Smallport block + bigport head = Interferance engine ?

[too_quick]

Hey Hey,

I'm adding my rebuilt bigport head to a ae92 100kw smallport 7 rib.

If i happen to snap a timing belt will a valve leave its mark in a piston ?

Head been shaved a little but other than that the head is stock as is the bottom end bar acl race bearings etc.

Thanks,

Des

[Ben Wilson]

With standard cams it should be fine.

[takai]

How much has the head been shaved though?

[too_quick]

How much has the head been shaved though?

Its been shaved 3 times because its been shaved every time the head has been off for head gaskets etc.

I'm getting 272 7.9mm lift cams as well, Genuine Toyota stock head gasket.

[oldeskewltoy]

Its been shaved 3 times because its been shaved every time the head has been off for head gaskets etc.

I'm getting 272 7.9mm lift cams as well, Genuine Toyota stock head gasket.

it'll be close..... just do your timing belt service regularly and you should have no problems........

[takai]

8.5mm ish is where you start running into problems. So think of it as you, at factory specs, have 0.6mm of "room", and of course shaving will reduce this.

[too_quick]

8.5mm ish is where you start running into problems. So think of it as you, at factory specs, have 0.6mm of "room", and of course shaving will reduce this.

How much do they normally shave to get the head flat ?

I'm expecting there to be problems if it snaps a belt i just want to be sure, I guess i will check clearances when i put the head back on.

[feral4mr2]

i'm yet to see or hear of a timing belt snap. in my personal over 12 year experience with 4age's and the variants i deffinatly havnt had it happen, and i've gone way over 100k on a belt.

[takai]

In order to check just wind on the cam to the highest lift point (i.e. pushing the valve down the most), and then turn the engine over gently. All without the timing belt of course.

Basically if you do it gently, youll be able to feel if the piston hits the valve at any point during the cycle.

[too_quick]

I'm yet to see or hear of a timing belt snap. in my personal over 12 year experience with 4age's and the variants i deffinatly havnt had it happen, and I've gone way over 100k on a belt.

That makes me feel better.

Takai i did that when i 1st put the head back on after its 3rd shave, Going to get road and track at Ipswich to check the block as its ment to be in good nick but i will get rings and bearings done at the minimum anyway, Will get them to check the head verse a less shaved head and see how much i have lost.

[mr2gze]

i'm yet to see or hear of a timing belt snap. in my personal over 12 year experience with 4age's and the variants i deffinatly havnt had it happen, and i've gone way over 100k on a belt.

I cant say I've ever seen a snapped timing belt either. But heres what happened to mine after 120k kms.

[fixeruperer]

my 4afe did that but the cam seized in the head and crank kept going hehe

[The Real Roadrunner]

the above is what they normally do first. ive only ever seen a snapped belt on a 3sgte and that was at 160k with no maintanence.

stripping teeth is fairly common though if your running big cams.

why not get the valve reliefs cut out if your worried? easiest way IMO

cheers
linden

[too_quick]

why not get the valve reliefs cut out if your worried? easiest way IMO

cheers
linden

I will talk to my engine builder about that one, Sounds dodgey to me though.

[The Real Roadrunner]

dodgy enough to be done by pretty much every engine builder.
commonly refered to as flycutting pistons.