For the love of a tractor engine: The life and times of the 18R-G

[o_man_ra23]

Have you tried swapping #1 and #4 leads at the dizzy?

[andrewzuku]

I just tried, It didn't make much difference - only a tiny bit rougher.

I just double-checked the firing order. 1-3-4-2. All good.

I keep wondering about the cam regrind. I still don't know their history. I have an 88253 Head, and I'm pretty sure they've been reground to 88210 specs, although I've only got 88251 pistons (8.7:1 CR).

[Suavemechanic]

nice bit of logical and thorough fault chasing ....
but , stop spending money on parts and do a compression check ,
while i have had some bad luck with re ground cams in the past ,my feeling is it would be unusual for a cam grinder to stuff up and stay in business long
more likely a shimming ? valve seating issue or your piston choice
any thing over 100 psi should run ,if so .....you have sparks so it must be fuel.......
cheers

[andrewzuku]

Here's the results of my compression test from about a week ago:

Cyl:	1	2	3	4
Dry:	135	130	130	133
Wet:	170	168	168	174

The head was rebuilt about 8 months ago (although I haven't driven it all that much). with a couple of valves replaced, and the surface machined.

Is there anything else I can check before the cams?

[Willofan]

I have a similar situation with an 18RG I have been doing an 18rc swap for someone I know. He bought this 18RG which supposedly had rebuilt head in recent times!!

When he picked it up, it was running rough, would barely idle and popping back through the carbs.

The first check was compression and it came up 120 across all 4. Next thing I noticed was it was a rebuild using an 18RC block. We pulled it out of this car and put it to another. New plugs, points and gaskets, we started it up again. It was still back firing and running rough. Timing was checked and carby tops off. Back carby was dry with no fuel. Fixed needle and seat blockage, now running on all 4 but still misfiring and popping back through the front carb.

Rocker cover off and cranked it over to TDC. Instantly you could set the inlet cam was 5 degree retarded and the exhaust was about 3 degrees out. No1 inlet valve clearance was about 0.002", checked all clearances and they were all over the place ranging from zero to 15thou. Meanwhile and oil leak was spotted at the headgasket so head came off and set for a full service and cam reset.

So head off and guess what, it appears there was a recently fitted head gasket put in but old gaskets and material left on the block causing the oil leak, however the bad news of what was causing low comp was revealed. 18RC flat top pistons..............Engine back out now to contemplate its future.

[andrewzuku]

What a bugger about your pistons! I know mine are standard 18R-GU pistons because I had them out to replace the rings and hone the cylinders. They have valve reliefs and "ART 88251" stamped on them.

Iit's a long shot, but could my timing chain be one tooth off?
I'm just making wild guesses here before swapping carbs around tomorrow.

[Suavemechanic]

I'd have a look at the fuel system then , you have sparks , and compression is enough to run .and seems even , Good luck

[roadkill]

Hi,

first of all what carbies? Dellorto? Webers? Solex (puke)? Does it have a balance pipe over the inlet manifold? Does it run ok if you lift the revs to say 1500 or 2k rpm? My guess is that you need to adjust the idle screws. Find which ones they are and screw them out half turn at a time, wait a bit, give it some revs and go again till it runs on all 4. One way to check too is get some start ya bastard (or similar product) and spray it down the carby that isn't running well. This will add fuel into that particular cylinder and if the revs pick up or stabilise a bit then you can guarantee that fuel delivery at idle is the problem. Given that the from what you're saying the engine runs fine at highers revs means that there's nothing wrong with the engine ie timing, compression and cam so rule them out now.

Whereabouts in qld are you? Might be able to offer some hands on help


bEn

[andrewzuku]

Hey Ben,

I'd love some help in person if you're willing to come over. I'm in Ashmore on the Gold Coast. PM me if you want my mobile # and address.

They're a pair of Weber 45 DCOE (13)'s

I removed the balance tube between carbs because it didn't fit with my cold-start devices on the back of the webers. Using a ceramic insulator, there's still a balance port between each barrel on the same carb.

I've used a synchrometer to balance the carbs, and adjusted the idle mixture screws on each barrel to the point where 1/4 turn each way makes the idle drop. I even tried with a colortune to make sure I was in the ball-park. The idle mixture screw on Cyl 1 makes very little difference. 2, 3, and 4 are able to change the idle speed significantly.
The barrels between each carb are ever-so-slightly out from one-another (less than one notch on the syncrometer). I'd say it's either slightly bent throttle-shafts, or a side-effect of the misfire, maybe?

