Inliners International Forums General Discussion Engines How many rpms does my 230 turn?

I'm putting my '64 GMC together with a stock 230 L-6, just headers and HEI, and I wanted to know how many rpms does it safely turn. These are torque motors, so I figured nothing past 4000rpm. I had my sights on this old school tach for it, 4k rpms. Does it safely turn any more rpms than that?

http://www.jegs.com/i/VDO/918/333353/10002/-1

Factory 250's turned to about 4800 shifted gears from the factory
So I am pretty sure a 230 can turn higher than 4800 w/no problems.

It won't make anymore power @ this high of RPM if it's stock.

MBHD

TwoFifty,
I wouldn't get a 4000 tach. Too low.
My stock 250 wants to shift at 4000-4200rpm with the stock 1v on top.
With a 4v Clifford it wants to shift at 4400-4600 depending on the carb. "Wants to" means that is where the best timeslips result.
You have headers already, so if you add a 4v it will want to shift at minimum 4600 - even with the stock cam.

As far as a rev limit, I think mine has seen 5000 though I usually shift at about 4500 as stated. It is a tired engine, about 10psi at idle, but it hangs together fine so far.

Hank,
Are you saying higher than 4800 is dangerous or just that the stock 1v doesn't breathe any higher than 4800?

I don't want to grenade my nice little 250, it's tired but valuable.

I could turn the stock 250 higher RPM than 4800,just from the factory w/a powerglide it was set to shift @ 4800.

I have held the rpm even higher than 4800,but the engine would just make noise (not valve float)& make less power there.

At 4800 on a stock 250,it did not feel like it made power there either,but if you made it shift earlier,the big drop in RPM from the PG would hurt the acceleration.

A TH 350 or 200R4 would keep the engine in the powerband & shift earlier then 4800 would have been better & let the torque push it through.

I would think if you had a Powerglide trans car & a TH 350 car,both being stock,I would imagine the TH 350 trans car, the factory set the shift points ealier than the PG equipped car.
Can't confirm this, I have only had a PG equipped car stock.


MBHD

I've got a 3speed column shift in mine. So I guess the consensus is it could turn to about 5K safely, but not much power about 4K, is that right?

Sounds like a good summary.
When mine was a 250-1v, 3spd on the tree, I used to shift at 4000-4200, pretty flat above 4200.

My car is a 3 in the tree, 250. I usually try to shift at 4200 when I'm trying to go as fast as I can. But WHY DOES IT SOUND SO LOUD past 4000? It's ROARING and sounds like it's about to explode by then...

Probably the fan.

Very good - I hadn't thought of that, but it's probably the source.
It's especially loud because there is no low-pitched intake moan (1 bbl. is too small), and minimal exhaust noise.

Deuce, what 1v and 4v mean? 4 barrel?

I've got a 1965 Nova wagon with a 230 inliner that I race on the occasional Saturday or Sunday in stock class. I run a 4.11 posi rearend and 24 inch tires. The engine has been rebuilt and still has stock valve springs, stock cam lift, Rochester monojet, Langdon headers, etc. I've had it on the chassis dyno which told me that maximum rear-wheel horsepower was 103 and the car reached this point at 4250 rpm. Horsepower stayed above 100 until 4500 rpm and then dropped after that. I usually shift the Powerglide at 4700-4800 rpm but have also shifted at 5000 rpm. I've taken it as high as 5500 without too much trouble. You're correct that a stock 230 will will turn 5000 rpm, but there's not much horsepower up there.

I actually bought the tach in the original post this week. It is going back as it was damaged in shipping.

Do you guys think a 4000 rpm tach would be good for my 292? it's just a cruiser and probably won't see the track.

Also if you exceed the limit on a tach, does it mess it up?

Yes, I meant 1v="1 venturi" = 1-barrel
4v= "4 venturi" = 4-barrel



Not sure if you over-rev a tach, if it would damage it.
I'd ask if you're buying one.
I have a tune-up tach and have over-revved it many times when it was set on "lo rpm" (about 1500rpm max scale) and no damage.

I'd get a 5000 tach even for a stock 292, but if you really want one and it only goes to 4000 and it will not be damaged if you outrev the tach, I suppose a stock 292 would not want to see over 4000 anyway, as it would run out of air even faster than a 230 or 250.