2TGEU and 3TGTEU Pistons/Crank Question

[GeneSPIDA]

I have a 2TGEU where the head has the symmetrical domes for the pistons. Apparently (and I've seen them), there are also 2TG heads with a asymmetrical dome (sloped to one side).

What I'm curious about is that my understanding is that the 2TGEU and 3TGTEU have exactly the same bore, and it's only (very simplistically) the stroke caused by the 3TG crank that alters the capacity (i.e. 1800cc as opposed to the 1588cc of the 2TGEU).

I know that with engine rebuilds, etc. the bore will vary from engine to engine, but is it correct that you could use a 3TG crank in a 2TGEU (particularly the later versions)?

I have forged pistons in mine with 8.5:1 compression, and a set of 3TGTEU conrods. I'm just curious because if, in future, I want to increase the capacity of my engine to around 1800cc, could I just put the 3TGTEU crank in and keep the same pistons, etc.?

Some posts seem to imply a difference with pistons between the 2. Perhaps that's more to do with the different head on the 3TGTEU? And as long as I keep the 2TG head, maybe the crank would just go straight in?

Any experience with this?

Gene

[TheToyman75]

Gene,

You will need different pistons to use a 3T crank.

The crank gives a longer stroke and as such requires a "shorter" piston. This is acheived with a different pin height between the to pistons. Otherwise it would push the piston out the top of the bore destroying your valves and your head.

I hope clears it up for you.

[GeneSPIDA]

Gene,

You will need different pistons to use a 3T crank.

The crank gives a longer stroke and as such requires a "shorter" piston. This is acheived with a different pin height between the to pistons. Otherwise it would push the piston out the top of the bore destroying your valves and your head.

I hope clears it up for you.

Ahhh yes, seems obvious now!

If the crank is in the same position (which it would be), and the stroke is longer, you would need a shorter piston to not clash with valves, etc.

Thanks

And sorry for calling you Troy. Not sure where my brain's at today - kind of mixed Toyman and Rod - don't ask me why.

["Z" UTE]

From a reputable source, who did the 2TG/3TG hybrid many years ago,. The rods are the same length, and the difference in crank throw, is accomodated by a higher piston pin height in the 3TG.

cheers Chuck.

[sillycar chick]

Yah, I can also vouch for Rod's info. I have recently built a hybrid and came across this issue when playing around with the ideas on which parts to use from what engine. Just be aware though (if you dont already know) that some 2T-G blocks ( i think it may have been the earlier ones) are slightly different to the 3T block and your 3T crank may hit. If this is the case, you may be better off starting from a 3T block and slapping all your twin cam gear on that. There is also a lot of information on these forums (and the old ones) about doing these sort of builds. Good luck with it all.

[Cool1]

I think it was only the 2T blocks that had the problem with the 3T crank counterweights hitting. All 2TG blocks should be fine.

[TheToyman75]

I think it was only the 2T blocks that had the problem with the 3T crank counterweights hitting. All 2TG blocks should be fine.

Actually mate the early 2T-G blocks have the same issue. The safest option is to use a 2T-GEU block or of course a 3T or 3T-GTEU block. If you do have a problem with the counterweights fouling it was common practice just to clearance the block as required.

As for rods all T series engines have the same length rods except the T which was only a 1.4L