Mark _australia

iTrader: (2)

OK my last thread was about my motor running hell rich during break in but idling high (behaving lean) so maybe an air leak. Well it is all sealed up now and it is easier to start and has more consistent idle, but its still a bit weird.
(It is a rebuilt RB WS7II)

It has a few tanks thru it (apparently) before I got it. Still has mecahnical pinch and can only barely by started when cold so I am preheating to be safe. I can juuusst turn it over by hand on the flywheel with a nice 'pop' at TDC.
Running it in about 18C (65F?) ambient temp.

I start it and it idles high, the wheels are turning as if it is driving at say 10-15mph. The low end is mega rich, spitting raw fuel and needs to be blipped now and then to clear it. But when I blip it, it often dies dies. If I don't blip it, it won't idle more than 30sec and it dies. So it had to be started say 15 times to do half a tank of fuel.
So it is an appropriate level of richness, probably a bit too rich on the LSN, for the 4th - 5th tank.

BUT at the same time, it is getting hot. Static on the box, after a 10 back to back runs of 30sec with hi idle, the head is almost at a race tune kinda temp. Spit on the top of the cooling head sizzles off aftter about 6-8 sec so it is almost as hot as a broken in engine on the track.
That has me worried.

BUT number 2 - if I lean the LSN it does not seem to idle any better, and blipping the throttle still kills it. In fact, leaning made it harder to get it to idle and just rev it now and then.

I have only had new motors and am used to having to cover the cooling head at this stage to try and keep it hot .... not have it just idle and get plenty hot by itself.
It is time to lean it out, but I wonder if it is going to be way to hot then.

Ideas?

j_blaze14

iTrader: (34)

start by setting hsn needle first so its in the "window". what does it do wide open? sounds like the top is lean and the bottom is too fat with big gap to compensate. what yopu want to happen is no matter how long you drive wot the motor never goes past 60-80% max speed. hold the car on the box wide open (max throttle) and richen the needle till it starts to loose rpm, then lean it slowly so it hits about 80% max rpm. next set lsn flush and drop the idle (gap screw) to .7-1.0mm. rb's are cake to tune, just have to know where your bookends are on the needles and not go past that. you will find about 1/2 turn window on hsn and about 1/4 turn window on lsn is the most you use.

Mark _australia

iTrader: (2)

Thanks man, good idea. I had sort of ignored HSN as I am just wanting to idle a couple of tanks thru so i was all about the LSN.

I have had it WOT but only for a second or two with lots of smoke so assumed it was in the ballpark however of course it could be too lean and the smoke is all the excess from the fat bottom end. If I ran it WOT a bit longer it could well be lean.

I gather u r an RB fella? If so, can you recommend base needle settings? I googled and found only 2 results for how far to screw them out from the bottom, and the 2 posts varied by a whole turn so that's a pretty big ballpark. I split the difference and from memory I went 5 turns and 3.5 turns which made the needles just a little bit in from flush.

Currently I have HSN about 0.75mm in from flush and LSN about 0.5mm in from flush.......... and a lotta oil running out of the pipe when I tip it over so it is loading up on idle for sure

I will give it a go but still worried about that heat - oh well it has oil going thru it...

Mark _australia

iTrader: (2)

Disregard last post as I am getting there!! ........ BUT...

I have the LSN pretty damn close as it will idle for 10-15 sec no problems, and pinch test kills it in under a second with only a very small rise in revs. Awesome - LSN is pretty damn fine.

I wound out the HSN whilst holding half throttle (now have a headache lol) and it never really dropped the revs. I wound it out to sit above the brass tube so any more is too much - gonna fall out lol!

Now it will hold half throttle if you take it up slowly, but if I hit the throttle hard at idle or even hit it at like 1/4 throttle, it will immediately die.

Thus HSN is way too rich?

I did notice that it would not prime when I ran it on the box and had my finger over the stinger, I had to blow in the pressure line. Is all this as simple as a leaky gasket in the pipe and it is not generating enough pressure? It is new and felt tight enough...

DerpDiggler

iTrader: (1)

Not trying to insult your intelligence but have you checked the seal between your glow plug and the head? If it was sucking in air you could have some of these issues.

j_blaze14

iTrader: (34)

1/2 throttle won't work, hold it wide open for a count of 3 if you are afraid and listen to how high it goes. you will be able to tell where it is too fat, struggles to rev up then just sputters some. if you get it here hold it wide open and lean the hsn needle slowly, you will hear and see it speed up slowly as the mixture gets even. once you lean it to where its got good smoke and wheels are spinning pretty fast, maybe ballooning a bit, let it idle. if the motor is warm enough, it should sit at a low steady idle for about 10 seconds then start to sputter a bit then die. if it starts at a high rpm then drops to like 2 or 3 levels of speeds then dies its too rich on the lsn. lean it 1 hour and rev it up again, do this until the idle stays consistent. once the idle seems to stay consistent but a bit high adjust the idle gap down to where it feels like it will quit. keep doing these rev's and make sure idle drops instantly and stays consistent, if it starts high and lowers slowly its still too rich on the lsn. once you do get lsn to idle consistent for 10 seconds or so, or even longer, you won't have to mess with it much. hsn will be the only adjustment for a while.