cam

[jay]

hay i have striped my motor down sent the head away to be ported an polished and dun up like new, i am wanting to do something with my cam dose eneyone know if you can put a bit biger cam in these little beasts.Has eneyone dun this?  

[city_cabriolet]

Charles ex Racecraft Engineering use to do a Sports and Performance cam grind...

[James]

If you go to any good cam rebuilder they can usually offer you a 'mild' cam grind this is when they take off a little bit of material from all around the lobes except on the high points, the net effect of this is that when you reinstall your cam and set up the valve clearences you've got a bit more lift and turbo engines do love their extra lift. Somewhere like kelford cams of Crane cams will be able to do this work and as far as i know it costs about 3-400 dollars to have done to a sohc cam

[jay]

thats all good but has anyone done this to theirs before and will the ecu handle it.

[Colza]

As it has absolutely nothing to do with the ecu then yes it will be fine.

There was somone who got a mild grind, cant remember who. Do a search.

I chose to have mine built back to factory spec.

[jay]

sorry what i meant is the cam attatches to a drive which runs the dizzy and the injection or am i wrong? if you change the grind of the cam and the keyway is left in the same place the injectors might not pulse at the rite time. i think this injectionn set up works like that.

[Colza]

If it was mechanical injection then why would there be an ECU at all? Injection is fully electronic (hence PGM-FI) and the cam has nothing to do with it

EDIT:
Or if i completely mis understood your post...

The cam lobes and the dizzy are all set up relative to the position of the pistons. The computer sensor that sits on the end of the camshaft is a TDC sensor, TDC is decided by the pistons not the cam.

[si]

i got the 946 grind done, they had to rebuild 2 lobes so it ended up costing $240..  
http://www.tighecams.com.au/honda12vsohc.htm

performance.... well the car was pretty much running on 3 cyl before i got the cam rebuilt, so cant really comment on it now compared to standard, but it is running rich when on boost/once revs are up. may be caused by the cam but could be another problem.

[James]

If you get a mild cam grind that doesnt change the times anything happens at all it just changes how far the valves open so the stock ecu can deal with that very easily. If you get slightly more hard-core grinds they can increase the duration, turbos don't really like that as it means youve got more overlap and your cylinder charge is more polluted by exhaust gases and also runs out of the exhaust gases, it means slightly more top-end power but its usually outweighed by the crappyier spooling and decrease in low down tourque.

More lift means more efficient cylinder filling which means more power for the same boost and better tourque all round. This would affect the reading of the cam angle sensor a big fat nada.

And yes colza the computer has a cam angle sensor for a reason although i am not sure why, as it doesnt control ignition. It must be to syncronise the injections with valve openings, even tho this has like a 1% performance increase and only at low revs or perhaps its just so it kjnows the revs more accurately than using the dizzy output.

[jay]

thanks for clearing that up

[Colza]

Doesnt the computer have a cam angle sensor so it knows where in the cycle it is? Otherwise the computer has no knowledge of TDC. And there by I have just proved myself wrong ;D excellent. Except the cam has an assymetrical end on it. The cam lobes will be set relative to the assymetrical end, and the computer sensor is attatched to the assymetrical end, so the only way changing the cam could affect the computer is if you changed how the cams opened relative to the assymetrical end of the cam. As there would be absolutely no point in doing this whatsoever and would not only be ridiculously expensive to do, but also serve no purpose other than to make your car not run, i think we can safely say that most cam-machinists wil not be doing that!

Now, did that make sense...

[jay]

year thats cool, i will just get a bit more lift put into my cam

[AnimaLector]

Just put my Camshaft in for a rebuild and regrind..  $210 and it'll be a mild performance grind, with 2 lobes being rebuilt one was almost completely round...  hmm.. anyways should be done Friday.

Andy

[jay]

nice, let us know if it makes a big difrence compaired to a standed one.

[Smithy]

animalLector you got your cam installed yet!?

I'm interested in if it effected hunting whatso ever....

Oh, and if its drive or performs any differently...

oh, where'd you get it done too!?