Engine and Transmission Tech

tips, technology, tools and techniques related to vehicle driveline components

Go to Thread: PreviousNext
Go to: Forum ListMessage ListNew TopicLog In

Ivor Duarte
Gloucestershire UK
(576 posts)

02/11/2010 04:29AM

Main British Car:
1974 Land Rover Lightweight V8

Tacho mystery
Posted by: 88v8
Date: January 14, 2017 06:23AM

My 327 has a rev counter, fitted from new. Runs off the coil neg.
Never seemed that accurate although as I (still) haven't driven the car yet, hadn't paid too much attention.

I'm sitting in the car yesterday running the engine, hoping I've got to the end of the problems and can take it out for a run, but no. As I rev up to about 2,000 there's a bad misfire. Shakes the engine. If I try to rev through it, I can and it clears, but while it's missing it's pretty bad.

Then I notice that the rev counter stops rising at the point where the misfire starts, and when it gets bad the needle goes all the way back to zero.
I tried disconnecting the rev counter in case it's somehow causing a problem, no change.

Misfires hot or cold.
Timing is OK plugs are new, firing order is right, points gap is OK. Original coil & ballast, the coil impedance is OK for the ballast. Fuel pressure is correct, I set the wet fuel level.

I'm inclined to replace coil and ballast, but I don't like randomly replacing things.
So, do you think the rev counter is trying to tell me something about the ignition, or is it just faulty?


Graham Creswick
Chatham, Ontario, Canada
(997 posts)

10/25/2007 11:17AM

Main British Car:
1976 MGB Ford 302

authors avatar
Re: Tacho mystery
Posted by: ex-tyke
Date: January 14, 2017 09:52AM

Running points?.......could it be something simple like a condenser?

kelly stevenson
Southern Middle Tennessee
(846 posts)

10/25/2007 09:37AM

Main British Car:
2003 Jaguar XK8 Coupe 4.2L DOHC/ VVT / 6sp. AT

authors avatar
Re: Tacho mystery
Posted by: kstevusa
Date: January 14, 2017 10:22AM

Perhaps a check to insure the GROUNDS are secure. Battery(rear) to body, body to drive train and drive train back to body at engine. Brit cars tend to have a few glitches and most I've had were related to the Poor Grounds, earths .

Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5517 posts)

10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Tacho mystery
Posted by: BlownMGB-V8
Date: January 14, 2017 11:46AM

That symptom is pretty typical for dirty points or coil breakdown. Possibly condenser. The tach is trying to tell you it needs a tune-up.


Sorry, only registered users may post in this forum.