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Location:
Adelaide
Registered:
June 2003
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18RGU help needed urgently
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Wed, 25 June 2003 14:26
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Here's the deal:
We have a very common but irregular (no one cylinder) misfire at idle, we can't seem to get rid of it through altering the idle mixture or balance or any of that. The idle vacuum is at 330mm/hg (standard) on both carbies.
Under full throttle at 3000RPM the engine makes odd noises and misfires like a bitch. It also does this under any full throttle work going up hill. Basically whenever it's at full throttle for more than just a kick up.
We've tried changing a few things to do with the dizzy vacuum advance and they haven't made any difference. We have had it connected before the butterfly valve and disconnected (holes plugged), no difference (we couldn't try after the butterfly valve because one of the front coolant hoses (thermostat bypass) blew and we had to roll it home (all downhill luckily). I guess we should have replaced that hose during the rebuild!!)
We are going to try putting the old 18rc dizzy in to see if that makes any difference.
If that isn't it then we will have a look at the carbies (newer model solexes, the unpopular ones)
Any suggestions of what the hell might be causing the problems and any remedies would be greatly apreciated!
Thanks.
Oh, and the compression is 183-184psi all around so there's nothing wong with the head or rings or anything like that.
by the way, does anyone know what the diaphragms built into the later model mikuni/solexes are for??
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Location:
Mornington Peninsula
Registered:
September 2002
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Re: 18RGU help needed urgently
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Wed, 25 June 2003 22:33
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faulty spark plug or leads?
Even if they are new they can still be faulty.
spark plug gap not correct?
Have you changed the rotor button or the whole dissy cap?
It sounds like it's not sparking, is the ignition coil ok?
Just a few suggestions.
Good luck 
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Location:
Brisbane
Registered:
December 2002
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Re: 18RGU help needed urgently
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Wed, 25 June 2003 23:04
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That compression sounds high. is it an 18rg or a gu? the 18rg from the manual should only be up to around 158 psi. And the GU should be lower.
If it is firing on all cylinders but number 1 at idle and then gets worst while reving, try disconnect the vacuum advance and see if that does anything. I once took out my dizzy and put it back in one cog too advanced. At idle the timing was good(set with light) but as soon as you advanced it coughed and farted like crazy.
When I had a look at the dizzy position I found out because of the wrong insertion, when timing was being advanced it was only giving a weak spark to the correct cylinder and another weak one to the plug next to it. When it advanced at full throttle it wasn't sparking on the plug it was supposed to at all.
One more suggestion. are the leads good?? maybe the number 1 cylinder lead it not too good.
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Location:
near chris and murray vic
Registered:
July 2002
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Re: 18RGU help needed urgently
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Thu, 26 June 2003 00:45
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sounds similar to what was happeing to mine when the tuning was way out... is it using a crapload of fuel??
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Location:
Adelaide and Queenstown T...
Registered:
September 2002
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Re: 18RGU help needed urgently
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Thu, 26 June 2003 00:50
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I am with the chick.
That sounds exactly what would happen to my torana, anytime it was under load it would burp and fart something hideous. I changed the leads and it fixed the problem immediately.
HiJack: Does anyone know what leads an 18RG takes. I am struggling to find someone who can tell me a part number, and the toyota genuine ones are $150, which seems a little pricey when you can get normal sets for $30.
Good luck
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Location:
Adelaide
Registered:
June 2003
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Re: 18RGU help needed urgently
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Fri, 27 June 2003 15:18
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We've tried 2 sets of new leads, and it is still crap.
We've rechecked the spark plug gaps, 1mm is what the book says.
The ignition coil worked fine on the old 18rc so I doudt that is a problem, if that is actually appropriate of the 18rg.
We've switched the dizzy to our old 18rc one, which we know works, and it is still crap.
For the reply that mentioned compression, we have 0.020 OS 9.7 CR pistons in there, so there's nothing wrong there.
I've tried the dizzy vacuum advance on all the places it could possibly run from and that did bugger all.
Can you tell me if running it on PULP and octane booster is likely to cause this problem.
I also ripped apart the carbies, none of the jets are blocked, but I did find something odd.
We also have a set of the original 18RG (210 head) carbies and a set of 2tg(88220) carbies. I checked the jet sizes and compared. Some irregularities were found.
The carbies we were using had the following:
Main air bleed jet - 140
Main jet holder- 132.5
(the little jet like thing) - 65 (left carbie, 63.5 (right carbie)
The original 18rg ones had:
Main air bleed jet - 200
Main jet holder - 140
(the little jet like thing) - 60 (both carbies
The 2tg ones had:
Main air bleed jet - 160
(didn't look at the rest, too lazy)
From this I am guessing that the guy who sold me the newer carbies (he was running very big cams) switched the jets when he gave his mate the throttle connections.
I doubt that the right carby should be jetted differently to the left one.
