Cold weather hiccups

Hey Guys,

Vehicle: RB30, dual fuel, stock carby

Problem: Drives like an absolute bastard on moist days(foggy, cold days etc). Very difficult to start on
LPG or won't start at all.

It's even difficult to start the engine as well. Drives like an absolute bastard on LPG on moist weather, backfires a fair bit, even after the engine is fully warmed up. It's not that great with petrol either, even though it's slighter 'easier' to start on petrol.

There is a fair bit of white smoke on idling(particularly on moist/wet/foggy/cold days), even after the vehicle is fully warmed up.

I have two 'theories'.

1)Some earth/electrical issue that gets amplified during wet/moist weather
2)Carby is stuffed & need some heavy work on it or replacement
3)LPG converter/mixer/cut off solenoid switch/filter faulty(issue is not just on LPG though)
4)TBA

Any other ideas, leads guys?

Thanx
Dom

Does it have an auto choke? That could be your issue.

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Originally Posted by Turtle_au

Does it have an auto choke? That could be your issue.

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It is an electric auto choke(Nikki carby)
Yeah, it's possible. I haven't checked it recently, so I should.
But, I reckon it's not the case. If the auto choke flaps stay shut, then starting shouldn't be too hard.
It runs like a biatch both cold and hot engine.
Having said that, auto choke might need adjustment for a friggin cold & moist winter lately.
Thanx for the tip and reminder. Two brains are always better than one. :D

Back in the day i had a few cabied jap cars and the electric choke was always a hassle i almost alway changed them over to a manaul

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Originally Posted by fat mick

Back in the day i had a few cabied jap cars and the electric choke was always a hassle i almost alway changed them over to a manaul

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Thought has crossed my mind few million times.
But, you might have had a chance to scurry through some of my build threads last year and the year before where I spend a considerable amount of time fixing broken auto chokes and documenting the process in here. I kinda perfected the process of restoring stuffed up electric auto chokes.
I reckon the electric auto choke function on it's own wise, I've done a good job. But, the other things related the auto choke may not be working properly, for example the choke break etc, but I just checked & the choke break diaphragm is in good nick.
I suspect there are few other issues with the carby due to wear and tear.

Also the preheat plumbing line of the air cleaner intake is not there.
It is a thermostat controlled hot air connection from exhaust manifold shroud to the air cleaner intake duct.
But, I don't think that is the issue, 'cos the carby's been running fine in other winters without having the need of that preheat.
Besides, first half a minute or so of the engine cold start, that air preheat duct isn't much use anyway.

I need a good quality working carby to test whether the carby is the real culprit.

Is there a bloke out there with a spare good Nikki carby that I can borrow for a day?
Or an RB30 bloke that can drop into my joint so I can swap the carby over and cold start mine to see how it goes?

I have couple of RB30/TB42 Nikki carbies, but I can't trust either one of them as they both are old and worn.


I'm in Melbourne outer east. And I can be pretty flexible with time.
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For what it's worth, mine runs like a pig too in this weather. I've wound off my electric choke, and am missing the heater grid and heater flap stuff, so I'm not surprised - it's not my daily so it doesn't stress me too much.

What I have noticed though, is that I think my carb ices if I haven't let it warm for long enough. Generally happens if she hasn't warmed much, and I jump on the freeway on these cold cold mornings. After a while at 100kph, she just starts losing power.

It still idles fine though at that point, so it feels like the secondary is closing or something like that. If I pull over for five minutes and just let it idle, I can take off again with it having warmed up, and the issue doesn't re-occur.

If I sit in traffic first, or let it warm up for longer at home (or just go on a more start stop drive first), I don't have the issue. #carbylife

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Originally Posted by Throbbinhood

For what it's worth, mine runs like a pig too in this weather. I've wound off my electric choke, and am missing the heater grid and heater flap stuff, so I'm not surprised - it's not my daily so it doesn't stress me too much.

What I have noticed though, is that I think my carb ices if I haven't let it warm for long enough. Generally happens if she hasn't warmed much, and I jump on the freeway on these cold cold mornings. After a while at 100kph, she just starts losing power.

It still idles fine though at that point, so it feels like the secondary is closing or something like that. If I pull over for five minutes and just let it idle, I can take off again with it having warmed up, and the issue doesn't re-occur.

