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General Car Related Discussion.To discuss anything that is related to cars and automotive technology that doesnt naturally fit into another forum catagory.
From: it's not where you are, it's where you've been and where you hope to be
be carefull and check that the lugs are in *precisely* the same position relative to the keyway.
I had a 36-1 V belt aftermarket pulley and later replaced it with a stock cast iron one which has the teeth cast into it (in order to run a ribbed water pump / alt belt). never gave it a thought but discovered later that the engine had been running 23 degrees advanced because the missing tooth gap was 23 degrees different on the aftermarket wheel compared to a stock one
From: it's not where you are, it's where you've been and where you hope to be
Originally Posted by nixon_2wd
You should have caught that with your 20/20 vision..
haha - actually, it was discovered by Stu's 20/20 ears!
the new engine had done a thousand miles with 23 degrees error though i hadn't booted it as running in. it wouldn't idle very well though otherwise it ran fine. there were lots of different parts / diff engine spec etc so it wasn't just a case of "oh it isn't idling proeprly since i've changed the pulley therefore it must be the pulley"! didn't put any effort into tuning it cos it was shortly going to Stu for mapping.
as soon as he heard it he said 'the timing sounds out' and sure enough his strobe told the story and we changed the setting in the ecu to relfect this. i couldn't understand how this had happened as the previous engine (same ecu setup but with the previous pully) had been running 37 psi and it would surely have melted with 23 degrees advance. it looked like somehow i had changed the offset in the software when i put the new engine in - though i KNEW i hadn't. even later when i got back from mapping, older maps from the previous engine running high boost had the same offset setting - it was a complete mystery for a while
Iv got a early MK 2wd on my focos . I bort it for my 3dr cosworth and the car would not start so I tuck it off put the standard one back on it started 1st turn of the key . So I set the standard pully up on the timing mark and removed it and put the after market one back on it was a mile out . So I removed the ring and re drilled it in the right place and it's been fine on my focos . but when I gave the car to NMS to have it mapped I told him about this witch he said it's the norm with these after market pulleys to need the timing tweaking to get them running ring . So be very careful
be carefull and check that the lugs are in *precisely* the same position relative to the keyway.
I had a 36-1 V belt aftermarket pulley and later replaced it with a stock cast iron one which has the teeth cast into it (in order to run a ribbed water pump / alt belt). never gave it a thought but discovered later that the engine had been running 23 degrees advanced because the missing tooth gap was 23 degrees different on the aftermarket wheel compared to a stock one
standard practise is to check timing with any pully.
From: it's not where you are, it's where you've been and where you hope to be
Originally Posted by Mark Shead
standard practise is to check timing with any pully.
Mark
but why don't the aftermarket manufacturers just make the feckin things with the correct offset? its no more complicated or expensive to do it right is it?
but why don't the aftermarket manufacturers just make the feckin things with the correct offset? its no more complicated or expensive to do it right is it?
That's what I was thinking while reading this thread
but why don't the aftermarket manufacturers just make the feckin things with the correct offset? its no more complicated or expensive to do it right is it?
your guess is as good as mine. But it may be that you need to adjust timing on the disc rather than adjust the offset in software on the later style ecus.
From: it's not where you are, it's where you've been and where you hope to be
the steel 36-1 ring i had was affixed with 8 screws to the aluminium pulley, there was no adjustment possible and technically it doesn't matter anyway as you would be telling the ecu the offset when its set up.
however, in the case of an aftermarket 2wd type pulley with 4 lugs to run weber marelli, not only does the lug get used for timing but its also the TDC reference. in addition, there's virtually no-one who could do anything about it on a weber marelli ecu so if the lugs are in the worng place on one of those its a dissaster
the steel 36-1 ring i had was affixed with 8 screws to the aluminium pulley, there was no adjustment possible and technically it doesn't matter anyway as you would be telling the ecu the offset when its set up.
however, in the case of an aftermarket 2wd type pulley with 4 lugs to run weber marelli, not only does the lug get used for timing but its also the TDC reference. in addition, there's virtually no-one who could do anything about it on a weber marelli ecu so if the lugs are in the worng place on one of those its a dissaster
When i read this,i went out and checked my one,
its an aftermarket aluminium ,3 pulley with 4 grub screws.
It was correct,but , have never checked it, never crossed my mind if i'm honest.
One of the grub screws was loose,was the reason for looking for a new one.
All sorted now
Cosworth bottom pulley/trigger wheel
