Cam Timing tweaking

[DvDRip]

well I just went and had a looksy at the cam timing on a motor
it's a2 cam and akunar told me retard it 3degrees for top end (aka a3)
So I always thought to adjust cam timing you just jump a tooth on cam sprocket.... but I just found out jumping a tooth retards it more like 12 degrees

so, how DO YOU advance or retard the cam timing?

 

[SGONE]

pretty sure ya slot the cam sprocket bolt holes

 

[DvDRip]

mmm yea that makes sense but it sound pretty permanent lol..... now would be a good time to have some spare sprockets

need cactus on this one

how would I keep the bolts from slipping in the slot? there's alot of pressure on the cam and I can't imagine the cam staying put if I slotted it

 

[grnman]

would it be easiler to reposition your ignition pickup on the rotor?

 

[DvDRip]

no mate that's ignition timing

 

[Cactus Jack]

The ignition timing , flywheel or backing plate position has nothing to do with cam timing ... Cam timing is the phasing/indexing/degreeing of the cam lobe centres to the crank ... The only ways to alter cam timing are :

1) By slotting the cam sprocket bolt holes ...

2) Re-drilling new bolt holes in a cam sprocket with the teeth advanced or retarded from their stock position ... For cars you can buy degree'd bushes which have an offset hole in the centre ... the O/D of the bushes is bigger than the stock timing gear bolt holes so you just drill the stockers bigger and use a hardened washer under the bolt heads ...

3) Removing the cam sprocket off the crank and re-pressing it on in a new position ...

4) Raising or lowering the head in relation to the crank centreline ...

5) Re grinding the cam to alter the lobe centrelines ...

Most people slot the stock bolt holes but it'd be better to put another sprocket on top of a stocker with the stock holes rotated so that they sit between the holes on the first sprocket ... move the teeth of the second sprocket to the advanced/retarded position you want ... clamp the two together in that position ... then drill new holes in the second sprocket using the holes in the first sprocket as a guide ...

You'd have to grind the old timing mark off the re-drilled sprocket and make a new one ...

3 degrees retard isn't much though ... You'd probably get that thru chain stretch on most old motors ... LOL ...

 

[DvDRip]

hrmm ok then I think I'm gonna give cam tuning a miss for now then... probly just better off buying an a3 if I wanted it

 

[grnman]

arrr yes of course. thanks guys

 

[sean01]

yeah 3 degree's is nothing to worry about... but maybe removing the base gasket would be good enough to get 3 degrees..

another thing you could do is slot the holes and add washers to the bolts, install it and retard the timing then mig the washers to the cam sprocket..

having said all this tho, you would have to degree the cam in to make sure that 3 degrees is wat you want/need as not many crank timing gears are pressed on in the same location..
most the time the dot on the cam gear is before the timing mare on the head anyways, which means its retarded already..

oh and another thing that may help is setting a larger tappet clearance, maybe jump up to 4 and 5 thou. this will allow the valves to open later(retarding)..may sound a little rattly tho