Carburettor options
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Carburettor options
Hi everyone
I’m considering some carburettor options for my 1098 with a 1275 head and a full mani flow system. Currently running a worn hif38 having changed needles rolling road and many hours spent I’m considering other options like twin carbs, Weber ect. My question is what benefits would these have over a rebuilt hif38 to make the most of the engine I have
I’m considering some carburettor options for my 1098 with a 1275 head and a full mani flow system. Currently running a worn hif38 having changed needles rolling road and many hours spent I’m considering other options like twin carbs, Weber ect. My question is what benefits would these have over a rebuilt hif38 to make the most of the engine I have
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Re: Carburettor options
These are my opinions for what they are worth.
Twin 1 1/4" SU HS2 carbs are not worth the trouble and expense. Whilst looking good there are no real benefits against cost.
Twin 1 1/2" SU H4 carbs - well worth the money and will give a real benefit to engine breathing. Downside - a good pair is expensive.
Twin 1 1/2" SU HS4 carbs - similar performance gains to the H4 but less expensive.
Weber 28/36 DCD carb - will give a good performance benefit but fuel thirsty.
Weber 40DCOE carb - best all round performance but again expensive to install.
Weber 45 DCOE - too big for a 1098cc even with the performance additions you have.
There are other carbs you could consider but they are not run of the mill types and finding spares may be a problem.
Overall I would suggest that you obtain a reconditioned or serviceable Hif38 to replace your worn carb but there again not cheap
http://sucarb.co.uk/hif38-carburettor-f ... 27227.html
Here is a reconditioned Hif38 for sale on 'e' bay
https://www.ebay.co.uk/itm/MANUAL-CHOKE ... SwydRbia0D
Phil
Twin 1 1/4" SU HS2 carbs are not worth the trouble and expense. Whilst looking good there are no real benefits against cost.
Twin 1 1/2" SU H4 carbs - well worth the money and will give a real benefit to engine breathing. Downside - a good pair is expensive.
Twin 1 1/2" SU HS4 carbs - similar performance gains to the H4 but less expensive.
Weber 28/36 DCD carb - will give a good performance benefit but fuel thirsty.
Weber 40DCOE carb - best all round performance but again expensive to install.
Weber 45 DCOE - too big for a 1098cc even with the performance additions you have.
There are other carbs you could consider but they are not run of the mill types and finding spares may be a problem.
Overall I would suggest that you obtain a reconditioned or serviceable Hif38 to replace your worn carb but there again not cheap
http://sucarb.co.uk/hif38-carburettor-f ... 27227.html
Here is a reconditioned Hif38 for sale on 'e' bay
https://www.ebay.co.uk/itm/MANUAL-CHOKE ... SwydRbia0D
Phil
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Re: Carburettor options
I would suggest that a hif44 at 1 3/4" choke is too big for a 1098cc engine even though fitted with the 1275cc head.
The hif38 with 1 1/2" choke will give a much better gas flow at the engine revs you expect to use - bigger is not always better.
The hif38 with 1 1/2" choke will give a much better gas flow at the engine revs you expect to use - bigger is not always better.
Last edited by philthehill on Sat Apr 04, 2020 9:15 am, edited 1 time in total.
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Re: Carburettor options
I do have a 1275 that I plan to rebuild one day and swap in, so ideally I’d like a good all round carb that would work on both of the engines
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Re: Carburettor options
I do have a 1275 that I plan to rebuild one day and swap in, so ideally I’d like a good all round carb that would work on both of the engines
[sig]9671[/sig]
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Re: Carburettor options
The hif38 will work well on both your existing 1098cc engine and the 1275cc engine you propose to fit at a later date.
Only if you gas flowed the 940 head and fitted a performance camshaft will you gain any real advantage with a hif44 SU carb.
Only if you gas flowed the 940 head and fitted a performance camshaft will you gain any real advantage with a hif44 SU carb.
Re: Carburettor options
Another option would be a single 1.5" HS/HS4 SU, as used on many 1970s (and early 1980s) BL A-series engined stuff, such as Mini, Marina, Alllegro, etc.
These were the defacto carb fitment for some years prior to the HIF carbs coming along.
I tried one many years ago on my standard 1098cc, and it gave a noticeable gain over the original single 1.25" SU.
The main benefit with the HIF, is far smoother throttle control in traffic, due to the cam operated progressive linkage.
These were the defacto carb fitment for some years prior to the HIF carbs coming along.
I tried one many years ago on my standard 1098cc, and it gave a noticeable gain over the original single 1.25" SU.
The main benefit with the HIF, is far smoother throttle control in traffic, due to the cam operated progressive linkage.
Maurice, E. Kent
(1970 Traveller)
(1970 Traveller)
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Re: Carburettor options
This might squeeze in ..
https://www.ebay.co.uk/itm/333521103768
https://www.ebay.co.uk/itm/333521103768
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Re: Carburettor options
The 45 DHLA is too big and the inlet manifold is too long.
Both carb and manifold would be suitable for big bore engines with large valve/gas flowed head, performance camshaft and turning at high revs.
The longer the inlet manifold the better the ram charge at high revs. That is - the mixture keeps flowing pushing the mixture before it towards the inlet valve - helps reduce/eliminate any pulsing of the mixture.
If you must go the Weber route this is a more suitable application:-
https://www.ebay.co.uk/itm/Weber-40-DCO ... SwbuJech8v
Both carb and manifold would be suitable for big bore engines with large valve/gas flowed head, performance camshaft and turning at high revs.
The longer the inlet manifold the better the ram charge at high revs. That is - the mixture keeps flowing pushing the mixture before it towards the inlet valve - helps reduce/eliminate any pulsing of the mixture.
If you must go the Weber route this is a more suitable application:-
https://www.ebay.co.uk/itm/Weber-40-DCO ... SwbuJech8v
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Re: Carburettor options
That Weber setup does look nice. Would it be as reliable as a hif? And much more performance to be had with it
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Re: Carburettor options
On a cost/benefit analysis you will not get a suitable return for your money.
You may have to re-jet etc to get it running right and Weber spares are not cheap.
I would stick with your hif38.
You may have to re-jet etc to get it running right and Weber spares are not cheap.
I would stick with your hif38.
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Re: Carburettor options
Good choice
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Re: Carburettor options
or something more exotic
https://www.ebay.co.uk/itm/193419010440
https://www.ebay.co.uk/itm/193419010440
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Re: Carburettor options
I may have miss read this advert. It looks as if the carbs are included.
Phil
Phil