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MG Midget and Sprite Technical - Starting new engine

Over the past few months I have been steadily re-building the engine in my 1500. During the build I have incorporated a number of minor modifications such as a reground cam, skimmed head and re-jetted carbs.

Anyway, yesterday I attempted to start it for first time, resulting in a backfire through the carbs. At this point I realised that the firing order was completely out (should have checked better beforehand...) and adjusted that. This change resulted in a few promising rattles, but it never properly caught.

At this point I gave up, unwilling to turn it over any more. However I did remove the plugs (picture hopefully attached) and noted that they were sooty and damp, I could also see that the chambers were wet with fuel.

If you couldn't tell this is my first time rebuilding and running in an engine, and i've reached the point where i'm relectant to continue cranking it for fear of galling tappets etc.

- The spark is strong
- Timing could well be out
- Fueling is likely very wrong thanks to the rebuilt carbs

Any help or suggestions would be greatly appreciated.

B.Harvey


Note: I cleaned up plug #2, prior to cleaning it resembled the others


B

Sooty + damp = fouled maybe and no spark when cranking and cylinder contents under high pressure.
Try cleaning and drying (hot-air gun with care!) all the plugs. Double-check the static timing and have another go.
Simon
Simon Wood

I rebuilt my engine over Christmas and modified with new cam, larger pistons, higher compression etc.
once its run in i'll have it on the dyno and do a write-up...

However very important for the cam is to make sure that once you do manage to start the engine then you run it at 2000-2500 rpm for 20-30 minutes, then change oil and filter.

I assume you got some black cam lube with your cam and put that on the lobes .

If you dont do this then the cam dosent harden properly and quickly wears out.

When i started mine, the timing was way out and i had about 35 deg advance at 2000 rpm, but kept it running for the 20 mins....



Andy Phillips (frankenfrog)

Im no longer a fan of NGK... ive started to notice NGK fouls alot more then they used to

My guess is the plugs

To test for a.fouled plug ... pull it, hook it up, and ground it at ONLY the hex wrenching section... nothing else touching and turn the engine over ... if the electroid sparks, then its fouled

Next if no spark at the electrode when grounding only the hex then gound only the threaded section and respin the engine if it sparks then the spark plug good


Also, id go back to a stock carb and set up, just to take it out of play and simplify the start up and run in process... then add the modified carbs later

What modds did you make to the carbs...

I here painting them fire engine red and knief blading the butterflys will give them the apperance that you added 50 hp

Prop
Prop and the Blackhole Midget

I fitted new needles and jets to the carbs to get rid of the waxstats, other than that they have just been cleaned and fitted with new gaskets. In hindsight I should have rebuilt them after finishing the engine, for the time being though these are the only carbs I have.

The plugs produce a strong spark now that they have been cleaned.

I am having trouble setting the timing though. The process that i'm using is:

-Hand crank engine till cylinder #1 reaches 10deg BTDC

-Fit bulb tester between LT ignition line and rotate dissy clockwise until the bulb flickers

The issue i'm having is that the bulb remains illuminated regardless of how much I rotate the distributor. The point gap is correct, and they open and close as they should.

I am also unsure of how to determine the firing order from the position of the rotor. I know that the standard order is 1,3,4,2 anti-clockwise, and had assumed that when #1 was at TDC the rotor would be pointing to that position on the cap. However some guides seem to imply that #1 is opposite the rotor, surely this isn't correct?

I'll try to attach some photos tomorrow.
B

You need to be on the #1 compression stroke... put your thumb over the #1 pistonband rotate till its got pressure

The rotor should be pointing at he #1 cyl

Next ... firing order 1342

#1 dissy spark plug wire goes to cly # 1 closet to the rad

#2 dissy spark plug wire goes to #3 cly

#3 dissy spark plug wire goes to cly #4

#4 dissy spark plug wire goes to cly #2

Prop
Prop and the Blackhole Midget

with the cap off ...

