2.25 petrol rough idle

This site contains affiliate links for which LandyZone may be compensated if you make a purchase.
having just stared with my brother at it for 2hrs. We decided to look at other things, the timing is right. Although, I do still want to clock the top of the piston to double check to be 100% sure we are spot on.
My brother has an old series engine kicking about and that too has the 90deg adaptor, but the distro shaft that clamps to that has a recess, mine don't. So maybe the distro is clamping down hard on the gearing underneath...can't see why that would cause this issue, but it's thing to check.
 
boguing said:
When did the rough idling start?
Click to expand...
Since I brought the car 1 y ago. I lived with it, and to be fair, it's rough running really, not just idle. Just not noticed as much when revving engine. It's now running slightly worse, so maybe a rethink on cam shaft position is needed. All valves are opening and shutting at the right places when I rotate the engine.
 
Ok, put it all back together today. The distro clamps down nicer and the skew gear is now in the right place (2h I'll never get back).
This is the best I can get it to run, around 10°BTDC, cannot get it to the 6° mark, so it's a guess. It's an improvement and I've been tinkering around with the carb to see what happens, guess I'll need a test run before I give full feedback here. but as you can see in the video, it's still rough.

photos.app.goo.gl

New video by Simon Tyler

photos.app.goo.gl photos.app.goo.gl
 
I wouldn't have called that rough. What I think I'm seeing (and if you could put the camera in a fixed position for a while it would help) is hunting which just happens to drop the revs through a speed at which the mounts come out in sympathy.

Take it for a drive and keep advancing until your get detonation starting at wide open throttle in higher gears, then back it off a bit until the detonation stops completely. That's good enough for now.

Next check everything air and fuel related. Vacuum hose etc. I think that's where your problem is now.
 
boguing said:
I wouldn't have called that rough. What I think I'm seeing (and if you could put the camera in a fixed position for a while it would help) is hunting which just happens to drop the revs through a speed at which the mounts come out in sympathy.

Take it for a drive and keep advancing until your get detonation starting at wide open throttle in higher gears, then back it off a bit until the detonation stops completely. That's good enough for now.

Next check everything air and fuel related. Vacuum hose etc. I think that's where your problem is now.
Click to expand...
when you say detonation, do you mean 'backfire', as in 'BANG' overfuel etc...
 
Jeez, just stuck 20ml of redex down each plug hole and about 40ml down carb.. fired it up and I can't see the garden for white smoke. Also running more wobbly, gonna make a cuppa and come back when the dust settles to start her up again.
 
styleruk said:
when you say detonation, do you mean 'backfire', as in 'BANG' overfuel etc...
Click to expand...
No! Detonation, otherwise known as 'pinking' is when the fuel/air mix in the cylinder actually explodes, as opposed to the very fast burn and expansion that you actually want. It sounds like there are something like 5mm nuts rattling inside the engine. Long term it'll damage the engine, but using it as a guide won't hurt at all.

Anyway, that's what it is and it's caused by too much advance. Retarding from there until it stops completely is just about perfect.

You'll also get backfires from being too far retarded.
 
Many years ago on an old car I had the same symptoms and rough idle cutting out but started up when cold, eventually not start at all, it turned out to be the coil.
 
styleruk said:
Ok, put it all back together today. The distro clamps down nicer and the skew gear is now in the right place (2h I'll never get back).
This is the best I can get it to run, around 10°BTDC, cannot get it to the 6° mark, so it's a guess. It's an improvement and I've been tinkering around with the carb to see what happens, guess I'll need a test run before I give full feedback here. but as you can see in the video, it's still rough.

photos.app.goo.gl

New video by Simon Tyler

photos.app.goo.gl photos.app.goo.gl
Click to expand...
On the unleaded fuel I was on 6btdc.
 
boguing said:
No! Detonation, otherwise known as 'pinking' is when the fuel/air mix in the cylinder actually explodes, as opposed to the very fast burn and expansion that you actually want. It sounds like there are something like 5mm nuts rattling inside the engine. Long term it'll damage the engine, but using it as a guide won't hurt at all.

