Griff 500 engine "pinging" at low revs
Discussion
My 1996 Griff 500 Serp "pings" at low revs (below 1500 rpm) when putting load on through each gear. The timing has been checked and is ok. I always use 99/99 RON fuel. Above 2000 rpm the noise totally disappears. Is there something more sinister in the engine of which I ought to be aware ?
Additionally, the engine is lumpy at low revs, and does not accelerate very smoothly. Any thoughts ?
Additionally, the engine is lumpy at low revs, and does not accelerate very smoothly. Any thoughts ?
You could try the oldtimers approx' setting the timing by ear with the engine warm and at idle.
With the dizzy approx' in the correct place, the slightly slackened dizzy would be turned slowly by hand until the revs began to rise, When they were at the highest and still twisting, the fast idlle would start to become unstable so turning the dizzy back a little bit would restore the steady idle, which if too fast could be reset elsewhere. Retighten the clamp. Timing was never far out with this method.
This is how I remember it anyway.
Bet there are a few elderly mechanics remember this method.
With the dizzy approx' in the correct place, the slightly slackened dizzy would be turned slowly by hand until the revs began to rise, When they were at the highest and still twisting, the fast idlle would start to become unstable so turning the dizzy back a little bit would restore the steady idle, which if too fast could be reset elsewhere. Retighten the clamp. Timing was never far out with this method.
This is how I remember it anyway.
Bet there are a few elderly mechanics remember this method.
Have you verified the tdc mark is correct ?
The pulley with them on is 3 separate concentric rings. Inner is metal, next rubber and outer metal with tdc marks.
The 3 rings tend to delaminate from each other and the outer ring slips making tdc marks move out of place.
Use a piston stop and rotate engine clockwise and Mark timing pulls. Then rotate engine other way until piston stop catches then mark again. Dead centre between the two marks is real tdc
The pulley with them on is 3 separate concentric rings. Inner is metal, next rubber and outer metal with tdc marks.
The 3 rings tend to delaminate from each other and the outer ring slips making tdc marks move out of place.
Use a piston stop and rotate engine clockwise and Mark timing pulls. Then rotate engine other way until piston stop catches then mark again. Dead centre between the two marks is real tdc
Edited by blaze_away on Sunday 2nd June 12:19
tvroom said:
My 1996 Griff 500 Serp "pings" at low revs (below 1500 rpm) when putting load on through each gear. The timing has been checked and is ok. I always use 99/99 RON fuel. Above 2000 rpm the noise totally disappears. Is there something more sinister in the engine of which I ought to be aware ?
Additionally, the engine is lumpy at low revs, and does not accelerate very smoothly. Any thoughts ?
They should not be lumpy. It can snatch badly if the ECU is making big corrections to the fuelling to try and keep it emission compliant, but you need something like RoverGauge and a laptop to look at fuel trim values. Otherwise take a look at the plugs for both colour and any signs of degradation, it can tell you a lot. Plugs should be an even light tan across the white insulator with no significant shift in colour or specksAdditionally, the engine is lumpy at low revs, and does not accelerate very smoothly. Any thoughts ?
Do as described above and find TDC manually then set timing.
If after that you still get a tinging and all other possibilities have been discounted I’d start to suspect a big end shell failing.. it’ll only get worse.
If caught early a new set of shells can solve it.
Sounds an extreme thing to say but I remember a friends TVR getting a light tinging or pinking at similar low revs and only under load which turned out to be a worn big end Shell.
Crank was fine, no heavy wear marks as noise had only just started and car hadn't been driven far.
Shells on one big end showed signs of wear so standard set was put in and all’s been well for some years now.
I would only test the car at this point and if sounds persist drive straight home until it’s resolved.
I’m not trying to scare monger but a pinking sound can be the start of a big end Knock so be careful how you drive it until you find the issue.
Usually and as others have said the timing marks are not always accurate after so many years and could well be your source of the problem.
For the distributor experts on here, could the bob weights in the dizzy be stuck causing over advanced timing at low revs?
If after that you still get a tinging and all other possibilities have been discounted I’d start to suspect a big end shell failing.. it’ll only get worse.
If caught early a new set of shells can solve it.
Sounds an extreme thing to say but I remember a friends TVR getting a light tinging or pinking at similar low revs and only under load which turned out to be a worn big end Shell.
