Cam / piston selection advice

[synoptica]

Hey guys,

In the process of freshening up the 202 (well - it's only about 10k old since rebuild but it was pretty badly protected and hence got a bit rusty in the bores...) so I'm pulling it down and figured I'd give it some go-fast bits while I'm there - seems it's been rebult to near-factory specs (with the exception of the 40 thou' overbore).

So we've got a standard carb cam and some generic-looking 40 thou' pistons... (not ACL's) - so I'm wondering what to do with them.

The pistons are pretty straightforward - am I going to see any performance difference if I chuck some ACL Race Series pistons in there? Or are the generic ones I've got really not going to make much of a difference?

The cam has got me pretty stumped, though. I'll give you a basic rundown of what I'm after:

1) I'd like a bit more low-end torque - but obviously this is going to work against economy. It's kind-of a daily but more of a weekender - but I don't want anything worse than what I see now (14.5/100 on a tired, carb-fed unworked 202), so if I have to sacrifice torque in the name of economy, so be it.

2) I need it to breathe. The current 202 is terrible at anything above 3000. It's REALLY loud (engine not exhaust), it struggles badly after about 3500, it sounds like it's about to explode and is just bloody awful. Even my mate's crappy 4-pot Pulsar running on 3 cyls can hit 6 and still sound better than the 202 at 3000 (though I guess this could be related to the tired engine...) I'd like it to be able to hit around 6k though.

3) I need most of the power after 2000 - if I need to bump that up to around 3000 for the sake of low-end economy then so be it - solong as it can get to 3 and not fall over like the current engine, that shouldn't be so bad.

Now I've been looking at a few cam profiles that'll hopefully produce what I want.

The first few are the Wade (http://www.wadecams.com/PoProf/Holden_149-202.htm) 818, 1147, 1147b and 373. The 818 seems to be a bit mild for what I'm after and not too far from stock EFI, after a little bit of research.

I've also read up on Project Berlina (Motor magazine's VK EFI build w/ T5) which ended up pumping out around 127kw - impressive figures for a stock ECU. I've attached the magazine clipping which gives some basic camspecs for said engine, which are vastly different to the 818.

So - what do you guys reckon?

- Chris.

[Sammy]

ok firstly, the pistons may be fine for a stock rebuild but they might not be able to handle the rpm's you have in mind ... acl duralite or hq race series pistons should be fine for higher rpm's though.

as far as cams go, if you after an everyday driver and economy, the big cams you've listed there are probably a bit silly ....

if it was me i'd go for the 242a or 818 at the most ... anything bigger is going to be a dog to drive around town.

bear in mind that as soon as you start going big cams you need upgrade, bottom end, head, valve springs and the like ....

cam by itself is also not going to give you the full power increase, alot of the performance will come from a good porting job on the head and the right valves and springs to suit.

i'm making a little over that project berlina's power figures with a smaller cam (fair bit smaller actually) and my gains come from the right head work ... it costs alot but its worth it in the long run ... my redline is about 4800-5000rpm

if you want low down torque and good economy go for a smaller cam ... alot of places make towing type cams, these are usually a good option for what you suggest ... but they don't rev to 6000rpm to make that power.

[synoptica]

Sorry - I neglected to mention that some mild porting is on the cards, as well as springs if required. I'm also looking into getting the crank balanced and nitrided while it's out if it's cheap enough to have done (and maybe the rods too).

Like I said though it's not so much of a daily, but still retains SOME day-to-day use, but often this is just nicking up to the shops or down the station... I'd be lucky to be putting 30km on it during the week at the moment... which is why I was thinking I could go for something a bit more aggressive than the 818.

When you say it'll be a dog to drive around town, how do you mean?

edit: I'll also be getting the dizzy recurved after the cam's done, should it require it...