289 Engine Redline

[RUNNER67]

Hi all,

What's the redline for a 289 without a load on it?

We have a fairly worn one up on jackstands, checking out all the basics, and got it revving really fast -- it was only afterwards that a friend told us we shouldn't run the motor at super high rpm without a load on it. Everything checked out great, and it still seems to run fine, but do you think we did any internal damage that will rear its ugly head later? We heard no snaps, pops, clunks, etc. I'm trying to put my son's mind at ease...

 

[2+2GT]

Depends on "how high". Some procedures require 2000 rpm. 6000 on a stock engine is bad idea, moving or parked.

 

[RUNNER67]

We THINK we ceased at 5100, and only held it there for a couple seconds.

 

[2+2GT]

We THINK we ceased at 5100, and only held it there for a couple seconds.

I've seen worse than that at cruise night.

 

[tx65coupe]

I doubt that it did anything. On a motor like that I don't see that there is much if any point taking it over 4k.

 

[6Stang7]

One issue that the old 289/302 blocks have is that, at high RPM, the block will start to twist which can cause cracking/failure.

 

[2+2GT]

One issue that the old 289/302 blocks have is that, at high RPM, the block will start to twist which can cause cracking/failure.

Interesting. Define "high".

 

[DJCarbine]

1. Rev engine untill rod failure
2. Back off a few hundred rpm

But seriously, on a stock 289 I doubt the head/cam are flowing or making any power past 4000-4500 rpm, they just fall asleep.

I run mine to 5300 intermitantly, it seems to make power up there with the intake/cam combination, and the motor has survived a few 6K rpm trips when the left foot just didn't want to switch gears just yet

 

[woodsnake]

IMHO, the down side to over revving an engine, either with or with out a load, is that you end up finding the "weakest link". On a fresh 289 with all new springs, valves, rings yada yada, a blip to 6K is no problem.

On a tired motor, springs have worn, valves are looser in the guides, the timing gear set is sloppy, and so failure is much more probable.

The difference between it having a load or not, would probably be the greater distance from home, I.E. ' Dude, I wound out that little 289 to 6500 rpm!! We were cookin'! and then I heard a noise, and then the motor locked up, it started smoking really bad, and I woke up in the hospital. It was AWESOME!! '

 

[blown65]

One issue that the old 289/302 blocks have is that, at high RPM, the block will start to twist which can cause cracking/failure.

I doubt he would ever see that point in a fairly stockish 289/302. You would end up with valvetrain issues before you see the block crack. Even then, its going to take a lot more than 5100 rpm for a few seconds in park to break a block, if even possible.

I would guess a rod would exit before the block would go on a situation like that.

 

[D.Hearne]

I doubt he would ever see that point in a fairly stockish 289/302. You would end up with valvetrain issues before you see the block crack. Even then, its going to take a lot more than 5100 rpm for a few seconds in park to break a block, if even possible.

I would guess a rod would exit before the block would go on a situation like that.

I was going to say the rods too, only in their case the rod bolts will be the failure point in a stock run of the mill 289 with high mileage.

 

[D.Hearne]

1. Rev engine untill rod failure
2. Back off a few hundred rpm

Good answer

 

[6Stang7]

Interesting. Define "high".

I was told around 6k-6.5k and above. One of my first part time jobs was working in a shop. My boss was building a race motor for SCCA racing for his 67, and brought this point up with me when we were working on his car one day.

doubt he would ever see that point in a fairly stockish 289/302. You would end up with valvetrain issues before you see the block crack. Even then, its going to take a lot more than 5100 rpm for a few seconds in park to break a block, if even possible.

I would guess a rod would exit before the block would go on a situation like that.

I agree that the rods giving out is by far a bigger worry. By all accounts though, it looks like block twisting was how his old motor failed. There was a nice crack that went from the oil pan surface to just pass the freeze plug. I can see an issue with reving the motor really fast. Cast iron isn't the best in elastically yielding, so I can see were a blind crack could develop and spread. How probable this is, well, that's another question.

 

[RUNNER67]

Thanks everyone... I checked it over, and the vacuum/timing/oil press/temp are still rock steady, no new sounds/vibrations/leaks, same slight wisp of smoke when you gun it, etc. I'm betting all we did was blow out some cobwebs. This motor has 214K miles on it (rebuilt at 100K), and is still going strong. My son has his eye on the car, but he'll have to put in some sweat equity to get his hands on it!