14 replies to this topic

[crock]

If running a single HIF 44 or dual SU's, do you really need a water heated intake manifold to avoid carburetor icing? I figure if anybody should know it should be you guys in the UK.

Thanks!

[Carlos W]

I'm not sure heating the manifold will stop carb icing, there will be very little if any heat transfer between manifold and carb!

[Barman]

There is a looooong discussion about the subject here...

[998dave]

I'd imagine you'll be okay in California, but an alternative may be to replumb the carb so it's on the heater feed, that way your inlet manifold is heated while your internal heater is on (when it's cold), and off when it's off, (presumably 364 days of the year in Cali).

Dave

[jaydee]

In california you can have carb icing due to the excessive dump
A heated manifold has nothing to do with carb icing

[Dan]

You can't say California is an excessive dump! OK LA maybe and Hollywood certainly but there are some lovely parts of the state.

[MRA]

In california you can have carb icing due to the excessive dump
A heated manifold has nothing to do with carb icing

A what ?

[jaydee]

Heated intake manifold Martin

[MRA]

No the bit about an excessive dump ?

Interstingly I couldn't find anything to do with the nice little thermal barrier that is situated between the carb and manifold, the 3 gaskets and the phenolic (plastic in laymans terms) spacer which is there to reduce heat transfer, I have only ever witnessed carb icing on an SU carb when there has been a fue leak, once on the 3 counties rally at about 03:00am (coffee sorted it out once, then another ...... well lets not go into that) and a few times on the road, its more common with cross flow engines as the exhaust (hot air source) is the other side, Mini has the exhaust sitting underneath and supplies enough warm/hot air to stop it from occuring at least in most cases anyway.

[jaydee]

No the bit about an excessive dump ?

There was a thread about that on the MG forum once, sounds like they've got very high humidity over summer in california, that rings a bell about the carb icing problem

I have to say in most cases other fuelling problems are mis-diagnosed as carb icing

[Vipernoir]

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Poor photos, but the whole carb was frozen - the piston was frozen in the dashpot !
Soon defrosted once stationary, but that was the result of a 20min drive in cold damp weather - I don't think it was even freezing.

A heated intake manifold doesn't prevent it, but it seem to do a smidgeon to prevent it - I've had icing on most all of the cars I've driven that have an alloy intake. Sometimes the throttle sticks open, sometimes it just stumbles to a stop when the piston jams.

[Dan]

Dashpot and throttle heaters were fitted by BL in arctic regions. Never seen one though. The weather doesn't have to be freezing because a carb is essentially a refrigerator.

[Spitz]

Carb heaters were fitted to MINIs in the 70's bound for CA ( and Switzerland I think )
These had a heated coil in a spacer between the manifold and carb, and also a heated band that went around the dashpot ( HS2 and HS4 ).
You could fit one of these if need be.

[crock]

Thanks for the info.

[maccers]

I ordered one of these very bands from SU a few months ago for my suck through charger setup, the carb would suffer icing when there is excess humidity in the air, summer or winter. I also fitted a tiny little heating element in the air filter at the mouth of the carb, I am sure how effective this was alone, but certainly the combination of that, and the heated strap worked very well.