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OK, what am I doing wrong?

Timing on 253 HJ Tonner, thought I was setting timing at factory spec of 6° BTDC (see picture) but when running and using a timing light, big surprise, was at about 24° BTDC! What the... Where did I go wrong?

Here's how I did it:

1. Checked No 1 piston at top of compression stroke.
2. Eyeballed piston through spark plug hole.
3. Confirmed harmonic balancer mark at 0°.
4. Confirmed distributor rotor pointing at No 1 plug position.
5. Evaluated harmonic balancer in correct crank alignment.
6. Cranked engine over twice, clockwise (looking at front) by hand.
7. Stopped short of TDC and set harmonic balancer mark at 6° BTDC.
8. Loosened distributor hold down clamp.
9. Rotated distributor until points were max open on cam lobe.
10. Checked points clearance 0.018".
11. Checked mechanical advance by hand moving the rotor, about 15° advance.
12. Observed the rotor spring back to original position.
13. Repeated step 11 a few times.
14. Observed that movement was smooth with no sticking.
15. Nipped up distributor clamp, not tight, enough to hold under power.
16. Removed manifold pressure hose from distributor vacuum advance.
17. Plugged the hose with a screw.
18. Left the distributor advance pressure nipple open to atmosphere.
19. Started engine, fired first crank.
20. Ran roughly with choke and initial carb idle mixture set 1¾ as instructed by carb overhaul mechanic.
21. Increased idle RPM to 850.
22. Allowed about 10 minutes to warm up and auto-choke to open fully.
23. Leaned the carb idle mixture gradually and maintained 850 RPM.
24. Engine running smoother but still slightly rough.
25. Checked timing mark with timing light. About 24° BTDC!

WHAT?

How come? Where did I go wrong? Why was the timing light not going off at 6° BTDC.

Anybody?

BTW - This is the first time I've ever set-up timing.

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Image icon 253_timing_marks1.jpg179.6 KB

Comments

its good you checked the balancer mark when at TDC - I got caught out many years ago when the balancer had slipped on rubber and so I was using the wrong ref point. why not use the light and adjust to 6 deg and see how it runs..is it pinging at 24 - I'd expect it would

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Andrew

Thanks for the reply. Yeah, I read about slipping balancers on this site so I was careful not to fall into that trap.

"why not use the light and adjust to 6 deg and see how it runs" - Yeah, good advice. With the hindsight of all these replies that's exactly what I should have done, but at the time I was so pee'd off with the reading I didn't want to push my luck.

"is it pinging at 24 - I'd expect it would" - Yeah, I reckon it was. It was making more racket than usual, but the noises weren't too unusual. The lifters and rockers are as rattly as. It's a very tired old engine with unknown mileage on its last legs, original untouched block, I think. But now you've mentioned it, I'm hoping I haven't done any damage, melting pistons or the like. I don't want to kill it, not just yet anyway.

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In the days gone by when we could not afford a timing light, we would loosen the dissy, and, once the engine was warm, bring the engine up to 3000 revs approx., then turn the dissy one way until the engine starts to falter and mark that point in the memory bank, then, turn the dissy the other way until the engine starts to falter and anything in between is perfect.
Worked for us.

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Thanks for the reply. Yes I do remember those days, but even though I've been pulling cars apart and putting them together again for over 50 years now somehow I've always lacked confidence in touching the timing until now. I left that to the blokes who knew. I remember my first stuff-up with an MGTC (first car) in about 1968. Rebuilt the engine after I broke the crankshaft on down-shifting gears (MG XPAG engines don't like that, they break at the No 1 bearing), anyway I did the usual dumb thing of putting the dissy in 180 degrees out. Couldn't figure out why it wouldn't start. Had it towed to a workshop where they sorted it out. Since then I've been under-confident about timing. Besides, like you back then, being a youth earning about $20 a week I couldn't afford a timing light either. Bad experience. Never touched timing again, until now.

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its because your on the top of the dissy cam lobe, you are on the right track but instead of max point gap you need to set it at POINTS JUST OPENING this is easy with ignition on as you will see and hear a little crack of spark from the points. other wise this is how i used to set timing prior to a road test before i had a timing light.

road test to optimise timing.

