1275 exhaust manifold questions.

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austinh7
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1275 exhaust manifold questions.

Postby austinh7 » Tue Sep 13, 2016 3:12 pm

Currently I have 1275 (Sprite I believe) engine, with a 12G787 combined manifold. HS4 carb.

However I want to fit a better inlet manifold, I have a nice Oselli torquemaster with HiF44, K&N etc ready to go.

It's currently running a standard exhaust, which I think needs to be upgraded to large bore so that it can "breathe out" properly.

So the questions are:

1. What is the best bet for exhaust manifold? If buying new it seems the options are fairly limited to a Large Bore L.C.B. Exhaust Manifold (See #2). Looking at previous threads / internet searches it seems some modification / butchery can be done to standard Morris 1000 manifold to split them. Can this be done on a Sprite version?

2. Is it worth biting the bullet and going for the full Large Bore manifold and exhaust in one hit (and hoping the wife is out when it gets delivered)?

philthehill
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Re: 1275 exhaust manifold questions.

Postby philthehill » Tue Sep 13, 2016 3:34 pm

There is no point in butchering a Minor thousand exhaust manifold because you will not then get the best out of the engine.
The Sprite/Midget exhaust manifold is a separate unit and can be used but the outlet points in the wrong direction (forward).
Personally I would go for a single pipe 1275cc Marina/Ital combined inlet/exhaust manifold and if not suitable for your purposes fit the Oselli torquemaster inlet manifold with a small bore 1275cc LCB manifold.
There is no point in going for the LCB manifold with the large diameter pipe unless you are intending to upgrade the camshaft with wider opening periods and port and polish the head.
Sometimes going large can be a backwards step.
The Maniflow exhaust suitable for your engine spec is Pt No:- LM053
http://www.maniflow.co.uk/index.php?vie ... tegory=209
There is a suitable Maniflow exhaust system to match the manifold.
Phil


Monty-4
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Re: 1275 exhaust manifold questions.

Postby Monty-4 » Tue Sep 13, 2016 4:13 pm

BM now do a (much) cheaper version of that Maniflow manifold but I have had some problems getting a good seal with the head (pipe tops weren't flat with each other) and also clearance with the bulkhead! Awaiting their response to see if I got a dodgy one, but you get what you pay for, perhaps.

Before that I used the bottom half of a 12G3538 cast manifold and a single "large bore" down-pipe from MMC Birmingham. This required a little adjustment to the bend but worked fine. I switched to the LCB so I didn't have to deal with the damned manifold to down-pipe clamp.
68' 4-door Saloon, another 'Monty'.

austinh7
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Re: 1275 exhaust manifold questions.

Postby austinh7 » Tue Sep 13, 2016 4:55 pm

Thank you both.

Having read up it did seem the larger bore would be to big, 1 5/8" seems to be the size that's right for me at the moment.

A couple more questions...

Who is BM?

The manifold that is currently on there is a Mini one going by part numbers. Looking for a Marina/Ital one seems to be tricky, is there a part number that anyone knows of?

In the long run I would like to do more to the engine, it is however a matter of time, money and that it needs to be kept running as much as possible.

Would it be a backward step to use the bottom half of the manifold I already have / or a 12G3538 etc and the new manifold / carb?

philthehill
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Re: 1275 exhaust manifold questions.

Postby philthehill » Tue Sep 13, 2016 6:07 pm

BM = Bullmotif

The part number for a Marina/Ital inlet/exhaust manifold is 12G3538 and the part number is cast into the manifold.
It would be a shame to spoil a Marina/Ital inlet/exhaust manifold just to get the exhaust manifold element.

You can use the bottom half of the Minor exhaust manifold but I would suggest that there would be little benefit in then fitting the Oselli manifold and HIF44.

You need to do it all together or not at all.
Phil


daveyl
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Re: 1275 exhaust manifold questions.

Postby daveyl » Tue Sep 13, 2016 7:58 pm

I may be wrong but I thought the 12g3538 was from a mini or metro 1 litre. It has 4 studs on the inlet for and a 38mm opening for a HIF38 carb. The Marina 1300 had 38mm opening But only 2 studs to fit a HS4.
The later 1300 Ital/metro (A+ engine) had the twin exhaust outlet and a bigger 44mm opening for the HIF44. Unless the later Marina's got the 12g3538 manifold, with a HIF38 carb?
i will add that the early Marina 1300 and the 12g3538 unit do seem to have the same exhaust angle when compared side by side.

philthehill
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Re: 1275 exhaust manifold questions.

Postby philthehill » Tue Sep 13, 2016 8:34 pm

The 998cc Mini inlet/exhaust manifold is Pt No: 12G3279 with two studs.
The 1098cc Marina inlet/exhaust manifold is Pt No: 12G3538 with two studs.
The 1275cc Marina inlet/exhaust manifold is Pt No: 12G3538 with two studs.
The 1275cc 12V engine Marina inlet/exhaust manifold - 1978 on - is Pt No: 12G3538 with a 40mm inlet bore and the option of either using two or four studs.
The carb fitted to the 12G3538 manifold with two studs was a HS4 SU AUD541 (saloon) or AUD589 (van). There were other SU HS4 variants fitted.
All the above part numbers were taken from official BL parts lists.
I do have a 12G3538 Marina inlet/exhaust manifold but currently it is not for sale.
Phil


liammonty
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Re: 1275 exhaust manifold questions.

