Welcome to our Site for MG, Triumph and Austin-Healey Car Information.
MG Midget and Sprite Technical - Maniflow inlet manifolds
|im planning to change over to a single HIF as I have one spare, the Maniflow product looks good, but pricey in my opinion. anyone used one that has any pointers. Or am I better to stick with twin SU's and upgrade to their twin manifold.|
The engine is mildly tuned, and pulls and runs fine, I guess I just have a thing for shiny bits !
|General opinion is that a single HIF 44 has advantages over the standard set up for a tuned engine. Certainly I have found it easier to tune, and experienced better low down torque and improved fuel consumption over the standard set up. |
What it will not do is improve bhp in any way over a standard engine with standard carbs. The engine will basically suck in what it needs and no more. If yours is in a mild state of tune, it may assist in yielding a few extra horses over standard carb set up, but having said that, there is some degree of overlap with the standard set up anyways, so consider whether you truly need it.
Manifolds - inlet is difficult to get hold of, but fleabay can pop up comaptible inlet manifolds - mine is a Titan lookalike thing - but seems to work. Mini sites are a good source. Main issue is bonnet clearance. Do not under any circumstances slam the bonnet down after fitting it and refitting the carb!
Exhaust manifold - Best is an LCB, but again, this will do nothing much for a standard engine. Maniflow are well respected, hence the price....
|Thanks Mark, I have a LCB and the Moss sports system in stainless steel, and to be honest I am happy with that. The Inlet is my next decision. . .I wasn't particularly after more horsepower, but if a new Maniflow inlet releases a few then great. Appreciate your reply and comment. Peter|
|Or am I better to stick with twin SU's and upgrade to their twin manifold|
Well.... if you like to tinker, then this would be a fun project
If your into driving over knuckle busting... there is truth in the old wisdom "dont fix what isnt broken"
Maniflow is priccy... I think they charge by the oz of metal instead of by the part....but its good stuff supposedly
|Prop and the Blackhole Midget|
|I'm in (or I was) in the twin carb camp, before I went twin cam...|
I used a set of 1978 MGB HIF carbs, used them and the needles, which are perfect.. It works very well, possibly slightly overcarbed, but the beauty of the SU is overcarbing is fine (up to a point). IMO the twins look better as well.
Once they went in, and were set up, they have needed nothing more than a dashpot oil top up every so often.
I suspect/know that an LCB will give gains on a standard engine, as will a carb upgrade (carb less so, as generally the carbs are less restrictive in std form than the exhaust).
After all - the Stage 1 Kit for a mini is an LCB, filter and needle change.
|I'm in the single camp for anything other than looks or originally. If I had a nice original looking car I'd stick with the twins. But the ease of working on, tuning and setting up makes the single a better option in my opinion. You also get smoother throttle and choke action as you do away with the nasty twin linkage.|
I'd go with an MG Metro manifold, cheap and easy to convert for bonnet clearance and gives good power potential.
|Just fit a weber or delorto. |
Easier to tune.
No wearing parts.
Easier acces to manifold bolts.
And the sound is awesome!
|Thanks to all. . .decision time post its MOT then I will report back, Peter|
If you have the carb, go for it. Pretty simple to effect and wholly reversible if you don't like it. Chris Hasluck of this parish has written an excellent "How to" see link below.
Inlet manifold - didn't know Maniflow did those, but other makes are available as previously stated. Bonnet clearance appears to be the main issue - one way of resolving this is by machining/grinding the mating face of the manifold at the block.
Also recommend a thicker gasket - minispares very good - with the reinforced metal surround at the ports.
|Hi mark. . .couldn't get that link to work. . .can you help ?|
|If you copy & paste, it will probably work|
|Dave O'Neill 2|
|thanks Mark and Dave, I had a good read from the pasted link as suggested, and reckon I will go for the conversion. As said its reversible and will allow me to run the car whilst having a good look at the twins, which I suspect are in need of some love.|
|Would suggest you start with a BDL needle, adjust the mix to the SU procedure, ensure there are no leaks whatsoever at mating faces , and fit a decent filter... K&N or something.|
|If you need a Bdl needle I have a few|
|Hi Dominic, sounds a plan, I found another HIF carb in a box off bits that came with the Innocenti Mini I am restoring, So now I have three carbs ! its a sign to convert surely !! I will happily take a needle of you for sure.|
|seen this ?. . .Kerrching !|
|Indeed so, but the similar Mini one at 20 quid below it looks suitable........|
|So, maniflow item is ordered, and I am cleaning the carb up ready for the install. I have read the how to guide, and all seems straight forward, however it mentions a fuel overflow pipe. . .where is this plumbed back to ?|
Apologies if it is todays 'IDIOT' question !
