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

[caam]

Quick question, still learning
With a pair of reground cams should valve clearance still be set at original toyota specs?
Set within spec my motor is still has tappety 'clicking' noise

And if not can I determine what the clearance should be?

Also +1 for Megasquirt
Cheers Cam

[jabbatron]

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[caam]

The cams came from a barn find motor I brought a while ago so no spec sheets
Any way I can measure the cams then find specs from there?

[jabbatron]

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[caam]

Ive got them set within the factory settings - although I've only set it measuring cold, might try hot if its any difference?
To go tighter ill need to buy new shims so finding a close target would be good.. will play with the few spare I have and get them all closer to the tight end

Inlet valve clearance - hot 0.204mm (0.008")
Inlet valve clearance - cold 0.178mm (0.007")
Exhaust valve clearance - hot 0.331mm (0.013")
Exhaust valve clearance - cold 0.305mm (0.012")

These are what i've set the cold off - its a 2TG not an 18RG, this just seemed like a good thread to post in

[o_man_ra23]

My understanding of valve clearances is that they are there for the same purpose as piston clearances, ring gaps etc. To allow for heat expansion of components. The thing with valves is that at full noise they will heat more than when the motor is at full temp and shut down (like the situation when you pull the valve cover off to check clearances) so still need clearance even when measured hot. If the cam lobe itself doesn't expand as much (smaller base circle from a regrind will expand less) then you can tighten up the clearance.

Bearing tolerances are a little different. They need to have a gap at full temperature for the oil film. This might explain why multigrade oils are so good. At cooler temperatures they are thicker, and would fill a larger gap. As the engine warms up, the crank and rods expand, making the clearance smaller, requiring the oil to be thinner to work effectively in a thinner film. At least that makes sense from a thermal expansion point of view.

[Pagie84a]

Just back on the topic of ecus for a second I'm compiling a to get list
http://item.mobileweb.ebay.com.au/vi...id=56931890487
From what I gather I need this and a map sensor and a 22re tps is there anything I'm overlooking

[jabbatron]

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[Willofan]

The cams came from a barn find motor I brought a while ago so no spec sheets
Any way I can measure the cams then find specs from there?

Hey Caam
If you check either end of the cams (with a mirror or behind the front chain gears), you will find some numbers stamped in them from who ever ground them up which can be traced back to the maker and specifications and possibly the set up sheets.

Let us know the number and I will list up the cam people you can talk to.

[jabbatron]

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[Pagie84a]

I would consider not buying megasquirt/microsquirt gear from ebay due to some people selling badly made or counterfit items there. Your better buying from a reputable ms reseller. (not saying that particular seller is dodgy, just it does happen and the cost savings usually isn't much).

You will need an external map sensor for the microsquirts, as for the tps sensor just a VL commodore unit does fine for the 'D' shaft. I do have a 22re variable tps sensor to suite later 22re's if you wanted it, i bought it off american ebay and there completely different to early 22re's and 18rg's... You'll also need IAT sensor and a coolant temp sensor, standard temp sensor seem to work perfectly out of the box.

If your doing fuel only then i had great success 'tapping' into the stock vr sensor. There's 2 wires, pink(red?) and white, just tap into the white one.

I did at once stage run my 18rgeu fuel+spark off the standard dissy (mech/vac advance locked out), but i found cold starting would kick back sometimes as the engine would get up to full cranking rpm's. Since theres only 2 lobes per rev the ecu has to guess how fast the engine is spinning between trigger inputs, so during cranking if the engine rpm changed slightly it would fire the coil way too early.

Id recommend either putting a tiny multi-tooth trigger wheel inside the dissy or mount a trigger wheel on the crank.


Damien

Is the later 22re variable tps sensor the one that bolts straight on the d shaft I was gunna go to my local upullit and pocket one if I can find it
Picked up elec dizzy of a 21r today gunna look into it when I bang it all together will this still need a trigger wheel

[jabbatron]

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[timbosaurus]

It does work ok with just the standard dizzy.

You can obviously make it better with dual sensors or trigger wheels, but its not critical.

[o_man_ra23]

I'm with Timbo. For a fairly stock 18R-GUE, the stock dizzy, or a stock dizzy with 22RE electronic internals will work fine and dandy. Personally I am going dual sensor with sequential ignition and fuel, however this is getting bigger than Ben Hur and far more complex than the average first time installer would care to play with. I would suggest not bothering with this route unless you plan to squeeze a hell of a lot more power out of these bad boys.

[jabbatron]

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