Weber DCOE 40 versus SU HIF44 carb....

[picky]

I am currently thinking about changing my carb, as with a gas flowed cylinder head, maniflow LCB system and several other mods, I think a 1.5" SU carb is perhaps too small?? I have a used hif44 (which is 1.75") SU carb, but also a weber DCOE 40 carb, and im not sure of the pros/ cons of fitting either of them. the weber came with a few spares jets and chokes etc.. but im guessing that I would need a rolling road expert to properly tune the weber??
Any help much appreciated,
Tim

[les]

Hif44 in my opinion, I think the Weber would compromise the simplicity and reliability of the Minor, and I don't think you would see an improvement.

[Stig]

Unless you've got a really hairy cam then the HIF44 should be plenty. The Webber might have the edge at maximum revs but unless you're racing I wouldn't bother. Someone posted a link for SU needle selection recently - WinSU or sommat?

[Cam]

The SU is MUCH easier to set up and tune and the power gains of the Weber are tiny if taken as an average across the entire rev range as the Weber performs worse at certin revs.

I would (and did) stick with the SU. It's more fuel efficient too! The HIF44 will flow around 240 CFM (If I remember correctly) which by rule of thumb should be able to provide sufficent fuel/air for an engine producing around 110-120 BHP (roughly). It CAN provide more, but will start to restrict the air-flow above that sort of power/flow.

Just out of interest, what is the cc of your engine and the expected BHP?

[plastic_orange]

You may find the weber will give you better throttle response and slightly increased acceleration. What it will give you is increased thirst and induction roar, and probably not so good part throttle running.
It also depends on the size of engine and state of tune, but if the weber's cheap, then give it a go, but I feel you'd be better of with the HIF 44. A good alternative however is twin 1 1/2's.

[Cam]

Trouble is that twin SU's don't really give you any 'real' advantage over a larger single carb and they go out of tune a lot quicker. They are fine for 'period tuning' but not many people run them nowadays.......

Have a look at Vizard's 'Tuning BL's A-series engine' book. It's got lots of performance graphs in there (SU vs. Weber) based on his tests.

[picky]

Thanks to all of you who have replied, in answer to cam's question, Im not sure wot BHP it would give, maybe I could have peoples opinion? Its a 1098cc block with ported and polished 12G295 head with larger valves, I think 33mm inlet/29mm exhaust. The exhaust is a maniflow LCB and 1 5/8" diameter twin box system, MG metro valve rockers standard cam with ported alloy inlet manifold and currently HIF38 SU carb and K&N filter. everything else standard, about 10,000 miles.
Thanks for your help,
Tim

[bmcecosse]

Hmmm - your cam is holding you back - not the carb !! Change it for an MG Metro cam (about 10 pds on ebay, but you need to change the oil pump too) for vast improvement. But by far the better carb will be the big SU on an MG Metro alloy inlet manifold. The Weber 40 is just about equal to a single 1.5SU - only IF on a long inlet manifold and fully set-up. BTW - the MG rockers are no different to any others ! Twin 1.5" SUs are even better - and there is no reason why they should go out of tune if set up properly in the first case - but the difference is slight, and the single carb will be more insurance friendly - and you have it 'in stock' already !!

[picky]

Thanks bmcecosse, about the rockers, i had been convinced at the time that they were a higher ratio than other A series ones.. but I think that was just exgageration in the ebay description!!! I have thought about replacing the cam, but will I have to remove the engine from the car to do that?? also fitting a duplex timing chain while Im there might be good.. what do people think about the adjustable timing chains?? David vizard reckons the HIF44 will supply enough air up to 100BHP.. probably more than I will get from the engine, even with the metro cam.
Thanks again,
Tim

[Cam]

To be honest, if it's a 1098 turning 'normal' revs then the HIF38 will be fine. There is no need for the HIF44 and in fact you might find the HIF38 a bit more responsive (I did with my 1293 Mini in a similar state of tune).

You will need to take the engine out for the oil pump replacment (if you get the MG Metro cam as bmcecosse said).

While you are reading Vizard's book, have a look to see what he says about twin SUs, and that should put you straight!

If you want an even better cam then you could get a Kent 276 but you will have to pay more for it than £10 from eBay.

Also, what compression ratio are you using? If you want more power then raising the compression to around 9.5:1 or 10:1 is recommended, but use an octane booster and some decent pistons!

