Maximum valve size in 3tc with original seats?

[ToyTA22]

As title says, what is maximum dia valves used in 3tc head with original valve seats still installed?
Anyone with experience, help would be appreciated.
I have tried searching but found nothing so far.

[brucey]

When I looked into getting oversized 3tc valves the machinist reckoned 1mm oversized before changing the valve seats. Probably could go bigger. Though without modification to the cylinder head there's not much to be gained by going larger than 1mm oversized, due to the coolant passages below the intake port:


http://www.toymods.org.au/forums/thr...ves?highlight=

[ctrain]

1mm is all you need to do, most high performance 2tc/3tc heads have 1mm oversize, you could chuck in better valve seats but its not really worth it, im going 1mm oversize on standard seats with my turbo 3tc

[ToyTA22]

Thanks guys. I did a lot of googling and found 1mm is about right, I didn't want to buy 3mm and have to machine them down. I think BRD do various sizes. It was going to cost at least $200 to machine them down.
Thanks ctrain. I know you do a lot of work on/with 2t & 3tc so I thought you would know.
It's for my TA22 as mainly a daily road car but occasional weekend dirt track car.
My other question is, are the standard seats in 1982 3tc suitable for unleaded without fuel additives.

[NME308]

My other question is, are the standard seats in 1982 3tc suitable for unleaded without fuel additives.

Hi mate,
I have used standard factory 3TC seats with unleaded & plenty of boost for years without problems.

Cheers
Jason

[ToyTA22]

Hi mate,
I have used standard factory 3TC seats with unleaded & plenty of boost for years without problems.

Cheers
Jason

Thanks Jason.
I thought the Japanese market used unleaded well before Australia. Just thought I better check before building engine.