13 replies to this topic

[noz1380]

Hello all, I'm new here and needed help.

I have a mini that has been off the road for a while. Bofore it was taken off the road it had been tuned on the rolling road.

Specs so far are.....
1380cc
Oseli Cylinder head
Twin carbs
lcb
1.5 rollers
Aldon 59d Dizzy (Points Ect.)

All ignition parts have been replace, and the carbs have been cleaned and de-gunked. The engine has never been converted to unleaded, I'm running on super unleaded and an aditive. But I'm having lots of problems.

Then engine is running on after turn off, when starting,using the choke kills it. Today after driving home and the engine got warmer (never past half way on the dial) it started to misfire, back fire and pop out the carbs. I have checked the points gap, and retarded the timing (due to unleaded fuel) and now it wont run!! The engine was also very slugish under load, until around 3000k. I plan on modding my unleaded head sat under my desk as i type, but for now i just need to get to work, so your help would be really good. I plan on getting it tuned after getting an Ignitor kit, but obviously i need to wait til it's delivered.

Thanks in advance for your help.

[dklawson]

Start with the basics and please don't change several things at once. It's important to troubleshoot making one change at a time.

Set the point's gap, then set an initial static timing close to 8 BTDC. Check the condition of your plugs, wires, cap and rotor while you're looking at the ignition system and replace them as necessary. Once the engine is started and up to temperature you can start looking at the other problems one at a time.

Backfiring out the carb is usually an indication of fuel starvation, not timing. You've made sure the carbs are clean but unless you flushed out the float valve in the carb(s) you may not be getting enough fuel. Since you've got dual carbs you may be running on 1 with the other starved for fuel. (I've been there. )

Always get the ignition system working properly and set at least to nominal before moving on to carb and fuel adjustments. Obvsiouly it won't hurt to confirm that you have fuel flow into the bowls... but save carb adjustments until the end.

As for the fuel, premium will let you advance the timing more and thus develop more power. However, regular (lower octane) fuel burns faster (rougher). If the engine has other problems, using regular fuel may make it a little easier to start until you sort all the bugs out. To keep it from pinging on regular gas you do need to retard the timing but don't carry it to far. As I mentioned above, start with something close to 8 BTDC for static and adjust from there as necessary based on how the engine knocks and pings.

[noz1380]

Thank you for the fast reply.

I'm sure the guys checked the float chambers as they said one was stuck.

I'm just a little confused as the engine ran perfect before i took it off the raod some 3 years ago.

I think the best plan is to convert to electronic ignition then set it up to 8 deg, the Aldon litreture points to this as a guide.
Is this 8 deg the tru measurement at 1000 rpm? Best to check with a strobe i presume?

[Sprocket]

Id set the static advance to 5 degrees at 1000rpm with any vac advance disconnected, and see how that is. All productiopn 1275 that left the factory unleaded are set at 5 degrees so should be a reasonable place to start.

You have not mentioned what cam or flywheel type.

[dklawson]

Sprocket... just a minor point of terminology....
"Static timing" is done with the engine OFF. You turn the engine over by hand to line up the timing marks you want and then rotate the distributor body until the points open. Since the engine isn't running during static timing you do not need to disconnect the vacuum advance.

Anything you set with a timing light is dynamic timing. You want to disconnect and plug the vacuum advance line when setting dynamic timing. (Disconnect the tube at the advance unit and plug there so the tube is not sucking air into the carb).

I only suggest 8 BTDC as a starting point. Once the engine is running you need to set the timing to whatever spec is correct for your engine. Timing is really subjective though. Yes, there is a factory specification, but what's right for your engine is really a function of its state of tune, general condition, how you drive, and the fuel you buy. The factory specification will be conservative. In practice, you as the owner, should advance the timing from the factory spec in small steps until you just begin to hear pinging/knocking when accelerating under load. At that point you back the timing off a few degrees until you no longer hear the pinging when accelerating under load. With the car set up for this maximum advance you'll get the most power your car can develop (at least based on ignition timing changes).

