and it's 2500rpms at 55mph on a 27 inch tire. If I were to street this car what can I expect for a safe long distance or highway driving rpm?
Just don't want to blow it up, it's been years to get it up and running. Any info from the forum is welcome.

 

[abdywgn]

should be fine driving. my 73 3/4 truck had a stock 360 2-bbl with close to 100K, 4.10 gears and 28" tires and drive it to the track, race and come back home.

 

[AJ/FormS]

My math says that you are running 3.55s. That gear is about perfect for a street car. It would be pretty good for a stick car to trap at the top of third gear, but I think it is all wrong for an automatic strip car. That aside, I ran 3.55s at 55/60 for a few years, and many,many thousands of miles. It was a lil hard on fuel, but the rest of it looked perfect at tear-down time.
At the time I was running 245/60-14s so 65 was 3030 rpm.
My old 70 Swinger 340 had those same gears and E70-14s. That lil hummer drove everywhere at 70mph minimum. For 5 years before I sold it.
I had (still have) a 69 Cuda that I stole those 3.55s out of,and I drove that hummer for over 5 years at speeds around 65 as well.I live in the country, eh. It's 20 to 30 minutes to anywhere I want to go.

 

[yellow rose]

I run mine at 3600-3700 RPM.

Unplug the tach if it is bugging you.

 

[MopaR&D]

Just got my 69 Dart back together. I have a fresh 360la with ported iron heads, .501 lift square intake/exhaust comp hydraulic cam, .060 kb pistons, stock stroke, fully balanced, stock rods, arp studs throughout. Built 727tf. Msd electronics.
This is mostly a strip car. I test drove it for the first time today and it's 2500rpms at 55mph on a 27 inch tire. If I were to street this car what can I expect for a safe long distance or highway driving rpm?
Just don't want to blow it up, it's been years to get it up and running. Any info from the forum is welcome.

That's nothing, it will be fine. You can probably cruise at 3000 RPM, I do that in mine and it's no problem (FWIW I have close to 30k miles on my 360 including a couple across-state road trips). When you start spinning high 3-4000 RPMs that's pushing it IMO, it gets way hotter from all the extra friction going that fast and that of course tends to make things wear out faster...

 

[abodyjim]

I drove my dart from Kansas to Minnesota and back for a show. Then turned right around and took it on power tour a week later.. 557 solid cam 340 big carb 3000 stall. Swapped out the 3.91 for a 2.76 gear, ran 3000 rpm at probably 85 mph on both trips with no problems.

 

[rumblefish360]

I run mine at 3600-3700 RPM.

Unplug the tach if it is bugging you.

Ran my 4spd 4.10, 27 inch tires car at 34/3600 rpm for 4 or 5 years.

 

[CurtDawg510]

My 360 is always around 3500...sumtimes for hours... and sumtimes even up around 4000, but it really echos off all the cars

 

[stixx]

As long as it's not overheating and has enough oil in it you can drive it FOREVER at 2500 rpm or higher.

 

[T56MaxTorq]

Mopar gods blessed us with 6.123" rods. Piston speed is reduced so you can run a well balanced engine with no problems.

 

[318willrun]

you can run the rpm's without hurting the engine, providing you are not overheating. However, I personally cannot stand going down the highway sounding like the car is in 2nd gear. Gets the muscles in the back of my neck tense.

 

[stixx]

Mopar gods blessed us with 6.123" rods. Piston speed is reduced so you can run a well balanced engine with no problems.

Piston speed has nothing to do with rod length... but with rod angularity (a well beaten horse). But you are right, the longer rod theoretically helps reducing side load.
Piston speed is computed from stroke times rpm.

 

[Dry Heat]

Thank you for all the comments. I will stretch this small block out some. They are hosting a Hot rod magazine Roadkill drags race about 100 miles from me. So I'll just get some tail pipes on this car and drive it. What would be and expected fuel mpg? Don't really care just need to plan my fill ups. Has a 750 holley vacuum secondary carb on an air gap. Even added a dial to the msd to add or subtract timing while cruising.

