Try starting it with the vacuum pipe disconnected. If it is better you will have learned something.
But definitely also put the old mechanical system back in to see how it starts and runs. A properly maintained system, although a bit of pain to maintain, usually runs fine.
 
Normally, you set the timing with the vac pipe disconnected and the engine running at about 1500 rpm. It's hard to judge that without a tacho so just run it at about half revs. Just as an aside, is the engine converted to run on unleaded or are you using the lead replacement additive?

Col
 
Hi Col - have been doing timing at idle (c 600rpm). I have a tacho so I can organise that if you think a good idea? Would the timing still be at TDC at 1500rpm (per the book)? It’s not a converted head - I occasionally add additive but am a bit lazy with that. How would that affect it? Am a little confused as to what ideal speed you set the timing. I have a strobe and tachometer. Also not sure whether I do by ear or as per book for emission controlled 8:1 which is TDC.

Interestingly, I also noticed last night that the vacuum setup is missing the vacuum delay valve on the vacuum pipe between carb and dizzy (part ERC8119). That I believe is meant to retard timing to start - could be interesting when the new part arrives as that could cure it based on what we’re seeing - kickback advance on timing.

I’ve also bought a second hand OEM original dizzy which I’ll convert to electric with a kit - I’ve heard a lot of bad things about the powerspark complete distributor. Some people have mentioned poor phasing so will go back to the original part and convert.

surely I should be approaching the solution soon!! I’ve replaced half the car!!!
 
thspeller said:
Hi Col - have been doing timing at idle (c 600rpm). I have a tacho so I can organise that if you think a good idea? Would the timing still be at TDC at 1500rpm (per the book)? It’s not a converted head - I occasionally add additive but am a bit lazy with that. How would that affect it? Am a little confused as to what ideal speed you set the timing. I have a strobe and tachometer. Also not sure whether I do by ear or as per book for emission controlled 8:1 which is TDC.

Interestingly, I also noticed last night that the vacuum setup is missing the vacuum delay valve on the vacuum pipe between carb and dizzy (part ERC8119). That I believe is meant to retard timing to start - could be interesting when the new part arrives as that could cure it based on what we’re seeing - kickback advance on timing.

I’ve also bought a second hand OEM original dizzy which I’ll convert to electric with a kit - I’ve heard a lot of bad things about the powerspark complete distributor. Some people have mentioned poor phasing so will go back to the original part and convert.

surely I should be approaching the solution soon!! I’ve replaced half the car!!!
Click to expand...
Yes set the timing at TDC at about 1500-2000 rpm once set, Rev the engine a few times to ensure the setting remains stable. Old engines with plenty of miles on them will often require a slightly different setting, that's why I prefer to set the timing by ear.

When I first had my my series, I didn't put any additive in it even though I knew it hadn't been converted to lead free. After I had driven it a couple of hundred miles or so, it started poping and backfiring and running rough, similar to what you described in your previous post. Some people say you don't need to add the additive but I disagree, mine has been good since I started putting it in.

I'm not sure what you mean by the vacuum delay valve, mine just has the vac pipe going from the vac diaphragm on the dizzy to the carb. Although my carb is a Zenith. My dizzy is the Accuspark type.

Col
 
Normally, it's not that important to get the initial timing exact - as Col and others said, engines wear and many people prefer to get to a final setting by ear. But in your case there's something strange going on, so worth checking.

45D4 tuning.jpg

Your strobe should show no advance at 600 RPM (vac disconnected) and a visible advance when the vac is connected. With the vac off, you should also see a definite advance as the revs climb (mech advance). Ideally you want to be around 16 BTDC at 2000 RPM, still with vac off.
The advance should be smooth - if the strobe shows the timing jumping around at different revs then the dizzy has a fault.
But the ultimate test is to swap out the dizzy and compare the before/after symptoms.
 
