Tuning the R-Series

[SimonR]

Never having tuned a car, I decided to work out how to do it with a Haynes manual, a timing light circa 1970, a selection of screwdrivers and my new R-Series Maestro.

It was running rich anyway, to the point where it was running very rough indeed when cold and making the plugs very sooty. Anyway I'd just removed and serviced the carb, so I thought what the heck!

The first problem was that the distributor seemed to be stuck - having undone the bolt at the back, it simply wouldn't budge and I didn't want to break anything so I left is as it was. The timing notch was between the rear two marks on the crank case which means that it's about 14 degrees which isn't too far out seeing as it should be at 16 for Optimax IIRC.

The second problem is that the exhaust manifold is blowing rather - not where it joins the engine, but near the base of the carb where there's a big square joint.

Anyway, the car was already running fairly smoothly when warm so I screwed the mixture adjustment anticlockwise until just before the engine started to go lumpy and then backed off the revs to the correct place.

Now when I drive it it seems very underpowered - with my foot to the floor, it coughs and splutters a bit and makes very slow progress. I'm guessing that means it's too lean...?

I also wonder how much effect that manifold is having on performance and my ability to tune the engine.

While I'm on the subject, I was looking for the ambient air temperature sensor and all I could find was a small black thing (about 1x1cm) with Lucas written on it and two spage fittings on oposite sides. Is this it? If not what is it? And more importantly where the hell is the AATS?!

TBH I think that the first thing I have to do is fix that manifold.

With hindsight, I can thing of better ways to spend a Sunday afternoon ;) Hmm, I've also just remembered that I forgot to replace the vacuum pipe on the carb so maybe that explains a bit of the rough running...

[Wonko_The_Sane]

The naff black block you describe is indeed the ambient air temperature sensor..:laugh:

Mine was destroyed in a crash, so I went manual choke and cut the wires off..:)

[G Force]

Hello, I think you are right to fix the exhaust blow before you do anything else, what often happens when the exhaust blows up front like on yours the fumes get taken up into the air filter and block up the elements.

It sounds like you have set the carburetor mixture setting too weak now so you need to look at that also. When you overhauled your carburetor did you check the vacuum switch diaphragm was not punctured and also did you check the orfco valve was not stuck.

The aats is the item that you have described and it is usually located on the n/s inner wing behind the head lamp.

Don't forget to reconnect the vacuum advance pipe, you should check the distributor vacuum unit is sound while you are in that area.

Regards Gary

[SimonR]

Thanks for that advice, Gary.

What you suggest about exhaust gasses getting into the air system and polluting the cleaner element rings true - when I replaced the element the old one was really black and sooty. I thought that it was just very old but it was probably only a year old but contaminated.

Since posting the thread I've been reading around on the old forum archive to see if others have had similar problems in the past.

It seems that my assumption that unplugging the fuel cut of valve would take it out of the equation is flawed- looks like it could be stuck open or closed. Also I'll check the vacuum switch and see if there's anything sloshing around inside it.

What I might do is use a carb from a later Monty that doesn't have a vacuum switch or fuel cut off valve. I've been told that these typically enable the engine to run smoother and more reliably. The question is whether or not this would be suitable for the R-Series engine.

I'm just about to replace the old-style carb on my S-Series Maestro with a later Monty one, and actually have one spare as well.

What are the differences between the two carbs (R-Series and later 1.6 Monty)? Could I just take all the gubbins out of the R-Series carb and fit them into the Monty 2.0L one and expect it to work?

Finally how do I make sure that my distributor vacuum unit is functioning?

As always MANY thanks. Now I have two Maestros I've got to do the work myself because I can't afford to run two cars AND pay for some monkey to screw them up when they need repairing.

I can do that perfectly well myself :laugh:

[G Force]

Hi, easy to check distributor vacuum unit just connect a pipe to it and suck on pipe, you should not be able to suck through it, then with engine running do the same and the engine should speed up.

Whether you can fit later Monty 1.6 carb to r series can't say because not tried, you can definitely swap the later Monty 1.6 to an s series maestro.

I would guess the main problem with the r series is whether you can swap the throttle linkages, once you have found out whether you can do that then you might need to change the needle, and see how she runs. If yours is a later 2.0 Monty carb then you would need to change the needle and the dash pot spring as it is the strong yellow one on the 2.0

If you stick with the original carb then it is OK to leave the orfco valve wires off as long as the valve is stuck shut.

Regards gary

[SimonR]

Good news! I think my car loves me ;) Whenever we do even the most minor bit of maintenance to MaestroMatt's car it either makes the job hell for us or decides to accept the repair but break somewhere else the same day.....

I think A335 realises I saved it from the scrapper and also that it's only a very short trip back there if it gets moody with me!

Last night, between 17:30 and 19:20 I managed to dismantle enough of the engine to get the manifold off. I was dreading trying to remove the bolts from the clinderhead, I had also heard that it was very easy to shear the studs off the manifold. Turns out that each bolt just cracked under the smallest bit of pressure and turned a sod of a job into something that took less than two hours.

