Guide to timing my sigma 150 -also useful for 140 supersport

[pilotprice]

Hi thought this may be useful for anyone who wants to swap their timing belt on any sigma 140 and 150 supersport (not sure if the 125 is the same)

Tools required

Dti guage
Magnetic base
Small extension for Dti guage (I used a small rivet which I tapped an m3 thread onto)
Timing wheel / disc
Tdc pin for ford engine (laser sell this also)
Large 18mm socket
Large breaker bar
21mm spanner for cams
8mm socket for cam cover
13mm socket for tensioner and cam gears
10mm socket
Torque wrench
Angle torque dial
Locktight
Stanley blade
Price of angle iron or steel to stick magnetic stand too
Small bit of 2.5 or 6mm wire (earth is easy to use)
Pad and paper
Patience and a box of tissues


Usual disclosure, this is not gospel and I can't be held responsible for anyone doing this wrong or causing damage following the guide, I did this on my own engine and have only decided to post as a guide

I had my engine out as I'm rebuilding the car entirely, I'm also converting my engine from 125 to 150hp
Access was very easy with the engine out

Step one
Turn the engine to tdc (remove the spark plugs to ease compression and locate tdc using a long 3/8th extension
Check the engine is at tdc by removing the 10mm nut near the sump on the exhaust side and insert the locking pin, turn the crank onto the pin, you are now at tdc. I double checked the accuracy of the pin - explained later in this guide

Step 2
Remove the crank 18mm bolt, my flywheel is currently removed so it was not possible to lock my crank this way (the tdc pin only holds the crank clockwise) so I used a 500nm impact driver while a mate held the crank pulley, I also heated the bolt prior but becarful not to melt the timing cover)
The bolt is required to be replaced but needs to be kept to size against the new bolt that comes with the timing kit

Step 3
Remove the cam cover
Front timing cover
Metal cover
Alternator

Step 4
Remove the belt, tensioner and water pump

Step 5
Replace the water pump, I used a small amount of liquid gasket aswell as the metal gasket

Step 6
Hold the cams via the 21mm cast hex section while you crack off the cam bolts, keep the cams very steady
Discard the bolts

Step 7
Replace the tensioner, if you don't have a solid tensioner found on the 150 then now is the time to convert! The standard tensioner can jump the belt at high revs or if the engine is reversed
If you are using the spring tensioner then keep the pin in

Step 8
Clean the crank surface where the belt gear sits, refit the gear and pulley.
Match up your new pulley bolt (must be replaced) to the old one and apply a small amount of thread lock (not essential but I did)
Insert the bolt finger tight so the gear can still move freely on the shaft
Fit the belt and the lower timing cover

Step 9
Replace the camshaft bolts finger tight so they can gears can spin freely on their shafts

Step 10
Fit the new belt anti clockwise over the other gears keeping an even tension

Step 11
Pull the tensioner pin or adjust your solid tensioner depending on which you have, solid tensioners should be set so belt tension is about 5mm lateral movement with 5kg of force over the entire belt
Rotate the belt through 2 full revolutions to even the tension on the belt (the cams and crank will stay idle)

Step 12
Tighten the crank bolt, I did this against the TDC pin and had no issues. From memory, stage one was 45nm and then 90 degrees on the degree wheel

Step 13
I cut a hole just big enough in the centre of my degree timing wheel to fit over my 18mm socket, the fit was snug and in the centre of the wheel for accuracy! I then placed my timing disc and 18mm socket on the crank bolt

Step 14
Using one of the timing cover bolts I set up my wire pointer to the top of the degree wheel

Step 15
I attached an angle iron bar to my cylinder head so my magnetic base for my Dti guage would having something to stick too (head and block are aluminium)

Step 16
Using a 3/8ths extension bar on cylinder one, I set my Dti to measure the tdc point and to verify that my tdc timing pin was accurate, I then knocked the engine back about 10 degrees via the crank and removed the timing tdc pin, turn the engine clockwise and wait for the max lift point on the guage, my crank lifted at 00.2' and then dropped at -00.4' the number between the two is true tdc ie 0.00'
Re insert the timing pin and see if you have play from the true position
Mark your tdc point on the timing disc if required
Line up your wire pointer to tdc on the disc also, you now must not disturb the wire pointer

Step 17
Holding the cams via the 21mm hex casting, tighten the bolts enough to connect the cam gear to the camshaft so it will turn with crank movements, I found about 30nm was sufficient

