2TG Rocker Cover Guide - With Pics

[TheToyman75]

The 2TG series of engine had alot of minor changes as they got newer. I'll try get pics of the changing rocker covers for production 2TG's and post em up. Keep in mind tho these engine have been around for quite a while so the rocker cover alone isn't enough to identify what series 2TG it is.

The First 2TG (11111-88220) Had "Toyota" and "1600" on the rocker cover. You can see it clearly on this 1970 TA22 GT.



The 88220 and 88222 heads also had a unique shapped alloy inspection plate on the front of the head.


This is a pic of the complete 88220 engine as issued by Toyota.


The 11111-88222 Rocker cover did not have "1600" on it. It had its EGR valve mounted there so only had "Toyota" on the left Hand Side.




The engine bay pic above is actually in a 1975 TA22GT. The airbox fitted is a period performance item and not the factory unit.
The 88220 and 88222 were the only two 2TG's that were factory fitted to the TA22 Celica.

[TheToyman75]

The 88260 Head appears to have received two styles of Rocker cover.


The one fitted to the 88222 Version (shown above) and the one used for the 88261. The 88260 heads were the first to have the steel oval style inspection plates and you can see here that the first series EFI intake plenum was blank on top,Just a black plenum.

With the 88261 version of the rocker cover the oil filler cap was relocated to the right hand side of the engine to allow more room on the passenger side for the DOHC. The lettering for the "DOHC" had raised edges. We also see the EFI lettering appear on top of the plenum at this time.

This pic shows the second generation of intake plenum as fitted to the 88261 series heads.


The 2TGEU 88262 Rocker Cover had "Toyota DOHC" on it and the DOHC was not with raised edges.


There is no head casting number on the front of the 88262 Head.

[TheToyman75]

The Toyota 2TG Race series heads are hard to get info on, best as I can identify the first series was refered to as the 126E and was a twin spark 8 Valve engine. The rocker cover is much the same as on the 88222 series heads but of course has 8 spark plugs. These heads are often refered to as having "blank" casting numbers. What they actually have is 11111 - "blank"





The 16V 2TG varient is refered to as the 151E and went back to being a single spark head.

[river]

Hi,

Interesting stuff. Are these covers interchangeble (to a degree) so you can mix and match?

Oh, and my historic knowledge of the 2T-G isn't my forte, so excuse my question..... but in the top pic of the 2T-G in the 1970 TA22... I thought the 2T-G didn't come out until around 72/73?

Can you illuminate us to the history of the 2T-G... build dates of engine variants etc?

seeyuzz
river

PS: After the 18R-G the 2T-G is my next favourite Toyota engine. It has better geometry than the 18R-G and this is good for modding (ie boring/stroking).

[TheToyman75]

River,

The rocker covers will all interchange except the 151E, the 16V head appears to have a unique rocker cover as expected with the addition of an extra 8 valves

The 1970 TA22 was released as a GT with a 2TG, its a common argue,ent that they didn't exist but I will post up pics and details from the genuine Toyota sales brochure when my most recent purchase arrives.

I have the 2TG specs in the TA22 thread but I'll copy the 2TG specific info I have over to here first chance I get. APril 73 was the changeover date from the 88220 to the 88222 form memory but I'll check that.

[TheToyman75]

Here is the beginning of the Stats and specs for the 88220 and 88222 headed 2TG engines as fitted to the TA22.

2T-G

2T-G Engine modifications as per April 1973 were from Engine Number 2T-8038333
Firing Order: 1-3-4-2
Ignition Timing: 16 Degrees BTDC / 800 rpm
Compression ratio: 9.8:1
Bore and Stroke: 85.0 x 70.0
Valve Size:
Intake – 43mm (Up to April 1973), 44.5mm (April 1973 Onwards)
Exhaust – 37mm (Up to April 1973), 38.5mm (April 1973 Onwards)
Cam Shaft:
Lobe Height In 45.87 ~ 45.97 (Up to April 1973)
Lobe Height In 46.37 ~ 46.47 (April 1973 Onwards)
Lobe Height Ex 45.87 ~ 45.97 (Up to April 1973)
Lobe Height Ex 46.37 ~ 46.47 (April 1973 Onwards)
Cam Lift: In 9.82 (Up to April 1973), In 10.27 (April 1973 Onwards)
Ex 9.82 (Up to April 1973), Ex 10.27 (April 1973 Onwards)
Compression at 200 rpm: Specified-165 or 185 Psi (Depending on publication)
Limit-142 or 163 Psi (Depending on publication)
Difference Between each Cylinder: Less than 14 Psi

[Rinmax]

Great info there Toyman.

Just to reinforce the interchange of rocker covers and heads. Here's my old style head with 6 bolt inspection plate, with a later version EFI rocker cover.



+ rep for you Toyman.

[Grega]

love this thread. good work guys

[RA28tragic]

Good stuff. Reigniteing an old flame.

[w810sc]

sorry to bring up an old thread,
The under-side of the 2T-G's "cam" cover also have differences. The cam cover with just "Toyota" written on it, hasn't got as much alloy reinforcement around the chain area's as the cam cover with "Toyota DOHC" non raised edges.

The oil cap surround in the just "Toyota" cam cover have a rubber seal, whilst the cam cover with "Toyota DOHC" non raised edges don't, it's just a flat surface.

The heads with a 6 bolt inspection plate don't seem to have the word "Yamaha" written on them whilst the head with a 2 bolt one have it next to the plate with the old Toyota symbol.

I'm not sure if the oil caps had something to do with what cam cover or head it was combined with but i know they come in zink plated metal and black plastic, both with the old Toyota symbol raised.

I know, picsorban, when i get both of the heads 222, 260 and covers back, i will post pics.

[edited]
The metal and plastic oil caps are "not" interchangable, metal cap has a coarse thread whilst the plastic cap has a fine thread

The external timing chain tensioners are different too. On the 88222 head, the tensioner has a bullet point that mates with the pivoting slipper, whilst the 88260 head has a dome surface that mates with the pivoting slipper.

fonzy

[goldta22]

yes there different heads the yamaha has bigger valves

[wombat]

nice thread, I think i almost have one of each type of cam cover in my garage excluding the 151E type of course.

+rep for you toyman

[Jaffa]

Great info Rod

Just out of curiosity have you ever seen one of the 8plug head's or the 16v head in the flesh ?? or for that matter did any ever make it to oz?

jamie

[TA22 GT]

The Toyota 2TG Race series heads are hard to get info on, best as I can identify the first series was refered to as the 126E and was a twin spark 8 Valve engine. The rocker cover is much the same as on the 88222 series heads but of course has 8 spark plugs. These heads are often refered to as having "blank" casting numbers. What they actually have is 11111 - "blank"

[]

Nice work Rod. I think the 2TG race engine also had no numbers marked on the block. Eg Completely blank...

I have a pic somewhere.

Cheers,
Simon

[ACT blue 22]

I guys i was just wondering if anyone had a 2tg rocker cover with the DOHC writen on it that they would be willing to sell? As mine cracked across the middle?

Thanks