Discussion
Hi all,
Quicky, which is the best carb or carbs set up for a road going 1330.
Twin 1.25's
Twin 1.5's
HIF44 (how do I recognise one of these, I have a single carb on a standard A+ manifold but no markings).
Weber?
All advice sought.
Preference is for one that is reliable, doesn't need constant adjustment (used to old MG's in the 70's) and is available second hand in decent nick.
Thanks all
Quicky, which is the best carb or carbs set up for a road going 1330.
Twin 1.25's
Twin 1.5's
HIF44 (how do I recognise one of these, I have a single carb on a standard A+ manifold but no markings).
Weber?
All advice sought.
Preference is for one that is reliable, doesn't need constant adjustment (used to old MG's in the 70's) and is available second hand in decent nick.
Thanks all
i think and im sure ill get corrected, but the hif44 will give you good amounts of power and also won't cause all of the trouble of trying to quick two carbs in balance. twin 1 1/4's are really for the smaller sized engines 970, 1071 etc. i guess another possibility is a weber 40dcoe. but im sure other people have thoughts on this
A single HIF44 on a decent manifold is likely to be every bit as good as twin 1 1/2" SU for a mildly tuned 1330cc engine, without the hassle of balancing them. The standard twin SU manifolds are absoluetly dire in terms of flow. You wouldn't have though it possible to make such a simple design work so badly, but they did it.
The twin SU's would be better for a "period look" though, assuming the rest of the car matches it (no 13" wheels etc!).
A 45DCOE is great for a really flying 1380, as long as you don't mind cutting a big hole in the bulkhead and being deafened by induction noise.
The twin SU's would be better for a "period look" though, assuming the rest of the car matches it (no 13" wheels etc!).
A 45DCOE is great for a really flying 1380, as long as you don't mind cutting a big hole in the bulkhead and being deafened by induction noise.
I once had twin 1.75" HS6's on a 1330 motor I built for a Mk.2 Cooper 'S'. It had a 544 cam and a Longman head and ran really well.
Mr2Mike is quite right when he says that for a road engine a single HIF44 on a decent manifold is probably as good as twin 1.5" SU's. Twin SU's on a decent manifold would probably give just a small increase, although it would be down to setting-up in all probability.
I always thing carb sizes are a bit of a red-herring, as the big restriction with the 'A'-series heads is the inlet tracts and the basic siamesed design. It also depends on your cam choice. For example, if you are using, say, a 286 Megadyne you need the inlet tracts well opened out and a lot of head modification in the area of the valve guide 'lumps' and around the bend. Then bigger carbs could be used to best advantage at high (say above 5500 rpm)revs to provide bags of top end, but you lose bottom-end.
It's all a trade off really.
Mr2Mike is quite right when he says that for a road engine a single HIF44 on a decent manifold is probably as good as twin 1.5" SU's. Twin SU's on a decent manifold would probably give just a small increase, although it would be down to setting-up in all probability.
I always thing carb sizes are a bit of a red-herring, as the big restriction with the 'A'-series heads is the inlet tracts and the basic siamesed design. It also depends on your cam choice. For example, if you are using, say, a 286 Megadyne you need the inlet tracts well opened out and a lot of head modification in the area of the valve guide 'lumps' and around the bend. Then bigger carbs could be used to best advantage at high (say above 5500 rpm)revs to provide bags of top end, but you lose bottom-end.
It's all a trade off really.
The intake, ie filters and stub stacks as well as the manifold can make or break a carb set up. I drop 5bhp from no air filters to k&n pancakes on twin sus. I debated fitting a webber but fitting a maniflow tubular manifold yielded 8 bhp, but this was all at the top end and even with a fast road cam may not see such a dramatic improvement. I also radiused the butterflies, removed half the spindle, cut down the butterfly screws (using locktite instead) and took out the sharp edges around the bridge of the carb.
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