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

[Steve M]

88231 and 88250 cams have a profile that is very similar (measured from used items, they can barely be identified as being different). My money would be on their being identical from the factory.
There is one key difference between them, and that is that the 88250 cams are centre-bolt adjustable and the 88231 cams are three bolt fixed timing items.

I've been told that the 88250 head had slightly larger valves on one side on one side that the earlier heads.
I've only seen two 88250 heads and they both had 88231 cams in them, so I'd check what you've got before committing to changing anything.

[The Witzl]

Time to add an informative post of the pictorial kind

Here's some info for the 18R-GEU guys wondering what all the ports are on your intake manifold.






In the pictures above:

1. This is the main PCV port, as seen in this pic, it connects to the cam cover PCV outlet. The port on the manifold actually routes to in front of the throttle, not directly into the plenum.
2. This is the input for the idle up valve - see http://www.18rg.com.au/tech/18rgeu-diagram.jpg - the other side of the idle up valve connects to the port underneath the throttle body.
3. Brake booster vacuum line
4. 3-pronged vacuum line outlet, for fuel pressure regulator and boost gauge. The other is blocked.
5. Single vacuum line outlet, for my ECU. In this location used to be the air-con idle up valve - a VSV controlled diaphram that increases idle when your air-con compressor kicks on.
6. Crank case breather outlet on the block. I've got this running to an oil catch can, partially visible under the intake pipe.
7. The other side of the catch can runs to the intake pipe, pre-throttle
8. These two vacuum port outlets on the throttle body, one goes to the vacuum advance on your dissy (i dont have this, cos my computer controls ignition advance), and the other goes to your charcoal canister.

Note the two outlets above the throttle body that arent connected. These circulate coolant around the throttle for emissions purposes, and also impede power output - disconnect them.

It's also worth noting that I have removed and blanked off the cold start injector. I never visit sub-zero temperatures, so i see no need to keep it.

[o_man_ra23]

Y'kno Karl... this info would have been useful when I installed injection a couple of years ago but anyways, good info and helpful for anyone who cares to look (and has an 18RGUE setup to install)

[Ren_RG28]

Interesting find...

Checked the nubers on my block today. Turns out it's a 88251. So it's not an 18R-GEU retrofitted with carbs, I'd say it started life as a complete 88251, then somewhere along the line the head shit itself so they sourced a 88270 head as a replacement.

So there ya go

[o_man_ra23]

Or somebody wanted the bigger valves Ren.

[timbosaurus]

270s have bigger valves ?????

[EldarO]

i bought it out of car, dizzy and alternator are missing...

also have the 230 head for sale.

the engine i have needs new bottom end bearings, so ill ring around on monday to see whether changing them is a viable alternative, if too expensive, ill just rip the head off, with the EFI gear, sell it, and scrap the block.

stupid me didnt think to ring and check prices before i bought it.

Elmo.

[EldarO]

double post poop.

Elmo.

[o_man_ra23]

Elmo, bottom end gaskets, rings and bearings are the same between the 18R-C and 18R-G. So the bearings will be cheap as chips. Changing them out can easily be done at home, done even need to take the motor out of the car (easier on a stand, but not necessary)

[river]

Hi,

270s have bigger valves ?????

The 270 was the final head, I beleive. It had the larger valves and better design to help recover some of the power lost over the generations due to emission controls.

The difference between the 210 and the 230 was the 230 had some water galleries that the 210 did not have... however, this was something I heard and cannot attest to how accurate this infomration is.

The 210/230 heads had the smallest valves, but with the high comp pistons and slightly more agressive cams, these engines put out more HP from the factory than later 18R-G versions.

Matching up various engine parts to get the the best head, with the best cams, with the best pistons - as mentioned - may only get you a handful of extra kw, and the time and cost of such an exercise would not be worth it.

seeyuzz
river

[Norbie]

Y'kno Karl... this info would have been useful when I installed injection a couple of years ago

Yeah, it would have been useful when I put my injection setup together in 1997. Where were you guys then??

[RAd28]

OT for a sec... Norbie, was that your Centurary at Morgans today i saw??

[timbosaurus]

Hi,

The 270 was the final head, I beleive. It had the larger valves and better design to help recover some of the power lost over the generations due to emission controls.

seeyuzz
river

Cool! I knew there were differences in design, but valve size was something I was unaware of. Are you certain?

If the valves are bigger, when did this change? As general belief is that the 253 was identical to the 270 bar the injector relief cutouts, and the 250/3 series heads i've got all have the same valves.

I'll take the cams off both to confirm the old story about 250 having single valve springs, and the 253 having double.

[Norbie]

OT for a sec... Norbie, was that your Centurary at Morgans today i saw??

Not sure what Morgans is, but the Century has been in the garage all day so no.

[Steve M]

88270 and 88253 heads are definately not identical. They have the same valve assemblies and use some of the same gaskets.

88253 heads have cast bridges on their top deck and a foot long casting line that is prone to cracking. They use a four bolt front inspection plate.
These heads have three air injection ports onto some of the exhaust ports.

88270 heads have no bridge reinforcement but are better reinforced throughout the rest of the top deck and don't have the problematic casting marks. They use a two bolt front inspection plate and have injector reliefs.