Doesnt hinder performance, but gets old when each passenger notices it. Has been becoming more and more apprent to me lately.

Tach will read fine on the "up" direction of revs, but lags on the way back down. and if im blipping the throttle, it bounces all over the place. But just cruising, the tach reads fine.


Any ideas on what I can do?

Try changing the points.

the old style tachs were just like that...electrically it can me modified, but the counterwieght is just so large that its going to bounce some no matter what you do.

if you want new-age tach operation, get a new-age tach

b

Mine bounced too and I found a shoddy connection to the 12v side of the coil. Once fixed it the bounce went away. I'd check the grounds too.

T

Ah, I think it's a sign that your points are going bad.

usually points, or some ignition based wire.
If you don't have points still, then check the wiring

brant

well that too...

drives ya crazy doesnt it.

b

Points and/or condensor going bad can cause this. So can wiring problems, as noted. Sometimes you just have to live with it, unless you want to send your tach to someplace like http://www.paspeedo.com and pay them a couple'a hundred bucks. They'll replace the guts of the tach with all-new parts and calibrate it for four-cylinder operation. No bounce.

--DD

Or an Autometer Monster fits right in the stock hole.

QUOTE (Mark Henry @ Jan 3 2006, 05:34 PM)

Or an Autometer Monster fits right in the stock hole.

and sticks out like a fart in church

QUOTE (Aaron Cox @ Jan 3 2006, 08:41 PM)

QUOTE (Mark Henry @ Jan 3 2006, 05:34 PM) Or an Autometer Monster fits right in the stock hole. and sticks out like a fart in church

I like the look. I don't give a if you don't.

I will never trust a VDO tach.

I've calibrated 4 VDO 914 tachs for V8s. Before I did anything to them I checked them with a fuction generator and all 4 were way off. One was 18% high at 6K rpm the others were anywhere from 5 to 10% off. I sure would not spend the kind of money the speedo shops get for mods to 30 year old gauges.

If VDO made calculators they would still have a handle on the side of them.


Bob

QUOTE (Mark Henry @ Jan 3 2006, 06:24 PM)

QUOTE (Aaron Cox @ Jan 3 2006, 08:41 PM) QUOTE (Mark Henry @ Jan 3 2006, 05:34 PM) Or an Autometer Monster fits right in the stock hole. and sticks out like a fart in church I like the look. I don't give a if you don't. I will never trust a VDO tach.

[beating chest - Tarzan yell heard in the distance...]

Several of my wiring harness customers have told me that replacing their FI and ignition harnesses have cured their bouncy tachs, and I hear that comment regularly, from Ed Davila most recently. I wonder if the tach issue is related to sketchy grounds or other questionable electrical connections.

QUOTE (BIGKAT_83 @ Jan 3 2006, 09:35 PM)

I've calibrated 4 VDO 914 tachs for V8s. Before I did anything to them I checked them with a fuction generator and all 4 were way off. One was 18% high at 6K rpm the others were anywhere from 5 to 10% off. I sure would not spend the kind of money the speedo shops get for mods to 30 year old gauges. If VDO made calculators they would still have a handle on the side of them. Bob

Even without the bounce this is my biggest beef with the VDO's. At 10% high your 6000rpm redline could be 6600rpm.

Would you trust your $5 to 15+K dream hi-po engine at 7500rpm to an el-cheapo tach?
I won't.

Lets face it if the stock tach was dead nuts on I'd never spend the coin to change it.

I thought the tach was ECU-controlled on L-Jet cars?

nope. just the fuel injectors are ECU controlled with L-jet.

b