My car with a 45 Dellorto often suffers carb icing on the freeway at speeds around 110KMH.
This makes the carb's butterflies stick at idle when you slow down, and if pronounced, can affect progression, from idle all the way to 1/4 throttle.
[It doesn't happen if I keep the speed to 100KMH max].

So, I have built a water heating pipe, the hot water from the fresh air heater will be piped through it.

It comprises a machined alloy tube 14.3mm OD x 8.5mm ID x 170mm long, threaded on end to suit a shortened 1/4" BSP brass elbow.
It is doglegged upwards to miss the throttle linkage. I will MIG weld it onto the manifold.

It's not welded on yet, but here are some pics-





I hope to fit it during the week.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

nice work

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the world is a book, and those who do not travel read only a page
66 Mini Minor sponsored by http://www.lifeonthehedge.com.au/ The Dog Harness Specialists
It was a pleasure ausmini. I'll miss all you misfits and reprobates

We used to watercool small air cooled aero engines by wrapping copper tube around the head a couple of times to wick away the heat.

Would this work in reverse around the manifold runners? Maybe in 1/2 " tube?

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Mick, I thought of winding some copper tube instead, but there is little room there.
And where it needs the warmth is at the manifold's carby flange.
This way, I can weld the flange to the alloy tube on both sides (after I screw the 2 top studs out).

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

How's the heat transferred Kev? Just through the contact points on each runner?

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

I will lightly file the top of each runner so the tube has pretty good contact, then MIG weld it to the flange, the 2 vacuum bosses, and around each side of each runner. Should be plenty of contact for heat transfer. It's all alloy....

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I bet it still freezes.

It doesn't ice up it all the time. Alfas with twin Webers or Dellortos don't ice up, and their carbs are mounted on rubber. They do get warm air in the engine bay though, from their front mounted radiator.

If this doesn't work, plan B is a clip-in Mini airbox to draw air from above the headers and duct it up to the filter. Only fitted for freeway running.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

A front mounted radiator would cure it.

But a heated manifold will defrost it quicker after the motor cuts out.

It's not ever that bad that it cuts out.
The other day going North after cruising @ 110 kliks I came off the M5 onto Camden Valley way, and only noticed when I stopped at the lights that the throttle pedal was tighter to move at idle. This symptom went away by the time I got to Victoria St, near Cumberland Hwy.
So I don't think a lot of heat is required.

On the track I never had this problem, because you are up it all the time, not cruising fast at light throttle.

[edit] I would have welded it up today, but the wind was blowing a gale through my garage. Roller door each end doesn't stop it.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Welded and hooked up.
It warms the manifold up nice, we'll go for a lap on the M4 tomorrow and see if it solves the problem.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

The M4 usually isn't too bad, you might get it near South Creek (near Mamre road) if it is a little foggy.
I used to get it on the Northern Road quite a bit.

Last time I got it bad was just before Northern Rd as I slowed down on the M4. It was 11am too... not cold.
I don't get it on Northern Rd, as I'm abiding by the 80kmh limit, +/- a little.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I once had it in my Brock commodore half way up river lett hill towing the sports sedan to Bathurst early one morning - that was interesting. Stopped on one of those blind corners and had to roll it back around the corner to get another run up once I got it going again - on my own of course.

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I just took it for a registrar approved `maintenance run' up the M4 to Northern Rd and back. Sat on 110-112KMH (GPS) where posted.
No carb icing yet, and since water heating the manifold it is smoother at low speed in traffic too.

[edit]
I am going to replace the carb's 4 steel mounting bolts with brass ones, for better heat transfer into the carb body.
These carb bolts don't need to be really tight.
I use a stock Dellorto flange gasket, not one of those damned soft mount things. Had no problems in 20 years running.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.