joe27979

Well-Known Member

• Jun 3, 2014

• #1

chaps.
Fitted a new crank pulley and the new pulley came without a notch in it for TDC!

its a 3mb 2.25 petrol, am I right in assuming that as valve 7 (cyl 4 inlet) is fully open then I am at 6DBTDC?

Just trying to work out the best way to mark up pulley, or should I stic a screwdriver in number one piston and mark pulley when screwdriver is at top of its stroke?

Or should I watch the lobes...

Old wives tricks welcomed please. :whoosh:

 

Dr_evil

Banned

• Jun 3, 2014

• #2

mark at tdc one way and then in reverse and split the distance

 

joe27979

Well-Known Member

• Jun 3, 2014

• #3

Dr_evil said:

mark at tdc one way and then in reverse and split the distance

Click to expand...

cum agen say what Doc?

 

Dr_evil

Banned

• Jun 3, 2014

• #4

screwdriver in bore, rotate clockwise, mark tdc, rotate anti, mark tdc, take the distance on a piece of paper and split then mark on pulley, thats tdc, there'll probably only be a cm or so gap

 

mrchurchill109

Active Member

• Jun 3, 2014

• #5

Use a piece of key stock to hold old and new pulleys face to face and transfer the mark from old to new. Of course, that prob'ly would have worked better before you installed it...

ajr

 

dominicbeesley

Well-Known Member

• Jun 4, 2014

• #6

What Dr Evil says, don't do it from the tappets as you don't know if someone else has set the cam wrong. Borrow a Dial test indicator you'll struggle to see/measure TDC accurately.

It's actually better to stick a DTI down the hole and mark off when it's about 1/10" down on either side and split the difference and 2/10" again and 3/10"...as much as you can be arsed. That will reduce errors due to the little end bearing being out.

 

joe27979

Well-Known Member

• Jun 4, 2014

• #7

cheers Dr and Dom,
I have a DTI that I can attach, its possibly not long enough reach to hit the piston face down the spark plug hole so I will have to attach something to it first.

Joe

 

joe27979

Well-Known Member

• Jun 4, 2014

• #8

ps why rotate anticlockwise? I thought it was a no no on these engines?
Is it to take up any slack in bearings etc?

 

Dr_evil

Banned

• Jun 4, 2014

• #9

No it's to get tdc at both ends of the revolution as there's obviously an error percentage so you then split the difference for true tdc between them

 

dominicbeesley

Well-Known Member

• Jun 4, 2014

• #10

They go backwards fine. You don't want to run em arseways but I've turned mine back and forth with a big spannerer on the crank nut.

 

jamesmartin

Well-Known Member

• Jun 4, 2014

• #11

joe27979 said:

ps why rotate anticlockwise? I thought it was a no no on these engines?
Is it to take up any slack in bearings etc?

Click to expand...

just turning clock wise takes up slack in chain so its as it will be when running, should be done when checking tappets or timing etc ,but if its just tdc you can rock crank back and forth, theres a couple of degrees were piston it at tdc going from up to down

 

joe27979

Well-Known Member

• Jun 4, 2014

• #12

muchos gracias.
so I stick my dial gauge in no1 plug, rotate on compression stroke and mark pulley when dial stops moving..then rotate it back the other way and marke when dial is fully up/stopped moving-and midway is TDC

cheers fellas