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Ah, thanks very much. That's exactly it for sure. The fog clears. I was really wondering about that. I searched for weeks on the internet about this matter, read lots of material, much in the Holdenpedia, but somehow I missed this point or nobody wrote about it. I've got an Ellery manual, given to me, and it doesn't cover this at all. In my opinion, the manual is not even worth wrapping up old prawn heads in. It doesn't even specify the timing marks are 2 degrees each. Found that out on this site. Anyway, this is obviously where I went wrong. Many thanks, all is crystal clear now.

Sadly, I can't road test, the thing's not registered. I can drive it a bit around the backyard, but it never gets over 10 kph or out of first gear. I need to keep the engine running so I can move it around when required. Besides, the tray makes a great mobile work bench when needed. A very useful machine. One day, I hope, it might get restored.

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Disconnect and plug the distributor vacuum advance line when setting the timing to 6 deg using a timing light.

Reconnect it after the setting has been achieved.

A small amount of vacuum is advancing the timing and causing the 24 deg.

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T

My Shed

Holdenpaedia, they're the brakes Mate.

Thanks T for your reply. I did disconnect the vac advance from the distributor and plugged the end connecting to the carb, but I left the vac advance nipple open to atmosphere because I didn't think this would have any vacuum effect. In future I'll blank off the nipple as well, just to be sure.

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" I left the vac advance nipple open to atmosphere"

I would leave it unplugged too. That will allow it to retard properly.
It can stick in position if it doesn't breathe.

Also make sure the rotor button springs back into replace when you rotate it (engine stopped, distributor cap removed). If it slops around freely, the balance weighs are worn out.

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T

My Shed

Holdenpaedia, they're the brakes Mate.

Just a tip...

Go to an Officeworks or similiar and buy a white felt permant pen [or white paint will do]

Mark the notch in crankshaft pulley.[in the notch]

Mark the ridge [or sometimes in the valley] on the aluminium lug thing where the degrees are marked.

You will find those marks will last forever.

Even with a dull timing light they stand out and you can adjust the timing spot on.

[On day I will take a photo on how to make an adaptor to clip your timing light on to number 1 plug.]

[Also how to make a good gasket scraper.]

Might I suggest an electric ignition.

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Disclaimer :- The above is purely speculation and is only posted for entertainment purposes!!!

Thanks for your reply. This is very good advice which I already follow. I use paint pens, white, silver and black for just about everything I remove these days. One day if someone buys my vehicles, they'll probably wonder what all these little marks are for. I did mark the balancer groove with white paint and it was highly satisfactory. It doesn't show in the photo because it's around the other side. I simply took the picture so I could illustrate roughly what was going on.

Electronic Ignition - good advice too. Eventually, when I get sick of the old stuff I might well do that, however for now, I'm one of those stupid people who tries to keep things original. It's an old vehicle with old mechanicals and I think it should stay that way for as long as possible. If it was a daily drive, electronic ignition would be highly practical.

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Number 9 on your list is where you are going wrong, the points should just be starting to open, not fully open like you said.
To set timing statically you can connect a 12 volt globe between earth and the low tension connection on the the dissy and turn the dissy slowly until the globe just lights which is the point where the points have just opened. Lock the dissy off then check it with the strobe light or road test.

Just noticed Ben Simpson gave you some good advice on an earlier post above re listening for a slight spark as points just part.

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Thanks for your reply. Yes, you're correct. Step No 9 is where the problem is. This makes perfect sense. I did wonder about it at the time, but couldn't seem to find that particular piece of important information. Maybe it was there somewhere but I didn't see it. With about 18 degrees over advanced, that should make about 9 degrees over advanced at the distributor (if my logic is correct). Retarding the contact breaker points to "just be starting to open" would be about where the 9 degrees retarded to rectify the 18 degrees over advanced at the crank. Good call.
I'll get at it when I can.

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Thanks everyone.

Q - Where did I go wrong?
A - Step No 9, timing the distributor to contact breaker points max open, instead of the correct position of points just opening. Correctly identified Ben Simpson and Drewie, plus good advice from everyone.

Chances are this contact breaker point information is written everywhere all over the place, but it seems I totally missed it.

Although I haven't the time right now to fix it, I feel 100% certain this is the problem solved. I shall effect the rectification and advise the outcome when I get the time to do it soon.

Mind you, it is a very old engine so maybe I should only feel 99% certain.

Anyway, thanks again to everyone.

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Keep in mind it should happily take a little more than the standard 6 deg initial timing and probably run better with about 10-12 deg. Modern fuels are a little better (except for the lack of lead) than they were when these things were new.

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Cheers
David

aka hq308belmont

www.hq308.com

My Shed

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