13 replies to this topic

[jameslearwood]

Followed several DTI timing guides in this forum as well as the yellow bible and after several attempts the recurring number is 107.
I have a 1993 rio 1275cc with standard cam and I've found it's lobe centre angle is 107.5 do basically I am timed in straight up should I get an offset key to advance it?
Some of you might know I have an engine build project on here already with full info and piccies but basically have rebuilt the engine standard except lighter flywheel and duplex timing chain and if course the usual LCB stage 1 upgrade.

I know it should be advanced to allow for slacking can you tweak it by redoing the dot to dot slightly out. Or is it worth getting a key or trying to get a vernier sprocket?

[Cooperman]

The standard Rover cam should be timed at 110 degrees ATDC, so if you've got 107.5 it is exactly right to allow for a bit of initial chain stretch.
Don't get confused with Kent cams which normally time in at 106 degs. ATDC.

[jameslearwood]

i was getting the 107.5 from this, from a link of Andy is this wrong or am i getting confused?

Shown Below is the OE 1275 A+ sprite/injection(50hp) cam.
It has 2 x 1/8" raised rings between lobes 7 & 8.


Checking height: 0.017" @ lobe

Timing: (Intake): 9/41 (Exhaust): 44/6

Nominal lobe lift: (Intake): 0.235" (Exhaust): 0.235"

Duration (Intake): 230 (Exhaust): 230

Lobe centre angle (Intake): 106 (Exhaust): 109

Lobe separation angle: 107.5

Lift on overlap: 0.025"

Accuracy: Very Good

Also when you are getting the tdc of the piston do you postion the dti in the centre of the piston or around the rim? sure bible says the centre but seen other thread with it around the rim or does it not matter?

[jameslearwood]

the website in question http://www.mlmotorsp....php?topic=11.0 or are they saying to time it in 107.5 so it is advanced?

cheers for your help Cooperman

[Cooperman]

With 107 degs for that cam it'll be fine. I have always seen Rover cams quoted as being timed at 110 degs, so 107 will be perfect. Unless an engine is well-modified a couple of degrees either way won't be noticeable anyway. The reason for DTI/Protractor timing on standard engines is really to eliminate any major manufacturing tolerances with non-OE parts. I once timed in a cam using the budget duplex sprockets and it cam up 9 degrees retarded when timed dot-to-dot. I was glad I checked.

[jameslearwood]

Belters cheers Uncle cooperman that's made my night was worried it wasn't advanced enough starting to get the hang of this engine building malarky

[ACDodd]

Not all rover cams are 110. This particular cam is 106. It is a very mild cam, so I would suggest leaving it at 107.

AC

[bmcecosse]

I suggest getting a better cam while the engine is in bits !

[jaydee]

I suggest getting a better cam while the engine is in bits !

+1

[jameslearwood]

I know kind of regret not doing it but cars been off the road too long and cash flow is none exsistant. Will be the next project when I modify the head After I redo the paintwork and go rust bashing it's my car for life so plenty of time to tinker with it

[Ethel]

It'll cost you to take it to bits just to fit a cam

[jameslearwood]

Aye but the next project is way off it will probably be another complete rebuild plus it's all snug inside the block now

[racingbob]

i see you got a lightened flywheel ass

i had one on mine and engine was just a bit mildly tuned

mg metro and lost all its torque

[jameslearwood]

Yup I remember reading something about that just will have to see