The rotor pointing to #1 cly is dissy #1

Rotate dissy 90 degree to the left (counterclockwise) ... dissy #2

90 dgrees cc... the rotor bug is opposite from its #1 starting location

Moving the rotor Another 90 degrees CC is dissy cap.#4

Prop and the Blackhole Midget

Another way to find TDC is to pull the valve cover and rotate the engine until both valves on number one are closed. That should get you close enough to fire.
Martin Washington

You mention the test lamp stays on solid when rotatjng engine

Is the test light connected.correctly, perhaps the points slipped and are not opening

It did.run before just recently.when trying to start? If not... then it could mean the points / condenser is not assembled correctly and the slrjng is acting as a ground... very common mistake


Prop and the Blackhole Midget

I should have gotten my college degree in art appreciation

Hahaha

Please honor copyright law and dont steal copy or redistribute my art work without my express written permission

Haha

Prop

Prop and the Blackhole Midget

Very artistic, although it could cause confusion, as the plugs and dissy are on the other side of the engine on a 1500. Also, labelling No3 plug wire with a '2' could confuse.

As has already been said, No1 piston needs to be at TDC on the compression stroke. This is important, as it is possible to have the timing 180 degrees out.

As Martin said, remove the rocker cover and check that both valves on No1 cylinder are closed when at TDC.

The rotor arm *should* be pointing to No1 plug lead.
Dave O'Neill 2


"The issue i'm having is that the bulb remains illuminated regardless of how much I rotate the distributor. The point gap is correct, and they open and close as they should."
I am not sure where exactly you have the test bulb connected, but this may suggest that the insulating washer where the contact breaker spring attaches to the post is in the wrong position. The only thing then you wouldn't be getting your fat healthy spark. Worth double checking anyway as its a very common fault. And treble check the order of the plug leads! Anti-clockwise rotor arm and 1-3-4-2 in sequence.

The idea of the bulb is to locate the exact moment that the contacts close. I find an easier and more accurate way is to turn the radio on, volume up, tune it off station, Then as you turn the dizzy body and the points make contact you will hear an interference click, giving you the precise position.

One general comment I think that engines are far less tolerant of inaccurate settings in the electrics than in the fuel. At least for starting. Though they won't run well if the fuelling is out, its less likely to be the reason for not starting.
Guy W

"The rotor arm *should* be pointing to No1 plug lead."

In that case something is very out. The attached picture shows the position of the rotor arm when #1 cylinder is 10deg BTDC.

I am fairly confident that the distributor is properly located in the skew gear (It only fits one way, doesn't it?), so perhaps the skew gear is incorrectly meshed with the camshaft?

B

And here is a picture of the points / capacitor setup. As far as I can see everything is right, however i'll double check the points gap and that the spring is properly insulated.

I am testing it by disconnecting the LT lead before the distributor and connecting the test bulb between the female spade connector and an earth. The bulb remains lit regardless of whether the points are open or closed.

B

There is a very good chance that the skew gear is not meshed as the manufacturer intended. All is not lost - reposition your plug leads so that they correspond with the new positions.

It sounds as though your points are correctly connected, as you are getting a spark.

If you have disconnected the distributor in order to connect your lamp, the dissy is now out of circuit, so will not affect the bulb.

I prefer to leave the dissy connected and connect the lamp between the dissy side of the coil and ground.
Dave O'Neill 2

Guy,

The spark occurs when the points open so you want to see when the lamp goes out for static timing, at least if your rotating the distributor to simulate the correct engine rotation.
David Billington

B Harvey,

The test light should be connected between the LT coil connection and the points. It sounds like you have it connected between the LT coil connection and ground so all that will tell you is whether your ignition is on.
David Billington

Yes David. You get a static click on the radio as the gap opens. Its a very accurate method and it saves messing around with a bulb and lead, or spending 15 minutes looking for where you last left it!
Guy W

Guy,

I realised that you could be right about the light, it depends on how you wire it. I always put the test light in series with the points so that when closed the light would illuminate and I wanted the point when it went out as they opened. After Dave O'Neill's post I realised that you could connect the test lamp in parallel to the points in which case the lamp would light when the points are open and go out as they close.
David Billington

I connected the test light between the spring and engine block and locked the distributor at the point it flickered.

