2TG heads,

[merc-blue]

I know there is some info posted somewere about the different heads?
where is it? or could it be reposted in here?
Cheers

[Rosey]

Is this the one mate ?

http://www.toymods.net/forums/showth...ight=2tg+heads

[merc-blue]

Rosey that not quite it.
but close,
See i have a 11111-88222 head and a 11111-88260 head, and decideing which one will be getting the love and want to see if there is any dfference apart from inspection cover and rocker cover,

i like the 88222 cause it only branded toyota not yamaha,

[Rosey]

Found this hope it gives ya some direction:
Quoted by September Squall.
Late model 2T-G blocks are the same casting as 3T blocks, just stamped with an engine number (2T#### or 3T####) to correspond with the internals (1588CC or 1770CC).

Late block is p/n 11411-28010 (possibly others also).
Early block is p/n 11411-26012 (possibly others also).

Date of change to the later casting would roughly correspond with the start of 3T motor production, approx 1980 I suspect. Accordingly 2T-G built after this date would use later casting.

In my experience,
11111-88222 head (and earlier) = 11411-26012 block;
11111-88260 head (and later) = 11411-28010 block.

IIRC 88260 head came in carb (2T-GU, 2T-GR) or EFI (2T-GEU) versions, from 88261 onwards 2T-G were EFI only (ie. 2T-GEU).

[merc-blue]

so bassicaly numbers dont represent any change internaly in the head just teh block they were on?

[Rosey]

Not sure mate thats all I can help you with, hopefully Toyman, River or Rinmax might be able to help...

[SeptemberSquall]

so bassicaly numbers dont represent any change internaly in the head just teh block they were on?

No, that's a misinterpretation. What I said there was about which motors had the later block casting for use with a 3T crank.

the number on the casting is the casting part number. if the part number has changed, then that is becasue the part has changed in some respect.

As for differences with the two heads, later heads came with dual springs. celicara45 posted some flowbench resutls suggesting max flow is slightly improved on later heads. if you're porting it and replacing springs to suit agressive cams, it probably is not too important which one you use so long as it isn't 11111-88220 which has smaller inlet and exhaust valves.

http://www.geocities.com/Colosseum/4883/

ps. i think choosing a head based on what branding or stamp is on the outside is probably the worst justification ever.

[merc-blue]

Micheal,
If the port casting etc is the same on the 2 then why not choose the more attractive one?

If either had a particular perfoamnce advantage i would obviously choose that but thats not the case

[river]

Hi,

I'm not too familiar with the various 2T-G heads, but this engine was in production along with the 18R-G and went through similar various models... 2T-G, 2T-GR, 2T-GU, 2T-GUE.

The lower number head (222) is from an earlier build 2T-G than the 260 head.

In the case if the 18R-G the lower number head had smaller valves than later heads, but it had the highest compression ratio and with the matching cams (ie 220 18R-G head and it's 220 cams), and dual Solex's, they were the most powerful factory stock engines.

The later head had a better flow but lower compression. If you're building a powerful NA stock engine then I'd go for the 222 head. If I was building a lower compression engine for turboing, then I'd go for the 260 head.

I think Toyman75 is the best dude to answer this question as he's the 2T-G guru.

seeyuzz
river

[TheToyman75]

Merc,

Mate the short answer is I would use the 88260 head. Its been a while since I compared the 88222 and 88260 heads.

If the heads are not on blocks back off all the can cam nuts so the valves all seat, that way you won't bend them if you put it down on some cardboard or rubber.

Take the rocker covers off both heads and look at the reinforcing webbing around the valve buckets. From memory the 88260 is better braced (Ie stronger) otherwise they are much the same other than cam specs and valve springs.

Then flip the heads over and look at the combustion chambers, I am pretty sure they are the same but give them a good eyeball just in case.

Hope that helps

[merc-blue]

im thinking i will stripp both and see which is in better nick and has done teh least work,

[Starfire]

Condition is an important consideration when picking which head to use, especially when they are old alloy ones.

Get them checked for straightness and corrosion - most workshops will do this for you for about $70 including a clean. A good one will also refund that money when you get work done (ie machining and such).

Whether you like it or not, Toyota has a lot of their casting done by Yamaha and they also do a lot of design work for them. It's part of their history and its a partnership that works. If it really bothers you and you end up using the 88260, just hit the yamaha logo with a die grinder/dremel/file and it will be gone forever

The 88260 apparently has bigger valves and may have double valve springs (was added later in the production run). It may also have more bracing in it but unless you plan on flogging the shit out of it that probably doesnt matter much.

Use whichever cams are bigger

Cheers,
Terry.

[TheToyman75]

Starfire,

The 88260 and 88222 both have the same size valves. Only the 88220 head has the "small" valves.

[Starfire]

Hrm,

The reference I was looking at said otherwise. I'll have to measure them