Idling issues with our t18 budget racer

[timtx5]

After the weekends flogging our t18 budget racer has found a dislike for idling. It still goes ok under throttle with myself and darren still running the same times we were all night last night before it started acting up.

At idle it idles a lot lower and almost stalls until the auto-choke kicks in and brings it back up above 1000rpm. It cycles like this every few seconds. If you give it a rev it will stall once it comes back to idle rpm's.

So far I have pulled the plugs, which looked good. They were just lightly black but didnt show any evidence of running too hot (which the car was due to a dodgy radiator). I cleaned them up which made no real difference.

Im pretty lost with carby cars. I changed the distributor and played with the timing which made no real difference. I changed the coil lead which was also to do effect.

Anyone got an ideas?
Im guessing it might be something carby related and nothing too serious. We were running very little few in the tank at the time it started acting up so is it possible we might have picked up some crud.

Im after any general direction to start looking at. We have a spare carb we might be able to swap across.

[Jim]

check for vaccuum leaks first up, if that's ok then try adjusting the idle and mixture screws.

[THE ASH]

Spray WD40 or something around the outside of the carby & intake mani - if the idle note changes you've found a leak.

[timtx5]

Yeah thats probably a good idea ash.

I know that little about carby's that I dont even know where to find them secoh!

I looked for vacuum leaks but saw nothing yet.

[postman]

sounds like what my 626 was doing.. turned out to be vacuum leaks + dizzy causing a miss.

[Jim]

take the air cleaner off, and with it running at constant revs (the closer to idle the better) slowly block the carby with your hand to reduce the airflow going in. if it speeds up, you have a vaccuum leak. If it slows down (and subsequently stalls LOL) then it's unlikely to be a vaccuum leak.


idle adjustment is usually a screw somewhere on the throttle linkage, and mixture will be somewhere about near the middle of the carby, usually a brass screw. base mixture is set with the motor not running, wind the screw all the way in, then wind it out two and a half turns. you can then fine tune the motor with it running, turn the screw in until the motor starts to run funny then back it off half a turn.

[Tripharn]

take the air cleaner off, and with it running at constant revs (the closer to idle the better) slowly block the carby with your hand to reduce the airflow going in. if it speeds up, you have a vaccuum leak. If it slows down (and subsequently stalls LOL) then it's unlikely to be a vaccuum leak.


idle adjustment is usually a screw somewhere on the throttle linkage, and mixture will be somewhere about near the middle of the carby, usually a brass screw. base mixture is set with the motor not running, wind the screw all the way in, then wind it out two and a half turns. you can then fine tune the motor with it running, turn the screw in until the motor starts to run funny then back it off half a turn.

That comes in handy.... runs out to the hilux.

[timtx5]

I think it is vacuum leaks, I wound up the idle until it was kinda steady and put my hand over the carb and it increased rpms as well as no longer 'cycling' (choke/no choke). I found one bugger large hose so far which I swapped over, there is probably more to be found yet.

[THE ASH]

Haven't you pissed off/blocked all the emmisions shit yet?

[timtx5]

Thats all long gone...

I swapped carbs over today, same issue. Didnt have a new gasket to replace between carby and manifold though which is something I will need to get. Takes about 5 mins to swap carbs over so its not a big deal.

Its funny, the new carb idled great until I gave it a rev and it went back to doing the same thing as the other one.

[THE ASH]

carby cleaner for the carbs & gasket goo to seal them to the manifold/spacer plate

Thought of making twin downdrafts with a pair of stock carbs?

[timtx5]

Yeah I did both today, might get some gasket paper and make a real gasket yet. And twin downdrafts sounds like too much work, I dont know how well it would fit anyway.

I think we will do this year with a pretty stock 3t then go unbudget and whack a 4age in for next year. At least we are learning to drive in the mean time.

[THE ASH]

get two inlet manifolds & butcher them!! it'll fit, somehow

[Datto-Zed]

Tim: I have gasket paper and gasket cork here if you want them.

[Gab]

take air cleaner off, then undo the screws that hold the top onto the carby, remove the jets, and eithier run degreaser through them or compressed air or fuel or something & poke them out with think wire to make sure there not blocked up.

Gab

[timtx5]

Gab, I have already swapped over the carbs so that option seems quite unlikely.

[dsmith]

I reckon the dirty little slut is only happy when shes being raped at WOT.

[Uncle Arthur]

WTF are you worried about it not idling properly, its supposed to be a competition car, the big cam won't let it idle properly

[THE ASH]

yeah, just say you have a big dam & turn up the idle speed

[timtx5]

Yeah im still counting on vacuum leaks, it idles at about 1500 rpm now though so it getting a tad bit better.I think all the hoses need replacing, just about all of them are looking tired and will tear if you pull at them. Its quiet anyway (until the side pipe goes on) so no one would notice what it idles on. The dodgy thermofan setup is pretty loud too.

[Jason Broadhurst]

ibheadgasket

you need to check compression, just because its not using fluid doesn't mean there is no leak.

[timtx5]

Although you suggest that for everything (I think you suggested that last time my car was acting up, turned out to be dodgy leads), I think you might be onto something. I think I still have that dodgy compression tester round, that will tell the truth anyway.

You could be right though, because it came on suddenly. It still starts good, but it does kinda sound like its missing on a cylinder every few cycles. Plugs looked good though. It did get hot (according to the temperature guage, if thats reliable). Im sure a head gasket wouldnt be too much hassle on this thing. The inlet and exhaust manifold wouldnt take much more than 10 minutes to take off I reckon.

What do you do about the valve gear on a push rod engine, never done one of these things with dinosaur bones before

[Datto-Zed]

Being push rod makes it bloody easy.

[Jason Broadhurst]

depending if the tappets have to come off the access the head bolts, its all pretty obvious when u take the head off

[Jason Broadhurst]

I think you suggested that last time my car was acting up, turned out to be dodgy leads

so why did it take you 3 years to fix it :P and still never returned my spare leads

[Datto-Zed]

so why did it take you 3 years to fix it :P and still never returned my spare leads

...and YOU still never returned my L26 bolt

[timtx5]

It took me about 6 months to fix, and at least I still didnt have to do a head gasket hey. Reason it took so long was that the new leads I bought were crap. Nothing else. You can come get your random selection any time you want. Last time I said I would go get them for you when you were here you said not to worry about it.

[THE ASH]

Speaking of having other peoples things - I have DZ's beer & the cash to buy the 2nd carton...

[Bitsamissing]

My first girlfriend still has my virginity, how do I get that back ?

[Datto-Zed]

Speaking of having other peoples things - I have DZ's beer & the cash to buy the 2nd carton...

Come and get the engine out yourself ya lazy pick!

I'll try and round up the lads and get that done this weekend mate. The thought of beer should do the job well.