Pickup restoration part three

[davidmiles]

exhaust putty and clamps done up, there does feel like more power,the throttle spring no longer fits the bracket, there's not enough space to give it tension, so Ive placed it here between to nuts. lets find out in a test drive if things improve...[frame][/frame]

[davidmiles]

the test dive showed me an increase in speed to 40pmh, so I'm pointing in the right general direction, after another turn of the nut on the carb for more petrol. There is a constant hissing, not from the exhaust, and a lot of engine heat, that suggests still some way to go on the mixture[frame][/frame]

[davidmiles]

the engine revs increase slightly when I lift the carb piston 8mm, so the mixture is now dead on, with that I twisted the Distributer till the revs increased at idle, so she's running quite well now. But I'm going to monitor the situation and adjust if needed.
So, on to the next article on the list, the wiper. the rack is jammed up tight, even with a small screwdriver in the end I could only just get it to move a few inches.[frame][/frame]

[davidmiles]

the wiper motor caused a short circuit, with the rack jammed up it's no wonder it went wrong. So I'll be renewing it with a recon from ESM next month. The supply the unit empty of winding gear, so I have to strip it out for exchange.[frame][/frame]

the worm gear is the only thing that doesn't dismantle, it's part of the wiper motor armature, I think?[frame][/frame]

[aupickup]

I have a very good used one if you are interested

[Neil MG]

the engine revs increase slightly when I lift the carb piston 8mm, so the mixture is now dead on, with that I twisted the Distributer till the revs increased at idle, so she's running quite well now.

You should only lift the piston 1-2mm!

[mogbob]

Dave
Keep all the circlips, washers and the electrical pick up for the self parking mechanisism ( unless the suppliers have confirmed the replacement wiper motor comes with them ).
It sounds as though your wiper wheel boxes have loosened up.They should grip the metal tubes ( in which the rack runs ) between two halves, held together with two screws. ( see http://www.moss-europe.co.ukdiagram ).The wiper blade spindles protruding through the bulkhead hold the set up rigid.
Slacking off the total of four screws ( 2 per wheel boxes ) and with some gentle pushing and pulling...you might just free up the rack..if you're lucky.Other wise dismantle the set up.
Use the biggest Phillips type screwdriver you have or tommy bar or punch... to put through the cable end.This will give you more control over the pulling and pushing ! Remove the wiper blades at the start, if you haven't already done so.The wheel boxes can then spin freely.
If you get everything out, clean and re-grease the tubes before re-assembling the rack back in place.
Your vast photographic record will remind you of the vital position of the self parking mechanism when you fit up the re-con wiper.
Post again if you need help/ tips on how to reinstate, without the wiper blades clashing or scratching the screen.
Bob

[MarkyB]

There is a constant hissing,

This may be an air leak into the manifold or carb, see if you can pin it down.

[davidmiles]

thanks for all that advice guys, Neil I lift the piston only one and a half millimetres now, makes more sense than the 8mm suggested in the Haynes. I believe I have the mixture correct now, but my regular short drives to work are still fraught with low acceleration in 2nd 3rd and in 4th I can't get much more than 30mph, getting there is slow and laboured. I have to take the side streets where speed above 30mph isn't needed. So my problem has to be the advance and retarding of the distributer. I've taken out the electronic ignition to get at the turning advance plate inside the dizzy.[frame][/frame]

not much to it as you can see, for 70 odd quid, there is only one screw fixing hole as you can see, Ive added a nut to reduce the screw length, so it doesn't jamb up the plate...

[frame][/frame]
this picture above illustrates my understanding of my problem. The vacuum advance doesn't seem to have enough "throw". when I suck on the pipe all I get is a couple of mm of rotation of the plate. that spring end needs to be further along to create more movement in vacuum advance. the Vacuum unit does have a small amount of movement. So I wonder if tightening that end nut used to adjust micrometer adjustment should be screwed up to tighten the vac unit, then re adjust by undoing the pinch bolt to re-adjust the timing back to what it is now. Does any of that make sense to anyone else?

[MarkyB]

For what it's worth I have only even managed to move one a few MM, I figure my lungs have less pull than a 1098!

[mogbob]

Dave
Movement of a few mm is good, it doesn't have to shift the base plate by much.Assuming that with the vacuum unit spring disconnected that the base plate is free to move and that the spring "unattached " moves when you suck then it appears to be working OK.Re-connect the spring to the post.
Is the vernier adjustment small wheel in the middle position ? i.e. you counted the number of clicks from one extreme to the other ( left to right or right to left ) and then halved it , to get the centre point.