Crank was fine, no heavy wear marks as noise had only just started and car hadn't been driven far.
Shells on one big end showed signs of wear so standard set was put in and all’s been well for some years now.
I would only test the car at this point and if sounds persist drive straight home until it’s resolved.
I’m not trying to scare monger but a pinking sound can be the start of a big end Knock so be careful how you drive it until you find the issue.
Usually and as others have said the timing marks are not always accurate after so many years and could well be your source of the problem.
For the distributor experts on here, could the bob weights in the dizzy be stuck causing over advanced timing at low revs?
To all fellow/fellowesse Griff drivers, thanks for your combined wisdom, especially taking a harder look at the distributor and timing issues.
The prospect of a big-end shell being worn does not fill me with glee - the car has only 42,000 on the clock. But, nonetheless, very wise advice about dealing with it.
The settings and behaviour of the ECU are beyond my payroll grade; I had thought of upgrading it, anyway - Emerald has been recommended to me.
I shall investigate all these issues further and keep this post alive as I do so.
The prospect of a big-end shell being worn does not fill me with glee - the car has only 42,000 on the clock. But, nonetheless, very wise advice about dealing with it.
The settings and behaviour of the ECU are beyond my payroll grade; I had thought of upgrading it, anyway - Emerald has been recommended to me.
I shall investigate all these issues further and keep this post alive as I do so.
tvroom said:
To all fellow/fellowesse Griff drivers, thanks for your combined wisdom, especially taking a harder look at the distributor and timing issues.
The prospect of a big-end shell being worn does not fill me with glee - the car has only 42,000 on the clock. But, nonetheless, very wise advice about dealing with it.
The settings and behaviour of the ECU are beyond my payroll grade; I had thought of upgrading it, anyway - Emerald has been recommended to me.
I shall investigate all these issues further and keep this post alive as I do so.
Until you have established your true timing etc I wouldn’t be considering my words about big ends just yet. It’s more a heads up. it’s very rare but driving it with any persistent noises under load is to be avoided is more my point. The prospect of a big-end shell being worn does not fill me with glee - the car has only 42,000 on the clock. But, nonetheless, very wise advice about dealing with it.
The settings and behaviour of the ECU are beyond my payroll grade; I had thought of upgrading it, anyway - Emerald has been recommended to me.
I shall investigate all these issues further and keep this post alive as I do so.
As non of us can experience your fault anythings possible so just be cautious and do very short journeys until you are sure where the problem lies.
Edited by BritishTvr450 on Monday 3rd June 08:18
Thanks BritishTvr45o : I appreciate your advice. I am onto the timing and distributor settings, which I shall exhaust before even thinking about the internals of the engine. Because the pinging noise disappears at over 2000 RPM, I have driven for over 1000 miles (on a tour) at normal road speeds. Whether deeper damage has already been done remains to be investigated ! Thanks for your comments.
What grade of plugs are fitted? How old are they?
'How' do you drive? If you 'pootle' using the low end torque then a 'wamer' plug would help keep them clean. If you 'press on' using the revs, then a colder plug would help but keep in mind you'll need to give it an Italian tune up every now and again to keep them clean if you turn into a pootler.
Do you still have the plug extenders fitted? If you do, junk them and fit resistive plugs.
Check / establish the timing first.
'How' do you drive? If you 'pootle' using the low end torque then a 'wamer' plug would help keep them clean. If you 'press on' using the revs, then a colder plug would help but keep in mind you'll need to give it an Italian tune up every now and again to keep them clean if you turn into a pootler.
Do you still have the plug extenders fitted? If you do, junk them and fit resistive plugs.
Check / establish the timing first.
Problem(s) solved !
A deeper examination of timing settings revealed that it was way out; that was easily remedied.
The other aspect of lumpy performance was cured by replacing the distributor cap, rotor arm and plug leads. There were two leads where the casing was cracked and presumably the spark leaked out.
Needless to say, the Griff is running more smoothly than ever, with a complete absence of the pinging noise.
Thank you to all correspondents for comments and advice !
A deeper examination of timing settings revealed that it was way out; that was easily remedied.
The other aspect of lumpy performance was cured by replacing the distributor cap, rotor arm and plug leads. There were two leads where the casing was cracked and presumably the spark leaked out.
Needless to say, the Griff is running more smoothly than ever, with a complete absence of the pinging noise.
Thank you to all correspondents for comments and advice !
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