I then drained the float chambers as the fuel was looking slightly yellow (although it was new only a few days ago) and refilled with new.

I then tried turning it over. This time it would occasionally emit a quiet puffing sound, it doesn't sound like it is firing, let alone catching. The sound seemed to coincide with the accelerator being pressed.

Note that at the moment only the tubular manifold and a short section of tubing is connected, there are no silencers.

B

And the strange collection of ignition wires:

B

B

Just to take the possiablity out of play that your 180 degrees off

Run the firing order as... 2431

Dissy 1 to spark 2
D 2 to S 4
D 3 to S 3
D 4 to S 1

It your getting a spark at the plug wire so your points set up is good, the plug wiring is correct, and the engine will fire and run if your ignition timing is in the genral area, and your getting some action out the exhaust

Thats why I agree with the above your cam timing maybe a 180 degree off



Prop

Prop and the Blackhole Midget

.
Prop and the Blackhole Midget

Whoa - dude........
What's that starter motor?

That looks expensive!
Greybeard

it looks 180 degree out

mark 1500 on the road Preston Lancs

another engine

mark 1500 on the road Preston Lancs

Are you sure you are getting to TDC on the compression and not on the exhaust stroke. If its making puffing noises it could be firing on the exhaust stroke, i.e.180 degrees out. For tidiness you would refit the dizzy drive, but with the top entry HT leads on a 1500 there really isn't any need. Just move the plug leads around.
Guy W

With 6 of us now making the argument that the problem is timing is 180 degrees off,

I HOPE we are right, or will have to rename the bbs to lawerwnce hates muslims day to day forum


Haha

Prop
Prop and the Blackhole Midget

If not 180 degrees out then the flicker could be the points closing to charge the coil and not the opening of the points to fire it so the spark might be very late in the power stroke as a result. I'm not familiar with the 1500 distributor rotation but I've set A series with static timing many times from first principles so knowing how the system works helps see http://www.ratwell.com/mirror/users.mrbean.net.au/~rover/ketterin.htm . When it is understood then the distributor orientation is not important other than making sure it doesn't foul other items and the LT wire and vacuum pipe reaches it, you then alter the lead positions to get the firing order correct for the orientation chosen and set the timing with the points opening.
David Billington

Alright, so I tried all of the previous suggestions regarding rearranging the leads etc. Most of them resulted in exceptionally smokey backfires through the carbs.

Eventually I reset the leads and twisted the dizzy clockwise by an arbitary amount (around 1/8 of a rotation), this seemed to improve things so I turned it a bit more...

And it started!!!

Sadly in my exitement I let go of the throttle and it promptly died. I tried restarting it but it refused.

-So being that advancing the timing resulted in it starting is static timing really supposed to be taken 10 degrees BTDC?

-Is there a chance that I have seriously damaged anything by starting it for such a short period?
B

@Greybeard

I think the starter motor is a Nippondenso unit from an Isuzu Trooper MKII. It bolts directly to the 1500 bellhousing but does require a dent in the passenger footwell for clearance. If I remember correctly it was ~£40 new on eBay, cheaper than a recon inertia starter.


I just had another look at the car and noticed that the carbs are literally flooded, it is running an electronic fuel pump, could that be over-pressurising the needle valves?




B

If advancing the timing worked to get it started then it's likely you're using the wrong point, ie closing of points, as your indicator, but that should be easy to see with the distributor cap off. 10 degrees BTDC sounds like a good value for doing the static timing, that sort of value always worked for me.
David Billington

When you have the ignition on and the fuel pump is pumping, does any gas drip out of the carbs? If not then you're OK. If fuel is leaking then you either have too much pressure or your needle valves need to be readjusted.
Martin Washington

### I just had another look at the car and noticed that the carbs are literally flooded, it is running an electronic fuel pump, could that be over-pressurising the needle valves? ###

Yes it sure can...the pump needs to be a low pressure pump

Ideal is 1.5 to 3 psi, you can go as far a 4.5 psi without a regulator but it gets tricky

What kind of rpm did you get when it was running

For no more time then it ran, I cant imagine there is any damage


Prop
Prop and the Blackhole Midget

Is the fuel in the tank fresh or has it been sitting for an extended period? If it is several months old, it will not ignite properly.
Glenn Mallory

Glenn

B mentioned that the fuel.is only a few days old.... but good call on your part, I had the same thought till I spotted his comment

Prop
Prop and the Blackhole Midget

Where did the idea of the fuel pump being a non standard electric one come from? As a UK 1500 it should be a mechanical pump and unlikely to over pressurise the carbs to cause flooding.

