Did you replace the clutch master cylinder? A while back there was a huge batch of CV master cylinders that were just a little different than the original ones. The difference was that they needed more adjustment/slack? when releasing the pedal than the original ones. I think it might have been a difference in where the pressure return hole was? Not sure. But, when used on the brake system, and setup exactly like the one you were replacing, they would hold the pressure. I had one on an 88”. It worked fine, until about 5-10 pumps. Then the pressure would be so great, it would lock all the brakes. The fix was to let the master cylinder return a little farther than the old one. That allowed the pressure to “bleed off” back to the reservoir. If one of these were used on the clutch side, it would have the effect of keeping the clutch in, or mostly in. The good news is that there is an easy check for this. Pump the pedal up about 10-15 times. Then slightly crack/open one of the fittings/lines on the clutch line. If fluid comes out under pressure, with the pedal up, then that’s a problem.
Other issues could be linkage related as mentioned or something actually wrong with the clutch.
61 II 109" Pickup (Restomod, 350 small block, TR4050)
66 IIA 88" Station Wagon (sold)
66 IIA 109" Pickup (Restomod, 5MGE, R380)
67 IIA 109" NADA Wagon (sold)
88, 2.5TD 110 RHD non-hicap pickup
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