Help me. PLEASE!!!!

Ivor · Post by **Ivor** » Tue Nov 09, 04 3:14 pm

Carb icing is caused by the sudden temperature drop due to fuel vaporisation and pressure reduction at the carburettor
venturi.
The temperature drop of 20?30?C results in atmospheric moisture turning into ice which gradually blocks the venturi. This upsets the fuel/air ratio and strangles the engine.
Then when you stop by the side of the road, the heat in the engine then seeps through the intake manifold, to the carb and de-ices it and hey-presto no more problems.
I had similar problems on one of my old Land Rovers and I ran a copper strip from the exhaust manifold stud to the carb stud, directly under the carb and that fixed it.
I'm sure there is a connection between the fuel air density too, so it may be worth checking your mixtures...the Land Rovers' was right up the creek because the carb was knackered.
HTH!

Anonymous · Post by **Anonymous** » Tue Nov 09, 04 3:42 pm

no thermostat, tut tut.

get one in and see if that helps. Many/most/all of these aftermarket carbs with electric choke work on a crude timer. An electric current is fed to a bimetalic strip which heats up and as it heats it opens the choke. If your choke is warming up before your motor is then that will cause idling and stalling problems.

Either (1) set the choke so it opens slower or (2) stick a thermostat in so your motor warms up quicker.

Have a quick guess which is the best option

OE autochokes work on a kind of heat stove feed thingy from the motor to the bimetalic strip so the two warm up more like in-sync.

Anonymous · Post by **Anonymous** » Tue Nov 09, 04 3:44 pm

Mogwai wrote:Well I have Mick and Alistair close by, fingers crossed it will be a month or so till I crank the beast!

having me close by is more of a liability than an assistance.

Give us a shout if you need anything though, or just for a gas. 0115 9525262.

Dave-R · Post by **Dave-R** » Tue Nov 09, 04 4:24 pm

He didn't say he was running without a thermostat did he?

No I didn't realise they could ice up that quick!

That should be added to the list of possible causes then Ivor you were right. I find it hard to believe you get that much of a temp drop though. I will have to get my thermometer out!

I think this maybe just a case of someone (yes I mean you Clivey!

) never having this sort of choke on an old car before? We are spoilt with the way modern cars operate. There are now LOTS of people out there that have NEVER operated a manual choke or this primative type of automatic choke. And of course with a non-stock engine and aftermarket carb I doubt the choke has been set right for the winter temps?

Here is another one for you.

I looked at a car a couple of years ago for someone up the street. He said the car (an older automatic) was "running away with him" and he could hardly hold it back.

The reason turned out to be the choke. He was starting the car and then not touching the throttle. As it warmed up it was reaching over 2500rpm and he was simply putting it in gear like that and it was shooting off. It never occured to him to press the throttle. He was spending all his time standing on the brake!

Anonymous · Post by **Anonymous** » Wed Nov 10, 04 10:57 am

Dave wrote:He didn't say he was running without a thermostat did he?

Clivey wrote:I had my thermostat removed

You're not a student are you?

Kev · Post by **Kev** » Wed Nov 10, 04 11:05 am

You're not a student are you?

I think Dave meant it would have been useful in diagnosing the problem if all relevant facts were listed in the initial question

Anonymous · Post by **Anonymous** » Wed Nov 10, 04 11:52 am

Yeah, that'll be it

Sorry, was I at risk of stealing your catch phrase there?

Mick · Post by **Mick** » Wed Nov 10, 04 9:13 pm

I had a similar problem with my old 440 Scamp but mine was'nt fuel related, it would cut out for no reason and occasionally bang when it stopped. Turned out to be a cracked ballast resistor and as it was broken on the back i could'nt see it untill i took it off.
Mike

Anonymous · Post by **Anonymous** » Thu Nov 11, 04 1:30 pm

yes no stat is BAD! they put these things in for a reason.

Yes carbs can ice up THAT QUICKY never underestimate. Especially if your intake heat system is not functioning. (most people's arent im guessing)

took me a while to figure out how mopar ones work but when cold the butterfly is closed in one of the exh manifolds, forcing the gasses from that bank to go through the passage in the other side of the head, through the channel in the intake, into the other head, then down the other manifold.

if butterfly not working, or intake has been changed to one without passage, or valley tray (BB) or intake gaskets (SB) have no hole then that is going to render the system inoperative.

some mopars also had warm air ducting from one manifold to the air cleaner, but perhaps that was just later vehicles? $0.02

Anonymous · Post by **Anonymous** » Thu Nov 11, 04 3:24 pm

Thanks will. I think thats me stuffed cos that exhaust manif. butterfly aint present on headers, so I dont have that

Dave-R · Post by **Dave-R** » Thu Nov 11, 04 4:05 pm

You don't need the heat crossover in a british climate unless you use your car all winter long. If you do use your car during the winter and you have headers then you may indeed have icing problems but really the heat given off by un-wrapped headers is enough to warm the intake air anyway once the engine is fully warmed up.

The heat cross-over is really to help vaporise the fuel in the intake during winter warn-up periods. Most people only use their muscle cars during summer months so for them there is a performance advantage to blocking off the heat riser because on a performance engine you want cold air going into the engine.

To get around these problems warm the engine up fully before setting off. It should only take 5 mins.

I have blocked off the exhaust cross-over on my Challenger and my 318 Charger before that. I have driven the Charger all winter long without any problems. The Challenger I have driven during Jan, Feb, and March before (Drove it 240 miles to Jeff Hausers one Feb.) and NEVER had any problems except keeping warm in the car with no heater.

Anonymous · Post by **Anonymous** » Fri Nov 12, 04 11:37 am

Many thanks Dave - its all interesting stuff.

Thanks also to eveyone else for taking the time to provide your help.

I'm introducing my new woman to my charger tomorrow afternoon so a through warm up will be required to prevent my embarrassment if the old girl plays up. I really dont think this young lady really appreciates how lucky she is.

Anonymous · Post by **Anonymous** » Fri Nov 12, 04 4:35 pm

Thanks Terry, but I am affraid as I havent had my trunk floor pan replaced yet, the young lady will have to wait before I allow her that sort of luxury. What I want to know is when she looks under that hood, will she REALLY be able to appreciate exactly what she is looking at? 440 cubes of death and destruction. Also, I shall have to explain that I have given her street cred an exponential boost by allowing her to be seen in such a classic conveyance.

She WILL learn to love the MOPAR yeeharrr