[Hydratech®]

Yes, you will insert the Wilwood supplied spacer bullet into the deep MC pushrod hole for use with the later design GM short MC pushrod configuration (which the CP3014 is setup for)(the CP3013 would not need to use this spacer bullet as it is the early spec long pushrod, for which the Wilwood 260 series MC is an out of the box plug n play).

ADVANCED TECH: We have observed that this Wilwood MC pushrod slug or spacer bullet has some mild innaccuracy to it from MC to MC, so double check that there is no MC piston preload by sliding this bullet into the MC, then placing the MC up against the face of the hydraulic brake assist unit. You should then experience a perfect MC casting to brake assist casting fit without any preload - if the MC seems to be floating off of the face of the brake unit casting (to where it would seem like you would want to draw the MC snug to the face of the brake unit by tightening down the MC mounting bolts), you should first double check that you do not have the brake pedal rod adjusted up to aggressively under the dash (back it off some if in doubt or disconnect the clevis at the brake pedal temporarily). If you still have the MC floating off of the face of the brake unit casting, coax the Wilwood spacer bullet back out of the MC (compressed air works well) and then grind the end of the spacer slug a few thou at a time and recheck. Continue to buzz the slug until you are confident that you have acheived a +/- .010" MC pushrod interface - essentially sneek right up to the point where you have just eliminated any MC piston preload when bolted up to the face of the hydraulic brake assist unit. If you had to err in either direction, you would be better off to have a slight air gap between the tip of the MC pushrod and the spacer slug - try to keep this at a .025" MAX. You can use some white lithium grease or suitable other material to see if / how the two interface for clearance (Plastigauge is going a bit into the splitting of hairs that isn't truly necessary). What we are really looking to do here is to insure that the MC pistons are allowed to go into a full definite state of release when the brakes are not applied. Excessive MC piston preload can cause delayed brake release in borderline cases, full on brake lockup when hot in sever cases (due to brake fluid thermal expansion just like engine coolant).

Note that the Wilwood 260 series MC's are essentially C3 Vette MC's by design (though of course much lighter and better looking):
Front port = front brakes / Rear port = rear brakes

This is good to know, as if you were out on the HRPT or elsewhere and this Wilwood MC was suspected of failure, you could pop in to a local autoparts store and source a shallow MC pushrod hole '77-'82 C3 Vette MC as a direct plug n play swap out for the Wilwood 260-8556P (with spacer bullet). If you are running the Wilwood 260-8556P without the spacer bullet on a long MC pushrod booster, note that the '68-'76 C3 Vette MC with the deep MC pushrod hole would be the unit to source...