Std Chim Ignition Timing ?
Discussion
Setting your timing at idle really doesn't tell you anything.
You need to establish your distributor is advancing the timing smoothly and correctly.
To do this you need to watch the timing marks as the revs rise.
It's also way more accurate to set your timing from the maximum point of mechanical advance.
It's certainly true 28 degrees is advisable for the 5.0 litre cars.
But a 4.0 litre can actually safely run 32 degrees of maximum mechanical advance.
On a 4.0 litre, 32 degrees will give you a fraction more economy than 28 degrees without any loss of performance or risk of detonation.
As Haircut Mike says, set the timing with the vac advance disconnected so you know you are looking at mechanical advance only.
The distributor will not mechanically advance the timing beyond 4,000 rpm (probable less in truth).
A proper advance strobe with a digital tacho is the best tool for the job.
If you have a pre-serp, you may want to confirm true TDC using a DTI, & then mark the pulley accordingly before you start.
If you use an advance strobe a full range of timing marks on the pulley is not essential.
Just use your true TDC mark as a reference, bring the revs up to maximum mechanical advance and use the controls on your strobe to bring the TDC mark in line with the pointer.
The reading shown on your advance strobe will be your maximum mechanical advance figure.
Adjust the distributor and repeat until the digital display on your strobe reads 32 degrees with TDC & the pointer aligned at the maximum mechanical advance RPM.
Job done.
The secrets to getting your timing spot on is to:
1) Establish the true TDC (you need 100% confidence in this before you start)
2) Use a decent strobe with both tacho & advance controls
After selling my lovely Snap-On strobe along with all my other tools
I purchased an "Equus Innova Pro" from the States for £85.00 including delivery to the UK:
Works very well
You need to establish your distributor is advancing the timing smoothly and correctly.
To do this you need to watch the timing marks as the revs rise.
It's also way more accurate to set your timing from the maximum point of mechanical advance.
It's certainly true 28 degrees is advisable for the 5.0 litre cars.
But a 4.0 litre can actually safely run 32 degrees of maximum mechanical advance.
On a 4.0 litre, 32 degrees will give you a fraction more economy than 28 degrees without any loss of performance or risk of detonation.
As Haircut Mike says, set the timing with the vac advance disconnected so you know you are looking at mechanical advance only.
The distributor will not mechanically advance the timing beyond 4,000 rpm (probable less in truth).
A proper advance strobe with a digital tacho is the best tool for the job.
If you have a pre-serp, you may want to confirm true TDC using a DTI, & then mark the pulley accordingly before you start.
If you use an advance strobe a full range of timing marks on the pulley is not essential.
Just use your true TDC mark as a reference, bring the revs up to maximum mechanical advance and use the controls on your strobe to bring the TDC mark in line with the pointer.
The reading shown on your advance strobe will be your maximum mechanical advance figure.
Adjust the distributor and repeat until the digital display on your strobe reads 32 degrees with TDC & the pointer aligned at the maximum mechanical advance RPM.
Job done.
The secrets to getting your timing spot on is to:
1) Establish the true TDC (you need 100% confidence in this before you start)
2) Use a decent strobe with both tacho & advance controls
After selling my lovely Snap-On strobe along with all my other tools
I purchased an "Equus Innova Pro" from the States for £85.00 including delivery to the UK:Works very well
Edited by ChimpanLucky on Monday 28th May 13:39
Not exactly.
It’s a test to find TDC of which you can then use to assertion where your timing marks are on your pulley wheel.
By knowing where top dead centre is you can then determine if your timing marks are in the correct position or if your wheel has moved,, hope that makes sense.
It’s a test to find TDC of which you can then use to assertion where your timing marks are on your pulley wheel.
By knowing where top dead centre is you can then determine if your timing marks are in the correct position or if your wheel has moved,, hope that makes sense.
Classic Chim said:
Not exactly.
It’s a test to find TDC of which you can then use to assertion where your timing marks are on your pulley wheel.
By knowing where top dead centre is you can then determine if your timing marks are in the correct position or if your wheel has moved,, hope that makes sense.
Thanks a lot a lot! So if i get it could findout that the the wheel has moved for any reasons (one of these is belt sleeping)... do you know if this test is required for a serp engine? it seems that is not needed from what i could extrapolate from forumers purposes but i would love to double-check...It’s a test to find TDC of which you can then use to assertion where your timing marks are on your pulley wheel.
By knowing where top dead centre is you can then determine if your timing marks are in the correct position or if your wheel has moved,, hope that makes sense.
The bottom pulley is mounted on a 'Harmonic Damper' which is made from two parts. These parts are bonded together with rubber the idea being that it damps out vibration. When they get old the rubber bond can fail and the two parts (call them inner and outer rings) can rotate in relation to each other.
The inner part is attached to the crankshaft and the outer ring is the drive pulley and has the TDC markings on it so if it rotates on the inner your TDC readings will be wrong.
Steve
The inner part is attached to the crankshaft and the outer ring is the drive pulley and has the TDC markings on it so if it rotates on the inner your TDC readings will be wrong.