If I sit in traffic first, or let it warm up for longer at home (or just go on a more start stop drive first), I don't have the issue. #carbylife

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Yours is slightly less complicated to pin point the issue 'cos it's pety only as oppose to mine.

You symptoms above(losing power after well warmed up) can be either due to intake sucking in the too moist air or it can be the mixture leaning due to faulty fuel return valve. But, afaict, RB30 fuel return valve is pretty good. It's controlled by an engine revolution sensor unit under the dash(kicks in when the rpm get to 1500-2000).

In mine, heater grid and flap are all in good nick as intended in the stock setup. Only thing's missing is the directional cup under the carby(inside the intake manifold) & the aircleaner preheat plumbing duct from the exhaust manifold shroud. I can't do much about the carby/manifold directional cup 'cos it was shattered into pieces late 2015 for some weird reason. I can put back the aircleaner preheat duct back(I would need an aluminium duct to join it to the air cleaner duct/pipe), but I don't think it can make much of a difference. We hardly get any really cold weather in Melbourne. Those preheat duct setups are mainly for sub zero freezing temperatures, which we usually don't get here. I think the carby is an absolute bastard to start with. I might have to bite the bullet and get a new carby. It's that I can't justify that much money for a carby, when I can put that money and add another couple of hundred bucks to get a good EFI engine. I'm also suspecting the LPG converter for LPG running like crap. I think the converter either need a rebuild kit through it or a new replacement. Mixer looks good, but I've heard that looks probably not the best way to judge the wear and tear of the mixer. Problem for me is that my Impco 300A mixer looks spotless and no rips or tears in the diaphragms.
I've seen raggedy looking mixers of the same model number running like a purring cat.

It's better to diagnose it rather than throwing a grand worth parts at it, to find out the problem's still there. And I like diagnosing it myself. That's the other problem. :D ;)

I would still suspect the auto choke as that would effect both petrol and LPG.

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Originally Posted by dom14

You symptoms above(losing power after well warmed up)

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Nah, it's more that it loses power if I don't warm it up enough before hitting the freeway (freeway is about two minutes from my place). Never have the issue if it's been sitting warming up at home, or if I run a couple of errands in it first.

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Originally Posted by Throbbinhood

Nah, it's more that it loses power if I don't warm it up enough before hitting the freeway (freeway is about two minutes from my place). Never have the issue if it's been sitting warming up at home, or if I run a couple of errands in it first.

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Auto choke probably need an adjustment, perhaps turn anti-clockwise a bit to keep the mixture rich bit longer, assuming the issue is mixture getting lean before the engine's warmed up enough.

Does your backfire(hiccup out of intake/carby)?

Choke is wound all the way off (ie, no choke), so yeah, makes sense I'd have that issue haha.

Nah no backfiring.

I have to run the pre-heat in winter or the the carby plays up badly. I run a manual choke and use the hand throttle to bump up the revs to about 1500 RPM. I back off the choke a bit after a couple of minutes. This gets my out onto the main road, and half way into town before its warm enough to run properly.
@dom14. I was told, in harsh terms, to keep the deflector as it will affect the mixture in some of the cylinders.

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Originally Posted by Throbbinhood

Choke is wound all the way off (ie, no choke), so yeah, makes sense I'd have that issue haha.

Nah no backfiring.

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Take the air cleaner out and see whether the choke flaps are moving after few minutes of cold starting.
The bimetal electrical choke unit fails more often than we would like to see.
I guess you remember my choke rebuild threads! :)

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Originally Posted by mudnut

I have to run the pre-heat in winter or the the carby plays up badly. I run a manual choke and use the hand throttle to bump up the revs to about 1500 RPM. I back off the choke a bit after a couple of minutes. This gets my out onto the main road, and half way into town before its warm enough to run properly.
@dom14. I was told, in harsh terms, to keep the deflector as it will affect the mixture in some of the cylinders.

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It won't be easy for me to find a one. I'll look around. I guess I can try to panel beat a one out of a piece of pipe and some TIG welding. :)

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Originally Posted by dom14

Take the air cleaner out and see whether the choke flaps are moving after few minutes of cold starting.
The bimetal electrical choke unit fails more often than we would like to see.
I guess you remember my choke rebuild threads! :)

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Nah, I deliberately wound it all the way off. Kept having issues with it, had a trip and was easier to work around having it off and having to let it warm up, than it running like a pig once warm.

