Practically Classics Forum

Right chaps,

Feeling pretty stupid, but can anyone tell me where on a 1979 MG Midget 1500 the vacuum advance line from the distributor goes to. I'm flipped if I can find a port on either of the twin SU carbs and currently someone has simply drilled an hole in the rocker breather to carbs pipe and shoved it loosely in there.

Just trying to get it running ok ready for the lad going for an MOT, seems to be running rich and grey smokey with some unburnt petrol at the moment and I want to get the ignition system set up correctly before playing with the carbs.

Cheers Chaps

Is it not to the left hand side of the right hand carb when viewed for the intake side of the twin carbs?

Kev

Thanks Kev, unfortunately all I seem to have there besides the linkages is a pipe running between the two carbs like a balancer pipe.

Ok, I'm getting convinced I don't have a vacuum port so something may be different about the set up from original... by the way, these carbs are SU's with integral float bowls (HIF's?)

IF I don't have a port, could I either run the engine breather to the manifold adapting the tapped plug (servo take off?) and then use the engine breather port on the carb as a vacuum port. Or alternatively while I know manifold Vac and Carb Inlet Vac are possibly somewhat different in characteristics, could I put a port in the manifold servo blanking plug and run the vacuum line to that?

Thoughts please?

Do you have a hole as shown in this thread:
http://www.mmoc.org.uk/viewtopic.php?f=4&t=50339

I run a single HIF38 taken from a metro in my mog and it has a normal vacuum connection there but yours may have broken off.

Thanks Terry,

No hole either, but where the port is located in that picture on the thread link, these carbs just have a slightly raised circle of the casting, as if there could have been a port there if the manufacturer had wished to put one, but didn't.

arceye wrote:Ok, I'm getting convinced I don't have a vacuum port so something may be different about the set up from original... by the way, these carbs are SU's with integral float bowls (HIF's?)

Sounds like non-standard carbs then - I would expect HS4s. If you can find somewhere to tap into the inlet manifold then that would do the job

Cheers Richard, Will do that, I've just tried it on one of the engine breather ports and that makes it run ok (it was stuttering and struggling to pick up revs before), but I do need to route the breather somewhere so inlet manifold would be better for the vacuum.

Bigger fish to fry now though I think, having sorted the vacuum at least temporarily, gone through the ignition system and got it to run properly with carbs more or less about right, the grey / black smoke has turned to a shade of bluey grey.....could be trouble ahead

Ah well, and on getting her warm now its running ok(ish) the oil light comes on bright and steady at tickover, along with a slight grumble from the bottom end when throttle is applied along with worsening smoke. I think it is going to be a bit more than a dodgy oil sender with this one.

Rebuild time me thinks, what is annoying is my lad dealt on this car at face value without getting it warmed up rather than being a bit more thorough as it belonged to a neighbour and aquaintance (I won't say friend at the moment we will have to see) of ours and had been on the road with no smoke (seen it around enough) up until a couple of weeks ago when it supposedly came off the road only due to MOT being up.

Not happy, think I will have to be having words, boys only eighteen and on 3.40 an hour being a first year apprent, he can't really afford to be had over.

Hmm, that's a bummer and that engine does tend toward a rattly bottom end as a result of its hugely oversized journals, long stroke in the case of the 1500s and troublesome thrust washers.
However, they are easy to sort and in many cases will respond to shells without a regrind being essential if the thrusts aren't worn enough to allow the end of the crank to chew its way through the block. Check for endfloat as that, more than a bit of a grumbly bottom end, is what can render a 1500 fit only for scrap. Trouble is, the large journal engines (late 1300 as found in Toledos and the 1500 in all of its applications) are a typically long stroke, low revving thing that delivers its grunt like a Diesel and ideally should have been treated as such but BL seemed not to consider the possibility that buyers of a small, sporty two seater might just want to thrash the nads off the engine. Best place to find a used one that stands a chance of being healthy is from an automatic Triumph 1500 TC (that's the RWD version of the 1500) or Dolomite 1500 auto, as the two pedal versions were almost impossible to wreck as a result of there being far less load on the thrust washers. Sumps would need to be swapped over but that's about it.
Assuming (and please let me be wrong here) that the seller of the car doesn't help out, then I'd tend to risk just putting fresh shells in one of these to extend its life if the endfloat hasn't become too serious. Then find a way to govern the engine to 4,500rpm at most, they can last well when driven that way. Sometimes.