Ford Focus Forum banner

1 - 15 of 15 Posts

·
Registered
Joined
·
389 Posts
Discussion Starter #1
I just ordered a set of Crower stg II cams (Walter gets a big
) and I want to get my heads port matched. If I want to raise my compression by having the head milled how much can I go with these cams?

Also, does the Zetec follow the "rule of thumb" for milling heads? That is for every .015 taken off the surface you gain .3 in compression. So, would .045 bring it up to 10.5:1?
 

·
Registered
Joined
·
473 Posts
not sure about those numbers. usually i don't get too technical like that. just put them in and go. the guy who installed my crower II's had to file down the block for the lobes to clear. not sure about the rest. maybe do a search or something. good luck!! or find through posts people that have the stage II's and find out there opinions, results, etc. good luck though!!
 

·
Registered
Joined
·
389 Posts
Discussion Starter #3
Just so everyone knows, I did a search on compression ratios and Crower cams. These are the questions that I'm left with. Thanks in advance for anyone with some info on this.
 

·
Registered
Joined
·
389 Posts
Discussion Starter #8
Originally posted by Pimp27:
Focus Central is running the Crower Stage 2's with 11.5:1 compression and the motor is still non interference.... I am running them with 10.5:1 and I am fine too..

Eric
<font size="2" face="Verdana, Arial">I finally settled on .040" milled off. When I installed the Crower Stage II cams I found out that they are NOT non interference. With the piston at TDC I can't turn the cam around without the valve hitting the piston. (that's what non interference means) Tried with both intake and exhaust, no good. Oh well I guess I'll just pay more attention to the timing belt.
 

·
Registered
Joined
·
1,608 Posts
really? I always thought the Zetec was non-interference. Also I didnt have to grind anything down to clear my crower 2's.


I know on one of my buddy's install we had to grind one of the crower camshafts b/c there was a notch on it that wouldnt allow it to sit properly on the cam gear.
I didnt have to do this on mine.
 

·
Registered
Joined
·
1,535 Posts
I didn't have problems with my head. dropped them in. No interference at all. even when they were 180 degrees off.
 

·
Registered
Joined
·
389 Posts
Discussion Starter #11
Originally posted by Carizme:
Also I didnt have to grind anything down to clear my crower 2's.
<font size="2" face="Verdana, Arial">The only grinding I had done was to the deck surface on the head to raise compression.
 

·
Registered
Joined
·
3,248 Posts
I installed a set for a friend a while back and didn't have to do any grinding on anything ...
 

·
Registered
Joined
·
266 Posts
Originally posted by Carizme:
really? I always thought the Zetec was non-interference.
<font size="2" face="Verdana, Arial">He had the head milled down .040 and that brings the valves down closer to the pistons when they open.
 

·
I change diapers now
Joined
·
14,444 Posts
Originally posted by Shiva Chaos:
I didn't have problems with my head. dropped them in. No interference at all. even when they were 180 degrees off.
<font size="2" face="Verdana, Arial">He had the head milled down .40 - Thus making the cams sit closer to the piston.

This is to far down, as when he attepmts to turn the cam, they cannot move - They have no room.

Hence why he says they are not non-interference.

- Drew
 

·
Registered
Joined
·
389 Posts
Discussion Starter #15
Non interference doesn't have anything to with normal operation. When the engine is operating normally there should never be a valve open to full lift when the piston reaches TDC.

Non interference comes into play when something breaks, such as a timing belt. If the belt breaks and one set of valves is at full lift in a non interference engine the piston will not contact (intefere with) the valve. Otherwise contact would occur and things break.
 
1 - 15 of 15 Posts
Top