At The End Of My Tether... KAD 1380 Road 100 & HIF44

[Marcos_Craig]

Hello all,

As per the title I am absolutely fed up with the issue I’ve got...

I’ve got a new (300 miles on it) KAD Road 100 engine which produced 104bhp on their dyno.

Since fitting it I have had starting / running issues.

From cold it would start (no choke) but would not idle without constant throttle input - any choke and it was flooding. Once warm it would idle anywhere between 1200 and 1500.

Took the car to a Mini specialist who fitted a fuel pressure regulator and adjusted the setup. 30 miles later it was back to idling at anything between 1200 and 1500.

Spoke to KAD and sent the carb back to them, they found it was way out of adjustment - set it up and ran it up on a same spec 1380 to mine.

Refitted it and now it is as sweet as once warm, but still a complete b’stard from cold. Any choke and it floods, no choke it starts but needs constant throttle to keep it running.

Clearly it is too rich from cold, but I do not know why.

Any input greatly appreciated

[bwaminispeed]

Wrong mixture needle.......

[kit of bits]

What type of carb damper oil are you using? Is the Breather hole clear?
D

[spoon.450]

I personally have never had good all round results with an HIF 44. Good power, but flat spots...
I’d go for a Weber...

[LarryLebel]

I don't know how the choke on a HIF44 actually works but there must be something wrong with it on your carb.

[Marcos_Craig]

Wrong mixture needle.......

I cannot disagree, but this is an “off the shelf” unit, and gave good figures so should be plug and play. The needle was part of the engine package.

Seriously thinking of ditching the HIF and going for twin 1” 1/2 - which I know a little more about.

[Marcos_Craig]

I personally have never had good all round results with an HIF 44. Good power, but flat spots...
I’d go for a Weber...

That would entail me chopping out a good portion of my bulkhead and making a box for it to fit in.

Sorry, but not keen.

[Marcos_Craig]

What type of carb damper oil are you using? Is the Breather hole clear?
D

I’ve tried 3in1 (thin) & Millers 20/50 (thick) no difference.

Breather from the carb is blocked off, everything I have read indicates that is ok?

[Marcos_Craig]

I don't know how the choke on a HIF44 actually works but there must be something wrong with it on your carb.

I’ve come to the same conclusion

[Catmint]

I don't know how the choke on a HIF44 actually works but there must be something wrong with it on your carb.

I’ve come to the same conclusion

I think from vague memory the choke (I stand to be corrected here as it is years since I have opened one up) has a bi metal strip that alters the choke opening depending on engine temperature - they are renouned for choke problems, but are a great carb with plenty of flow potential

[harrymini]

Would you not be tempted to send it to KAD and get them to look at it? To they offer that service?

Worth sometimes paying the price if it means not getting to the end of your tether and selling and maybe loosing money on the build?

[goff]

Craig phoned me last night , I told him to post on the forum in the Tech section , i know nothing about HIF's , Harrymini he's already sent the carb back to KAD , and it was better when refitted, well it does tick over better , but the problem as Craig say's starting from cold , it gases up the plugs and then will not start , there must be someone on here that can point him in the right direction , Craig lives in Bury , Great Manchester if anyone is close enough to take look !!!! , end of is tether after spending a arm and leg on the engine , HELP Craig out please .

Goff

[kevs 1961 mk1]

id get ac dodd to tune it he will find the problem for sure

[Catmint]

a quick google - some info on HIF Choke arrangement here

https://www.mgexp.com/forum/mgb-and-gt- ... m.2373310/

https://sucarb.co.uk/technical-carburet ... ttings-hif

Kieth Calvers comments on the HIF https://www.calverst.com/technical-info ... -hif-type/

(I was wrong about the bimetal strip for the choke, it is a variable hole for the choke and the bimetal strip is for fuel metering when running)

to grasp at some straws

If it works OK on a dyno setup, is there something else going on when the engine is in the car ???? - connections, fuel, venting, air leak ? Is there a good heat sheild between the carb and exhuast? - might be just one of them random things that you don't take into account when you put it all together

What is the inlet and exhuast manifold you are using ? I seem to recall that the single HIF manfolds are a different thickness to the exhuast and I had to make up stepped washers so it all bolted together nicely - grab hold of the carb and see if it moves independant of the engine

What is the carb's history, what has been replaced in it - the needles are renouned for wearing as they are spring biased. What air filter are you using compared to the dyno set up?

is the fuel pressure still too high?

Photos of the installantion may help. ATF oil is a good compromise for the dash pot.

the final option would be to get it on a rolling road dyno with someone who knows su's. The final setup can be a real pain when you think everything is right, been there

['S'-type]

If you could beg / borrow another hif 44 from someone in your neck of the woods, swap your needle in and see if you still have the over choking problem. If no problem, indicates an internal fault on your carb.
You could experiment with a cheap hs6 just to get it up and running. Sort the hif 44 out later.

[bwaminispeed]

Long shot here, but, using a .090 needle in a .100 thou jet would do this......if it would even run......

[Peter Laidler]

My only experience of the HIF's was two of them in my monster MGB GT V8, now living in Tasmania! As I recall, the principle of this carb is the same as the old SU H type but with a horizontal intergral float chamber. On that basis, it should be a simple fix as you've narrowed it down to the carb. Alas, it's another of those SEEING and DOOING jos as opposed to just troubleshooting over the net.

As we seem to have agreed, someones living nearby has got to see what's going wrong there

[wantafaster1]

Brilliant carbs.
The choke operates like a barrel with a crosshole, when you rotate the barrel the holes line up and fuel goes through.

There is a bi-metallic strip that alters jet height, this is to compensate for underbonnet and fuel temperature.

I can't suggest anything other than is the throttle cable too tight, and are you certain there aren't air leaks?

[bwaminispeed]

Tight throttle and air leaks, won't cause the over rich situation he has......

It starts cold with no choke, then gets very rich, so, not a gasket/air leak/spindle leak problem.....

[Fanfaniracing]

Even a Engine set up on a engine dyno needs to be set up on a rolling dyno once fitted in the car.

It's always different once the engine runs on the own fuel pump, radiator, alternator ect...

This money should always be calculated when building-/buying a new engine...