[bmcecosse]

The MG cam is slightly more 'driveable' than a 276 - but if can get one cheap !! The only snag is the oil pump needs to match the cam - duplex gears are an option but not absolute necessity. I have them on my engines ! A crank damper is very very necessary for crank life. As for adjustable timing - it's all very well - but what will you set it to ?? Unless you can rolling road it, you have no idea what the best set-up will be for your engine. The best 'normal' setting is to have equal lift on the inlet and exhaust valves when they are rocking at exactly TDC. To check this you need a dial gauge and a very accurate way of finding TDC - not easy !! Some then say there is better torque if it is slightly advanced on this setting - yet others say better to retard (miles and miles of this chat on the Mini forums). So to be honest - for a road car - just set the dot to dot and be happy. The well established Morspeed owner (engine_tuner) says he has rolling roaded cars with the timing set forward and then back - and no more than 1 bhp variation !! But the equal lift at TDC is a quick check that can be done simply by taking the rocker cover off - provided you can trust the TDC marks on the crank damper !! It is very much worthwhile setting up the ignition timing curve - quite a lot to be gained and lost there !!

[picky]

thanks bmcecosse, I can see now that using the standard cam is very much limiting the engine. I am now all for changing the camshaft.. but for me removing the engine would be a bit of a challenge. If i bought a camshaft that was compatible with the existing oil pump, could I slide it in from the front with the radiator grille removed?? as this would be alot easier.

[les]

If I were you I wouldn't want to fit another cam in the original bearings, the best practice is to fit new. In fact most things that run together wear together, strictly speaking this applies to the cam and followers as well. If you do not worry about such things you could fit a cam from the front, but you need to remove more than the grill!! also the pushrods and followers have to be lifted to let the shaft pass, and you'll need to find a pin drive camshaft which may be difficult, old coopers used them, but I don't know how suitable they would be for a 1098.

[picky]

thanks les, as the engine was a reconditioned unit and has only done 10,000 using the standard cam should mean that the wear is not too great.. although i will fit new followers with the new cam, as they wear to the profile of the cam?? I think that if I order a new camshaft from kent cams or similar you can specify the type of oil pump drive.

[Cam]

You should be able to, yes.

[bmcecosse]

Don't worry about the cam bearings - they will be fine. If you are SURE you have a pin drive pump, then yes you can change the cam from the front - just need to 'ease' the grille bars apart slightly !! BUt to make the change worthwhile you would need to go to a 276 - anything more is wasted on a 1098 which can't rev enough to make good use, and anything less is not worth the change. As for the Weber 40 - there is a long thread on this running on a Mini board at the moment - problem with a weber 40 is that the biggest chokes it can take are 34 mm - not even as big as twin 1.25 SUs. So go for either the big single on a well modified MG Metro inlet manifold, OR get twin 1.25SUs - but only if you modify the standard manifold and carbs as per Wizard, or lash out some cash and buy a Maniflow inlet !!

[ramajon]

what about the DGV weber??? I have 1 on my bugeye and my sunbeam and on both cars there seemed to be an improvement in power...I was going to snag a DCOE40 for the bugeye and put the DGV on the minor...I was hoping to extract just a pinch more power out of the 948...anyone got any other easy suggestions to power it up a bit?
thanks
ramajon

[bmcecosse]

You will need to hope the engine has a pin drive cam - it should have ! Then find a suitable uprated cam also pin drive - the 997 Cooper cam was the 2A948 - and the timing is only very slightly better than the AEA 630 cam you already have - so it's not worth considering. The cam suppliers will make you a 276 cam with pin drive but it won't be cheap !! It's easy to fit from the front - it can be eased through the grille bars if you are careful ! Remember to pull the dizzy drive shaft out - and then refit it without dropping it - at least on the Minor it's not a disaster if you drop it - just pop the sump off - unlike the Mini where it's engine out time !! One of the tappet chest screws fits the dizzy drive and gives you a handle !

[Kevin]

what about the DGV weber??? I have 1 on my bugeye and my sunbeam and on both cars there seemed to be an improvement in power...

Ah but so will an 1 1/2" or 1 3/4" SU with far fewer problems and better fuel consumption as Webers are not known for their economy.

[bmcecosse]

Aye - stick to the good old SU if you want economy. The variable choke design was a masterpiece of engineering all these years ago.