MK1 GTI timing

Hi everybody,
Just a quick question,
What?s the timing supposed to be set to on a mk1 gti cabby (1.8 8v)
I thought it was 6deg BTDC but im not 100%

Anyone know off hand? :dontknow:

6? btdc is correct as far as I know…

Rich

sorry, excuse me if I'm being thick, but I'm just putting my own engine back together and having trouble with the cam belt.
I've just basically been lining up TDC on the cam wheel at the top & the same at the bottom end. Should I not be lining up the TDC marks exactly?

I've also had problems where it has jumped a tooth & failed to start, then noticed that when I put the belt on the top cog & then tighten the tensioner, it pulls the bottom cog round and off TDC about a tooths worth…

I'm not the best with cars, so any help to avoid blowing up my classic mk1 cabby would be much apprieciated & i can repay the favor with  computer support\porn etc. ;O)

Cheers,
Chris

Chris,

The belt should be tight or not loose on the non tensioner side - get the belt teeth meshing correctly and then mess with the slack on the tensioner side.

Cheers

Rich

yes line them up exactly. the 6deg business is for dizzy timing.

cheers, i've lined them both up exactly, but no matter how carefully i turn the tensioner, it always pulls the bottom cog out by about a tooth
i darent try and start it as even just turning the engine with a spanner makes the belt jump a tooth, i saw it happen while my mate turned it, it was over the little cog which you can see near the altenator so not sure if it's also jumping on the bottom cog also or not… plus, after a few times turning over by hand, when you bring the top back to tdc, the bottom is about 2 inches out!!.. is this because it moves when the tensioner is tightened back up? i was wondering if I should try putting the belt on with the top at TDC, but the bottom 1 tooth out so that when it pulls round with the tensioner it takes it to the tdc mark?
i've made sure that the bottom mark is correct by checking that piston 1 is at it's highest point and the rotor arm is pointing towards the block (i.e. 12 o clock)
i'm worried that even just turning by hand may damage the valves if the timing is loosing 2 inches after only a few turns?

I think i should just stick to computers!!
… nah! i cant just quit an addiction that easily! i've gotten this far thru a headskim, so i cant give up now!! Any help wud be lifesaving!
Many thanks in advance,
Chris.

Are you saying the timing gets worse as you turn it over???  If that is the case you must have the wrong sproket for either the cam or crank!!  There should be 4 times the number of teeth on the crank sproket to the cam sproket as the crank goes around 4 times as fast as the cam.

The critical thing is that the crank and cam are set correctly the auxiliary shaft can be a bit out as this runs the oil pump and dizzy - the dizzy you adjust to get it's timing correct.

Cheers

Rich

You could also have the wrong number of teeth on the belt.

Do you have the original to compare it to?

HTH

Rich

crazy> yes, i think that is what is happening.. maybe i've got it wrong tho as i've been turning it from the cam.. so, if i do 1 turn of the crank, the cam should go round 4 times? and both marks should line back up at TDC? that sorta makes sense as it seems about 4 teeth off tdc when the cam mark is correct.

Rich> it's the original belt, i've put that back on just in case the new one was the problem.. but it's exactly the same.

Someone today mentioned a belt tensioning TOOL.. whats one of those?
do NEED to use one? is it essential?

Thanks for your help guys, i can wait to get back in the thing! I bet we'll have no more sun as soon as its finished!  sods law states!

Cheers,
Chris.

There's no need for a tensioning tool as such - I used an adjustable spanner across the flats of the cambelt tensioner to get it right. It's not that sensitive as the belt and sprockets have teeth, so usually, provided you line things up right, the belt won't jump over the teeth and you'll be ok.

There's two other possibilities that have just occurred to me: -

1. Which way are you rotating the engine?
2. Are you sure the bolts holding the crankshaft and camshaft sprockets on are tight?

Ideally you should only rotate it using the crankshaft sprocket bolt, and you should turn that clockwise (as you view it from the offside wheelarch).

Let us know how you get on…

Rich

VWaxilMK1cab said

crazy> yes, i think that is what is happening.. maybe i've got it wrong tho as i've been turning it from the cam.. so, if i do 1 turn of the crank, the cam should go round 4 times? and both marks should line back up at TDC? that sorta makes sense as it seems about 4 teeth off tdc when the cam mark is correct.

No the crank goes 4 revs for one rev of the cam

Not Rich's comments on direction and rotation by the crank

Cheers

Rich