Who'd have guessed that you'd have to drain the cooling system? - the thermostat housing is directly above the manifold... I also had to remove the camshaft cover because it was overlapping slightly, preventing the manifold moving up. Other than that it was very easy.

The old gasket was just a rusty iron plate and some monkey had put exhaust putty all around it on both manifolds. I managed to scrub it clean in the kitchen sink last night - thank God I don't have a wife or girlfriend living with me :)

Now for the reassembly: Am I right in thinking that the gasket between the two manifolds is just a thin metal plate? Do I just have to clamp that between them?

I will, of course, make sure it's all very clean and shiny before I reassemble - all the mating faces on the inlet manifold are shining so I'll just tidy up the Exhaust which it obviously still on the car.

One last thing - do you think I'll get away with not replacing the gasket between the two manifolds and the cylinder head? I've not disturbed the exhaust and the part the the inlet clamps onto seems in very good condition. I also wonder if it's under sufficient pressure to warrant a gasket change.

[G Force]

Hi, I would definitely renew both gaskets if you can get hold of them. You have not much more work involved in doing the manifold to head gasket, so it would be wise to do it now rather than take a chance and find you later have a leak. The hot spot gasket has a small corrugation in it if I remember rightly which crushes to give a good seal, that’s why it is best renewed.

Regards Gary

[SimonR]

Thanks, Gary.

In that case I'll try to remove the exhaust manifold from the head. If it comes off easily I'll replace that gasket as well, if not then I'll take my chances....

I shall update tomorrow, hopefuly with good news, although I may take this chance to clean it all up in that area and therefore take a little longer for reassembly. Whatever happens I have to get this car on the road by the weekend as the major work starts on F153 this Thursday.

[SimonR]

Damn! I've found out why it was bodged in the first place now! I've been expecting this so it's not so much of a surprise.

As I was doing up one of the nuts that clamp the manifolds together, it got nearly tight and then turned but went no tighter. Then the whole stub fell out! It seems that the monkey who last worked on the car had over-tightened the nut and stripped the thread.

I'm going to have to get some sort of glue from the motorfactors and rectify it this afternoon. Failing that I'll retap the hole and use a larger stub.

What a pain! :banghead:

[E_T_V]

If you get stuck you can always helicoil it and use the original size stud.

[SimonR]

I hadn't heard of the Helicoil product before, just read about it on the Interweb that I've installed inside my screen and I shall remember it for the future. I can think of many applications where it'd turn a serious problem into a half hour job.....

Have just spoken to my local friendly motorfactor and he has a product called JB Cold Weld which will glue the stub back in. Looks like I'll be removing the manifold again, cleaning the joint and gluing it this evening..... Lets hope and pray that I can get it working by the weekend. :cool:

[E_T_V]

yes it is extremely useful in alloy castings and especially spark plug threads in alloy heads, which you can't get a bigger bolt for! :D

[SimonR]

Even better than actually PAYING for something, I've just found out that the maintenange guys here at work have a set of Helicoils so I've brought the manifold in and they are going to sort it out for me.

Ah, the joy of car maintenance on a shoestring :)

[SimonR]

Got the manifold repaired and was in the process of fitting it when it ocurred to me that the two manifolds aren't mating correctly at the joint - it seems that there's quite a gap. A little more investigation with a straight edge revealed that one side of the exhaust manifold is about 1mm lower than the other at the joint:


/###\
/#( )#\
/#################\
###################
## ### ##
## ### ##
## ### ##
## ### ## <- This side is 1mm lower than the rest
## ### ##
## ### ##
## ### ##
## ### ##
###################
\#################/
\( )/ \( )/
### ###
Please excuse the rather shoddy representation!

I now finally understand why it was bodged in the first place - the previous monkey had tried to close this gap by overtightening the nuts on the studs in the manifold, failed and then used a whole load of exhaust putty to fill the gap.

The question is, what can I do about this, short of removing the exhaust manifold and remachining it? What I think I need is a nice squidgy gasket, rather than/as well as the metal one I'm currently using, but I'm probably wrong. More exhaust putty is probably too much of a bodge, even if I *am* able to tighten the joint correctly.

Views please!

This whole job started off with me thinking I could learn how to tune my car in a Sunday afternoon... D'oh :laugh:

[E_T_V]

You could try getting another gasket and cutting it in half. Then use the half a gasket (as well as the other one) for packing the side with the gap to try and level it out a bit.

Otherwise yes the only solution is to re-machine the manifold :(

[G Force]

A good sharp file could sort that out.

regards gary

[SimonR]

Well, I'm sure you've been waiting for the latest news...

I have had to replace the exhaust manifold because after I studied it very carefully and scraped off all the old exhaust putty I found that it was also perforated by what looked like a chisel or screwdriver.

Someone obviously had a lot of fun trying to fix it last time!

