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MG Midget and Sprite Technical - Needle choice for HIF44

Hi,
I have just rebuilt my engine and taken it for a little run down to the Ace last night. All is going well.

When installing the engine, I just refitted the carb and to be honest, I have adjusted the idle and that is all. I have not checked the mixture or investigated which needle I should use as a starting point. I know I should get it on the rolling road to get it all tuned correctly and will be on the way up to Peter Burgess once the engine has a few more miles on it.
It seems to be going well with no flat spots, bogging down, hesitation, misfires, lumpy idle etc. (idle is set quite high at present 1200rpm)

The spec of the engine is -
1275 + 0.040
Peter Burgess fast road? head
HIF44 carb (unknown needle)
LCB exhaust
RC40 single box
sw5 cam
1.5:1 rockers

The only difference to the last engine is the SW5 cam has replaced the standard cam and the bore is 0.040 larger.

Has anyone got a similar spec engine? If so what needle are you using? Or any suggestions of which needle I should be considering. Or should I just leave alone until my trip to see Peter?

I know how you all like a picture, so I have uploaded one!

Dave



Dave Brown

I've got pretty much the same set up apart from the head and 1.5 rockers and use the mg metro needle. Seems to run well.
Only issue I am thinking about is whether the vacuum take off on the hif44 gives the correct signal for the midget distributor.
Cheers Tim
T Dafforn

I have a very similar set up (except +60 thou overbore = 1330cc). I thought with all that I would need a richer needle but trips to a rolling road have confirmed several times that the original MG Metro needle (BDL) was right. Not what you might expect but scientifically established (if you regard a RR as scientific). The best advice is start with BDL (check what you have - it's marked on the needle) and then have a RR session as every engine may be a little different.

Chris
Chris Hasluck

As long as it runs fine and plugs have an even coffee with cream colour it will be fine until you get it to the rolling road.
Onno K

BDL is the best starting point

Peter started with one for my HIF then fettled it until the RR liked it best

Remember Rover technicians gave us a reasonably well tuned car with the MG Metro, BDL was their choice for the engine they fitted.

Good journey home last night?

:)



bill l

I have a load of BDL needles if you need one for the postage.
dominic clancy

Well timed thread as I've just picked up a hif44 plus mg metro manifold which I'll be fitting next week and I too was wondering about needles.
How about the spring? Is the standard metro spring acceptable?
graeme jackson

Hi,
Yes, Bill, and good journey. How about you?
Thanks for the advice and offer of needles. I am sure I have one so I will fit it at the weekend.
Now, should I set the CO with the gunsons co gas meter, or go for the lift the dash pot method?
Dave


Dave Brown

I'm running with a BDL and seems fine although will have a rolling road session at some point.
I use the vac take off from the HIF but plumb it into an Amethyst unit as the dizzy doesn't had a vacuum point.
Running screwed up big time the other day when the suction link from the timing cover fell off the carb end! Quite relieved that the solution turned out to be that simple.
Graeme W

A right fine ride home thanks Dave

I love that ride up the M40 with a full moon filling the mirror (when the Bemmindubbaya drivers get out of shot)

I would do the gas, man

Rover techs almost certainly didn't use the lift pin method when setting up a fine little motor car

How was your clutch?
bill l

Hi Bill,
Clutch was ok. The peddle still feels a bit floppy, but it works ok and is consistent. For the sake of £16.00 and a few hours of contorted joy on my back, I have bought a new slave cylinder to fit at the weekend.

Looking forward to getting the suspension sorted, a couple of hundred miles on it and a trip to Peter's RR.

Dave
Dave Brown

Dave

I have a very similar set up - see profile - and echo others that BDL is a good starting point.... so good that I have not changed it. I also employ a "red" spring in the dashpot.

My thoughts

Mix is crucial, but easy to do - just follow the SU manual. Personally I run it just a very wee tad rich.

Idle set at about 900

Ignition timing - I have a 123 set by the book and then by trial and error driving hard up the local hill. Basically I listen for any pinking and retard it until it just goes.

Definite improvement in mpg, low down torque, and throttle response.

Mark O

Grahame J. Be careful of bonnet clearance issues with the Metro manifold. It may be OK, but if not, you don't want a dent in your bonnet.

Bernie.
b higginson

Thanks bernie. I did some reading earlier so I'm already resigned to machining the manifold.
graeme jackson

Can you not machine the spacer instead of the manifold?
Inlet manifolds for HIF44s is the most confusing topic, probably because individual variations between vehicles make a difference between something which works on one car but not on another.
When you read the archives it really muddies the waters. Even FWBs are more logical!
Graeme W

I'd guess if I were to machine the spacer then the fixed studs in the manifold wouldn't line up with the carb. machining both sides of the manifold means the head studs will still be perpendicular the the mounting faces.
once I'm happy that this setup works I'll be investing in the maniflow sprite and midget Hif44 manifold.
graeme jackson

I cut my spacer. The studs line up just fine.

This was discussed not so long ago, this year I think. It'll be in the archives somewhere. ;).



Lawrence Slater

Tempus fugit. It was back in 2011. "HIF44" in the technical archives. Started by Dave Brown. Last post, 11 July 2011, by yours truly :).
Lawrence Slater

lawrence. following simple geometric rules I'd have to cut substantially more from the spacer to lower the carb by the same amount as removing say 2mm from the manifold. presumably losing too much of the spacer could potentially lead to over heating of the carb?
having said that, messing up a £6 spacer is better than messing up a £35 manifold :-)
graeme jackson

I have a mini spares manifold, standard spacers, but I have reduced the height of the dashpot damper lid. I don't have any clearance issues.
I have heard that it all depends on a host of things - engine mounts, how much has been skimmed off the head, how the bonnet fits/aligns etc.

Dave
Dave Brown

Been on there for over 10 years graeme, clears the bonnet easily, and hasn't caused any heating or performance problems at all.
Lawrence Slater

I believe you can also fit the dashpot from the HIF fitted to the big Rovers. THis is lower that the standard.

Get some Playdoh, stuff it on top of the dashpot, shut the bonnet carefully and check the height of the squished 'doh.

Graeme W

I think the mg metro needle is pretty good. I ran my car with a wideband air/fuel ratio meter. Mixture seemed pretty reasonable during a range of driving conditions.
Cheers Tim
T Dafforn

This thread was discussed between 13/08/2014 and 16/08/2014

MG Midget and Sprite Technical index

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