Does anyone else have the newer carbies? If so could you please tell me what numbers are written on your jets, top, bottom and the little ones'tops. But don't go to too much bother, I don't want to cause people to go out of their way for this.
Does anyone out there in Toymods land suggest switching the jets over, at least for a trial run???
I reckon I will do this with the original carbies to see what happens, If I need something in between, I could go for the 2tg jets.
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Location:
Adelaide
Registered:
June 2003
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Re: 18RGU help needed urgently
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Fri, 27 June 2003 15:28
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Oh, and blaze, I think you might have misunserstood me slightly.
by no one clinder misfiring I didn't mean number one, I meant no particular cylinder, as in they are all grumpy.
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Location:
Brisbane
Registered:
December 2002
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Re: 18RGU help needed urgently
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Sat, 28 June 2003 05:27
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Got ya,
On the leads, go to super cheap and they can order them in for you. they are blue leads from champion I think, and have the rubber caps on top. cost me $35.00.
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Location:
Brisbane
Registered:
October 2002
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Re: 18RGU help needed urgently
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Sat, 28 June 2003 08:33
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lead part number is TG4446, top gun
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Location:
Brisbane
Registered:
December 2002
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Re: 18RGU help needed urgently
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Sun, 29 June 2003 11:01
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Thanks philmelvin, thats right they are topgun leads. I said champion as they are red,(the ones I wanted) but they didn't make them for this engine.
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Location:
Perth
Registered:
May 2003
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Re: 18RGU help needed urgently
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Sun, 29 June 2003 12:50
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Changing the jets will be ok for testing. To really see what is going on you want a good gas analyzer / O2 meter to check that it is not leaning out. If it does you might get some detonation. Not too much of a hassle in an NA car.
I know you have checked the jets, but did you check all the passages in the carby too? Like blowing them out with compressed air... If so then it must be an electrical problem.
BTW the diaphragm on top of the carby is the power diaphragm, and yes both carbs should have the same jets. Becareful though incase the numbers on the jets are different, but someone may have attacked the jets with a number drill and resized both jets the same size anyway! (Read about a case like this in street machine)
I know you said you have changed the leads, but did you change the coil lead too? One dud lead or dud spark plug will affect only one cylinder, the coil lead affects all cylinders.
Dumb question, the coil was never dropped or struck across the top. It only takes a hairline crack down the tip of the coil to stuff it.
Presuming you checked points gap, rotor condition and dizzy cap too? Have you checked for arcing inside the cap? Usually given away by a fine dark line between electrodes in the cap. I don't know, maybe your cap is new... Kinda hard with out looking at it 
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Location:
Adelaide
Registered:
June 2003
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Re: 18RGU help needed urgently
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Mon, 30 June 2003 00:46
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The missing at idle has been fixed, I think we were a cog out when we put in the dizzy each time, the last time I told my brother to try it a little differently and it works much better.
We had also advanced it too much.
for an 18rgu with 9.7:1 CR pistons the ignition timing needs to be 5degrees btdc.
This was difficult to do as the marks on the harmonic balancer were at tdc and 9.5degrees btdc, so we had to do some calculations and they got us in the right spot.
It still won't rev over about 2500-3000rpm at full throttle.
We have replaced:
- ignition coil
- coil lead
- spark plug leads
- spark plugs
- dizzy cap
- dizzy points
- put in carby jets from older syle carbies and it it still shit!
(it ran quite well up the first hill at full throttle but then it started shitting its self again about 5 minutes later)
we sorted out one high rev, full throttle prob.
- the air filters we'd made sucked into the carby throats (didn't go past the venturi or cause any damage, but did disrupt air flow)
that is fixed now.
Anyone got any tips.
I spoke to a guy at the guy at the carby centre who got it passed its basic emissions test and he recommended putting it on a DYNO for some tuning.
Would it be worth it or should we keep buggering around with it 'til we figure it out.
What is a fair price for dyno tuning also, I don't feel like getting ripped off.
Thanks for all you input though, it has at least backed up some of our theories.
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Location:
near chris and murray vic
Registered:
July 2002
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Re: 18RGU help needed urgently
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Mon, 30 June 2003 03:12
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sounds like the tuning might be too rich and is fouling up the plugs.. the only way to get 18RG's in tune properly is to get it dyno tuned by someone that knows what theyre doing. trust me.
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Location:
South Aus
Registered:
June 2003
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Re: 18RGU help needed urgently
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Mon, 30 June 2003 09:13
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i had a similar problem a while ago, it would start to misfire when under pressure (going up hills and stuff) at about 3000rpm, and 5000rpm with no pressure (outa gear). It turned out that there was a bit of gunk in one of the carby jets, we cleaned it out, problem solved
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Location:
Adelaide
Registered:
May 2002
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Re: 18RGU help needed urgently
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Mon, 30 June 2003 09:28
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I have had similar probs with 2tg's..... once was blocked jets like Aussie just said, once was cos the points gap was too big in the dizzy, are you using points ?!
as for dyno tuning, I think Morpowa charge bout $100 for first hour, then $80 every hour after that, dunno for sure, ring round.... But I have heard bad things bout Road and Track !
