Fuel rail shims vs machined plug
- Thread starter John13296
- Start date
I did a race plug, didn't want to mess with it again just in case I jacked up the shim install. Either way it's kinda a pain to do. Not horrible but plan on bloody knuckles. The bolts for the glow plug module bracket are tricky to get to & the valve is usually really tight in the rail. A 3/8 impact will fit in there to bust it loose if you have one
The shim kit will still let pressure off under extreme conditions. A plug will not.
I run / recommend shims. Bosch put that valve there for a reason.
I run / recommend shims. Bosch put that valve there for a reason.
Get the plug. I've had a shim still bleed off on me before. Plug you won't have to worry about that.
This!
You might just need to shim the spring with another wahser, how many did you use? I used two on mine IIRC and have had no issues in 4 years and 50k tuned miles
I don't remember. Whatever came with the little kit. It really doesn't matter which one you go with, they both work fine. This is the only issue I've ever had with a shim. Never any issue with the plug or have ever heard of a issue with one. The plug just reassures me that I won't have to ever worry about it bleeding off.
IIRC the kit comes with 4 little washers, using all 4 is the equivalent of installing a race valve/plug...I wanna say I only used two, but maybe I used 3, Knowing me, I probably used 3
Its a finicky little job, to take apart, shim and reassemble the FRPR valve...easy enough to accomplish but easy enough to screw up too...
Ya I don't remember it was years ago. Ever since I've just done plugs. Easier to do. Unscrew stock and screw in plug. Done deal. Lol.
I have 4 LB7's and one LMM. LB7's don't seem to have this issue so this is new ground for me. I'm on the fence right now about what way to go too. Hopefully more people chime in. But, as of now I'm leaning toward shims.
A lot of the shimmed plugs will leak also but they will send the fuel into the return line so you can't tell. Once you break the seal of the factory plug its harder to get it to seal since its a machined surface seal.
I have had a shimmed valve for ever. Never had any issues with it but watching my rail pressure up top, it has a little bounce to it when at 26,000+ psi. I wonder if the valve is bleeding pressure off.
My buddy with the same pumps and injectors had a race plug, watching his rail pressure, it was steady. Both same tuners, 120% injectors, dual 85% pumps on a 2700us tune. Maybe I'll install a race plug and compare.
My buddy with the same pumps and injectors had a race plug, watching his rail pressure, it was steady. Both same tuners, 120% injectors, dual 85% pumps on a 2700us tune. Maybe I'll install a race plug and compare.
for the cost of a couple of washers from the hardware store, id rather try that first but its all personal preference.
a quick/simple bottle test will tell you.
Actually now that you say that, I am positive the valve isn't leaking. Because I've never had a hose hooked up to the nipple on the relief valve block and it's never dripped or leaked fuel. Totally forgot about that.
If your a meathead and don't use soft jaws in the vice, then yes you could mess up the sealing surface. Nothing is idiot proof...
I don't see how a shimmed fprv would leak unless you scored the internals during the process.
I only used 2 shims on mine, and it popped once before I shimmed it. I've gotten away with 1 shim on a LBZ fprv that hadn't been popped before.
I only used 2 shims on mine, and it popped once before I shimmed it. I've gotten away with 1 shim on a LBZ fprv that hadn't been popped before.