Step 18
You now need to time your inlet cam to 118' ATDC
You need to relocate the Dti guage to the top of the bucket lifter, I had to extend my pointer on my Dti guage with a rivet tapped to m3 and rounded end not to damage the bucket surface
The gap to measure the bucket is very small and gets a lot of adjusting to get right!
Turn you crank clockwise until you see the inlet cam about to start to depress the bucket, watch the Dti guage until the pointer stops rising and record that degree point on the timing disc, continue to rotate the crank until you notice the lift decreasing on the Dti guage, the middle point of these two numbers is the true maximum lift point, ie lift stops at 116' and decreases at 120' then true lift is 118'
Retard or advance your cam by how many degrees is required to get the timing to 118'

Step 19
Repeat the process for the exhaust cam but using 111' BTDC for the max lift point

Step 20
Once you are happy with the timing then tighten the cam bolts to 60nm holding them steady with the spanner

Step 21
Rotate the engine two or three times, check for interference issues and then recheck the timing again

Step 22
Put everything back together and double check all the torques!

Please do not use my toque values as anything other than a guide, check with your belt manufacture or the ford workshop manuals for the accurate numbers

The timing degree values are correct

Edited by pilotprice on Friday 17th June 20:24

[pilotprice]

A few pictures, I should have taken more, sorry

[pilotprice]

[pilotprice]

[pilotprice]

[mharris]

Very nice, thanks for taking the time to write this up.

Can I ask where you got the timing values from?

Also everyone talks about the standard ford cam locking tool not being correct for the Caterham sigma engine. I guess this wasn't relevant in your case as you re-timed the cams, but did you note that this could be a problem if just changing the belt?

[pilotprice]

No problem
I noted a lot of people were having issues with timing this engine due to caterhams tweeks on the inlet cam

I can confirm the standard timing bar does not fit to caterhams own timing, people who time there engines using the ford insert bar will have incorrect timing for their mapping

I firstly calculated the timing by DTI'g my friends 150 engine and then contacting CC who confirmed the timing values I had calculated were correct for supersport camshafts

[downsman]

Do you happen to know the inlet cam timing for the 125 engine? Caterham were less than helpful when I asked.

[pilotprice]

I'm guessing that the timing is the same, the profile of the cams on the supersports are altered.

I just called caterham service and they gave me the information, I didn't realise there was an issue with them giving it up.
I'd be surprised if there was, they sell kit cars to diy builders

[downsman]

Thanks
I will try phoning again.

[pilotprice]

You could always just Dti your current engine to find the timing before swapping the belt

[Eccles52]

This sounds a bit weird, when I had my belt changed I asked CC what the timing was and they said 110/110 degrees and measuring the timing it was 110/110 for max lift. This is for a Sigma 150 as well.

Do you know if there are two types of cam used on the 150??

Cheers
Ivan

[pilotprice]

Not that I'm aware, mine defiantly DTI'd at 118 111
CC also confirmed those values which is why I felt so confident
With the ford tool in my inlet timed at 110, didn't check the exhaust as was just curious on the inlet cam

[pilotprice]

You can make the cam read any degree at max lift say between 105 to 125, that doesn't nessasrly mean that the degree set is the correct degree, just you have set the cam to achieve max lift at said degree

[Eccles52]

Agreed, it was just odd that we possibly have the same cams and yet both being told different timing by CC and can both verify CC's settings with our own measurements

I'd also noticed that the inlet could probably have been set by the Ford timing bar for 110 although it was set by measuring the max lift.

[pilotprice]

How much did cc change for the belt swap out of interest?

[kev b]

You can use bicycle spokes to make dial gauge extensions, no need to cut a thread and cheaply available.

[Eccles52]

From recollection (was over two years ago now) it was a little over £200 but I had it done by Stewart at Premier Power.

Ivan

[mharris]

Could it be a case of Caterham simply telling each of you what you want to hear?

It may be a good idea for you both to write a joint email to Caterham asking them to clarify why you've both been advised different timings.

I'm interested because I have a factory built 150 and am keen to learn a bit more. Mine had a belt change at Midway Motors in Barnstaple (was an approved caterham service centre) but dont really have any confidence it was done correctly.

[pilotprice]

I will contact them tomorrow

I did DTI my engine prior to removal of the belt though and got the same numbers