Is A Cam Change A Workshop Or Home Job?

[Twitch]

Hi all,

 

I am in the process of working on my 5K motor. As it is a new 5K I am looking at working on the head, putting a supercharger on it and putting a different cam in it. I am after a fairly lumpy sound and I am interested to know whether replacing the cam is a home job or a mechanic job. I have reasonable techical experience i.e lowering suspension, changing gearboxes, changing carbies etc so I need to know what is involved in it if I attempt it myself, also what needs to be changed along with the cam or will it just slip in?

 

Cheers,

Twitch

[philbey]

It's definitely possible from home, you want the lifters faced as well, so you'll need the head off to get them out. Timing cover comes off and the dizzy comes out.

 

lumpy cams are all about duration/overlap and you probably won't want to go too far with your overlap for forced induction. I'll let one of the boost guru's answer that more thoroughly though.

[Taz_Rx]

Big cams and superchargers don't work all that well together, you're actually better off with a stock or mild cam.

Because the boost response of the charger is pretty instantanious you might find yourself on full boost suffering from "cam lag" giving you a general slocky bottom end. Then by the time the cam its in its power range then the charge will be starting to run out of chuff.

Basically you need to have both your charger and cam working in much the same RPM range.

If you want a 'top end' performing engine then maybe you should look at a turbo conversion instead of the charger.

 

As for changing the cam, tracking down a gregory's manual might not be a bad idea. That will talk you through it all step by step.

 

You don't actually need to remove the head to get the lifters out, but if you're doing other head work etc this won't be a problem. As Philbey mentioned the lifters will have to be re-faced for the new cam.

 

You'll also need to get yourself a new timing chian as well as a timing cover gasket kit..... or at least a new front main seal. Might also want to get another chain tensioner if the current one is pretty worn. Oh and if you have a single chain then do yourself a favour and get yourself a double kit.

[Twitch]

Thanks guys

[philbey]

Really, I didn't think you could get the lifters out, although I never tried as I always had the head off.

 

I looked at it and thought it was just that little be too tight.... Cool.

[Taz_Rx]

I did a cam change on a 4k in a few hours couple of years back. I actually used a snapped bolt remover to get them out! It was one of the tapered square ones which was pretty big..... obviously.

Just dropped down the lift hole and let it sit in the top of the lifter, gave it one gentle tap with a hammer to get it to bight and then lifted them both out.

 

There was 1 or 2 that were a little bit of fun due to the casting inside the head but after you held your tongue the right way and gave them a wiggle they all came out. :blinks: