After noticing my car struggled a bit to go uphill I thought maybe the timing might be a bit off. I've read about advancing it until "pinking" occurs but for the life of me I can't hear it.
Originally I had set the distributor through static timing exactly like the instructions on the Haynes Manual said, and from this setting I've moved the distributor about 6mm clockwise but I never manage to hear that elusive pinking.
I think I have the timing way off now so I'll have to start again from scratch tomorrow; for an initial setting I think I'll plug a rev counter and rotate the distributor to where idle is fastest and then go on from there. My question is, about how near/far from this point should I expect to be?
Also, how do I recognize the "pinking" from the myriad other noises the car makes?
Another thing I noticed was when the timing was advanced the car had explosions when I took my foot off the throttle. I retarded the timing until this didn't happen anymore but I'm afraid that in trying to get my car to climb hills like a group B rally car I might have thrown all the settings way off.
Timing
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liammonty
- Minor Legend
- Posts: 1205
- Joined: Mon Apr 23, 2007 2:32 pm
- Location: Dartmoor
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Re: Timing
Next time, put a reference mark on the distributor and clamp so that you can put it back to where you started! For what it's worth, I've never been able to hear pinking from my standard cars when timing is well advanced - I think maybe there just isn't enough compression. To get timing back in the ballpark, set the engine position using timing marks to around 5 degrees btdc and then, with the ignition on, turn dizzy slowly until you hear a tick as the points spark when they open. You'll be in the right region then.
Re: Timing
First check - is the vacuum advance working? If not - the 'best idle' point will be far too far advanced. So - take the little pipe off at the carb and suck - you should pull a vacuum - and the base plate in the dizzy will move - and fall back when you let go. Pinking is a rattling noise when you accelerate up that hill in 4th gear. In general - a setting of the valve gaps -and a compression test will determine general engine condition. As mentioned above - if the compressions are poor - it may never 'pink' audibly. You may have to spend a bit of cash/do some modifications - to keep up with that Rally car...... 
Re: Timing
Thanks for the responses, I'm off to work on the car in a few minutes to see if I can solve the problems.
The vacuum advance works, I can still taste the petrol in my mouth from sucking on the tube but I presume that's normal.
Compressions are very good, between 125 and 130 on all cylinders so I think it might be my ears that are deaf to that particular frequency or I was revving the car too high.
I set the points gap as close as I could to 15 thou. but when I connected a dwell meter it's reading 30 deg. My theory is that the gap is correct but the meter is connected wrong somehow (90-30=60 so something backwards?)
I'm supposing the explosions when lifting were also caused by too advanced timing so I guess I'll retard until they're gone and report again. People complain that I drive too fast as it is so maybe I'll wait on the modifications.
On a completely unrelated note, brakes pull to the right when braking hard. I checked and all pistons are moving, sanded down the shoes and that helped a bit. My hope is a bit more "bedding in" might cure it, especially since it appears my car is invisible to other road users and they always cut me off.
The vacuum advance works, I can still taste the petrol in my mouth from sucking on the tube but I presume that's normal.
Compressions are very good, between 125 and 130 on all cylinders so I think it might be my ears that are deaf to that particular frequency or I was revving the car too high.
I set the points gap as close as I could to 15 thou. but when I connected a dwell meter it's reading 30 deg. My theory is that the gap is correct but the meter is connected wrong somehow (90-30=60 so something backwards?)
I'm supposing the explosions when lifting were also caused by too advanced timing so I guess I'll retard until they're gone and report again. People complain that I drive too fast as it is so maybe I'll wait on the modifications.
On a completely unrelated note, brakes pull to the right when braking hard. I checked and all pistons are moving, sanded down the shoes and that helped a bit. My hope is a bit more "bedding in" might cure it, especially since it appears my car is invisible to other road users and they always cut me off.
Gabriel
Re: Timing
Hmm - 125/130 is poor compression - assuming readings taken on a HOT engine, all plugs out and throttle held open ... It should be nearer 160... When you sucked - did you see the dizzy base plate move? 15 thou gap is fine - don't worry about 'dwell'. Back firing is fuel burning in the exhaust - could be caused by sticking (or burned) valves. I would have associated it more with retarded timing rather than advanced.
Re: Timing
Compression was measured cold and I forgot to open the throttle; I'll measure again like you say.
The base plate did move, more than I expected in fact, I'd say about 6-8 degrees at least.
You are right about the backfire, it would make more sense if the timing was retarded but on reading a bit about it it may have been unburnt fuel exploding in the exhaust. I do have a small exhaust leak at the manifold clamp (there's no exhaust paste for sale here) and it seems that may cause it as well. Also, being a LHD pick-up the pipe is much shorter so there's less back pressure. Engine was partially rebuilt recently so the valves should be fine, they looked well so only the guides are new.
However, there's good news. I set the distributor to roughly where it was, plugged a rev meter to the engine and slooowly turned it to both sides until I found the point where the RPMS were highest. Then I turned it back about 1-2mm (to retard just a bit) and the idle was smooth even at 600 RPM.
On a test drive the engine feels very smooth and even the explosions are almost completely gone from the exhaust and when they do happen they're very small. Hills still aren't the car's best friends but that's possibly never going to change, I'll still try small adjustments until I get it exactly where I want it but without straying too far from where it is now.
The base plate did move, more than I expected in fact, I'd say about 6-8 degrees at least.
You are right about the backfire, it would make more sense if the timing was retarded but on reading a bit about it it may have been unburnt fuel exploding in the exhaust. I do have a small exhaust leak at the manifold clamp (there's no exhaust paste for sale here) and it seems that may cause it as well. Also, being a LHD pick-up the pipe is much shorter so there's less back pressure. Engine was partially rebuilt recently so the valves should be fine, they looked well so only the guides are new.
However, there's good news. I set the distributor to roughly where it was, plugged a rev meter to the engine and slooowly turned it to both sides until I found the point where the RPMS were highest. Then I turned it back about 1-2mm (to retard just a bit) and the idle was smooth even at 600 RPM.
On a test drive the engine feels very smooth and even the explosions are almost completely gone from the exhaust and when they do happen they're very small. Hills still aren't the car's best friends but that's possibly never going to change, I'll still try small adjustments until I get it exactly where I want it but without straying too far from where it is now.
Gabriel
Re: Timing
Well done ! The exhaust leak will be the problem. You should do a plug colour check after a good run, Should be 'beige' - not 'white' (or black...) ...