Always intended to fix it, but, time and effort and all that.

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Originally Posted by Throbbinhood

Nah, I deliberately wound it all the way off. Kept having issues with it, had a trip and was easier to work around having it off and having to let it warm up, than it running like a pig once warm.

Always intended to fix it, but, time and effort and all that.

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If you wanna drop in I can fix it for ya for free, or alternatively get rid of it and attach a manual cable to it, so you can open and close the choke at will.

Come to think of it, I think I owe ya a visit, I was talking about dropping in but never did, did I? :D

Check the choke break diaphragm. It should pull the choke off after just a few minutes.

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Originally Posted by mudnut

Check the choke break diaphragm. It should pull the choke off after just a few minutes.

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Do you know how the choke break diaphragm work? I mean how the diaphragm get the vacuum in it to trigger the choke break after few minutes?

It has a constant vacuum.

I did vapour test(CO test) and exhaust gas is definitely leaking into the coolant.

So, it's clear the head/head gasket is stuffed. Right now I'm wondering whether I should just get a fully reconditioned head as well as well as have the bottom end rebuilt.
I wonder whether the old bottom end might go kaput soon after installing a reconditioned head.

Just bite the bullet and get an rb30et motor. You know you want to.

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Originally Posted by Throbbinhood

Just bite the bullet and get an rb30et motor. You know you want to.

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You mean the EFI one from a Skyline or a VL Commodore?
If you meant the turbo one, that's bit too much of a bigger bullet to bite atm, and yes
definitely on the lookout for an EFI one, either a dirt cheap one that I can rebuild from bottom up or
a good low km complete one. I'm searching right now. Let me know if you know anybody with a good one or even a crapper
for a dirt cheap price.

Yeah I meant efi+turbo haha. It's on my wish list, if only funds allowed.

I would love to find an RB24S which can be fitted with the twin cam head and twin carbies. Apparently they were made for an overseas niche market, so are like hens, teeth. The block is a lot stronger than the dirty 30.

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Originally Posted by Throbbinhood

Yeah I meant efi+turbo haha. It's on my wish list, if only funds allowed.

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You can find an RB30 turbo kit off fleabay. Personally, I would either use a genuinely low km RB30 block or if not possible to find, rebuild
a 300k+ block with suitable turbo parts like turbo pistons, & on the head use a turbo cam. If you're not that fussy about rebuilding the engine to suit turbo, then converting to turbo shouldn't be that expensive. Most likely PITA thing you might have to do is to pull the head out and fit a thicker turbo compatible head gasket. Some of the bits and pieces can be located cheaper as used ones. Just don't expect the engine to last ten years with a quick turbo conversion like that. Carby turbo is not that expensive or hard to convert. It's that you need to find a good turbo tuner, unless you have the gear and knowledge yourself to do the tuning.

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Originally Posted by mudnut

I would love to find an RB24S which can be fitted with the twin cam head and twin carbies. Apparently they were made for an overseas niche market, so are like hens, teeth. The block is a lot stronger than the dirty 30.

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RB30 block can benefit from a RB25 head(twin cam) from what I've heard. More power and better fuel economy due to better arrangement of extra valves with twin cams. Obviously pretty good for LPG and better for turbo tuning as well.

https://www.gumtree.com.au/s-ad/oran...et-/1151101416

RB30 engine definitely provides more choices than the TB42 due to wide availability of RB30 and compatible blocks/heads.

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Originally Posted by dom14

You can RB30 turbo kit off fleabay. Personally, I would either use a genuinely low km RB30 block or if not possible to find, rebuild
a 300k+ block with suitable turbo parts like turbo pistons, & on the head use a turbo cam. If you're not that fussy about rebuilding the engine to suit turbo, then converting to turbo shouldn't be that expensive. Most like PITA thing you might have to do is to pull the head out and fit a thicker turbo compatible head gasket. Some of the bits and pieces can be located cheaper as used ones. Just don't expect the engine to last ten years with a quick turbo conversion like that. Carby turbo is not that expensive or hard to convert. It's that you need to find a good turbo tuner, unless you have the gear and knowledge yourself to do the tuning.

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I'd love to do it. I wouldn't rebuild, mine is still under 135xxx kms, so she should last a while. I wouldn't be running massive boost, 6-8psi should see a notable increase in power.

