4AC Head on 20V S/T Block?!?!

[Matt]

Reason I said to swap the pistons is the cr ratio, 4ac is quite low and even if there wasn't clearance issues it'd be pretty uninspiring to drive

[AidoKsev]

Ahh yes good point, although I could just smash it on the dyno after work and do a 10 minute tune to drive around on temporarily, not sure if worth it, possibly, as the motor will have to come out of the rolla anyway if I do a complete swap. Just pull the sump off, crank, rods and pistons out, 4AC shit in, head on. All sweet!

[joeschmo_57]

That's one way around the legalities

[Course_Out]

FWIW I know guys in the US have run 4ac head on bigport 16v 4age bottom ends. Don't know if anyone has done it on a 20v though?

Interesting way around it I guess!

[rthy]

iv seen a small port on a 20v block, would assume the pistons match the con rods, not sure about 4ac/bigport pistons (18mm pin) on a 20v conrod (20mm pin)...

[Matt]

If the 4ac sits on the 16v it'll sit on a 20v silvertop and most likely still not be interference