|Fuel overflow pipe on mine is open ended and goes down to a suitable location under the engine somewhere and held in place with a tie wrap.|
It is there in case your float sticks and gas decides to pour from the carb.....
|gotcha Mark. . . can't wait for the shiny bits to arrive now. . .sad isn't it :)|
|...watch out for any balance orifices on the inlet to the carb. Do not block them with either gasket or filter housing. They must be free. Your carb may or may not have them, but wise to check before offering up the gasket - which I have found does not accomodate for any balance holes and may lead you down a severe head scratching session when the car does not rev.|
|Thanks Mark. . .|
Dominic, what's your email address so we can talk needles ?
|mark, I take it you run a K & N filter without any clearance issues. . . . |
|I do. I use the cone filter ...but had to snip out the mounting plate to the carb/gasket so as not to block the balance holes of the carb.|
The (rare)inlet manifolds by Titan are supposedly a different angle to the classic mini ones, which is why the big difference in pricing.
here's a pic of my Hif44 on the Manifow Midget manifold. You can see there's 'Just' enough room to fit the larger K&N...
|Thanks for the Pic Graeme. . .did your car just win 'Best in show' after that photo was taken ? that's the filter I am planning on.|
Just heard from Maniflow and the item should be with me tomorrow ! only ordered it Monday, so a nice quick turn around.
Will post once its on the car.
Cheers again guys
Hmmm...for a hundred quid or so difference, I would be willing to file the mating face away to a suitable angle...
|Mark, so would I. But I was just pointing out why the price difference.|
My Titan (Spridget variety) cost me £15, but that was a few years ago when the HIF44 conversion hadn't really caught on and become so popular.
|Understood. The nearside of my engine bay looks distinctly bare though.... |
|On my HIF44 conversion in a Frogeye, I bought a Howley Racing inlet manifold (Ebay about £25) and had the face wedged by an engineering shop (£40) and it was ok with a cone filter. Not tried a pancake filter but it could (just) fit.|
|Rob aka MG Moneypit|
|well its arrived. . .and it looks bombproof and smells like a proper engineering workshop. . .out to the garage this eve :)
|I'm sure it will do the job and with Maniflows reputation should flow well but you've got to admit it's pretty crude. I really want to try one on mine back to back with the Metro one but I can't justify the cost, especially if it ends up giving less power!|
|well its on the car albeit not yet connected, that's tonight's job.|
You mention less power John than the Metro one, I read that to mean there is a third version ! have I got the wrong end of the stick ?
|Yes, see post 6 on this thread. They used to be really cheap and are probably still cheaper than a Titan or similar. You just need to either file or machine the port faces to lower the angle for carb clearance.|
Here's one on't ebay:
The two rusty tubes you see are for water heating, you can either plumb it in or leave as is. I cut them off to tidy things up. There is also a port for a servo take off if you want one.
All the manifolds seem to work well and none of them are anything special port/flow wise. When mine is in bits I look at it and wonder how it can give such good power - especially comparing it to a weber 45 which 'looks' like it will give 50% more!
|Sorry, I meant to say that I don't think the Maniflow one will give less power just that I would be disappointed if it did after spending a fortune on it! I'm sure Maniflow will have tried to make it flow better than the other options.|
|Hi John, saw your replies. I will report back on how the car feels after. I did consider wedging a 'Mini' version but given my skill with a file and no access to a Mill I took the plunge. My extravagant purchase was made all the more palatable by selling off old spares to others, so yes the Maniflow item is pricey but lets see how it goes.|
|Before you shut the bonnet, put some plasticine or playdough on top of the screw cap to reliably check clearance. Then make a judgement how much the engine will rock during driving.|
|They are the gold standard on intakes|
I was a bit taken back by its appearance also.. id thought they would have at least used rattle can paint
Something id strongly consider at this point is have the outside cermic coated that would aid in performance during summer as it will reduce heat soak affecting the fuel charge
Congrats on a great part.
|Prop and the Blackhole Midget|
You should see my email now
|Cheers for the ongoing advice guys.|
I was out in the Garage last night and its fitted but will not start ! the fuel filter looks empty so no doubt its feeling rejected and wants some attention before playing nicely with the other bits !!
