Oil bypass springs - does a '77 need upgrading?

[cowtown]

My '77 930 engine has its original two 70mm springs in the relief and safety valves. I want to replace both springs as a precaution.

Is it adviseable that I replace the vertical pressure relief spring with the newer 86mm spring and spring guide? Or should I just use the original 70mm size?
Thanks!
Colin

[cowtown]

Bump. Someone must know! Thanks,
Colin

[Early_S_Man]

Colin,

Yes, I think it would be advisable to update to the 86 mm spring and guide.

That spring is mounted in a shorter bore and subject to twisting and binding ... hence the need for the spring guide.

[Rich911E]

I have a 1977 engine in my car (finally) that is running well (amazingly). My question relates to the purpose of the 86 mm spring? What is the benefit?

Rich

[cowtown]

Thank you Warren! I will update.

Rich, I believe that the longer spring allows the case oil pump to generate slightly higher engine oil pressure before the relief valve opens and diverts oil back to the sump. But I'd like to hear other views too.

My confusion stemmed from the fact that my '77 engine already has the bypass update from the factory (ie, the pistons have solid rather than perforated skirts), so I didn't know if the new spring was appropriate or not. My engine's in spec but a little more pressure is always nice.
Colin

[Wayne 962]

Right - the springs have been superceded to the newer style. I would upgrade...

-Wayne

[alan911]

O.K. I'll bite too if it will get me a little more oil pressure.

Wayne,

do we need both the pressure relief and Safty Valve parts.

If so, where in the cataloge are the parts ?? Can't seem to find them.

[Mukilteo911]

wayne, would this update also be good for a 2.4 cis?