Thankfully BigLad has a replacement item so I'll finish the job off when I get it. In a way it's quite good because at least it means that I will have repaired the original fault to a high standard which means it's unlikely to break again. I've also been able to clean up that part of my engine while I've been working on it so it'll look the part as well.

Hopefully it'll be fixed within 10 days, then I can Tax it at the beginning of next month and begin to enjoy driving it.

We'll see ;)

[Ricky]

Originally posted by F153JUE


Hopefully it'll be fixed within 10 days, then I can Tax it at the beginning of next month and begin to enjoy driving it.


Famous last words! I've been saying that every month since I bought my MG this time last year, and it still hasn't happened! 1 replaced engine, gearbox, much body filler and welding, many many frustrating hours, far too much money, and not to mention all the blood sweat and tears have gone into this car, and for all that it runs lumpier than a subaru and has no reverse! Still, hopefully i'll be able to sort these before the end of the month, and then i'll be able to tax it and drive it.....:banghead: :banghead: :banghead:

The end of the dark tunnel is nearing, I can feel it!!!!!

Thinking about it, the manifold on the donor maestro had a blow in the place you describe, is it necessary to have that particular manifold, or (if i need to revert back to the su) could I use the MG's manifold without this mounting point on it??

Good luck, and whatever you do, don't touch that rocker cover!!!!! They're not the strongest things.....

[SimonR]

Er... Sorry Ricky, I've had to remove it! :eek:

Couldn't get the inlet manifold off as it was in the way....

After the trouble we had with MaestroMatt's R-Series cover cracking I'm going to be super careful. Of course after I finish this maintenance I've still got to tune the bloody thing.

Good luck with your Motor!

[BIGLAD]

Originally posted by F153JUE
Well, I'm sure you've been waiting for the latest news...

I have had to replace the exhaust manifold because after I studied it very carefully and scraped off all the old exhaust putty I found that it was also perforated by what looked like a chisel or screwdriver.

Someone obviously had a lot of fun trying to fix it last time!

Thankfully BigLad has a replacement item so I'll finish the job off when I get it. In a way it's quite good because at least it means that I will have repaired the original fault to a high standard which means it's unlikely to break again. I've also been able to clean up that part of my engine while I've been working on it so it'll look the part as well.

Hopefully it'll be fixed within 10 days, then I can Tax it at the beginning of next month and begin to enjoy driving it.

We'll see ;) :)

Well then,
seeing as its now been publicly announced that you want it done in 10 days and you're waiting for me- i better get my a**e into gear & get it posted!
LOL
Biglad;)

[SimonR]

Oops - sorry Wayne - didn't mean to sound pushy! :rolleyes:

If you can't do it within 10 days then don't worry, it's not the end of the world... Hopefully I'll have F153 roadworthy again within that time anyway!

[BIGLAD]

Originally posted by F153JUE
Oops - sorry Wayne - didn't mean to sound pushy! :rolleyes:

If you can't do it within 10 days then don't worry, it's not the end of the world... Hopefully I'll have F153 roadworthy again within that time anyway!

Hi,
10 days is no probs- i'll get it sorted across the weekend and aim to have it posted Monday.
Send me a P.M with your address on if you want, so i can get it sent asap.
Thanks Biglad

[MaestroMatt]

Originally posted by Ricky
Good luck, and whatever you do, don't touch that rocker cover!!!!! They're not the strongest things.....

I wish someone had told me that! Stupid rocker cover cracked under the slightest torque. Still, I found the best stuff in the world to fix it with - I think it is called Leak Fix and it is a bit like Araldite (only jet black) - sets rock hard in about 10 mins and, so far, has been impervous to hot oil and, most importantly, hasn't cracked when I put the cover back on.

[SimonR]

Good News!

After a severe bout of the flu I have been able to put A335 BWV back together again with a new exhaust manifold and gaskets all round.

It started and ran beautifully and interestingly enough all the hesitancy had diappeared as well. I've got to set the idle correctly so that it doesn't run at about 2,000 rpm on idle!

Many thanks to people who helped, especially Wayne and Gary - without you it'd still be on the drive, not working. I was especially grateful that Wayne didn't separate the two manifolds and sent me both!

I'll tax it at the start of next month and finally I'll go from having no working Maestros to having *two* in the space of a month.

Wey hey! :cool:

[BIGLAD]

Originally posted by F153JUE
Good News!

After a severe bout of the flu I have been able to put A335 BWV back together again with a new exhaust manifold and gaskets all round.

It started and ran beautifully and interestingly enough all the hesitancy had diappeared as well. I've got to set the idle correctly so that it doesn't run at about 2,000 rpm on idle!

Many thanks to people who helped, especially Wayne and Gary - without you it'd still be on the drive, not working. I was especially grateful that Wayne didn't separate the two manifolds and sent me both!

I'll tax it at the start of next month and finally I'll go from having no working Maestros to having *two* in the space of a month.

Wey hey! :cool:

We aim to please!!lol:
laugh: ;)
Biglad