MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Drat! Anyone got a 1098 inlet manifold?

It was all going so well until I offered up the inlet manifold and discovered it doesn't fit the new 1098 head. I think I need a manifold with lugs on the sides to hold it in place. The manifold I have locates with rings but the new head isn't machined for rings. The casting for the one I have is 12G586. Am I right in assuming this is for a 1275 head and that for a 1098 I need a different manifold? Does the 1098 also locate with rings because my head hasn't been machined for them if it does.

Stuart K

The rings fitted to standard metro manifolds? are extra fittings (simply pull them out) and the manifold should lacate and fix with the normal bolts as like every other A Series manifold. Have these been cut off on the one you have?
Robert (Bob) Midget Turbo

ouch!!!

Now theres a kick in the old nads,

You need to make a call to the privious owner and demand the original parts that was on the head before they sent to the mechanic, just before they sold it to you, because if that manifold dosnt fit, My guess the carbs wont fit, meaning they maybe HS1s like on the old bug eyes....if you dont get all those old parts... and want to RE-source them, expect another $300 to $600. And No the Idiot mechanic did not throw away the parts...to inconcievable.

Are You sure the intake manifold out lets dont match up to the inlet ports on the head...if not by how much, might be ahead to have a new piece welded into the intake log..(tig welded) then you dont have to source anything

If the ports DO line up, then center the ports as close as you can and drill a small hole to the side on the intake going into the head, then tap that new hole and get a screw to go thur the intake into the head....that will be your new locating stud...do it for each port, and only drill into the head just far enough for about 4-6 fine thread turns, about a 1/4 inch, you dont want to tap into a water jacket inside the head.



Prop
Prop

My only point of reference is the Moss catalogue which shows the 1098 manifold having lugs that locate on the manifold studs. The 1275 doesn't have these but does have rings that fit inside the bore which I presumed help locate it. Pic below is my manifold which looks like the 1275 in the Moss catalogue.




Stuart K

Not sure how to identify the carbs, Prop. They look like HS2s to me comparing them to pics in Haynes and the linkage looks like it is right so I had assumed they were HS2. To save me going out to the garage and taking a pic, here is one of them on the car before I started all the work.




Stuart K

The manifold you have photographed has been modified. the tabs on the side of the inlet holes have been shortened and would normally be a little wider and have half a hole in them to locate the studs on the head. It is a common modification on Minis and Metros and allows the manifold to be slid into place without removing the manifold nut and washers completely. Sometimes we leave the top part of the extensions on which is then the best of both worlds.

I am wondering if this would bolt up alright as is, Worth a try I think.
Robert (Bob) Midget Turbo

I'm going to have a good go! My manifold looks exactly like the one pictured on page 156 of the current Moss catalgue which is why I took mine to be a 1275. There are no lugs on that one.
Stuart K

Sorry Stuart I have mislead you a little.
I think the last time I used that manifold was 25 years ago. :-)) just checked some twin carbs and manifold in my garage and it is exactly the same as that. Evidently different to the later manifolds used on Minis and Metros.

As you say give it a good try. :-))
Robert (Bob) Midget Turbo

prop
one reminder stuart lives in the uk
so a replacement manifold and carbs won't cost him that mutch if he needs one

midgets and sprite ar not that gold plated in the uk and europe
Onno Könemann

Stuart,

It's been a long time, so my memory may be off. But, I am almost positive that I have bolted ring-located manifolds on heads with no ring recess. Just remove the rings, center the manifold on the ports, and bolt it on. It will be easier to center if you put the manifold on without the carbs attached. That way you can look through and check your centering. Yes, there will be some flow disturbance from the missing rings, but you are not building a competition engine.

If I understand the SU numbering system, an HS-1 will be 1 - 1/8 inch diameter measured where it meets the manifold. An HS-2 will be 1 - 2/8 inch dia. An HS-4 will be 1 - 4/8 inch dia, and so on like that counting the eighths.

I also agree with prop that you should try to get your other parts from the previous owner.

Charley
C R Huff

So was the 1098 head machined to take rings or not? It would make lining up and the seal so much better if it was. If it should have been I can take the head back and get it fixed.
Stuart K

Stuart

I think a basic point is being missed here.

Both 1098 and 1275 inlet manifolds locate on rings.

Which cylinder head have you fitted? What is the casting number?
Dave O'Neill 2

Aha. Well this head is not machined for rings. That may be my problem. Casting is 12G202 which looks like it was for early 1098 and 998s. Guess I should have had the 12G295. I did tell the supplier it was for a 10CC engine.




Stuart K

According to Vizard, the 12G202 was fitted to 997 Mini Cooper, Austin/Morris 1100, Midget Mk1 and Sprite Mk2 - 948cc, presumably.

The Mini Cooper 998, MG1100 and Midget Mk2/Sprite Mk3 were fitted with either 12G206 or 12G295, both of which had location rings.

Also, the 12G202 combustion chamber is 2.2cc smaller than the latter two.

Sounds like you've been supplied with the wrong head.
Dave O'Neill 2

I had a 1275 head that had no ring recesses - so I cut them with a dremel. Took about 1/2 hour, freehand. It wasn't difficult.

I cannot remember which head it was on, or which engine it came off. Possibly a Metro or a Maestro. But the point is, not all 1275s used the locating rings.
Guy Weller

Stuart, your engine (10cc) should have the 12G295 head but the 12G202 is in a lot of senses a better head (if modified), as Dave says, it is a smaller combustion chamber so one can work that to a C/R advantage. Calver will always prefer to 'flow' a 202 in preference to a 295.

As for Manifold location, is the head still off the engine? if so, take it to a machine shop and as them to machine the ring grooves into it or find a suitable manifold. I have a stack of them which I could look through for you. It is only a location thing, so the ports line up, so you could even do it by eye as once nipped into position, it shouldn't move, but then again....

Mark.
M T Boldry

If they are only used for locating and I can do it by eye then that's what I will do. I thought they might have some function with flow and to stop leaking. I'll remove the carb setup from the manifold this evening and attach the manifold on its own. If it looks ok I'll continue with the build up.

According to what I have found on the net the port is slightly smaller 1.156" instead of 1.218" on the 295 casting. Hopefully that isn't going to make any difference and allows me a margin of error on the line up.

Thanks again for the advice folks.
Stuart K

as mark has stated
the 202 is a good head for a 1098
the 295 has a nasty tendency to crack

the 202 will if modified wel flow almost as mutch as a well modified 12G940!
if you want i have got a modded 202 with larger inletvalves on the shelf....
Onno Könemann

Onno, may I have second refusal on that...?

Mark.
M T Boldry

Go for it Mark, I don't think I'll be needing it.

Panic over. When I came to look at it in the light of day today I found that the manifold has semicircular indents in the feet into which the large washers locate. It is held very firmly in place and because the holes are that shape there is only one way for it to go on so no problems with alignment. Doh!

Stuart K

Mark
I will be at sliverstone in july
Mail me at onno#konemann.eu (replace the # with @)
I need a few parts for my midget we might be able to make a deal

stuart
is it up and running yet?
Onno Könemann

Onno - yes! See here:

http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs&mode=thread&access=&subject=97&source=T&thread=2009060922002027024
Stuart K

This thread was discussed between 07/06/2009 and 09/06/2009

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.