Inlet Exhaust Manifold Question...!???

[Motor-Mouse]

I have just acquired a Nippy and in a box of bits was this manifold.....

Any idea what it is please? 

Were they any use, or does the fact that it is in the box and not on the car answer that question?


Regards


Stewart.

[Bob Culver]

Whatever, any carbs would be outside a conventional bonnet.
I suppose it is guarded as intellectua knowledge but experience of various exhausts to moderate rpm has been little dicussed on the Forum. Separation of successive cyls is always desirable but whether 4,3 or 2 pipes a more distant joining of  the two groups probably preferable.
I dont suppose Austin would have made it larger than necessary, but the stock non sport Seven seems to have a large immediate sized pipe compared other cars.

[Speedex750]

It's an after market manifold made in the 50's and 60's for A7 specials by the tuning companies of the time. It takes twin H1 SU's and works quite well compared to the standard set up. But as Bob says it doesn't fit under every bonnet, nor every owner wanting it. A short four into one manifold like this one releases most of the pent up A7 horsepower. One with longer primary pipes or a four into two into one might be slightly better but probably not measurably so. It does look unused to me so would probably sell well.

Dave

[Chris KC]

Personally I wouldn't waste effort on twin carbs. Otherwise as advice above.

[Motor-Mouse]

Thanks for your remarks so far, I presumed it was an aftermarket item, it has what look to be stamped GN on the manifold Flange top edge... probably the makers mark, or initials.

It's certainly a clean and unused bunch of bananas, I was just interested to know more about my new piece of automobilia to hang on the man cave wall, I have so much stuff now, you sort of inherit it as you go along...


Always interesting to know if these aftermarket parts actually worked, or not, who ever made it, even if they didn't understand the dynamics of an engines performance via the exhaust, and inlet, they certainly knew how to fabricate, and weld a nice component together, it's actually quite a nice looking piece of kit.


It would be a shame to hack a hole in your bonnet too, I agree...



Any more remarks, I'd love to hear.


Thanks again.


Stewart.

[Jack in the Box]

Thanks for your remarks so far, I presumed it was an aftermarket item, it has what look to be stamped GN on the manifold Flange top edge... probably the makers mark, or initials.

It's certainly a clean and unused bunch of bananas, I was just interested to know more about my new piece of automobilia to hang on the man cave wall, I have so much stuff now, you sort of inherit it as you go along...


Always interesting to know if these aftermarket parts actually worked, or not, who ever made it, even if they didn't understand the dynamics of an engines performance via the exhaust, and inlet, they certainly knew how to fabricate, and weld a nice component together, it's actually quite a nice looking piece of kit.


It would be a shame to hack a hole in your bonnet too, I agree...



Any more remarks, I'd love to hear.


Thanks again.


Stewart.

That's interesting. I have recently acquired a 4 branch manifold (but one without the inlet pipes welded on) and it is stamped on the flange with GN too and also N7. 

Does anyone know what these signify please?

I echo Stewart's comment about neat welding.

Thanks

Alan

[Charles P]

GN silencers were an aftermarket firm of the post war period specialising in manifolds. I have one as well.

---

Footnote. Noting to do with the GN car of the vintage period

[Dave Wortley]

You could easily convert it into a single carb manifold by cutting back the two inlets and welding on a log type piece with single central carb flange.

[Chris KC]

You could easily convert it into a single carb manifold by cutting back the two inlets and welding on a log type piece with single central carb flange.

Or easier still cut off the inlets, file the face flat and mount an inlet onto the existing studs. I think John Barlow does one for SU which would suit. You may have to use an imaginative combination of tube nuts or perhaps allen screws instead of studs in order to have sufficient access to tighten them, but it can be done.

[Jack in the Box]

You could easily convert it into a single carb manifold by cutting back the two inlets and welding on a log type piece with single central carb flange.

Or easier still cut off the inlets, file the face flat and mount an inlet onto the existing studs. I think John Barlow does one for SU which would suit. You may have to use an imaginative combination of tube nuts or perhaps allen screws instead of studs in order to have sufficient access to tighten them, but it can be done.

I found that old valve guides, shortened if needed and ground to give clearance, work well with regular brass exhaust nuts. Alan