Postby liammonty » Tue Sep 13, 2016 8:45 pm

I've got a Marina one with the inlet manifold removed, and if I can find it, it IS for sale, unlike Phil's. If you want it, let me know and I'll try to dig it out.

daveyl
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Re: 1275 exhaust manifold questions.

Postby daveyl » Tue Sep 13, 2016 8:52 pm

Ah, well done phil. I did also fit that manifold to my Morris and I found that the 'off the shelf' downpipe conversion wasn't a brilliant fit but at the time I put that down to the gearbox I had fitted, maybe changing the angle.

Monty-4
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Re: 1275 exhaust manifold questions.

Postby Monty-4 » Tue Sep 13, 2016 8:55 pm

I have the bottom half of the 12G3538 (will save somebody destroying another one) and the "adjusted" Birmingham down-pipe sitting around somewhere now I have the Bull Motif LCB. If anybody wants them for a token number of pounds sterling do let me know.
68' 4-door Saloon, another 'Monty'.

austinh7
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Re: 1275 exhaust manifold questions.

Postby austinh7 » Wed Sep 14, 2016 12:02 pm

Thanks again for the help.

So pricing up on the BM site a system comes in at £200 + VAT. It doesn't mention the size but does say large bore so I'm guessing is not what I want. I've asked the size and am waiting for them to get back to me. It also sounds like they aren't a great fit.

On Maniflow (1 5/8") it's £285 + VAT. (Without the fittings).

(Both for exhaust manifold and full replacement exhaust).

So if I go with the Maniflow system is there a specific fitting kit that I will need?

Monty-4
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Re: 1275 exhaust manifold questions.

Postby Monty-4 » Wed Sep 14, 2016 1:06 pm

BM's "large bore" LCB is 1.5" so I'd guess the rest is too. Maniflow provide a fitting kit for the Minor but I found the straps to be too short for the usual mounting points and left only 1/4" clearance between the top of the front silencer and cross-member. The rear box is also quite tight with the rear damper arm, but doable!
68' 4-door Saloon, another 'Monty'.

philthehill
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Re: 1275 exhaust manifold questions.

Postby philthehill » Wed Sep 14, 2016 4:20 pm

The Minor exhaust system to suit the 1275cc LCB (Pt No: LM053) manifold at 1 5/8" diameter is Pt No: LST053 @ £139.50 plus VAT.

The fitting kit is Pt No: FKT053 @ £10.50 plus VAT.

With all these things they have to be fitted - do not expect it to all fall into place. Fettling is the name of the game :wink:

You will not get better than a Maniflow system but there again you pays your money and takes your chance with anything else.
Phil


bmcecosse
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Re: 1275 exhaust manifold questions.

Postby bmcecosse » Wed Sep 14, 2016 10:06 pm

On that otherwise standard Sprite (is it??) engine - I would not spend a lot on a fancy exhaust - the gains will be not be worth the money unless you modify the engine further (camshaft + better head ).
ImageImage
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austinh7
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Re: 1275 exhaust manifold questions.

Postby austinh7 » Wed Sep 14, 2016 10:34 pm

Engine number is 12CE-DA-H 12789
According to here http://www.mg-cars.org.uk/news/news498.html it's a Sprite Mk4/ MG Midget Mk3.

I'm not sure if it's been modified at all, the previous owner didn't seem to know very much about it. Apparently a previous owner posted on this forum and it was posted in the for sale section of the site but the ad has since gone. Once my membership comes through I'll ask if someone can show me the thread.

Back to exhausts, looks like ESM do a manifold and exhaust system as well. Manifold a bit more, exhaust a bit less!

philthehill
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Re: 1275 exhaust manifold questions.

Postby philthehill » Thu Sep 15, 2016 7:17 am

For the spec of your Sprite engine (which I suspect is standard and which is no different to the 1275cc Marina in its basic form) and to keep costs down I would go for the cut down Marina exhaust manifold and the Marina front pipe as supplied by ESM.
You can always upgrade the manifold/exhaust system at a later date.
Phil


bmcecosse
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Re: 1275 exhaust manifold questions.

Postby bmcecosse » Thu Sep 15, 2016 12:45 pm

2nd vote for the cut down manifold.The HIF44 is a good move, and will help with future upgrades such as a 'big valve' head.
ImageImage
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austinh7
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Re: 1275 exhaust manifold questions.

Postby austinh7 » Thu Sep 15, 2016 12:52 pm

Monty-4 is putting a cut down manifold in the post for me. Hopefully will get it fitted next week at some point.

Next job is to identify what head & cam I have fitted and think about upgrading those.

philthehill
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Re: 1275 exhaust manifold questions.

Postby philthehill » Thu Sep 15, 2016 12:58 pm

If your 1275cc Sprite engine is standard you will have the same head and camshaft as the 1275cc Marina.[frame]Image[/frame]
If you take the camshaft out - take care not to loose the oil pump drive spider as they are like hens teeth.


austinh7
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Re: 1275 exhaust manifold questions.

Postby austinh7 » Fri Sep 16, 2016 2:55 pm

Thanks for the list Phil. Just had a quick look and it's a 12G940.


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