cam question

[zesinlijn]

hello!

i'm currently rebuilding the cil head of my m20b25. valve seats, valve refacing, valve guids, valve seals, new valvesprings, new rockerarms. Now i'm thinking about putting in a new catcams 285/285. does anybody has experience with this cam? I've read a lot about schrick 288 and that some people love it in a stock m20b25 and other say it's a waist of money and that it's to agressive.

what about piston to valve clearance?

this is info about the cam: http://www.catcams.co.uk/acatalog/1300525.pdf

tnx

[SkiFree]

Regardless of what is said, you need to do a manual piston/valve clearance check as a part of your reassembly. CANNOT stress this enough.

Just had a customer in New Zealand this week who blew a brand new 8k race engine because the machine shop took more off the head than they said they did.

[zesinlijn]

Even if the block or head are not going to be decked? Just a light resurface of the head.. I'm thinking this is more a problem with stroker motors where they take more material off for upping the compression?

[SkiFree]

Yes, especially with a high-lift cam and what I'm assuming is a higher comp. euro "i" engine.

And anyone doing a proper stroker would not be decking the head/block unless absolutely necessary (and in those cases a new block/head is preferable). Decking the block/head for the sole purpose of gaining compression is a short cut indicating a hack-job build ethos.

[zesinlijn]

Ok i see :-) yes its a euro motor.. what is the best way to check this clearance? I've read about a method where they use clay. What is the minimum clearance that you need to have to be safe?

Is it a good idea to fit this kind of cam on a stock m20? Any gains? Or should i save me the trouble and just fit the original cam?

[Northern]

Just remember that schrick recommends their uprated valve springs with the 288, so there's some more money to spend to fit this.

By itself, I wouldn't expect much difference with just the cam/springs on an otherwise stock motor.

[SkiFree]

Yes, claying is a good method.

I personally wouldn't use that aggressive of a cam, you'd be losing a fair amount of bottom end in favor of a peakier top end (not fun for around town). I'd say a 272 or even a 284/272 would be nice (but in conjunction with a proper chip and new rockers).

There's a lot of pertinent information on this if you use the search function.

[zesinlijn]

The e30 is not my daily driver. Just did a full restoration that took about 8 months and i'm planning to use it as a weekend fun car and taking it to the nurburgring from time to time. So losing a bit off torque down low and some street drive abilty doesn't concern me. I allready have this cam in my possession because i had the chance to pick it up for cheap. But after some searching on the web i'm not sure if im gonna install it.. Read a lot of contrary statements about fitting such a hot cam on a stock engine..

[Bullhead]

Here is a good article on checking p t v clearance. http://www.enginelabs.com/engine-tec...lve-clearance/
Here is some plastigage, you can also use it and scoop it up at any decent auto parts store. http://www.autozone.com/autozone/acc...igage/_/N-25xn

[digger]

The 285/285 is very popular with the UK guys running with stroker 2.7 and 2.8L but I personally I wouldn’t run a 285/285 catcams on a stock bottom B25 id be looking at a schrick 272 as it seems a better tradeoff.

From what I have seen the catcams 285/285 camshafts tend to lose more low end torque than do schrick of similar advertised duration (284/272) but they also seem to make more top end and midrange power than schricks trading bottom end and topend. This might not be so bad for a track car.

[603Racing]

If you are willing to give up the low end power for peak power then go for it. But absolutely check clearances. I would also recommend HD rockers. There are a lot of threads about busted rocker arms and cam upgrades.

[Bullhead]

If you are willing to give up the low end power for peak power then go for it. But absolutely check clearances. I would also recommend HD rockers. There are a lot of threads about busted rocker arms and cam upgrades.

^ And don't forget good springs, for some reason people spend big $ on a head and put stock springs back on them.

[digger]

new stock springs are pretty good even for a mild cam. At some point you do need to upgrade

[Bullhead]

new stock springs are pretty good even for a mild cam. At some point you do need to upgrade

Roger that Digger, I meant "cheap" springs sorry about that.

[zesinlijn]

I allready ordered some HD rockers because i didn't trust the old ones anymore and they're not that much more expensive than stock rockers.. so if i'm planning to use the catcams i need to put in stronger valvesprings? the company where i ordered the rockers also sell catcams valvesprings but they are not cheap. if i put in the catcams i'm thinking i also need a chip that raises the Revlimiter to use the topend power? how many hp can i gain with this setup?
If i put the original camshaft back in is it ok to just leave the old springs?

still not sure what i'm going to do..