The V8 Owners Forum -

I took this out of the thread about hotwire and Piper 270/110:
Sorry that I didn´t give all the necessary info.
The engine ( RV8 4.6 in a LandRover Ninety ) is fired by a Edelbrock/Weber 500 Carb, Dizzy is a Mallory that was a Dual point and now converted to Unilte. Cam is an old, but bought new, 270/108 ( fact sheed tells more lift than the webpage of piper now says ).
Comp Ratio is 9.35-1 ( standard 4.6 heads, ported and polished to gasket size by me, standard valves, composite head gasket )
I had no issues when I tested the engine ( after conversion ) late in September 2008 on a 2500km ( altitudes between 0 and almost 3000 m ) trip around the swiss, french, italian Alps.
The engine performed well, when the street was a bit wet and I floored the bitch, all 4 wheels grabbed for grip. ( Tyres are Mud Terrains 255/85R16 BF Goodrich )
But during the Afrika Trip ( started on the 26th of December 2008 )
I had issues with the engine starting to pinging when using petrol ( 95 octane ) of the same quality as before, and the engine didn´t stop after switching it off ( when warm ). ( ignition was set to 6-7° before )
The pinging came up when I accelerated hard ( but just started with the 3 gear upwards, 1 and 2 was no pinging ) or when I floored the throttle in a high gear ( accelarating from cruising ),( is this WOT then !?)
In Egypt, Sudan etc, the best I was able to get was 90 octane.
But I was able to control the pinging by retarding the timing.
No Probs, but the engine even didn´t stop.
The probs started just on the first day of the trip with 95 octane that was filled in in switzerland.
The 3-4 month before, there were no such probs.
No changes were made to the engine after the trouble free time of the 3-4 month.

If somebody is interested in pix of the trip:
http://www.offroad-forum.de/viewtopic.php?t=25291

I forgot about to say, that I changed the exhaust.
Years ago I fitted a ss rimmer brs sports exhaust system ( 4-2-1 ).
The last years I just had an Edelbrock 3" muffler after the y-pipe.
After that , the exhaust system ended.
As this configuration seemed to loud for such a long trip, I refitted the "original" system. I took out the edelbrock muffler and replaced it with the rimmer bros sytem that laid in the corner for the last years.
I thougt that I noticed a decrease in power and performance after that, but my mechanix-buddy told me, that this is just an illusion, because it´s not as loud as before.

You say you changed the exhaust and it is not as noisy as before - was it previously noisy enough that you did not hear the pinking? Perhps it was there but you did not hear it.

Have you had the emissions checked? Perhaps some bad / dirty fuel and the carb jets slightly blocked causing a lean mix

Just 2 of the things I would chek / think about

Ian

Thanx
for the reply, Ian!
But I think that pinging distroys an engine.
After years of not hearing it, the engine should be ruined, shouldn´t it?
No, the exhaust was loud, but not such loud. I hope so.
But as said above, the engine would be damaged after these years.

No ideas anybody how to get rid of the engine-won´t-stop problem.
Thanx
Stephan

Getting rid of the pinking should automatically cure the running on. It's running on because some part of the combustion chamber is hot enough to set fire to the next fuel charge, and that is usually caused by the flame front touching the metalwork somewhere which you can hear.

Have you tried altering the timing (maybe a lot) to stop it pinking?

Chris.

Hi desertrover,

You must have a hot spot for run on to occur. What plugs are you using?
Have a look at these websites you may find them informative.

http://www.dansmc.com/sparkplugs1.htm

www.nightrider.com/biketech/spkplghnbook.htm

Hope this cures your problem.

Ged

When the pinging get too bad, it makes little indents either in the heads, pistons or both, it can look like sombody had been over the piston with a centre punch!! IF it gets to this stage, the tips of the indents can start to get that hot, the enging pre ignites, causing more pinging, and will cause the engine to run on, the big downside of this may cause the pistons to melt, its got to be worth a look at the tops of the pistons with an endoscope

Many Thanx so far!!
Can this all be caused by the camß
As this was the main change during the engine rebuild for the trans africa trip.
I changed the cam ( from 3.9 efi RR to the Piper ), the heads from 3.5 8.13-1 cr to 4.6 heads with 9.35-1 and I converted the dizzy to unilite.
I think it must be the cam, isn´t it?
Stephan

desertrover wrote:Many Thanx so far!!
Can this all be caused by the camß
As this was the main change during the engine rebuild for the trans africa trip.
I changed the cam ( from 3.9 efi RR to the Piper ), the heads from 3.5 8.13-1 cr to 4.6 heads with 9.35-1 and I converted the dizzy to unilite.
I think it must be the cam, isn´t it?
Stephan

Nobody any more ideas?

Possibly a build up of carbon in the combustion chamber that is getting hot

If it is it needs to be decoked - open the engine and scrape off the carbon. (Can also be done with brake fluid poured through the carb when the engine is runnig at about 3000 rom - but normally only done when you need to sell the car in a hurry! - Loads of crud will come out the exhaust.

Or 2 - you are going into different territories here and perhaps the fuel is a "blend" with added methanol / grain spirit.
Back in Rhodesia 30 years ago they did this and there was a lot of pinking problems We gor around it by running an upper cylinder lubricant something like REDEX - about 100cc for a tank. Helped cool down the combustion chamber. (I also used Castrol R40 as upper cylinder lubs - gives that historic racing smell)

Option2 is cheap and easy to try

Ian

Hello Stephan,

If the fuel/air mixture is too lean, this can not only lead to pinging, but also to running on.

Ron.

So here Í am again!
I´ve studied the books about RV8 tuning again and found out, that the 4.6 needs a total advance of 28-30° before.
During the rebuild of the engine and the conversion of the dizzy from dual point to unilite, I changed the "in-built-total vacuum advance" from the factories 24°at 3.000 rpm to the max of 28°.
Adding the 7° the dizzy is turned gives a max of say between 34-36° before.
That´s to much according to the books.
Q to the specialists:
Can this cause my pinging,
as reducing the 7° to, let´s say 3° ( had no strobe with me ), reduced the pinging dramatically while using 92 octane fuel ( almost no pinging )or 90 fuel with booster ( also almost no pinging ).
Just the engine won´t stop didn´t cure.
When I´m back to Nairobi, will tarding the inbuilt advance curve to the regular 24° cure my prob?
I droe the car years with the setting at the factorys state and had no issues.
I just ask not to be disappointed when doing the job and there´s no reaction from the engine.
Des Hammil says ( in my words ): You can go as far as the engine starts pinging, but just gear down.
My problem was just under hard acceleration in a high gear, almost nothing to hear during accelaration in 1st oder 2nd, if fast enough in 3rd.
Cheers
Stephan

Stephan.

Having re read your last post you mention adjusting the vaccuum advance. did you mean mechanical advance as you would not want anything like 28 deg of additional advance from vacuum.

For the very poor fuel your forced to use you will need to run less initial mechanical advance and have a total additional mechanical advance of no more than 22 - 24 deg. so say initial of 8 + 22-24 deg. + total mechanical advance of 30-32 deg, this is set with the vacuum disconnected.

I believe that with the Mallory you can adjust the vacuum advance and if possible I would suggest trying it within 5 -10 deg. and see what happens.

Kevin.

PS have you checked or changed the plugs since running on the African fuel.

Thanx Kevin,
I want to check and if nessessary change the plugs when I´m back in Nairobi.
What I´ll do also is to put the additional mech advance to the factories setting at 24°, perhaps less, and set the vacuum advance to the 6-7° before,
as I used to before the rebuilt, as I´ve had no probs with this.