What CAM is that??

[Bluerex]

OK, so I have the new G-grind in one hand and the old cam in the other.... is there any way of knowing what it is that I am replacing. I know that sounds daft but I am curious and totally ignorant of how to "read" the lobes.

Only numbers I can find are
2752 C49 (maybe G49) 3 3

The G-grind says
W 5c 049 WWO 1c

Any ideas guys?

C

[gotrice]

Hey Chuck!
All I know is, put the biggest most unfriendly cam in there and go hell bent for leather! At least thats what I did with mine.
Good luck.

[Bluerex]

Hey Chuck!
All I know is, put the biggest most unfriendly cam in there and go hell bent for leather! At least thats what I did with mine.
Good luck.

Hehe thanks Tim, but you forget - I am an idiot when it come to judging "biggest most unfriendly" The old cam looks "more pointy", does that make it friendlier than the fatter one??

C

[Peter Jones]

"Pointy" means lower duration. Broad tips on the lobes mean that the valves are open for a longer period of time. The actual timing of the lobes would be nearly impossible to tell by looking at the cam although it is possible to work it out if you're really determined.

There's a lot of complicated concepts at play in cam timing!

Don't think about it too much! Stick it in and drive it!

Pete Jones

[gotrice]

If you really wanty to work it out it is very possible but I dont have the gear to do it. I think MMI might. Let me know if you want me to get him in touch with you.

But Peter is right (I like how the man thinks! Sounds like he dont owne a MK2) the fatter the lobe the longer the duration, and you also have to look at overlap and how many degress the cam is etc.

The higher the lobes and the fatter/less pointy they are the better really.

Tim-MEH!

[Peter Jones]

Thanks. I think of all sorts of stupid stuff like how on a reground cam the base circle diameter is reduced resulting in greater valve velocity causing valve bounce sooner than a standard cam.

Which is all great stuff to have in your head but then on the other hand I can't remember peoples names!

You can work out the cam timing with a protractor bolted to the cam pulley (or a degree wheel if you're feeling rich), a dial gauge and a sheet of graph paper.

But even if you manage to measure it you still need to be a rocket scientist (or at least an automotive engineer) to figure out what it means.

Pete Jones

[Bluerex]

Thanks guys, I think I will just put it in an forget about the technical reasons
Another stupid question... will I have to re-shim with a different cam?

C

[Peter Jones]

Unless your car has hydraulic lifters most likely. At the very least you should check that the valves actually close!

Pete

[Golf Loon]

Yeah what Peter said. If you have hydraulic lifters, bung it in. If not. Shim city!

[mrgolf]

His car will have hydraulic lifters....

The G-Grind has a bigger duration than the stock 1600cc cam, and has a bigger lift. It is bigger in all directions. It may not look too much bigger in some perspectives, but it will be.

As for cam gears, check out mine if you want, Charles. I swear by the cam gear. We gained an extra 8bhp atw with a cam gear...

[mrgolf]

His car will have hydraulic lifters....

The G-Grind has a bigger duration than the stock 1600cc cam, and has a bigger lift. It is bigger in all directions. It may not look too much bigger in some perspectives, but it will be. Also, the valves will close with no worries with the G-Grind cam as it is a factory cam. It is not too wild (wild enough), and 8V heads didnt change much at all over the years...

As for cam gears, check out mine if you want, Charles. I swear by the cam gear. We gained an extra 8bhp atw with a cam gear...

[Bluerex]

Did some checking since last post and I am sure that it's shim-city for me Peter has ofered me the "kit" for the measuring and the re-shimming which I will do once the bits are back in one piece. The cam-gear looks cool... but it might wait for engine #2 which will follow on in about 12 months. The idea is to have enough oomph to play nice with the other boys, but still hold a bit back while I learn to keep it out of the trees. THEN we break out the bigger valved head, lightened/balanced bits etc etc

C

[HillFlog]

Ok I think there are a few things you need to check out, shimming only takes place with the mech lifter heads not hydro's. If you have a g grind cam from an early mechanical head it wont fit due to a different base circle radius. You need to calculate and compare the base circle radius to see if that cam will work in your head, to do this measure the height the cam base sits above one of the bearing surfaces, if the 2 cams get a different measurement dont bother using the one that was never in the motor. When you are ready to do a crazy head get a mech lifter one or convert a hydro one to mechanical, hydro lifters wont suffer much larger cam lifts than stock anyway.

[gotrice]

I'm pretty sure that he has a mech lifter head and not a hydro.

[Bluerex]

G-Grind fitted, couldn't resist dry-fitting the exhaust and webers... what do you think?







C