Is it necessary to use an external tachometer to check/set the idle speed on a 22R-E or is the dash tach accurate enough?

 

If it were me, which it's not, but if it were, I wouldn't trust the internal tach to be accurate enough to set the idle or the timing.
Even a Harbor Freight cheapie I would trust over the internal. Mainly, you don't know if the internal was ever calibrated. A commercial one, even a cheapie, was probably calibrated, if nothing else, before it left the factory.

All calibration concerns aside, it's a lot easier to have the tach right in front of your face when doing the adjustments, isn't it? Rather than changing the setting of the idle speed screw a little, running around to look in the cab, running back out, adjusting the screw a little, etc etc, it would be MUCH better to have the tach staring right at you as you adjust the screw.

All this is just my opinion, of course. I don't know the Toyota calibration setup, so who know how well the gauge was calibrated when it left the factory. By the same token, how long ago was that, and how much has it's cal drifted over those years? Even the cheapie tacs have an easy to use calibration adjustment screw on the face you can use to set it's zero before you use it. Maybe not the best way to calibrate it over a wide range, but it's a lot better than no adjustment at all. No adjustment at all is what the internal tach has, isn't it?

Good luck to you!
Pat☺

 

yep, I set idle with the timing light. The dash isn't accurate. That's mine though.

 

No way to set the calibration, or even zero it out before starting the procedure.

Just my 2 cents worth...
Pat☺

 

I am willing to bet that the factory tachometers were accurate when they were new, and would have been just fine to use to set the idle "back in the day".

However, after 30 or more years of use, it is certainly possible that the factory tachometer isn't as accurate as it used to be. You can verify the accuracy of the dash tachometer with an external one.

You can adjust the factory tachometer, but you have to take the instrument cluster apart and adjust a little potentiometer soldered to the tachometer circuit board, which isn't easy (well for most of us). The factory tachometer has a "zero stop" pin, so its resting position will always be zero unless something is broken.

For what it's worth, the factory repair manual procedure shows hooking up an external tachometer to check engine speed.

 

I should have specified by timing light I mean with the built in external tachometer and according to the directions. My built-in tachometer is off by a few hundred if I could make out specifically where it's at. 😉

 

No it is not necessary. If you have a calibrated pulse counter with a currently valid certificate it wouldn't hurt to compare the two, but if you had that you wouldn't be asking I don't think..

I'll trust the old grey beards at Toyota over the guys slapping together HF or any other big box chain's tools.

An inductive pickup is way more error prone than the hardwired tach signal in my experience.

 

You have an after-market tach installed, is what you're saying?
If so, that will work. I have an pretty old, but still accurate if I zero it before I use it, tach/dwell meter. I needed it to set the dwell on the points on my 78 Chevy Love. Small pickup, 4WD, 4 speed manual, manual hubs, kinda thing. Actually, I found out from a dealer it's an Isuzu Trooper II with a Chevy body on it.
Anywho, being the cheapo SOB I truly am, I still use it to set the idle speed on my 4Runner, and pickup. Still works great. Don't need the dwell part of it, any longer, as points are a thing of the past. I'm glad, too. I was always cleaning them, filing them down flat again, and then setting the dwell, which is a real pain. Every Saturday, before I went 4 wheeling out around Yuma, I had to "do" the points. Not any more!
I traded the Love for my Toyota pickup, and haven't looked back ever since. Few years later I got the 4Runner, same color as the pickup, pretty cheap for the time. Still have, and drive, both of them, and I love em both

Have fun!
Pat☺

 

I set my tach with a dwell meter.

 

Yep! Mine's like that, but it's wedge shaped, with the meter on top, the switch down below, and the wires coming out the bottom. Wires are a lot longer, too. It's made for working under the hood easily, you know? Same dial, though. Really nice having a Volt meter included, but use it almost exclusively RPM's. Not much use for the dwell portion any longer, for which I am grateful. Points were a royal PITA to keep operating at their best.

Remember to always zero the meter before use

Have fun!