964 Cam Gear conversion for 1996 993

[mradovan]

Steve

I just bought a 96 993Vram for my 911SC. Like all 70K mile cars it needs the valve guides replaces so I will be tearing it down. The engine has really good cold leak down numbers. 5 of 6 cylinders are 1 percent an the out lyin cylinder is 4-5% so I am hoping everything looks good when I take the heads off. I would like your advice on the following:

1. Should I tear it down all the way and rebuild it? The cost of the bearing is not really significant
2. Can I buy 964 cam Gears as a bolt on replacement? The 993 requires 400 dollars in tools to do the job. I can get gears for less and then it will be the same procedure as for my 3.0 which I have already done. Does this make sense to do?
3. What are the common wear items and issues for these engines.
4. Is there any performance to be gained by investing 2-3K in the engine? I think the starting point is 5K for displacement upgrade to 3.8 and another 5K to enlarge valve, add RS Cams and switch to mechanical rockers.
5. What gains can be realized by doing RS cams and larger intake valves only? Machine work to replace 6 intake valves and the cost of the RS cams is relatively modest if I can retain the hydraulic rockers.

FYI I posted a comment to a related thread. The engine is 1996 VRAM with 95 DMU and no CAT. I will be removing the SAI system.

The car is primarily a street driver.

Thanks

[Steve]

Hi,

1) Normally speaking, a 70K mile engine needs nothing but a good valve job and attention to oil leaks. I always do a hot leakdown to see where any problems may lie, but thats not possible with the engine removed from the car. I do rely on visual inspections to see if I need to delve deeper into the engine,..... Experience plays a big role in determining how far to proceed.

2) No need for the special tools or the backdate. Simply install a pair of mechanical rockers into #1 & #4 when you time the cams and time them as you would any older 911 motor.. When you are done, reinstall the hydraulic ones.

3) Same as any engine: valve guides, piston ring lands, IS bearings, rod bearings, chains, ramps, etc.

4) Yes. Go for RS cams and an ECU tune. A 3.8 conversion is $8K just in parts, not to mention machine work. No mechanical rockers unless you are building a race engine.

5) You already have big valves,......those stock heads support up to 350 BHP which you will never, ever see. Its over $3K to install the RS 52mm ones (and seats) which isn't worth it on a V-ram engine.

[mradovan]

Steve,

Thanks. So I need to buy two 964 intake rockers and two adjusting screws. Is that all I need? If I am following you correctly even if I changed the cam chain gears I would also need a pair of mechanical rockers to do the setup. Is this correct?

Is it difficult to hold the cams to tighten the end bolt without the tools that interface to the back end of the cams?

[Steve]