However, start with either 5 or 8 BTDC for the static timing. It really doesn't matter which you choose. 3 degrees won't be a significant difference for starting. Once you get the car sorted out and running again you can adjust the timing wherever you want it.

Now... before we leave the subject, you said that "the guys" checked the carbs and one float was stuck. Who are these guys, when did they check the carbs, and do they know SU carbs? You left the car sitting for 3 years. If you didn't drain (or run dry) the float bowls, they will have been sitting full of nasty stuff for three years. You said in the opening post that the carbs had been cleaned. By whom and when? If it was 3 years ago you need to clean out the jet tubes and cean the needles again. If the carbs were disassembled for cleaning... did you re-center the jets (assuming you don't have the scraping type needles)? Did you check to make sure there was oil in the dashpots?

Give us a little more detail on how the car was put to sleep 3 years ago and what's been done since you woke it back up.

[noz1380]

Well I took it off the road after having problems with insurance, they wouldn't touch it with the roll cage. All was running well on LRP fuel.

Didnt really think that the storage would last that long, but 3 years later I decide to get her going again. I didnt do anything other than drive it into the garage and leave it. I'm sorry i know it was a bad thing to do.

So After 3 years i tried to fire it up, made sure i had oil pressure. All the fuel pipes leaked so all were replaced, I replaced all ignition parts and the baby fired up. A quick run around the block and it would die. So i managed to get it to the MOT station were it died again 10m from there yard.

At the station they said one of the floats were stuck and the carbs were gunked so they cleaned them up. Also replaced the points and condenser because they said they were burnt out due to a bad earth.

So then i have been driving it for about 2-3 days, covers 150ish miles. On the way home she gets a little warm, never past the white middle line, but she starts to misfire, back fire and pop out the carbs, the point seem a little rough but i've ran on worse. So i checked the gap on the points adjusted them slighty, from .018" to .015" too it down the road and she died totally.

So to set the timing statically, i use the mark on the crank, lines up at 5-8 degs, this is the point that the "points" start to open?

Cheers

Mark

[dklawson]

I think the garage hosed you with regard to what they did to free up and clean your carbs. The backfiring through the carbs is symptomatic of a lean condition which may indicate blocked jets or a hung float valve. I also think they hosed you on the points. Points provide an opening and closing ground connection for the coil. They don't fail from having a bad ground. If they don't have a good ground the car won't work and under those conditions... the points don't wear.

It was good for you to check that the points gap and the timing were correct. 5 to 8 BTDC is a good starting point. As you said, turn the engine in its normal direction of rotation stoping at the desired timing marks (don't back up if you overshoot). Hook a test light between coil (-) and chassis ground and switch on the ignition. Loosen the dizzy clamp and turn the dizzy housing CCW until the light goes out... then slowly turn it back CW until the light just turns on indicating that the points have opened. Then lock the dizzy down.

DO NOT assume the garage knew what they were doing when they worked on your carbs. Are these a pair of HS2s? Will you be comfortable doing some basic cleaning of these yourself? If so, let me know and I'll give you an abriged method to clean the carbs that hopefully won't mess up their adjustments (assuming the garage didn't already try to "help" you by adjusting them).

Edited by dklawson, 06 June 2007 - 05:04 PM.

[noz1380]

I got the impression that they are not really cowboys but only work on modern cars.

I have ordered my ignitor kit to get it sorted, but I have no markings on the crank pully, it has been converted to a belt drive and the timing notches are not present. Not had a look thro the peep hole in the cluch housing, will they still be there with it being a later model?

I have ordered the haynes manual on the SU carbs, so i think Im gonna get a run around til i have modded the unleaded head, that way I'll get the carbs off, clean then and get a refurb kit. Then replace the head and sort any oil leaks while im there.

Never simple eh? But I'm sure it wil be worth it.

Any ideas on the timing? Without the marks m not sure how to do it?

Thanks again for the help.