Prop, it does look a bit industrial for sure, and I take your point on ceramic coating, but I will see how I get on with it first. . . I do like a bit of under bonnet bling, so watch this space !
PM you Dominic, so look forward to hearing from you as and when.
|I like Graeme's comment. I can see it now, manifold and carb all fitted, stand back and admire all your hard work, then with a Mike Brewer style flourish slam the bonnet shut and see a nice big outward dent appear! |
Oh a bit of a warning with the HIF, when you get your pump working quickly check the carb for leaks. A couple of times after my carb has been left dry for a while the rubber seal on the bottom of the foat chamber has leaked badly. I keep a few spare seals in stock now.
|Did fuel flow before? |
Have you plumbed the HIF in correctly?
Is the HIF working as it should - as far as you know?
|I am hanging my head in shame that I didn't make it to the garage last night, maybe this eve.|
The carb came off a friends metro about 15 years ago, and appears to be sound. So far as I know I have it plumbed in properly, I will check, but the fuel filter was empty just as the rain ran down the back of my neck and the light began to fade, so I thought I will look at this tomorrow.
There was a smell of fuel, but no leaks. I have another two carbs, one from the project Mini Cooper Export I am restoring, but that hasn't seen fuel in 24 years, so whilst I know it ran, it was a good time ago.
I will get to the garage tonight and check it all over and report back. No doubt something is stuck or similar, but I have the hammer ready !
|Rain ran down the back of your neck? |
Forget the HIF - get out there and mend the garage roof first!
|Nick and Cherry Scoop|
|Graeme Williams and John Payne - the Maniflow manifold has been specifically made for the midget. there is plenty of room above the dashpot.|
|cheers for the Pic Nick. . .surely its buy a brolly, then repair roof, then repair car :)|
|I'd be interested to hear how loud you think your Maniflow silencer is. I bought their mild steel downpipe and SS Silencer about 10 years ago and either the silencer is quite loud or the poor running I was plagued with (before life took over and I left her sitting in my parents garage for 10 years) wrecked the baffling in the silencer!|
Not meaning to hijack your thread, but can I just confirm that the standard exhaust diameter is indeed 1 5/8"? My Maniflow system seems to be 1 5/8".
|well I performed the mechanical version of a re-boot last night. Not sure why taking the manifold and carb off, and replacing it made a difference but it did.|
The throttle pedal is a lot lighter, and this needs a mod as it isn't long enough for all the travel needed. On the test drive it feels like it is trying to catch its breath almost, but im sure a prod and poke here and there will see it running nicely.
Next up is playing with the mixture, once i have neatened up the pipes up, and got the filter on.
At idle it sounds like its going to suck your shirt off you, and once i set the idle it seems very smooth.
On the exhaust note Robin, it seems pretty similar if not identical, the system i put on mine is the Moss sports stainless one, and although i haven't measured the diameter it must be there or there abouts to the 1 5/8 you mention. It is quite loud, but i like that.
More to follow once i have had a further tinker.
|My Maniflow with RC40 back box was sound tested at 98Db last Sunday . It's 1 3/4 I believe. Its louder than my old standard system but much deeper and less taxing on the eardrums, though I do tend to use earplugs on longer motorway journeys.|
Yes indeed, throttle travel is longer and lighter. I simply added an extra return spring to the linkage to firm it up and obtain a more controllable set up...Yes, do ensure everything is fitted up correctly before tinkering. The SU manual for setting the mix is as good as any, but err on the rich side if in any doubt. Pretty simple with just the one carb....
Clearly there are other indicators of incorrect mix setting - temp, plugs, exhaust note etc etc, and as readers of this fine organ will know, I am a keen trial and error man rather than a dedicated follower of (whichever book tends to be in) fashion. That is not to say procedure is not a good guide - it is - but it is a guide only. The number of variables on each car is simply too great for procedures alone to be adequate. For me, a bit of tweaking after observing the results from a good blast do yield some further improvements.