The major concern raised by other folk is more likely to be the problem.The hissing sound.Air is leaking somewhere.
Look very critically at the sealing points, gaskets... exhaust and inlet manifolds and the gaskets on the mounting of the carburettor.Make sure the nuts holding down the manifolds and the carburetter are good and tight.

I was asked to tune an MGB two weeks ago, the owner, a friend of my son's said it was " difficult to get a steady tickover ".
Having " had a look " I soon concluded that the fact that I could do his twin SU carb mounting nuts up by hand ( they were so loose ) probably had something to do with it !! His carbs " hissed ", sucking in air...but not through the usual air intake.

Adjust the distributer as described before.. aiming for highest / smoothest tickover and the tweak the vernier after a road test, if you need to.

Bob

[davidmiles]

thanks marky, I've tried all sorts today to try and get her running over 30mph. I'm stumped. The metal bracket shown above with the electronic package, the hole goes perfectly over a stud and the screw does up fine, so I know that's in the correct position, I wonder if it's 180 degrees out. Would that give good tickover and then turn roapey as she gains speed and goes further up the gears?

Sorry Bob didn't see your post, I'll read and digest... yes I'll go through and check everything is tight, the hissing continues, that may be my problem then. (The plate is free to move inside the Dizzy, I checked it with the spring vacuum advance off.)
I'll post back when all of that is done

[drivewasher]

To check for inlet manifold leaks (sucking air) LIGHTY spray wd40 or similar on the manifold & carb joints/gaskets whilst engine is warm & ticking over. If the speed o tone changes then thats where she's sucking air in

[davidmiles]

Thanks Steve I'll try that. The nuts are all tight on the manifold and head, I'll try the carb joints using the wd40 idea

[MarkyB]

running over 30mph

I didn't realise it was this bad!
A duff vacuum advance just takes the "pep" out of the engine, it doesn't make much difference to the top speed, just how long it takes to get there.
Does the points cam move separate to this dizzy shaft and the carb piston lift easily?
What colour are the plugs?
Sorting out the air leak seems like top priority, check the carb flange and the manifold one for flatness with a straight edge.

[drivewasher]

You know David call me old fashioned but,.... I would put the points and condensor system back in whilst you get this sorted. You can do proper physical checks on points and set timing up exactly so thats one variable you have fixed. If you see what I mean.

Also I see you have an alternator, did you swop the coil leads over to make the spark jump the right way. Mind you the pickup has run ok hasn't it?

[Neil MG]

Yes 30mph is something drastic, not just slight tuning/timing adjustment.

Sounds like your timing is horrendously out, or you are back to running on three cylinders (or you have two plug wires swapped - 1342 anticlockwise!)

Another possibility is fuel starvation due to a partially blocked jet pipe. That happened to me and could easily be the case if the carb was rebuilt. the old O ring gets stuck in the bottom of the float chamber and when the new jet and pipe is fitted it is squashed partially blocking the fuel flow. The car runs fine, but as soon as you try and rev, particularly under load it just loses power.

[davidmiles]

well I tried the WD40 spraying over all gas tight joints and there was no change to the engine tickover speed, it takes all four gears to get up to 30mph eventually, in third gear she bucks a little and looses power, in 4th she runs smooth and gradually reaches up to 30mph if I don't press too hard on the pedal. the points cam moving separate to the Distributer shaft I don't know, I know that when I drag on the vacuum pipe the disc rotates a couple of mm. The carb piston lifts nice, smooth and easy, plug colour was uniform, grey/black, the carb flange seems ok with the WD40 test, all four cylinders are running but there are currently flat spots when she's ticking over.
Coil leads, I did have a problem with a duff coil connection earlier on, I changed it over and taped it up. But I don't think I thought it through when I originally fitted the original alternator way back last year or more. Maybe there's something in that...[frame][/frame]

the coil connections look like this[frame][/frame]

the connector at the bottom nearest the camera is white black tracer, top connection furthest away red wire and below that white wire.

[aupickup]

well it would still run either way with the coil connections my bet is on the timing

[mogbob]

Dave
The Red wire and the White wire ought to be on the " + " SW terminal and the White ( Black tracer ) to the " - " CB terminal
but as stated it will work either way ( incorrect connection not conducive to long life of ignition parts in a conventional set up ).
Bob