Can any one explain a vernia pully

[nova dosed]

I need a vernia pully to set me car up propperlky apparantly as its camed can any fully explain what it actually does and how it works please im unsure

cheers

[Chris LR]

Thats a new one to me?

[Slatter]

Right Vernieer Pully

Basically it is a Cam pully that u wrap the cam belt round !

But it has the added extra of like being turnable for optimum settin up of timing. Not just on the teeth of the cog, u can adjust to mid way between the teeth..


If u understand lol

[nova dosed]

so ur basically saying that having one of these its easier to tune and make ur car go faster.

Better tuned up on a rolling road then?

Any1 have a spare or any idea how much they are

[Stuart]

they tend to be around ?50-70 from rip off tweeks but cheaper else where.

ideally set up on a RR but if not then get incontact with someone that has got the same mods OR find out the setup from the cam makers, they will be the best to ask with regards to cam timing.

trust me a few degrees makes hell of a diff, i mapped an engine at lambda 0.875 and then had to put the cams back to std timing and the AF ratio is all to pot, anf runs lean at top end (red exhuast and alloy head is a bad thing lol)

you can cheat on some cam pulles by filing the holes out so taht you can turn the pulley on the camshft and then do it up nice and tight to lock it.

cheap and easy way to do it if you only need a fraction to sort it

[nova dosed]

cool that helps never new it was that important really to have onme i think ill pay a rolling road place to do it prob euro parts.

I was quoted ?103 today for one inc pandp i thought that was well dear so i said bollocks that was from road runner in notts.

No change my local shops must have em in cheaper

[mikeoxford]

i got one you can buy

its anodised blue...........

it will fit but just out of interest what engine and cam you running?

email me if you want it

[CP]

Its quite a fiddle to fit and use a vernier pulley to adjust your cam shaft but it can be very worthwhile. If you have a stock or an uprated cam its something that you really should fit if you are searching for the best power available. How it works is that it allows you to turn the center of the sprocket which is attached to the cam relative to the outer part that the belt is attached to. In other words you can alter the cam timing relative to the crank position. The reason for doing it is because production tolerances can be such that with a std cam pulley the timing can actually out from the std specs and also it allows you to pay around with advance to get more power out of a trick cam that you may have fitted.

To use it you really ought to use a dial gauge to measure firstly top dead centre (TDC) for no.1 piston. You do this by setting it up so it is connected to a piece of wire fed down the plughole onto the piston crown. As the piston rises the last little bit you can very accurately measure TDC. Next with the no.1 piston at TDC you securely attach a 360 degree protractor ( you can get these from a cam manufacturer like Piper) onto the crank pulley that drives the alternator. You set the protractor to 0 against some kind of reference mark next to the pulley and mark it all off so thats its showing TDC. Now with the cam cover off, the dial gauge needs to be set up on either the inlet or exhaust valve stem for no.1 piston so as you can tell accurately when the valves start to open or close. If you have bought an aftermarket cam you should have been supplied with( or they should send you) full info on the cam profile and how any degree BTDC or ATDC the cam makes the valves start to open or close. Armed with this information you slowly and carefully turn the engine manually ( take all the plugs out to make it easier) and read off on the protractor exactly when, in crankshaft degrees, a valve opens or closes. It doesnt really matter which you do but i would suggest testing to see when the inlet valve opens. You need to do this several times and take at least 5 or 6 readings so as you can average it out for accuracy.

If you find for instance that the inlet starts to open at 9 degrees BTDC and the cam literature states that it should open at 10 degrees BTDC you slacken off the clamp on the vernier and slightly turn the engine until you have altered it the necessary degree to match up with the cam spec. You then need to check this to make sure that the markings on the vernier pulley actually translate accurately on the cam timing.

Once this is done and its all set as in the specs, mark off the vernier so that you have an accurate reference point. Once you get to a rolling road you can then work off this mark to look for best power. I have read that advancing the cam timing on a std cam a few degrees can yield a little more power. If the production tolerances mean that the timing is a fair way out you may find significant improvements. The greater the state of tune the greater the potential power gains.

NB Cam timing is different from dizzy timing although you will be altering dizzy timing in relation to the crankshaft ( NOT the cam!) by using a vernier pulley on the cam shaft.

[nova dosed]

right that seems alittle complicated for me cud work it out but wud prefer to pay some one to do it.

Mike ive e mailed u and im goin to pm u now.

So in that long essay then cud it be that if my cam timin needs setting up as it will be out cud this be the reason why every 30 miles or so my car dies to the point u have to stop leave for a min and then restart then its fine will that have sumet to do with it ive tried everything else and its doin my head in i traveled to yorkshire today from stoke and had to stop 3 times on the hard shoulder as it kept loosin revs but ive changed the carb and coil etc.