Hello all - 2 years on and still battling problem. Must have spent hundreds of hours and definitely thousands of pounds trying to sort. Am a little desperate now. As a reminder, it’s a 5mb 2.3 petrol from early ninety. Starting is slow (cranks over a fair amount before starting) and has a horrendous grinding which appears to be kickback (I.e. the engine momentarily turning the wrong direction before violently correcting) - I assume caused by preignition. Once running, it’s the sweetest 2.25 you’ve ever heard. Timing is TDC (am confident this isn’t an over advance kickback) - checked 100s if times with strobe. battery is new, Weber carb is new, distributor is new powerspark electronic, uprated new coil, new leads, new sparks And new starter. I’ve had the electronic ignition module replaced to no avail. I don’t think it’s distributor because it runs so well once going and module has been replaced. I don’t think it’s starter or ring gear as turnover perfectly with ignition disconnected. Where I am at now is either (1) voltage fluctuations at cranking when battery under cranking load causing the coils field to discharge a early spark - I’ve seen on a multimeter this drop to 10.4 but that should be enough for the Dizzy to work as normal. Powerspark thinks it only needs 6v. The evidence to support that theory is that the few times it hasn’t done this was when the battery was used for the first ever time and after plugged into a trickle charger. But it’s not happened enough to be conclusive. The wiring and alternator is the only part of the system not new so that could also point to a voltage drop issue. (2) second possibility is air leak or lean condition - this supports the slow to start observations and might fit with it being fine once all running. I understand (largely from reading airplane engine forums) that a lean fuel mixture is notoriously unstable and can pre-ignite especially with new low octane fuel. If you can help me I’d be really grateful. It’s such a lovely car but every time I go to start it, it must be doing terrible damage to the internals of the engine. Thank you. Tom (desperate).
 
thspeller said:
Hello all - 2 years on and still battling problem. Must have spent hundreds of hours and definitely thousands of pounds trying to sort. Am a little desperate now. As a reminder, it’s a 5mb 2.3 petrol from early ninety. Starting is slow (cranks over a fair amount before starting) and has a horrendous grinding which appears to be kickback (I.e. the engine momentarily turning the wrong direction before violently correcting) - I assume caused by preignition. Once running, it’s the sweetest 2.25 you’ve ever heard. Timing is TDC (am confident this isn’t an over advance kickback) - checked 100s if times with strobe. battery is new, Weber carb is new, distributor is new powerspark electronic, uprated new coil, new leads, new sparks And new starter. I’ve had the electronic ignition module replaced to no avail. I don’t think it’s distributor because it runs so well once going and module has been replaced. I don’t think it’s starter or ring gear as turnover perfectly with ignition disconnected. Where I am at now is either (1) voltage fluctuations at cranking when battery under cranking load causing the coils field to discharge a early spark - I’ve seen on a multimeter this drop to 10.4 but that should be enough for the Dizzy to work as normal. Powerspark thinks it only needs 6v. The evidence to support that theory is that the few times it hasn’t done this was when the battery was used for the first ever time and after plugged into a trickle charger. But it’s not happened enough to be conclusive. The wiring and alternator is the only part of the system not new so that could also point to a voltage drop issue. (2) second possibility is air leak or lean condition - this supports the slow to start observations and might fit with it being fine once all running. I understand (largely from reading airplane engine forums) that a lean fuel mixture is notoriously unstable and can pre-ignite especially with new low octane fuel. If you can help me I’d be really grateful. It’s such a lovely car but every time I go to start it, it must be doing terrible damage to the internals of the engine. Thank you. Tom (desperate).
Click to expand...
have you got the wrong starter for ring gear
 
Hi James - right starter. Like for like replacement and checked with parts book. Also no grinding except when ignition wired up. Thanks for your help. Tom
 
Hi James. I did - they looked in reasonably okay condition given the grinding. What’s your thinking? Given it’s sometimes fine and turns over without issue with ignition disconnected, I thought it was unlikely to be starter/ring gear connected. The kickback also sends the crank momentarily back the wrong direction which suggests to me a piston is being fired before TDC. I don’t know how the ring gear or starter could cause crank to be forced to turn the wrong direction. Let me know if you think otherwise though - I’ll explore any theory at this stage.

Tom
 
Given how weird this all is, I suggest you find some one locally to have a look - two heads and all that - any classic car folk near you ?

Have you tried bump starting it - does it still kick back ?

it's sounding more and more to me like you have a serious Timing issue - either slop in the system, or it's out of whack - plus, as you imply, the starter seems to be able to turn the injun over without issue with the ignition system disconnected ....