But why in the photo are both the jet tubes down? Is the choke pulled out or are they sticking like that? Or is the linkage assembled right? I cannot see the choke cable connection in the photo.

On an SU you should never leave it with the choke pulled out as it lowers the jets and allows petrol to drain through into the carb body. Done habitually the petrol drains into the combustion chambers and washes oil off the bores and eventually dilutes the oil in the sump. Not relevant to the non starting at this stage (well choke adjustment could be) but worth being aware of on any car.
Guy W

Guy, B said just 6 posts ago
'it is running an electronic fuel pump'....
David Smith

Thanks David. Missed "B"s line on that. So delete 1st part of my comment, it could be over-pressurised.
But the rest of it - those jet tubes don't look right, stands.
Guy W

Following on Guys comment about the carbs in choke postion

That (the last one posted) photo is really strange...if you blow it up, there is a shaft that gies thur the jet and then is connected to the linkage on the side of the carb

Im on my phone so I cant see alot of detail

Are the carbs HS 4 ? ( I dont think this carb set up is orginal the the midget )
Prop and the Blackhole Midget

Cropped photo.. hopefully enlarged to show the detail

Prop and the Blackhole Midget

See how that shaft does a stair step bend and appears to run thur the jet and once thur it bends downward agian

That shaft seems to sit abreast the fuel/ air adjusting nut not allowing the jet to fully retract into the carb and creating what appears to be a full time ON choke situation


What I fail to understand ... if that linkage does pass thur the jet... how does that work ?

It has to be an optical illusion... even tho I see it on both carbs, my head tells me the little shaft must be passing behind the jet and not thur it, even tho my eyeball is saying differant
Prop and the Blackhole Midget

Cropped photo of the rear carb shows the same linkage set up

Prop and the Blackhole Midget

Have the bridges inside the venturi been filed away... I can barely see bridge in the front carb and I can not detect a bridge in the the 2nd photo
Prop and the Blackhole Midget

B

Can you pull the dashpot, and pistonwith the needle out and take a fairly close up photo looking down thur the carb piston cavity showing the jet level as it relates to the top of the bridge

Id like to see what its height is in comparison to the top of the bridge...does it sit down to low or is it level with the top of the bridge

And if the bridge has been modified

Prop
Prop and the Blackhole Midget

You all know that my knowledge of these cars only comes from what I pick up here and I've been watching & learning with interest on this thread.

But based on my rudimentary knowledge of SU carburettors (and whats on our 1500), if the pump is generating too much pressure, doesn't the float chamber just overfill and petrol (or diesel:-)) just come out the overflows, if the chambers are vented I can't see how that would flood the carburettor

tim
timmyk

Okay... im a in a little over my head

The red jet is a wax stat conversion for the mini set up... it a 2 part modification... from what I understand the "red jet" is a bit oversized for this modification

Im guessing the carbs are from a mini cooper/ variant ?

Part 1

http://www.minispares.com/product/Classic/BFS701SUL.aspx
Prop and the Blackhole Midget

I found this on one of the mini forums conserning a wax stat conversion

http://www.theminiforum.co.uk/forums/topic/298850-hs4-non-waxstat-jet/

Prop and the Blackhole Midget

Opps ... I forgot to list part 2 for wax stat conversion...

The red jet

At this point... im just a passanger along for the ride i have no knowledge or experiance beyound this locked gate...

But I do have the gift of wild hyperbole and wild speculation if thats of any use.

Haha


http://sucarb.co.uk/waxstat-jet-conversion.html


Prop and the Blackhole Midget

B.

My best advice considering this is a new engine thats not gone thur the break in procedure yet.

