Colthebrummie
Well-Known Member
Also, check that the advance mechanism in the distributor is working ok and that the advance pipe is connected
Col
Col
No I'm running an electronic ignition
I've had the problem before I changed the ignition system it started about a year or more ago
Yeah the advance is working and I bought and changed the advance pipe
Colthebrummie
Well-Known Member
Apart from worn big ends, I'm running out of ideas. It's hard to work out what's causing a noise without hearing it.
Col
Col
Hi back to basics. Check the tdc mark is really tdc. Check you're actually getting a spark on #1 at the set point. Have you got a timing light? Have you got the right plugs in and what do they look like? Are the plug leads in good order? What about the coil?
Sorry if I'm repeating anything
Sorry if I'm repeating anything
TheMegaMan
Well-Known Member
Checking TDC is correct, is well worthwhile. When I was getting my engine running after swapping the distributor, I was struggling to get the engine to run much faster than idle, even with the throttle wide open. Engine was getting very warm but wasn't going to have enough power to pull the skin off a rice pudding. Turns out the pulley mark was completely wrong, and I was sparking at something like 45 degrees ATDC, if not more. Doh!
Checked the real TDC with a thin stick in number 1 cylinder plug hole and remarked the pulley. Ran much better after that!
However, if it's still pinking when you're retarding the ignition enough to notice such a significant drop in engine power, then I think something else is definitely wrong. I assume it's known-good fuel, and not been in your tank too long? Might be worth running at 3 degrees ATDC, and see how much it's pinking vs the engine power at that setting.
How are you checking your timing?
Checked the real TDC with a thin stick in number 1 cylinder plug hole and remarked the pulley. Ran much better after that!
However, if it's still pinking when you're retarding the ignition enough to notice such a significant drop in engine power, then I think something else is definitely wrong. I assume it's known-good fuel, and not been in your tank too long? Might be worth running at 3 degrees ATDC, and see how much it's pinking vs the engine power at that setting.
How are you checking your timing?
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TheMegaMan
Well-Known Member
I was thinking about this some more. This might be a bit farfetched on a Landy engine, but do check the compression.
On 'performance' engines, if the head is skimmed, it can increase the compression too far and you get pinking if the fuel octane rating isn't high enough. You mentioned this started when the head gasket was changed. Was the head skimmed at the same time?
I know the Landy engine isn't normally what you'd call a high compression engine, so unless *a lot* of metal was removed, it's unlikely this would be the cause, but might be worth checking to be sure.
On 'performance' engines, if the head is skimmed, it can increase the compression too far and you get pinking if the fuel octane rating isn't high enough. You mentioned this started when the head gasket was changed. Was the head skimmed at the same time?
I know the Landy engine isn't normally what you'd call a high compression engine, so unless *a lot* of metal was removed, it's unlikely this would be the cause, but might be worth checking to be sure.
I've heard folks skim to get extra compression and more power, never heard of any problems as a result. Always a first time i guess
TheMegaMan
Well-Known Member
There's a limit. Otherwise, you'd just keep skimming and skimming and getting more and more power...
The Landy engine is deliberately lower compression so it can run on almost any fuel without problems and less fussy about having the timing spot-on.
Or you bend a valve
TheMegaMan
Well-Known Member
True, although a less-aggressive cam profile can avoid that. I'm assuming Landy cams aren't particularly 'hot', in which case the valves might be firmly closed towards the top of the stroke.Or you bend a valve
Was the replacement head gasket thinner than the one it replaced? That's another reason the CR may have risen...
Checking TDC is correct, is well worthwhile. When I was getting my engine running after swapping the distributor, I was struggling to get the engine to run much faster than idle, even with the throttle wide open. Engine was getting very warm but wasn't going to have enough power to pull the skin off a rice pudding. Turns out the pulley mark was completely wrong, and I was sparking at something like 45 degrees ATDC, if not more. Doh!
Checked the real TDC with a thin stick in number 1 cylinder plug hole and remarked the pulley. Ran much better after that!
However, if it's still pinking when you're retarding the ignition enough to notice such a significant drop in engine power, then I think something else is definitely wrong. I assume it's known-good fuel, and not been in your tank too long? Might be worth running at 3 degrees ATDC, and see how much it's pinking vs the engine power at that setting.
How are you checking your timing?
No that head gasket wasn't I don't think but I know it has been skimmed 2-3 times, the valves are all fine I'm guessing because it's very smooth on the flat it's only under full acceleration or uphill that it happens
Okay could it be 180 degrees out or would the symptoms be way worse, also I was reading on series123 and that the emission controlled engines stock were timed to 6atdc? I'm using a timing light and the original knotch in the pulleyChecking TDC is correct, is well worthwhile. When I was getting my engine running after swapping the distributor, I was struggling to get the engine to run much faster than idle, even with the throttle wide open. Engine was getting very warm but wasn't going to have enough power to pull the skin off a rice pudding. Turns out the pulley mark was completely wrong, and I was sparking at something like 45 degrees ATDC, if not more. Doh!
Checked the real TDC with a thin stick in number 1 cylinder plug hole and remarked the pulley. Ran much better after that!
However, if it's still pinking when you're retarding the ignition enough to notice such a significant drop in engine power, then I think something else is definitely wrong. I assume it's known-good fuel, and not been in your tank too long? Might be worth running at 3 degrees ATDC, and see how much it's pinking vs the engine power at that setting.
How are you checking your timing?
Colthebrummie
Well-Known Member
The engine probably started as 8:1 compression. I read somewhere that the highest you can go is just slightly above 9:1. I don't know what that is 1000ths of an inch of skimming but skimmed 3 times sounds too much to me.
Col
Col
Oh okay so you think it may need a new head, I'll buy and do a compression test to see if it has increased to much
TheMegaMan
Well-Known Member
It wouldn't run at all if it was 180 degrees out...you'd be firing at the bottom of the stroke, when the mixture isn't compressed, so won't really do anything. You might get a backfire if the mixture ignites as the exhaust valve starts to open.
You could check the accuracy of the pulley notch by using a very clean, think stick in the plug hole and rocking the engine back and forwards to get it spot on TDC, but I think the fact that it's mostly OK and you're detecting the loss in power at 6 degrees ATDC, you're probably about right and you've not got a pulley with it's notch way out like mine was, so I would guess you are about right with how you've set it.
TheMegaMan
Well-Known Member
You might be able to get away with finding a thick head gasket from somewhere. I think they can be cut from copper sheet, but never tried it or know anyone that has. Might not be terribly cheap, either....but hopefully cheaper than a replacement head.