I might also be inclined to try starting it on the handle - but given the kick back you describe, then, unless you are both familiar with, and confident of the correct procedure / placement of your hand - it could end quite painfully .... so be careful :eek:
 
Two thoughts.
!/ if running a car on unleaded with no additive, if you set the timing to where it should be with leaded fuel, it will be too advanced. Unleaded doesn't burn the same way. Wifey's BX blew an exhaust completely apart with a backfire once due to this. Me and a garage owning friend had to dig deep to find the proper setting. Setting it to what the strobe says, is only a starting point, from then on you need to alter it to cope with fuel and wear. In the old Haynes manuals it always used to tell you how to alter the igntion to cope with "poor fuels in other parts of the world" in otherwords, unleaded. Unleaded burns faster and in a less controlled manner thus leading to knock or pre-ignition. So you need to retard the ignition or simply put premium fuel in it until you have sorted it.
2/ if there is carbon build up in the head, that can lead to pre-ignition, The carbon simply glows red hot and thus fires the mixture too early, before the sparkplug does its biz. (Pre-ignition again) Have you had the head off and decoked it?
 
That’s super interesting. The coke thing I’m less convinced of due to the issue occurring on starting up cold. I understood you need a hot engine for a carbon deposit to glow enough to pre-ignite. I like the fuel point however as I was beginning to thing about that. I have been using additive but not loads and I’ve been inconsistent (it only seems to need a few a 125ml per tank which seems nothing??). Can you advise on how much additive should be used, whether 94/96 octane counts as premium fuel at the pump and how you might adjust timing for unleaded? Thanks Tom
 
This may not help much but I have an old series 3 diesel used just as on farm run around. It has the same sort of grinding sound on start up. If turned over with pull stop out it turns over smoothly, push the stop in [ start position ] it does the starter grinding as it try's to fire. I recon this is because it has poor compression on two pots [ 2 and 3 nothing to do with head gasket ] giving uneven firing. Once started it runs decent enough.
 
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thspeller said:
That’s super interesting. The coke thing I’m less convinced of due to the issue occurring on starting up cold. I understood you need a hot engine for a carbon deposit to glow enough to pre-ignite. I like the fuel point however as I was beginning to thing about that. I have been using additive but not loads and I’ve been inconsistent (it only seems to need a few a 125ml per tank which seems nothing??). Can you advise on how much additive should be used, whether 94/96 octane counts as premium fuel at the pump and how you might adjust timing for unleaded? Thanks Tom
Click to expand...
Short answer to the "how much additive to use and how much adjustment to make" is not easy at the moment. The thing being that I have only one vehicle like this and I have fitted a carbonflow to it which solves the problem. But you need a tin hat on your head if you want to discuss this as many people do not believe that it works. https://www.carbonflo.com/
You need to know the background to it before you can believe in it. I know this which is why I use it on one of my kit cars based on a vehicle from 1972!
However, I suggest you wind the timing back 10 degrees or so. If it still preignites take it back 5 degrees more, and again if this still occurs. Once it stops pinking, move it forward i.e. advance it until, in third gear at about 20 mph, when you floor it, it starts to pink, then move it back again. As for the amount of additive to use, I have only used it a coupla times and I suggest you simply follow the directions on the bottle, and if in doubt err on putting a bit more in than it says. It can't do any harm! Remember you need either the additive or the retarding in the timing, to prevent the pre-ignition. You don't need both.
The debate about unleaded petrol always used to centre on the effect it had on receding valve seats. Lead acting as a lubricant to prevent this, also, the hotter an engine runs the more you will get a sort of mini-welding happening at the valve/seat interaction point. Which is why with old engines you fit hardened valve seats to stop all this.
Do hope you get to the bottom of this!
 
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UPDATE


Issue COMPLETELY FIXED..... a mere 2 years and a few thousands pounds later.


I approached a guy called the Distributor Doctor who rebuilds original Lucas dizzies and rebuilds them, etc. He immediately said it would be the cheap powerspark electronic distributor and for £300 (!!) I could try one of his fully rebuild models.


The prospect of sinking yet more cash made me nervous but it is the best cash I’ve ever spent. Next day delivery of an original Lucas 45D4 fully rebuild and mapped (including test graph) with points. It’s genuinely a think of beauty. If I closed my eyes, I wouldn’t know it was my car, the difference is truely remarkable. It starts faster than my 2019 XC90 (barely get the key turned and it’s purring), pulls hard, sounds amazing and just so willing to run.


Martin (the Distributor Doctor) basically said the Chinese dizzies are made so badly that poor magnets and bearings can throw timing out randomly. Not hugely scientific but the bottom line is the difference between a £70 powerspark electronic and a £300 rebuilt original is night and day. I feel like a plonker for describing the Powerspark as running sweetly when finally going. Truth is, I’d not heard sweet before.


So there you have it. My deepest thanks for all your help and support for 2 years. A simple (albeit expensive) solution but I love my car again and that is priceless.


stay safe.

Tom
 
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