[Sprocket]

Sprocket... just a minor point of terminology....
"Static timing" is done with the engine OFF. You turn the engine over by hand to line up the timing marks you want and then rotate the distributor body until the points open. Since the engine isn't running during static timing you do not need to disconnect the vacuum advance.

oopsie, yes, you are right of course .

LOL its been that long since i did anything with a mechanicl distributer.

[dklawson]

No worries Sprocket.

noz1380... please hear me out. It is in your best interest to sort out this running problem before you start swapping components. You don't want to install an Ignitor module until you know the car will run more or less normally. Fitting it before you have a running engine may leave you scratching your head wondering where the fault lies (is it the Ignitor? is it the timing? is it the fuel system?) When troubleshooting it's very important to attack one problem at a time. Don't change many things at once, you'll never know what caused your problem or worse yet... you'll introduce new ones and not know what happened.

I'm not sure how late BMC/BL/Rover kept the marks on the flywheel. In the event they're not there, all is not lost but you've got to improvise. Working through #1 spark plug hole carefully turn the engine over by hand with the plugs removed. You'll find a spot when #1 piston is at the top of its compression stroke (piston full up and both its valves will be completely closed with the rocker arms loose). If you "feel" the crank pulley at this point you'll find a range of free motion CW and CCW as the crank pin moves over center. Tape or bolt some bit of metal up on your timing belt cover in a position that points at a front pulley. Determine the limits of the crank's free motion and make a mark on the pulley in the "middle" of this motion. This will be your TDC mark. Now you have to use your high-school math. Measure the OD of that pulley. Multiply this diameter by PI and you've got the circumference. Choose your timing now (8 or 5 degrees). For argument, I'll say 8. Take the circumference you calculated above and multiply it by 8/360. That is the distance "ahead" of the TDC mark you made on the pulley where the 8 BTDC point will be. Using micrometers or an accurate scale, make this second mark on the pulley. Now set your static timing using the mark.

I encourage you to confirm all your static ignition settings (with the points), then go through the carbs again. I really suspect that the needle/jet tubes are gummed up and that at least one float valve may be stuck closed. You didn't answer my question about whether these were HS2s or if the garage tried to adjust your carbs. If they have not, you can partially disassemble the carbs in place, clean the jet tubes, needles, float valves, etc. WITHOUT changing the jet adjustments done during the rolling road 3 years ago. I'd hate to see you loose those settings. A complete bench rebuild of the carbs may not be necessary.

[GraemeC]

In the latest Mini Magazine Calver does an excellent walk through of how to establish a TDC timing mark on the pulley. Does require head removal though.

It might be possible to do it with at DTI through no.1 spark plug hole - not sure, never tried!

[dklawson]

Taking the head off to accurately find TDC is the traditional method and involves using a dial indicator. This is a normal task when dialing in the angle for a new cam. When necessary (on non-Minis) I've attached a piece of bent coat hanger wire to my dial indicator and used this through the spark plug hole to find TDC. Not everyone has a dial indicator so I didn't mention it. You can certainly pull the head or use an indicator through the plug hole but to get this car started I was trying to avoid major work and provide a quick method that will be within a couple of degrees.

[noz1380]

Thank you all for the responses.

Ok, i think the garage didn't touch the carb settings, which i think are HS2's. I'm hoping they were just cleaned and one float free'd up.

I understand that i shouldn't change too much in one go, but having to change the head i might as well crack on and get it sorted. I'm doing my own porting and machining, so all will have to be rolling roaded after. It also makes sense to check the TDC with a clock/dial indicator, then set up a mark on the pulley while i'm there.

I'm wondering now, if it might be time to build up an engine and gearbox and do a straight swap, this way I can do all the work away from the car then swap right over. I have never been pleased with the original engine build, done by the previous owner, the gearbox is very clunky, the clutch slips, there are oil leaks every where. So i might bite the bullet.

Thanks again for all your help!!

[dklawson]

PM sent. Good luck and let me know if I can help.