Next thing to do is bolt on a Metro head to release the full potential of the HIF....but one step at a time.....
|Hi Mark....mine has a freshly skimmed 12g940 head on it with new valves and seats. . .not sure of their respective sizes for inlet and exhaust, but this will be changed. I also have a hi lift roller rocker assembly, and it seems to pull along nicely.|
All of that said, it will certainly be a positive step to have the head ported. . .that's going to be my next job. I have a spare head and fancy a go at that task. . all I need now is the tools for the job.
Much advice on the Interweb as regards porting and polishing. Having had a go myself, personally I would hand the job over to a machine shop - unless you have some serious hand tools, some nice expensive TCT grinding tips, lots of time to experiment and a couple of old heads to trash......
Metro head has larger inlet valves and thus yields a few extra horses....but again, personally I would simply stick to changing the HIF for this summer, enjoy it, see how it goes,tweak it to your requirements and consider doing further mods over the Winter.
|Peter, it can be quite difficult to get full throttle on the HIF, especially if you have the organ pedal. I removed the organ pedal but there still wasn't quite enough travel to give full throttle and also the pedal to throttle ratio was very slow. In the end I modified cable quadrant on the carb spindle to make it faster acting and to give full throttle.|
When first fitted mine it was a little too weak with the BDL needle. So to richen it up I filed a flat on the needle where I thought it needed more fuel. A bit hit and miss but with care and progressive filing and testing it worked a treat until I could get it on the rolling road. It's the same method that Peter Bugess uses but he has the benefit of co2 meters, a dynamometer and lots of skill and experience!
Another thing to get is a full radius ram pipe or stub stack for inside the filter. Pipercross do one that can be made to fit in the K&N or MED do some nice solid alloy ones. MED also do a nice filter and ram pipe kit for the HIF for about £70.
|I found that the standard organ pedal operation was insufficient to fully open the butterfly. However, as John suggests you can ditch the organ pedal bit but I found it was possible to bend the existing arm to improve the throw. I made up a short length of angle to which I could fit a pedal rubber and bolted this onto the eye at the free end of the modified arm. Works just fine.|
|Might I ask, how much tension is the choke lever under?|
I stupidly fiddled with the fast idle cam (part 10 in the earlier diagram) and as we would say at work, "It fell off in me 'and chief".
Now I'm struggling to work out how and where to engage the spring and still be able to bolt the cam back on.
|righto gents. . .thinking that I needed to improve the travel of the inner throttle cable, I made up a new stop so to speak so the outer cable is no longer as taught looking as it was. The lash up will be improved, but for the sake of experiment I drilled a long bolt through its length and then drilled that hole out further to accept the end of the standard throttle cable. This I guess is about an inch and a half long so the throttle cable is now nice and free. I was then able to bolt this to the abutment plate. . .all looks abit overdone for now, but when I get access to a lathe I will make a nicer version. |
I set off on my test drive and whilst I think it is better, the throttle certainly feels so much smoother in its use, however, the car seems to struggle to catch its breath almost. I hope to have another look at this over the weekend, but as yet the air filter hasn't arrived, so I haven't had a proper play or get it set properly. Perhaps this is a combination of poor intial set up and the butterfly actuation described by others.
Whilst writing, I have a ram pipe as such which I got from Keith Calver, see the earlier photo, which will sit nicely in the K & N when it shows up.
So then I can fiddle with the throttle actuation, mixture, fast idle etc.
Am I barking up the wrong tree here, but as it feels more responsive should I be looking at advancing the ignition timing too ??
Correct adjustment of the mix as per the SU manual will make a significant difference. From your description, it sounds a bit weak...Do this first before fiddling about with timing - which incidentally is not something that should not require a deal of adjustment - if any - unless it is out in the first place of course!
|Cheers Mark. . .I would have thought that too, given that it appears to be sucking harder than a (. . . . . . . . . .) fill in your own answer to that one :)|
Just before I switched the car ever so slightly pinked, which I have not noticed in the 'round the block' trips I have done since the install, but needless to say I will check this out over the weekend.
This thread was discussed between 10/04/2015 and 01/05/2015
This thread is from the archives. Join the live MG Midget and Sprite Technical BBS now