North Coast Cab

You guys are great! I wish I was a little closer to Oregon, although I feel closer to NY since I have Bill's old wheels on my car If I go that route I may just have to send a package to Oregon!
Stay tuned......

Bill Verburg

I did the RS valves in my M64/21 heads too. Not sure that the stock valves are a limiting factor here. Geoffrey just did a 964 w/ stock 993 heads that was close to an honest 300hp, Motec and some cams significanly happier than RS were used. The RS cams are slightly happer than stock and are designed for hyd. lifters, I get a little bit of a funky idle w/ mine on a 3.6 nothing noticeable on the 3.8 though. SS are a little happier yet but need the solids, that is probably the limit for Motronic. As noted previously a nice sidebar to a cam change is the change to the more positive lock, 964 type cam drive gears. Stock 993 is purely friction locked and is notorious for moving.

I agree w/ Steve that there are other valves that will flow better, the undercut sort seems to do very well, but again for a stockish engine I don't know that it's worth it. If you were going to a high revver some nice light Ti valves would help the top end, but you still would need to address the bottom end.

You need to decide what you want and draw the line despite all the candy dangling out there.

North Coast Cab

Are the 964 cam gears different than the earlier 3.2's? I have a set of 3.2;s I could use, or I could dig up a set of 964's if necessary.
Thanks again.

Bill Verburg

3.2 is the same as 964, only the hydraulic tensioners are different.

Mike J

Sorry, but I am not sure what a "cam gear" is? If you mean cam sprockets, in order to backdate to the older setup, you need a keyway in the cam. If yours do not have them (like many 96+ 993's) then you can get a machine shop to cut you a keyway. However, the sprockets you need for this have been around for many many years. I picked up the locking pin and inside bushing at a junk yard, and then bought new sprockets since I had put in new chains as well.

Cheers,

Mike


Cheers,

Mike

North Coast Cab

Mine appear to be the old cam gears/sprocket set-up already. Maybe it was an early '95. The cam has the keyway too. Should know tomorrow about the condition of the heads.

Bill Verburg

Early 993 did use the old style, it'll be obvious what you have the new style only has 4 holes


old style has lots of holes for adjustment


yeah, they are not gears because they don't mesh, but you get the idea

North Coast Cab

I have the old style.

North Coast Cab

Update:
The valves and springs checked out fine.......so, fortunately or unfortunately I will stick with the stock heads.
New questions:
Is it worth going to 993RS cams with standard heads? It has a Fabspeed cat bypass and will get a custom chip when everything is done.
After that it's v-ram decision making time.

Mike J

You might end up with what i did, stock insides. For me, it came down to money as well. You can put in the RS cams, but without the extra valve size etc. its not as effective.

BTW, go onto my web site www.pcarworkshop.com, there are tons of engine rebuild pictures including a whole section on timing the cams, retrofitting to the older style many-hole sprockets.

Cheers,

Mike