It runs OK at around 1500-2000, but I've noticed on my wideband sensor that it's very rich (10-11) rolling along with a tiny bit of throttle between 2000-3000.

The engine lacks power, and only really feels like it pulls (a little) at around 4-5000 RPM, but doesn't make any more power over that.

Spraying "Start-ya-bastard" into Cyl #4 makes the idle drop (I haven't tried the other cylinders).

At the moment, I'm running 34mm venturis, 4.5mm Aux, F16 emulsion tubes, 130 mains, 190 air correctors, 50F9 idle jets, and 40 pump jets.
I've got a tin of idle jets (45F11, 50F8, 50F9, 50F13, 55F8, 55F17), mains (125, 130, 135, 140, 145), and air correctors (160, 170, 190), as well as spare 36mm main venturis. I've tried quite a few combination when I was tuning out my flat spot (which is much better now).

I've also go my brother's set of 40 DCOE's I can try with 32mm main venturis.

P.S. Thanks for all the help guys, toymods.org.au rocks!

[roadkill]

Hi,

if the idle screw doesn't change it then my guess is there could be something amiss with the amount of fuel going in at idle. If the engine isn't making much power till about 4-5k then i'd also be a little concerned but it depends on what else you drive and what your expectations are. Spraying too much start ya bastard will drown a motor too so i guess you put too much in. If screwing the idle screw on 4 changes the revs then at least that one works and is doing what it should. Maybe even try swapping the one on cyl 1 with one on cyl 2.

I'd love to come have a look but i don't get enough time to go to the goldy these days.

I also have a pair of 45mm dcoe 13's here that i last had on an 18rg. Could always swap them over and see if that makes a difference too (if you came to brisbane when i had some time free lol)

bEn

[allencr]

I've used a synchrometer to balance the carbs,

Front carb to rear carb, AND front throat/barrel to the rear one on each carb?
Valve lash/gap OK?

[andrewzuku]

Swapped front - back carbs
I just swapped the front and back carbs (effectively swapping barrel 1 <-> 3 and 2 <-> 4), but the problem stayed with Cyl #1 and #4. If it was a problem with the carbs, I'd expect the problem to move to Cyl #2 and #3. Am I thinking the right way about that?

Balance with Synchrometer
I'm able to balance the front and rear carbs (Cyl #1 and #3) to be spot on with each other. At the same time the barrels within each carb are ever-so-slightly out from one-another (less than one notch on the synchrometer).

Valve lash / gap
How do I check the valve lash / gap? I'm pretty sure they'll be OK though. The engine builder who put my head together is very experienced (Abbotts Engine Reconditioning in Southport, Qld).

Bum dyno
My last car was a 1981 RN40 Hilux that I swapped a 1UZ-FE into with the standard ECU and auto transmission. obviously an 18R-G won't be as fast as a 1UZ, but I know it's got a lot more to give. I'd guess it's making about 70rwhp. my (optimistic?) goal is 120rwhp.

[Rodger]

Do those model Webers have Idle Air Bleed Screws?

This may help with those Webers.

http://www.redlineweber.com/html/Tec..._typical_i.htm

Regards

Rodger

[andrewzuku]

Unfortunately, no air bleed screws. They're 45 DCOE 13s, and don't even have a removable progression hole inspection cap. I'm pretty sure it's only the newer 151 and 152 models with the air bleed screws.
Thanks for the link though, I'll have a read now

[ian]

it was a weird feeling reading this
as it is almost identical to the problem that i am having at the moment
what started as a simple changing of a blown head gasket has escalated into the point that i am considering selling the whole shitfight
i have done the same , tdc on no 1 cam slots line up ,new leads electronic dizzy
now it idles rough as guts , pops back through no 4 , backfires under revs ,
pulling plug off number one at idle makes no difference, although there is heaps of spark there ,
firing order is correct , i did not remove cams at all , just changed the gasket , compression is a bit all over the shop ranging from i40 to 180
i put this down to 15000 klms, mostly on the track over 10 years ,
its driving me nuts ,