18 replies to this topic

[thebullet]

1983, 998, 12g295 head, stage 1, single HS4, single box maniflow.

Hi all, for around a month or so now under part throttle, at around 1800-2000 revs there is a ticking noise, an increase or decrease in throttle and it wont do it. Won't do it on idle either....

The temps are fine and there is no running problems but now I am starting to think it is pinking,

It was on the rolling road nearly 2 years ago and nothing has been changed since.

It's like rapid fire 'ticktickticktick' then stops after about 2200 revs.

Cheers.

[jaydee]

Try retarding ingition timing by a couple degrees.

[thebullet]

Will do, just wonder why it has started doing it? was going to let it warm up which is when it does it and pull the choke out to see if it stops, I think sometimes it is running too lean.

Edited by thebullet, 15 May 2012 - 10:02 AM.

[jaydee]

A wrong needle too lean at cruising/pick up and too rich at top end can cause strange noises.
Also the lack of oil in the dashpot cause problems at pick up.
Your sounds more like pinking, could just be the dizzy was not clamped very well so has moved around advancing too much.
What needle are you using in the carb?

[thebullet]

Just a stage 1 needle not sure on the number, taking it to Southam Mini and Metro for them to have a listen, I will take Colin out to let him hear.

[jaydee]

An AAA needle should be fine, getting it rolling roaded is a good option to sort out timing and mixture problems.

[thebullet]

It already has been tuned about a year and a half ago. It needs to go back on soon anyway when I put twin carbs on,

[thebullet]

So i have been told it is pinking, and is down to poor fuel quality. Colin was going to retard the ignition timing but it was only on at 8 degrees so he said it will kill performance, so we left it and I have been told to just rev through it. It needs setting up soon when i get twins anyway so i will bear with it untill then.

[racingbob]

do you use 97 octane bp

[thebullet]

No just Morrisons unleaded!

[jakejakejake1]

Maybe there is carbon build-up in the head is causing hot spots, which leads to pinking?
Just thinking out loud here.

[thebullet]

Maybe so, I think what I will do is buy some redex and fill up with high octane stuff and stop using dirty morrisons!

[racingbob]

good idea

[jakejakejake1]

One way i have found to clean carbon deposits is to do water decarbonization, which basically consists of slowly putting small amounts of water through the engine via the inlet.
Basically the water instantly evaporates as the fuel is combusted and it helps clean the carbon out.
I put about 500ml, over about 20-30 minutes of fast idling.
That solved my pinking and running on issues.
But don't put too much in, too quickly, or you could hydro lock the engine.

Edit: wrong word!

Edited by jakejakejake1, 15 May 2012 - 12:16 PM.

[thebullet]

My head has only been on since October 2010 a completely restored 12g295.