Id barrow the correct set of SU carbs plus mg intake mainifold to do the break in then come back to these carbs at a later time

Im assuming the intake is mini also so there is a problem with the angle of the carbs also about 20 degrees ... I cant remember which way... I think its flatter then the midget because of the angle.of the engine sits
Prop and the Blackhole Midget

Prop, you are letting your imagination carry you away!

I think you were right about the flooding, but not because of excessive fuel pressure. As Tim points out this simply overcomes the needle valve and the excess pours out of the carb overflow. And there is nothing magical in swapping standard jets for waxstat jets, or via-versa.

Flooding could be because the jets are low as in the photo. The jet control arm doesn't go through the brass jet. It goes behind it as seen on the photo and then bends twice X 90 degrees to enter the plastic part of the jet from the other side. I think they are designed like that so that operating the choke doesn't put as much lateral twisting pressure on the jet.

I think the only thing that is "wrong" is that the jets are in the fully out choke position, so my question was is the choke out, or are they failing to close because some part of the linkage is wrongly connected? If there is a fault here - and there may not be - then I suspect it is in addition to the likely 180 degree out timing issue. That problem is most easily corrected by moving the leads around. No one ever said there had to be only one fault!
Guy W

Guy

B ... stated its NOT 180 degrees out, he tried reversing and got nothing, then repositioned back and advanced the dissy and it started and ran for a while then died agian and wasnt able to restart it

It appears the issue is probably to much fuel as you locked on to the choke situation



Im not aware of wax stats and conversions on HS4 midets ... its a new one on me, im just reporting on what is visable and what I found googling

Its not somthing ive seen come up except for on the zeinth usa carbs


Guy..
From what I can piece togather... his carb situation is from a mini... is that correct

Do you think B should stay with the current carb set up for breaking in the new engine or go back to basics... to me it just feels to expermential for a new engine break in considering how much has been modified

Prop

Prop and the Blackhole Midget

**(or diesel:-))**

Low blow Tim. Low blow.

Haha!

Greybeard

I think the only thing that is "wrong" is that the jets are in the fully out choke position, so my question was is the choke out, or are they failing to close because some part of the linkage is wrongly connected? If there is a fault here -


From what I read on.some.of the mini forums .. sticking and binding is fairly common on the red jet wax stat conversion
Prop and the Blackhole Midget

Sorry Prop, I keep dipping into this whilst busy with another car, and keep missing vital bits of the conversation!

It seems, if I have got this right, that when adjusting the dizzy the car fired and ran briefly, stopped and wouldn't start. So it sounds like the timing is nearer than it was before and most likely that it was previously being set at 10 deg BTDC as the points were closing, not as they were opening. So a quick readjustment should get that right enough as a static setting to get it started.

Failing to restart sound like typical of a flooded engine (oiled/ wetted plugs) maybe down to the main jet/ choke setting issue. Put that right and I think this is then very close to getting resolved with these carbs.

I would put the battery on charge so it is ready for the next session and then wait for a synchronised light and no rain event.
Guy W

Aimed at me though- I found that diesel was very good at flushing all the crud out of the fuel lines and into the needle valves - which then needed a good clean out.
Somehow went straight through the filter - which turned out not to be diesel compatible !
timmyk

If the fuel is coming out the float chamber overflow then the level is too high and possibly above the top of the jets, if so it will flow out there also. That should be easy to see with the ignition on and nothing happening with the engine.
David Billington



Guy

I feel.your pain, im taking the morning off with a cup of hot tea, watching it rain outside and just enjoying the puzzle that is B 's engine...these are always my favorite, getting them started

Just another thought from the photos... does it appear that he is using a mini intake manifold... the angle of the carbs seems to flat in my view

That can be an issue with flooding ?

Like you said..its possiable.to be more then just one issue.

B being " retarded " was just part.of it....

(haha, that never gets old, its as funny now as in jr high small engine shop class)

You could be right about the carbs being okay.. its just when you see one deer on the road there are always plenty of others you dont see just around the bend.