 

[j par]

I've never shifted my 360 stroker under 5800 rpm's ...
heat is the enemy, not rpm's ....

 

[nm9stheham]

I'd expect anywhere from 8 to 13 mpg; you have not given enough detail on the cam, and none of us can tell how good/bad your AFR tuning will be at cruise, or your throttle habits.

 

[jbc426]

LA motors used in boats cruise at much higher rpms than one would think of as normal in a street car.

 

[moper]

LA motors used in boats cruise at much higher rpms than one would think of as normal in a street car.

.... and under a much higher load.

 

[j par]

Okay the first thing I need to say is that I'm extremely bored to be going this far! But for a rule of thumb on this thread I looked up an Industrial 318 and it was of the 1985 vintage to like run a big generator or something and it showed a 3300 RPM cruising speed. Now this likely isn't the (Fully balanced)LA 360 with custom parts inside and outside. And it's probably not running under the same torque conditions and heat cycling conditions. And in hindsight there's probably ten thousand different ways this rule of thumb could be tore up. Again I'm bored and I know how to use the voice command on my phone so I don't have to text all this stuff out....
EDIT : and lazy and

 

[IQ52]

I'd expect anywhere from 8 to 13 mpg; you have not given enough detail on the cam, and none of us can tell how good/bad your AFR tuning will be at cruise, or your throttle habits.

244/244 @ .050, 110 LSA not exactly a mileage cam.

 

[318willrun]

If somebody wants to know what it's like going from 2.76's to 3.91's in a true cruiser/street car, before you make the switch, just take a steady 80 mile cruise one way with the car in 2nd gear at around 60 mph for the distance. If that doesn't bug ya, then make the swap. It drives me nuts. The rpm's don't match the fence post going by

 

[rumblefish360]

244/244 @ .050, 110 LSA not exactly a mileage cam.

LMAO, yea man, been there on a similar duration. The daily driver was having surgery so I called apon the toy to make the 80 mile a day round trip to work.
10-1, 360 with the Purple 292/.509 cam, 4spd/4.10's, '73 Cuda. Even though "93" fuel was a whooping $1.50-ish a gallon, I went through a lot of it.

If somebody wants to know what it's like going from 2.76's to 3.91's in a true cruiser/street car, before you make the switch, just take a steady 80 mile cruise one way with the car in 2nd gear at around 60 mph for the distance. If that doesn't bug ya, then make the swap. It drives me nuts. The rpm's don't match the fence post going by

LOL, yea, that's about right. Funny stuff there. True as well.

 

[sorcerer]

LMAO, yea man, been there on a similar duration. The daily driver was having surgery so I called apon the toy to make the 80 mile a day round trip to work.
10-1, 360 with the Purple 292/.509 cam, 4spd/4.10's, '73 Cuda. Even though "93" fuel was a whooping $1.50-ish a gallon, I went through a lot of it.

LOL, yea, that's about right. Funny stuff there. True as well.

 

[rumblefish360]

"sorcerer,

You must reply outside of the quote tags. ;)

 

[sorcerer]

My mistake; sorry. But just to add a point of view on cruising rpm. The engine package will dictate where ideal cruising range should be. If high rpm is the goal by design ( cam, heads, intake, headers) let's say from 3000-7000, don't expect 1800-2200 will give you great efficiency. Crane cams specs on their cams suggest cruising rpm which should make best torque and fuel mileage. I personnally ran a 417 W2 stroker with 248-252 duration @.050 and .595/.584 and my best fuel mileage is when rpm is 3000-3200. I've tried different gearing and lost 4 mpg with 3.23 compared to 3.91. As long as temperature and noise is under control; cruising rpm can be quite high or low depending on engine parts combo.

 

[rumblefish360]

But just to add a point of view on cruising rpm. The engine package will dictate where ideal cruisin. I personnally ran a 417 W2 stroker with 248-252 duration @.050 and .595/.584 and

Agreed and that is a nice sounding combo.