Tacho gone mad

[ewolg]

Not having had the Griff too long, the tacho started out working OK but now it just has a mind of its own. Seems to work a bit from cold, when i fiddle with the coil occasionally and worked beautifully after a terraclean, then reverted to type soon after. Also seems to shoot up when I accelerate or blip the throttle but not true readings.
Any ideas welcome!

[Barreti]

Check and clean the earth point under the left (passenger) side of the whale tail.
Poor earthing on these cars is generally the thing which makes weird "voodoo" issues pop up all over the place and it might just be the cause of yours.

[ewolg]

Whale tail? Not entirely sure what that is!

[Barreti]

Sorry, it's the nickname for the centre armrest section.

[blitzracing]

Do you have magnecr*p plug leads by chance? The core resistance is too low (red are the worse) and causes glitching in the coil primary that can make the tacho bounce about.

[ewolg]

I'll check that, thanks. Might also get a new Bosch coil too.

Barreti said:

Sorry, it's the nickname for the centre armrest section.

[G5FTH]

blitzracing said:

Do you have magnecr*p plug leads by chance? The core resistance is too low (red are the worse) and causes glitching in the coil primary that can make the tacho bounce about.

Hi,
I was considering buying magnecore leads. Are they that bad? I had only heard people say good things about them.
Thanks,
Steve

[Toma500]

Ive heard its also a sign of the ignition amp on its way out .

[blitzracing]

G5FTH said:

Hi,
I was considering buying magnecore leads. Are they that bad? I had only heard people say good things about them.
Thanks,
Steve

That will be from the people who make a huge profit selling them!. There is a lot of cr*ap talked about low resistance lines and hotter sparks, but the resistance in the HT leads is there for a reason to suppress radio interference and reduce primary glitching of the coil. Using low resistance "race" leads just introduces problem you dont need when the system was designed for carbon cored leads in the first place. There is a time and place for low resistance leads if you are running very high compressions, high boost or alternative fuels, but the TVR set up is none of those. Quite simply you don't need them on an RV8 engine, good quality OEM ones are fine for a fraction of the price. There are also enough reported cases of them failing as well (Ive seen it first hand) and you don't expect that from a £100 "premium" product.

[stevesprint]

G5FTH said:

Hi,
I was considering buying magnecore leads. Are they that bad? I had only heard people say good things about them. Thanks, Steve

The blue Magnecore leads on my Griff are 10 years old and been 100% reliable and so have the spark plug extenders.

[Big Ashy]

stevesprint said:

The blue Magnecore leads on my Griff are 10 years old and been 100% reliable and so have the spark plug extenders.

I've had the red Magnecore HT leads on my Griff for well over ten years and never had an issue with them

[Argent]

I have just replaced my Magnecor blue leads with standard Bosch silicone leads, they were a third of the price and seem fine. I measured the resistance in both out of curiosity, the Magnecors were showing 5k ohms against the Bosch which were showing 8k ohms ( equivalent lengths of course).

A.

[ChimpOnGas]

Watch those Magecor leads...

http://www.pistonheads.com/gassing/topic.asp?h=14&...

Utter rubbish and very poor customer service from Magnecor when they let you down, and they will most likely let you down at some point.

I now use MSD Suer Conductors and they've proved faultless, I protected mine so I could delete the troublesome extenders.

http://www.pistonheads.com/gassing/topic.asp?h=14&...

MSD Suer Conductors are very low resistance, and all I can say is the car ran so much sweeter at soon as I fitted them.

My car burns LPG which is notoriously hard to strike and puts a much higher load on the leads, combine this with my wasted spark system that fires each plug twice as often and my 40,000 volt MSD coil packs, and my MSD Super Conductor leads have been given a proper workout.

Fit Super Conductor leads to a standard Chim or Griff running a distributor and single canister coil and they won't even come close to being stressed compared with my set up, if the MSD leads are proven reliable on my LPG powered TVR with its way more powerful double duty ignition system we can safely say they're an excellent choice.



https://www.msdperformance.com/products/spark_plug...

Fit these leads and a set NGK BPR6EIX iridium plugs, then delete the dreadful heat extenders used by TVR and pretty much any Chimaera or Griff will immediately run massively better.

Edited by ChimpOnGas on Friday 3rd June 14:43

[TV8]

ChimpOnGas said:

Watch those Magecor leads...

http://www.pistonheads.com/gassing/topic.asp?h=14&...

Utter rubbish and very poor customer service from Magnecor when they let you down, and they will most likely let you down at some point.

To balance that, I had blue Magnecors on my last car and they were fine. This car had red fitted when I bought it and during the first service he did on the car, Dan Taylor noticed a couple of burn marks on the leads and had them replaced for me. I didnt have a receipt or know the age but they were changed without question or cost to me. Things dont always go to plan but in my case Magnecor or their agent were very good.

[ukdj]

TV8 said:

To balance that, I had blue Magnecors on my last car

Graham, they are still on there and going great!!