Hi

Just had a new a timing belt installed on 2001 KJ Verada. Used a Dayco belt and new seals etc also fitted. Noticed however that I am seem to have lost a little bottom end pull, but it seems to pulling better at the top end. Mechanic is honest as the day is long and swears that the timing marks were all set correctly and double checked (he knows how fussy I am).

Car seems to be running smoother actually (other than usual rough idle shakes - but actually better in drive now than in neutral????), and no belt noise so it has been tensioned correctly.

Is the timing adjustable on these models? What could be an explanation for this (imagined??) shift in power to higher in the rev band. I am assuming that if timing was out (missed tooth) I would definitely know about it. Are there any tricks to setting the timing?
thanks
LouisK

Only thing i can think off is tooth up or tooth down on the Belt. From what i remember Chantras was setup like this as well. Otherwise if battery was disconected for a long period of time vehicle may need time to re learn its operating parameters via ECU.

Regards

Interesting. If your old belt was stretched, then your valve timing would have been slightly advanced, accounting for the power difference. Someone else noticed this ages ago as well...

EDIT: As someone pointed out, it would be retarded rather than advanced (now I feel retarded :P)

If the belt is out by two teeth, then valve meets piston on these engines (told this by an engine rebuilder) Even one tooth can be messy. They are an interference head.

Cheers
Heath Young

Sounds like the cams are retarded, which would lose some bottom end grunt.
Get your mechanic to pull your covers off and double check the marks.

Interesting. If your old belt was stretched, then your valve timing would have been slightly advanced, accounting for the power difference. Someone else noticed this ages ago as well...

If the belt is out by two teeth, then valve meets piston on these engines (told this by an engine rebuilder) Even one tooth can be messy. They are an interference head.

Cheers
Heath Young

Kinda agree on those lines - but would the belt stretch that much? Perhaps it was incorrect before and resulted in different engine functon?
I always though Magna donk as clear of valve crashes? But I take your word.

Kinda agree on those lines - but would the belt stretch that much? Perhaps it was incorrect before and resulted in different engine functon?
I always though Magna donk as clear of valve crashes? But I take your word.

I've seen a Magna engine with valve damage from timing belt mishap first hand, defiantly an interference design as Heath pointed out. :confused:

Before Chantra has his timing belt changed, his was out by a tooth or 1/2 a tooth, which made his engine a lil rough, but his engine is so much smoother after he had everything lined up, but he also has a driver's side engine mount replaced at the same time.

I've seen a Magna engine with valve damage from timing belt mishap first hand, defiantly an interference design as Heath pointed out. :confused:

Ok. So be it. Nasty stuff when valves and pistons decide to have a boxing match.

Im not 100% on the 24 valve engines but on the 12 Valve SOHC's there are actually little indentations on the pistons for the valve to sit into...so 1 tooth out and your pretty much gone!

Also i dont know if its for the valve to actually "sit into" but well when the valve comes down there is a bit of room on the piston for it. Someone else will be able to explain it better then me.
I agree with heathyoungs theory

Interesting. If your old belt was stretched, then your valve timing would have been slightly advanced, accounting for the power difference. Someone else noticed this ages ago as well...

EDIT: As someone pointed out, it would be retarded rather than advanced (now I feel retarded :P)

If the belt is out by two teeth, then valve meets piston on these engines (told this by an engine rebuilder) Even one tooth can be messy. They are an interference head.

Cheers
Heath Young

Yep. Valve timing would have been retarded by a few degs with the old belt, retarded timing will give the feeling of more bottom end power, but will be definately lacking in top end... as your new belt stretches a bit, it'll even out the timing a bit more.

No offence mate, but i think it might be all in your head. Unless the tensioner is stuffed, and the belt is real sloppy.. I can't see how the engine would feel "different" with a new properly aligned timing belt!
By the way, I've seen a belt out 2 teeth, and no valve damage on a 6G74 TL Magna

so my timing belt must still be pretty good then since i have a boring engine under 3000rpm and its all hell and glory past 3000rpm, even though i have 149000km on the clock

Doesn't advanced timing give you more bottom end at the expense of the top end? The car really feels stronger up top which suggests maybe retarded slightly.

If the markers line up, how would you miss a tooth? Besides the engine losing power, what can I expect the engine to do if it is not aligned properly (ruling out rough idle cause it is a magna phenomen)

Can I expect more bottom end as the belt losens up? I did fill the car up with vortex 95 octane the same day I had the belt done. Maybe fuel has something to do with it.

i have run my car with Shell Unleaded, Optimax (in the old days), Shell V-Power and Shell V-Power Racing (by accident) i don't remember seeing much difference in performance, maybe just a smoother idle

Doesn't advanced timing give you more bottom end at the expense of the top end? The car really feels stronger up top which suggests maybe retarded slightly.

Yep! Heh... sorry, disregard what i said in my previous post then lol.

Give it a few days....

Every time I get my car back from a service it lacks a bit of power down low but is smoother then comes good.

Unless yours is uber lacking..