Rpm

My wife is getting me a tach for Christmas....

Was the original 6,000 or 8,000 RPM?

I can't find in the FSM what max RPM is or "redline"

Thanks

(I know timgr will know this one)

 

For a stock pushrod engine, it's all over well before 6000, so there's no point in choosing 8000. Not that the engine is going to blow up, but that you'll have minimal power available at those RPMs, so why go there. I don't know what the original tach was like though.

Re redline, again I don't know that it's very meaningful on a stock engine. Are we considering a 258 or a 304? In either case, the peak HP is at a lot lower RPM than you might guess (304 = 4200, 258 = 3500). You may as well shift by that point. HP is basically torque times RPM, and the lower-RPM side of the torque curve is almost certainly going to be falling off slower than the higher-RPM side. Thus you're better off (in terms of reserve power) below the power peak rather than above it.

 

Thanks timgr....I knew you'd have the answer.

I'm running the 258 - according to FSM 100 HP @ 3500 RPM & 195 ft lbs of torque at 2000. - So I didn't figure going to the 8,000 would be worth necessary and I couldn't tell by the picture in my dealers' brochure.

 

Seems to me the 258 would output a lot more than 100HP

 

My 76 factory tach was a 6000 RPM and redlined around 4500 RPM. I can't see a 75 being much diferent.