Steve
Steve_D said:
The bottom pulley is mounted on a 'Harmonic Damper' which is made from two parts. These parts are bonded together with rubber the idea being that it damps out vibration. When they get old the rubber bond can fail and the two parts (call them inner and outer rings) can rotate in relation to each other.
The inner part is attached to the crankshaft and the outer ring is the drive pulley and has the TDC markings on it so if it rotates on the inner your TDC readings will be wrong.
Steve
Steve i wasn t even asking for a that much precise answer that is really kind!The inner part is attached to the crankshaft and the outer ring is the drive pulley and has the TDC markings on it so if it rotates on the inner your TDC readings will be wrong.
Steve
I was late to buy a strobe so i will exceptionnaly get the advance done by a shop. I need to get there tomorow morning but i didnt found the time to check my true tdc now. Do you it is worth trying to see what my advance is without checking this true tdc (i mean are the chances that what you described happen are great woth a good external shape pulley?) ?should i really try to cancel my appointment and get it done properly after i checked my tdc is true.?
Ps: my car is pinking hard right now and i want it to stop now even if i need to re-check my true tdc after to get the job properly done. If values are totally offset i think it will prove i "lost" my tdc (or idle valve control is stuck fully open at worst) if they arent or if the slipping is minor i can get the advance lowered a bit and it will maybe stop my problem?
I appreciate greatly and profundly!
Steve_D said:
The garage you use should be able to adjust the timing to remove the pinking. This can be done by driving the car and making adjustments. It may then become obvious if the damper has slipped.
In your last post you mentioned the idle system. This cannot effect/cause pinking.
Steve
No i was thinking about the idle advance valve. In my comprehension if stuck in full (added) advance i will have a very high value all the time (at max +15deg and this from 0 to full rpm)...In your last post you mentioned the idle system. This cannot effect/cause pinking.
Steve
I m sorry i was very sleepy i spent a few nights with this car...when this piking problem will disapear i'll have fix all that s needed with my darling (i know the majority tinks that s a men, but these curves, how i look at it... couldnt be a male...).
Ok so today i ll just ask him to check the advance value but most important to limit this advance from a few degrees.
Thank you again
Edited by Lolo256 on Tuesday 17th July 13:36
Lolo256 said:
Ps: my car is pinking hard right now and i want it to stop now even if i need to re-check my true tdc after to get the job properly done. If values are totally offset i think it will prove i "lost" my tdc (or idle valve control is stuck fully open at worst) if they arent or if the slipping is minor i can get the advance lowered a bit and it will maybe stop my problem?
I appreciate greatly and profundly!
Ye Gods- I have never managed to get my engine to pink even when messing around with a programmable timing set up- I tried commercial knock detectors and even an amplifier on the knock sensor outputs feeding into headphones, so to hear it above the noise of a TVR set up it must be a mile out?I appreciate greatly and profundly!
blitzracing said:
Ye Gods- I have never managed to get my engine to pink even when messing around with a programmable timing set up- I tried commercial knock detectors and even an amplifier on the knock sensor outputs feeding into headphones, so to hear it above the noise of a TVR set up it must be a mile out?
So lucky you are...when i see all the other threads i still think it s pretty common on this engine (didnt even had it when i self supercharged a na high compression engine car...). Some of these threads are going so far they pretend you could keep it, if not constant (for me only at wot) and i can see with some research that it is true that some engines are more tolerants to it than others (it seems detonation already did some domage to some members chims' so i dont think it s the case at all there).On your prespcriptions i also tought it was the exhaust headers leaking but for me it was to much rpm and throttle dependant to be that. This video convict me i had pinging :
https://www.google.com/url?sa=t&source=web&...
Yes the noise of the engine dont interfer because it s on a different sound frequenz. You can hear it on the video only the evilish laugh disturb your hear (why so is he so stupid? )...
Edited by Lolo256 on Wednesday 18th July 11:39
So i went to the shop and i had 12++deg at idle and 34 at 4'000 (this is from my calculations, we tested at 3000 to avoid ping...and we where very high at this point).
The guy checked my true tdc + did all the adjustment in 1hour (120£/h hier in switzerland that s why time is counting!)...my hat to him...
I m now at 7-8 deg at idle and approx 23 at 3'000tr. It seems i have now 28deg at 4'000tr if purely proportional and 29-30deg if the mechanical advance go up of 22deg from 0 to 4000tr (as i read in one techincal sheet).
I ll do my test this afrernoon but the engine sound already seems much more adequate.
The guy checked my true tdc + did all the adjustment in 1hour (120£/h hier in switzerland that s why time is counting!)...my hat to him...
I m now at 7-8 deg at idle and approx 23 at 3'000tr. It seems i have now 28deg at 4'000tr if purely proportional and 29-30deg if the mechanical advance go up of 22deg from 0 to 4000tr (as i read in one techincal sheet).
I ll do my test this afrernoon but the engine sound already seems much more adequate.
Edited by Lolo256 on Wednesday 18th July 11:40
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