FPRV....to shim or not to shim

[LBZ]

If you run any kind of power, the LLY almost requires a shim because with a big pulse width, the rail pressure will spike on a shift and blow open the valve. It isn't usually a problem on smaller tunes though. I haven't seen it to be a problem with the LBZ or LMM though. They obviously changed that part when they raised the rail pressure in 2006. Maybe you should get a valve from an LBZ or LMM and just install that instead of shimming your stock one if you're worried about screwing up the shim job.

X2.
But if you haven't had any issues yet no sense fixing what ain't broke IMO. Unless your already working in that area. Just remember the FPRV was tightened by the hand of God when you do go to remove it so be prepared for a fight as already mentioned.

 

[mattv]

Thanx for the tips gents!Think I'll just say f#$% it and shim 'er.:thumb:

 

[Kappa9012]

You could be right, haven't done one on a NBS truck

I do them by myself, 18" 1/2 drive craftsman ratchet with a flex head. That's the key. the Flex head lets you bend the bar back towards the truck the clear the firewall and still get plenty of leverage to pop it loose and tighten it up. Never rounded one off and never had one leak.

 

[mattv]

So an 18" long 1/2" drive ratchet is the shizz huh?

 

[Kappa9012]

with a flex head! it works great! I can do them by myself.

 

[mattv]

Nice Kap!