Anyway, that's what it is and it's caused by too much advance. Retarding from there until it stops completely is just about perfect.

You'll also get backfires from being too far retarded.
Click to expand...
Ah, pinking, that I understand. Thank you sir
 
holy smoke. Started her and my garden filled with white smoke. The redex was working then! Took her for a spin this morning and clouded the village in smoke too. Took about 3miles before it stopped.
Still lumpy, link to video below. However, it feels a little better but still not right. What was amazing though was the felts I fitted in the back sliding windows, no rattles, maybe this is why it felt better.
Popped once on slowing down and changing gear.
massive flat spot if I floor it and open the second choke. If I ease it up it opens ok and I can go full throttle...all 75 horses, although I feel a lot of them have sodded off since 1985!
So it looks like 10BTDC is the best I can get without it just stopping, although, I think it's more like 15BTDC @ 700rpm with vacuum disconnected.

I took the jets out and cleaned them in case. checked for air leaks again before I tested.
Oh well, this looks like a problem for future-me. I'll keep researching what it could be, but feel an engine strip will be on the cards in the future.





photos.app.goo.gl

New video by Simon Tyler

photos.app.goo.gl photos.app.goo.gl
 
styleruk said:
holy smoke. Started her and my garden filled with white smoke. The redex was working then! Took her for a spin this morning and clouded the village in smoke too. Took about 3miles before it stopped.
Still lumpy, link to video below. However, it feels a little better but still not right. What was amazing though was the felts I fitted in the back sliding windows, no rattles, maybe this is why it felt better.
Popped once on slowing down and changing gear.
massive flat spot if I floor it and open the second choke. If I ease it up it opens ok and I can go full throttle...all 75 horses, although I feel a lot of them have sodded off since 1985!
So it looks like 10BTDC is the best I can get without it just stopping, although, I think it's more like 15BTDC @ 700rpm with vacuum disconnected.

I took the jets out and cleaned them in case. checked for air leaks again before I tested.
Oh well, this looks like a problem for future-me. I'll keep researching what it could be, but feel an engine strip will be on the cards in the future.





photos.app.goo.gl

New video by Simon Tyler

photos.app.goo.gl photos.app.goo.gl
Click to expand...
Without reading back I think you did a compression test? If so there's nothing to be gained by stripping the engine, you'll be wasting your time.

Did you try advancing to pinking and backing off? If so, you've got to go over the air and fuel.
 
boguing said:
Without reading back I think you did a compression test? If so there's nothing to be gained by stripping the engine, you'll be wasting your time.

Did you try advancing to pinking and backing off? If so, you've got to go over the air and fuel.
Click to expand...
I'm at a loss what else to do with air and fuel. I did the advance to pinking.. taking the head off means I could check all the followers are good, or even if the cam is worn, but that's a long way off.
 
All this worrying about how many degs before TDC at whatever revs.
Bit of a waste of time with such an old engine.
Better off using the tick-over screw to set the revs highish, 2500 or so?
Then unlock and rotate the dizzy back and forth until it is running comfortably as high as it can, then lock it up and back off the tick-over until it runs reasonably comfortably. This will account for wear and the changes in fuel since the car was built.
This is old skool but works, with an old skool engine.
Once done you can set up your strobe and see what it tells you. If you like.
When you drive it, if it pinks on acceleration, in high gear from low revs, then back it off (retard the dizzy) a tad until it doesn't. This'll be because the vacuum advance is doing its job.
 
Last edited:
You must log in or register to reply here.

Similar threads

A
Engine cutting out 2.25 petrol
Replies
3
Views
1K
Tony Monsantoe
Tony Monsantoe
C
2.5 Petrol Timing
Replies
4
Views
451
styleruk
styleruk
Lej
Fast idle speed (tick-over) + other queries!
Replies
3
Views
253
lynall
L
19J
Landy will crank over but wont fire.
Replies
17
Views
832
Dippypud
Dippypud
A
No spark ?
Replies
5
Views
450
mystery
mystery
Back
Top