Brendon
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Location:
nth ringwood, Victoria
Registered:
August 2002
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Re: 18RGU help needed urgently
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Mon, 30 June 2003 10:39
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the jets sizes for 18rg with 9.7 to 1 are 145 mains 170 aircorrectors ,34mm chokes the pumps near the butterflys are 65 and check the venturies to see if they are not loose cause if memory corrects me stage 3 starts at about 2500 to 300 0 ,being stage 1 idle stage 2 slow runs then stage 3 the mains
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Location:
Perth
Registered:
May 2003
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Re: 18RGU help needed urgently
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Mon, 30 June 2003 11:29
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Dumb question, fuel pump is keeping up ok?
If it is mechanical, it may have a sticky valve or something in the pump. Or worse, damaged diaphragm.
Float levels not set too low in carby so bowl runs low on fuel at higher revs?
Even before it hits a dyno, the engine should have no problems revving out, as the motor is relatively standard and the carbys were designed for the engine.
The main jets may not be blocked, but how about the rest of the fuel passage.
Dyno costs sounds right. But like what was mentioned earlier, make sure you get someone who knows what they are doing with the Solexs (Mikunis)!
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Location:
brisbane
Registered:
March 2003
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Re: 18RGU help needed urgently
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Mon, 30 June 2003 21:16
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re the plugs fouling up straight after the first run when you put them in? thats the same as what mine is doing.. if its doing that it is running rich as fuck for some reason... i am thinking it might be the needles and seats in the carbies
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Location:
Adelaide
Registered:
June 2003
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Re: 18RGU help needed urgently
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Wed, 02 July 2003 07:01
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Ok, a few things have been worked out, not all of it good.
We've got it through regency (now we can register it legally) even though it didn't work right.
We've decided to swap the carbies for the originals we have. (back before the days of the externally adjustable float position)
It has 200 main air bleeds
140 main jets
60 slow jets (these worked fine when we switched them into the other carbies)
65 accelleration ones (seems about standard) and it is adjusted to spec duration.
the large venturi is a 32
(the other carbies had a 31) (swithcing them made no difference)
small venturi is a 10.
Main reason we swapped was so that when we get it dyno tuned it will take less time. The less fucking around we do the better.
Someone must have played funny buggers with the jets in the newer ones as the 140's had bigger holes than the 200's and looked tampered with.
And yes, she went through over a third of a tank in approx 40km of very light driving.
Diagnosis - WAY TOO RICH!
We found a bugger of a problem that has nothing to do with the carbies.
We are getting coolant in the oil but no oil in the coolant.
- indicated leak from coolant point near an oil drain hole.
The head will be shaved and (another) new head gasket will probably be bought.
I am really glad we found that problem as we were planning to drive to canberra on the weekend.
Thanks for all the input but CelicaRA45, couldn't you have told me to use some jets that we actually have, that would have been so much better. 
Oh well, I guess we are flying to Canberra and will worry about the other stuff at a later date.
the points gap has been checked and redone too many times, and yes they are new.
I think it basically comes down to jets being too big and burning coolant.
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Location:
Madrid - Spain
Registered:
August 2002
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Re: 18RGU help needed urgently
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Thu, 03 July 2003 00:26
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The Solex carbies have an inherent problem in that the venturi tubes work loose. When this happens, they run really rich and misfire and generally run like a dog. try sticking your finger down the throat of the carby and feel if the venturi tubes are loose.
That had me stumped for weeks, and like you I went through the entire electrical system, carby jets etc plus multiple tune ups.
I replaced the crappy grub screws and lock nuts on the bottom of the carbies (for tightening the venturi tubes) with allen key bolts and some decent size nuts. At least then you can get them reasonably tight.
For anyone who has webbers on their car, I think they are keyed in, so you won't have that problem. I have only seen one set of Dellorto's and they were the same as the solex. I think the Italian made Solex (Lancia use them) are the same.
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Location:
Adelaide
Registered:
June 2003
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Re: 18RGU help needed urgently
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Mon, 14 July 2003 11:34
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Well, after many hours spent trying to find out what might have gone wrong we pulled the head to work out how the hell coolant was getting in the oil.
The head was taken to a shop to get it surfaced and pressure tested. The pressure test showed up what we'd been fearing.
The head has a ten inch crack running along the exhaust side from the front to the back on the top, but under the bridges.
We've located an 18rgeu head that we will use to replace it.
What a bitch, and we'd gone to the trouble of a port and polish too. The head could most likely still be used with some sealant but we just couldn't justify that after doing a rebuild. Oh well, at least we have a spare parts head now!
As for what caused the crack, who knows for sure but my brother reckons it has resulted from a previous owner torquing the head bolts too hard.
Has anyone else had cracking issues with a 88253 series head?
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