993 Updated Camshafts

Mike Juzenas · 08-01-2005, 10:49 PM

Greetings! I am new to this list and have a 96 993 with about 76,000 miles on it. I have been getting rough idling and misfire codes and, after a leakdown and compression check, I (and others) have concluded the valve guides are shot. Its seems to be a common thread for these engines and now I am looking doing the the top end at least. This forum appears to be the place to be!

I have been searching and reading lots of material (including Wayne's book) and am interesting in discussing where to source backdated cams for my 96 so I don't have to get the $$$ tools. I have a few questions:

1 - It it better to buy new or look for used? How much should I budget? At the end is it cheaper to buy the tools than replace the cams/sprockets?

2 - If I change the sprockets do I have to change the chains (I was only planning to change the chains if they were worn out)?

3 - I was also interested in all the talk about Alusil vs. Nikasil. I don't know what is in my car yet and apparently its impossible to tell from the outside?

My plan was to just do the heads and reassemble. However there have been lots of discussions on this list about splitting the case and going the whole way. I am not sure I want to do this given the mileage. One mechanic suggested I re-ring the car even at this mileage, then again I am not sure. It all costs lots of money and this problem caught me unawares...so I am trying to control the costs and start climbing the learning curve.

Anyways any help would be appreciated and I am sure I will have more questions!

Cheers,

Mike

P.S. I am away for the next week starting tomorrow and will check for replies then.

Bill Verburg · Bill Verburg's Garage

Most if not all of the cam grinders I spoke w/ when I did mine only provide the old style as replacements. You might want to think about RS valves "while you are in there".

yes, change the chains, they are cheap enough and worn chains will accelerate wear on new spockets

993 only has nikasil

splitting the case isn't really that much more work, the main cause of concern in the bottom is the rod bolts. Replace them w/ ARP or Raceware.

Mike Juzenas · 08-02-2005, 07:52 AM

Thanks Bill!

I did not know that the 993 only uses Nikasil...that's good news!

I heard one of the weak spots on the 993 is the rod bolts, I will consider looking and replacing them.

Anyways what would be a reasonable price for reground cams?

And what is the advantage of RS valves? I know I am likely to have to replace all the exhaust valves anyways...but I was hoping to keep the intakes.

Thanks for any help!

Cheers,

Mike

camgrinder · 08-02-2005, 09:56 AM

How much are the cam timing tools?

Bill Verburg · Bill Verburg's Garage

Quote:

And what is the advantage of RS valves?

I assume that a performance cam somethigl ike the RS hyd. or SS mech will be installed. if so you will want better intake flow. The RS intakes are Na cooled as are the stockers but are 51.5mm an increase of 1.5mm over stock vram. The exhausts are also Na filled (oem are not)

rod bolts need to be done if the rev limit is raised. Such as when cams and chips are added to the mix.