Still, adds up though. EFI conversion gear, exhaust manifold, exhaust, turbo, lines, etc etc, be a few grand sitting there. I know some people say they've done it for less than 1k, but so far I haven't been able to find any complete conversions that cheap.

Still hoping I find a smashed vl turbo somewhere cheap, but alas I will keep searching.

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Originally Posted by Throbbinhood

I'd love to do it. I wouldn't rebuild, mine is still under 135xxx kms, so she should last a while. I wouldn't be running massive boost, 6-8psi should see a notable increase in power.

Still, adds up though. EFI conversion gear, exhaust manifold, exhaust, turbo, lines, etc etc, be a few grand sitting there. I know some people say they've done it for less than 1k, but so far I haven't been able to find any complete conversions that cheap.

Still hoping I find a smashed vl turbo somewhere cheap, but alas I will keep searching.

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Yeah, if you wanna go EFI path, probably won't be that cheap, but carby shouldn't be that expensive.
Your engine with low mileage suits carby turbo conversion. If I had your engine, I would go for the carby turbo conversion.
Only thing we don't wanna muck around with is the tuning, 'cos seemingly harmless detonation with an NA engine can be pretty bad for a turbo engine. Not that rocket science though. Armed with a good wideband AFR gauge kit & timing light, if should be doable at home. For the best results though, you probably wanna put it on a dyno.

I'd probably go EFI to be honest. Be a bit better on fuel with the boost and EFI, and let the ecu worry about timing etc.

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Originally Posted by Throbbinhood

I'd probably go EFI to be honest. Be a bit better on fuel with the boost and EFI, and let the ecu worry about timing etc.

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Standard EFI ECU probably won't cut it for a turbo conversion. Facotyr turboed EFI RB30(VLs and Skylines) are good 'cos the ECU or the addition to it is pre-tuned for the turbo. No question EFI is the best way to go for a turbo, as long as the right ECU and extra electronics are employed.
The places to gather all the information are Skyline and Bombadore forums. Because many young nuts have been playing with the VL & R31 turbo conversions, there is plenty of information on those forums.

Yeah, I'd be using the turbo ecu without a doubt.

This is all hypothetical anyway and largely dependent on my stumbling upon a suitcase full of hundred dollar bills.

Quote:

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Originally Posted by Throbbinhood

Yeah, I'd be using the turbo ecu without a doubt.

This is all hypothetical anyway and largely dependent on my stumbling upon a suitcase full of hundred dollar bills.

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It may not be as expensive as you think. Keep looking, used gear go for peanuts sometime. Many guys do gradual conversions rather than overnight by collecting the bits and pieces slowly. I haven't bothered to collect any yet, 'cos I've been bit anxious about the outback reliability of turboed RB30. Probably a misguided fear, but it's still there.

ecu is more or less the same piece of hardware its just the mapping thats different, all it needs is a nistune board added to make it a fully programmable ecu. worked perfect when i turboed my old tb42e

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Originally Posted by billyj

ecu is more or less the same piece of hardware its just the mapping thats different, all it needs is a nistune board added to make it a fully programmable ecu. worked perfect when i turboed my old tb42e

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Where do you get the Nistune board from?

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Originally Posted by dom14

It may not be as expensive as you think. Keep looking, used gear go for peanuts sometime. Many guys do gradual conversions rather than overnight by collecting the bits and pieces slowly. I haven't bothered to collect any yet, 'cos I've been bit anxious about the outback reliability of turboed RB30. Probably a misguided fear, but it's still there.

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The other thing is that I've heard it's pretty difficult to make EFI turbo(or carby turbo) dual fuel which is a bit of a turn off for me.
It has to be either petrol or LPG, not both??!!!

That's fine with me, I'm straight petrol and cant stand gas anyway :P

a decent tuner could get one or go to nistunes website

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Originally Posted by Throbbinhood

That's fine with me, I'm straight petrol and cant stand gas anyway :P

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Yeah, it suits ya, 'cos you're a semi hardcore mud trekker. I like sand and distance. I'm desperate for economy for that reason. :D

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Originally Posted by dom14

Yeah, it suits ya, 'cos you're a semi hardcore mud trekker. I like sand and distance. I'm desperate for economy for that reason. :D

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I like sand and distance too! No LPG in a lot of outback locations, plus I can store extra fuel in jerries etc.