16 replies to this topic

[Spherix]

Hi Folks,

I'm trying to get my engine set-up properly but the timing mark on the crank pulley wont stay in 1 place with the strobe, it's like 60-70% of the time exactly still on a timing mark, and then just goes either far out top or bottom.

To make sure I'm not screwing things up:
I got the engine up to temperature (thermostat opened)
Increased idle speed to 1500 rpm
Choke was closed
Vacuum advance was pulled off
Strobe was hooked up to spark plug 1.

Because the timing mark doesn't seem to wanting to stay in one place once hit with the strobe, I can only make a somewhat estimate timing. As the mark does seem to stay in one place 60-70% of the time, I set the timing at 5 deg BTDC, but it you can clearly hear the engine not running as smooth as it should, even though the cam is standard and whatnot. I've checked mixture (by checking spark plugs) and it seems to be ok, not far out in any case.

Bought new;
Spark plugs, leads, rotor, dizzy cap.

I've had contact with Cooperman on this forum, he suggested there might have been an issue with the weights in the dizzy not moving freely, this is not the case, the dizzy was compared at a garage next to a brand new one, there was no difference in play on the shaft or weights coming loose or not. Compression is the same on all cylinders, and they all fire properly.

I've also posted this issue on the Dutch mini forum, but I thought I'd get some extra input.

Engine specs atm:

1275cc block coming from a '91 Mainstream Cooper
Richard Longman GT6 12G940 head (35.7mm inlet, 29mm exhaust valves; bronze bullet-shaped valve guides, Longman valves, double valve springs)
1:5 MiniSport rollertip rockers (set at 0.35mm)
Duplex timing chain
3.1 diff on gearbox
HIF44 with K&N Cone filter
Fletcher big bore LCB
PlayMini 2.5" linkpipe, 3" center exit damper

Here's two samples of noise that the exhaust makes, you can hear the variation on the engine there. It's running idle there, nobody is touching it.

[newnham500]

whats the problem it sounds like a v8

[dklawson]

I am not allowed to stream videos at work so I have not seen your movies.

First, when you disconnected the vacuum advance line, did you plug it? What you need to do is disconnect the vacuum line at the dizzy and plug the open end of the tube. Failure to plug the line will let the carb draw in a bit of extra air leaning the mixture.

Second, were you setting the timing to 5 BTDC at 1500 RPM? If so, that's not right. 5 BTDC should be the static timing figure. Once the engine is operating the advance mechanism in the distributor will have started working and advancing the spark. Setting to 5 BTDC at 1500 RPM will in effect retard the timing a lot.

As unrelated as this may sound at first, set your valve clearances and make sure your ignition components are new and/or in good shape. Set your idle ignition timing, then adjust the carb(s).

[lrostoke]

Try this, just set up 2 minis this way and both sound sweet and running nice.

Now this may be wrong but it worked for me.

Keep the vac advance connected. now set the revs to 4500 rpm.

Now set the timing to between 28 and 30 degrees, you need a timing light with the advance function.

turn the revs back down , see how that feels.

I've got mine set at 28 this gives an advance at tickover with no vac attached of 12 @ 1000 rpm.

[Spherix]

whats the problem it sounds like a v8

The only problem is that is sounds as if it has a lumpy cam, but it hasn't got one . The sound is nice, but I'd rather have a nice stationary engine.

First, when you disconnected the vacuum advance line, did you plug it?

No. Heard the carb sucking air. Was wondering if that was right, but saw more post not caring than those who did.

Second, were you setting the timing to 5 BTDC at 1500 RPM?

With the vacuum off, I turned the idle screw to 1500 RPM, then set the timing (which lead to some extra rev's). After that reconnected the vac pipe, turned the idle screw back to 1000rpm.

If so, that's not right. 5 BTDC should be the static timing figure. Once the engine is operating the advance mechanism in the distributor will have started working and advancing the spark. Setting to 5 BTDC at 1500 RPM will in effect retard the timing a lot.

Makes sense, but could you explain the correct order of setting it up then? I've read quite a number of topics on this, and they all seem to describe it that way. Unless I'm interpreting it wrong.

As unrelated as this may sound at first, set your valve clearances and make sure your ignition components are new and/or in good shape. Set your idle ignition timing, then adjust the carb(s).

The head has just been installed a few days ago, and I've set the valve clearances at 0.35 mm; engine hasn't run very long besides from driving home and having it run stationary for tune up. Spark plugs, leads, rotor and dizzy cap are brand new.

You need a timing light with the advance function.

Sadly, I don't own one. If I can't get it right the usual way with tips above, I'll see if I can find one.

Thanks for the replies so far!

