Thermactor
Member
<- here I am with 130,000 on a timing belt on an interference UZ --- gulp!
My friend, I can tell you for sure that the '95-97 1UZ motors are of the interference design. When I did the crank seals on my sister's '95 LS400, I had to take off the timing belt. For the heck of it I rotated the cam sprockets by hand and, yep, a valve smooched a piston. Rotated it the other way, same story.Thermactor, unless you're driving a VVTi motor or you've put some wild cams in your motor, you should be OK?
The early 1UZ's are non-interference (stock), and the later ones (VVTi) are interference motors.
My #1 motor is currently sitting in the garage without any cams, and next time I'm home, I'll take some measurements to see just how much valve lift it takes to kiss a piston. These wouldn't be absolute type measurements that someone could use for cam sizing, because I don't have stock pistons, plus my heads have been shaved, but it would still be interesting to see.
If someone has a stock motor on an engine stand they could do the community a big service by popping their cams out and taking these measurements to see how much valve lift it takes before the motor becomes an interference type.
With beefier rods, too....The '90-94 is smelling like a rose.
Non-interference, beefier rods, thicker cylinder sleeves, lower compression ratio.. the facts just add up.With beefier rods, too.
The latter model ones are still no dud. I have an unopened 96 model motor with turbo pushing 400 wheel hp and no problems. Ran a best of 11.91 @ 117 mph in a 1450kg ute. Fairly safe tune though.. cheers kris
I wish we could edit posts after 30 minutes here.
Thanks for defending the later motor, but let's try to keep this going on topic... Interference or Non Interference.
Definitely a very interference motor on the '95-97. Mine is back together now and running. While I was down there I drilled and tapped a 1/2" NPT hole in the oil pan for the supercharger oil return. I have to say that reassembly is far more unpleasant than disassembly!John, cannot find my old reference material but quite sure that I read factory details stating the engine went interference on the 1995 LS400 with the increase in compression. Curiously that is also when Lexus changed the timing belt replacement interval from 60k to 90k... go figure. I change my belt at 100k and it was still good for 10k+ miles. Obviousy the VVti engines are interference.
Good advice, I tried doing it in retrospect with the old belt after it had been removed but the cam and crank marks had all been long worn off and were impossible to find even in very bright sunlight.Line up the timing marks and mark the old belt with a paint marker before you remove it lay it along side the new belt and transfer the marks. Done this a million times on other vehicles.