Carbs freezing??

[andrew muir]

Hi Guys
Just wanted to pick some brains,
Last week I travelled to York from Edinburgh leaving 6.00am the outside temp was -3degrees, has anyone had much experience with a S30 below freezing. I noticed the diff seemed noisier for the first 30 miles etc also when running a longish time on overrun as in downhill to a junction the car would not tickover and cuttout and was a pain to start. It did this 3 times, but once the sun came up and the temp rose never happened again. I suspect that the low fuel flow on overrun was causing icing in the carbs?? Am I correct???
I have not had any problems since and car even passed its MOT yesterday with no work required at all hoorayyy!!!

The car is a 260z 2+2 running pertronix ignition and 240z carbs with no water plumbing into manifold. It is using 2 x pancake K&N filters.

[johnymd]

Try connecting the manifold heating system. I think it was there to stop this type of problem.

[RIDDLER]

I had my manifold heating system disconnected, as I kept getting leaks from it, on advice from people on this forum who told me it was next to useless anyway. So far I have had no problems with my car - however I have not had freezing temperatures such as you describe yet.

[Rob Gaskin]

Being Scottish is the problem - cold weather and I expect you are running it on fumes to save money, try adding a drop of Single Malt to each tankful of fuel.

Congrats on the MoT - back-hander?

Yes try connecting the manifold plumbing but it may be blocked or rotten. I never needed it but my 'new' 240Z has it in working order. Could you source a standard airbox? - I think some models intake hot air off the exh manifold (thermo controlled).

[andrew muir]

So much for cold air intakes ehh.
Doesn't get much denser than Ice,
Imagine the smell if you ran it on single malt!!!
Its not me officer its the car!!
Need the money Rob as respray and prep is going to cost me big time, anyone need some decent HiFi??? and not the cheap stuff Dale sells, sorry Dale!!
Only want to do this once so needs to be done right!
don't think I'll bother with the plumbing etc to much hassle for little benefit so it seems.

Must admit chuffed with MOT result, no backhander required!!

Originally Posted by Rob Gaskin

Being Scottish is the problem - cold weather and I expect you are running it on fumes to save money, try adding a drop of Single Malt to each tankful of fuel.

Congrats on the MoT - back-hander?

Yes try connecting the manifold plumbing but it may be blocked or rotten. I never needed it but my 'new' 240Z has it in working order. Could you source a standard airbox? - I think some models intake hot air off the exh manifold (thermo controlled).

[JK240]

Originally Posted by Rob Gaskin

Being Scottish is the problem

[andrew muir]

Actually I am a bit more of a mongrel,
1/2 Austrian
3/8 Scottish
and would you believe it 1/8 English

[racer]

Hey Andrew
Now that it's passed the Mot, I hope your coming to Spa next year?
Give your body man a deadline!

[JK240]

Originally Posted by andrew muir

Actually I am a bit more of a mongrel,
1/2 Austrian
3/8 Scottish
and would you believe it 1/8 English

Hey, I can talk, I am part Dutch, part Irish, part English and 100% Yorkshire

[Rob Gaskin]

This will do the trick:

? Datsun 240Z 260z Air Cleaner Air Box | eBay

[andrew muir]

Yes might be a good idea, spoke to him yesterday asked how far do I want to go with this restore, said I didn't want to do it again! he then said you won't be needing that MoT then!! eek, So SPA deadline may push him on a bit. I am next in his queue, after a Bently and a model T!!

Originally Posted by racer

Hey Andrew
Now that it's passed the Mot, I hope your coming to Spa next year?
Give your body man a deadline!

[Ian Patmore]

I don't think your carbs are icing up.... if so, where is the water coming from?

My 260z spent a lot of time back in Scotland many years ago, and it does take a long time for everything to be up to temp.

I take it your pancake K&N filters don't have an air trumpet in....?

[andrew muir]

Hi
The pancake filters do have a trumpet in then or (stub stacks as they are sometimes called).
The car has been fine whenever the outside temp has been above freezing. So suspect it must have to do with temprature?

[Rob Gaskin]

Originally Posted by Ian Patmore

I don't think your carbs are icing up.... if so, where is the water coming from?

Ian, not sure if your were 'taking the mick' here but the water comes from the air drawn into the carb.

The venturi effect of a carb causes cooling and ice build-up in the carb if the weather is cold enough and the air humid enough. Probably the conditions you experienced Andrew.

So you need to buy that big filter box I linked to - drawing air from around the exhaust manifold when necessary.

[Ian Patmore]

No Rob, "not taking the mick". Genuine question. Happened at only -3 degrees centigrade?

I must have been lucky running my car in colder and damper conditions back in Scotland than Andrew had experienced, mind you I was running flat top carbs.