Prop and the Blackhole Midget

Prop its a 1500, not an A series. I doubt that it is a mini manifold.
Guy W

Huh DUH,

I keep for getting.that..I wish could take the rest.of the day off... god knows I need it


Prop and the Blackhole Midget

Guy

I think you got the gold star win on this one.. if B has the correct needles and fixes the choke issue, I think he is off to the races

Recheck points, check what static timing is set to, and fix the chock situation ... and will probably never see B agian for another 87,000 miles
Prop and the Blackhole Midget

No one wins any stars until the car sings
Guy W

Is it running yet?
Lawrence Slater

B must have... he is probably out thrashing it about as we text

I bet he is closeted japenese drifter... kicking the back end out sliding around turns

you know he has the mask and secret identy of racer X from speed racer cartoon tv show .. probably stevens devines unknown older outcast black sheep brother.

The tangled webs of perception we protect
Prop and the Blackhole Midget

Not quite running yet, I didn't get to spend as much time as i'd hoped on it today, and it is a long way from driving.

Anyway, as I was resetting the timing for the fourth or fifth time I noticed that there was a lot of play in the rotor arm, so I took it off and the locating lug had been mangled, allowing the rotor to rotate free of the distributor.

The cap was also damaged, with most of the contacts twisted at an angle and slightly chipped. I think that the metal inserts must have slipped, allowing the contacts to twist and come into contact with the rotor. Thus throwing out the timing every rotation.

I replaced the rotor, found a Lucas cap, fitted everything up and set the static timing to 10deg BTDC.

And this time it started, however the revs kept on climbing regardless of the accelerator position, so I killed it by pulling the coil lead after a few seconds (removing the key had no effect, nor did cutting off the battery). I think that this may be an issue with the idle adjustors within the carbs?

Regardless, the neighbors threatened to call the police if I kept on making noise so i'll try again tomorrow.






B

And the jets (which are waxstat conversion items from Burlen SU) were sticking in the fully open position, allowing fuel to pour out of the carb throats. Tapping them back into place prevented leakage, as per Guy's suggestion.



B

Progress. Although... Having to pull the coil wire to shut it off is drastic. Turning the key off should have killed it and cutting off the battery should definitely have done it. There are obviously other problems.

The jets should move up and down freely so that is something that must be addressed. From your photo it looks like there are no throttle return springs. Make sure everything returns to the normal shut position before you try to start it again. As for the not shutting off when you turn the key an disconnect the battery, I have no idea but something isn't right.
Martin Washington

When you say disconnect the battery and it still keeps running...what does that mean? Do you mean it was running on, (diesel ing) and would not completely die or do you mean it held a constant rpm as if you never pulled the key ?

You Disconnected the battry cable, which one ?positive or ground ?

Prop
Prop and the Blackhole Midget

Disconnecting the battery won't cut a running engine as it will get sufficient output direct from the alternator. So probably nothing wrong there.

If switching off the key doesn't stop it then the most likely thing is the wiring to the key switch is hooked up wrong and you have the coil wire connected to the permanent live, unless you were perhaps hot wiring it?

Revs continuing to increase was as Martin says, just because you have no throttle return springs. Its the effect of induction on the butterfly valves giving WOT, and not to do with the jet positions as such.
Guy W

Disconnecting the battery with the engine running is not good for the alternator, either.
Dave O'Neill 2

When i removed the wax stats the new jets did not return to the up position freely i had to mess with them to get them moving freely took a bit of trial and error.
mark 1500 on the road Preston Lancs

I didnt realize that disconnecting the battery cable.would keep the engine.running

But if you do have the pos side.of the coil jumper wired to the pos side of the batt..the key becomes just another passanger

I always pull the coil wire in that situation because as dave mentioned... alternators are not 3 for a dollar

Prop
Prop and the Blackhole Midget

Correct Prop - don't leave a car hot wired when its not running! If the engine is stopped with the points in the closed position the coil will quickly get very hot indeed,and probably melt!

Same goes, I guess, for if the wire to the coil is connected to the permanent live instead of the switched live at the ignition switch.
Guy W

Yes... I should have mentioned that.. disconnact the pos wire from pos coil to pos battery post when not running
Prop and the Blackhole Midget

This thread was discussed between 06/01/2016 and 10/01/2016

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