Edited by Spherix, 21 February 2012 - 05:59 PM.

[dklawson]

To clarify the timing bit, you static time to 5 BTDC just to get the engine started. If you are not familiar with this, see the PDF I am linking below.
http://www.sites.goo...taticTiming.pdf

Once the engine is static timed it will be "close enough" for the engine to start. Once the engine has idled up to operating temperature, shut down. Disconnect and plug the vacuum advance line. Refer to your maintenance manual and find what the default timing and RPM for your engine is supposed to be. Connect your timing light per its instructions. Re-start the engine and bring the engie RPM to the figure mentioned in the manual for setting the timing. Loosen the locking bits holding the distributor to the block. Aim your timing light at the timing marks and gently rotate the distributor housing until the appropriate timing marks line up. Re-check the engine RPM. Adjust if necessary, then re-check that the timing is the same and hasn't drifted. If the timing has drifted, turn the dizzy housing again and... make sure the RPM stays close to where it is supposed to be. Tighten the dizzy clamp, lower the RPM to the desired idle speed you want, then shut down and remove your timing light. That all assumes you have a basic timing light without advance. This is how you set the factory specified dynamic timing.

What Steve is suggesting is also what I do. It sets the MAX advance your engine can handle based on its condition and the fuel you use. (More advance = more power and better economy... up to a point). To paraphrase what Steve said, bring the engine to temperature and connect your ADVANCE TYPE timing light (knob on the back). Use the idle speed adjustment to bring the RPM up to around 4000. Set your timing light to the desired number of degrees (I use 32 degrees). Aim the light at the timing marks and as before, twist the dizzy but this time... you line up the pointer and ZERO timing mark (because you are using the advance setting on the light). Tighten the dizzy clamp, lower the engine to the desired idle speed, then test drive the car. You need to accelerate HARD in too high a gear so the engine is working really hard. Listen carefully for pinging and knocking. If you hear any bad noises like that, hook your light back up (at normal idle) and note where the timing marks line up. Retard the timing about 2 degrees, then repeat the load test. Keep retarding the timing until you hear NO pinging. That will give you the most advance your engine can handle for its unique condition and the grade of fuel you are using.

[tiger99]

All the previous advice is good, but also check for a worn distributor shaft. It happened to me a long time ago, not on a Mini, but a very similar distributor, and it was stable enough to set the points, but when I measured them a few minutes later, when the engine cut out, they seemed to have closed up, or even opened up. I must have adjusted the points about 10 times to get home from Heathrow to south London. Naturally, ot was causing havoc with both timingh and dwell angle.

You can easily feel for side play by trying to wiggle the rotor arm. If in doubt, take the arm off, turn the engine till the points gap is very small, and put sideways pressure on the cam. You will easily see the small gap open or close if there is a problem.

[dklawson]

Just so you don't panic... remember that when you twist the rotor, motion is not just OK, it is needed. The wear Tiger is telling you to look for is evident as "sideways" motion when you push or pull left and right on the rotor.

[racingbob]

Try this, just set up 2 minis this way and both sound sweet and running nice.

Now this may be wrong but it worked for me.

Keep the vac advance connected. now set the revs to 4500 rpm.

Now set the timing to between 28 and 30 degrees, you need a timing light with the advance function.

turn the revs back down , see how that feels.

I've got mine set at 28 this gives an advance at tickover with no vac attached of 12 @ 1000 rpm.

what engine is this you have this set on

[lrostoke]

They are both 998's but principle should be the same

[tiger99]

dklawson,

Yes, and I could have explained it a bit better. I did mean to push the shaft sideways, but should have added that it should also be able to be rotated slightly, and spring back, but apart from that, should not move. I think some slight vertical movement may be possible but that is irrelevant, and difficult to assess without some act of vandalism such as gripping the cam with Mole grips..

[dklawson]

Tiger, I did not mean to sound like I was questioning what you said. I was just adding a warning. I have told people to look for play in a distributor and they have freaked out when they find they could twist the rotor.

[Spherix]

As stated in my first post, I have already checked for play and wear, and have compared it to a brand new one at the garage.

Also, it's an electronic unit as supplied on the '91 mainstream cooper blocks. So no fiddling with points here.

[Cooperman]

Am I imagining it or does it sound like it's seriously retarded?
Undo the dizzy clamp, start the engine and rotate the dizzy clockwise until it runs at its best, then back it off a few degrees and re-set the tickover to around 1000 rpm. Try it like that.
Is the exhaust pipe glowing red? If it is, then it's definately retarded.
That's worth a try.

[dklawson]

If he set it to 5 BTDC at speed... yes, the timing will be way too retarded.