Confirmation: ZE Pistons okay in 20v head?

[Zyros]

Just confirming, although my engine is built (mostly)

Are, 4agze 16v pistons okay to use in a 20v 4age silvertop head.
Just was thinking how the pistons have the four dishes on the top for the valves on the head, yet a 20v has 5 valves per bore...

Just making sure incase the piston does rise high enough to hit a valve?

[Mr Revhead]

yes fine

jsut becomes an interference engine

[Zyros]

jsut becomes an interference engine

What do you mean?

[sergei]

it means if cam belt breaks then the valves touch the piston.
Most of the other make engines are interference .

[thegreatestben]

If the cambelt snaps or whatever the pistons will smash into valves.

beaten to it.

I think smash is better for dramatic effect though

[d1 mule]

im pretty sure im 99% wrong seeing as revhead, sergei and tgb.mr2 have said i thought the early ZE pistons have a mega dish in them?

[Mr Revhead]

yeah big dish

i wasnt sure if they would contact or not

untill matt set me some pics of his experiments.

they do touch

[d1 mule]

hmm i would have thought the dish was bigger than the recess cut for the valves, oh well iv learnt something today then haha

[Mr Revhead]

i think its to do with the positioning of the inlet valves rather than overall piston dish.

[d1 mule]

ah that makes sense, so m ust hit on the outside lip bit thats not recessed?

[ChaosAD]

Their was a thread not long ago about someone that sold a 20v with gze slugs and it skipped a tooth or something. That engine was definately an interferance one

[matt dunn]

Ypu can quite clearly see here where 3 out of the 5 valves touch when the cambelt breaks,





And if it doesn't break but just slips a few teeth or so,

you end up with 12 out of 20 valves looking like this,



Matt

[Alex B]

Yea, don't $&#$% up the timing

[Bling]

20v are interferance in some case anyway, for example, stuff up a gear shift and drop down a gear rather than go up a gear, cambelt slips, engine revs till it can rev no more, valves get bent.

still I guess if you are driving like a nana when the timing goes out you might be ok

[Mr Revhead]

only in blacktop. silvertop is non interference

[Bling]

why is it always the good one with the downside

[matt dunn]

only in blacktop. silvertop is non interference

But a BT would throw a rod first, lol.

[Bazda]

The 20v blacktop head will only hit on the exhaust side using 8.0:1 gze pistons (dish ones), if you look at a BT piston there are no cutouts for the inlet side only the ex side.
The Siltertop head is a diff story as the head chamber is alot shallower so would prob hit as in matts pics.