last night the Race to the Oppo rally truck rebuild project came to a screeching halt due to some wrong & defective parts.
Turns out I made two big mistakes.
Mistake 1: I bought the correct 10.5" flywheel & clutch for my old 230 engine. The newer 250 has a different crank end and it doesn’t fit the earlier flywheels. This motor had an 168 tooth flywheel & 11" clutch that won;t fit my bellhousing or starter.
I was able to find a 153 tooth 10.5" flywheel for a later 250, ordered it last night and Rock Auto claims I will have it by Tuesday. This lists as taking the same pressure place and clutch disc as the earlier motor, so with luck I’ll have something that will bolt together properly.
I bought the wrong Master Cylinder. I bought one from a ‘72 C10 (the first year with disc brakes), which has the disc circuit on the back. However the proportioning valve is for the slightly later MC with the disc circuit at the front. This was why the little lines that came with the proportioning valve didn’t fit. So all of the custom lines I spent most of yesterday making are wrong, and need to be re-made from scratch.
EDIT: I’m wrong again! The MC is correct for a truck with manual brakes. The prop valve is setup for the MC used with power brakes. They don’t mention this because of course you’d be upgrading to power brakes. what kind of idiot puts disc brakes in and stays with manual brakes? (hint: this kind). So I need to get another of the same MC (already ordered), and get inventive with the lines. I may toss/modify the original bracket and make one that holds the valve pointed back instead of forward so the ports line up with the correct resivour. That will let me re-use the small lines & only have to re-do the larger (and easier to make) lines.
I figured this out because the MC is also defective and won’t build pressure in one circuit. I’m frustrated by defective parts, but also incredibly grateful that the defect caused me to figure out my mistake with the prop valve. Had it works I would have been driving with 5lbs of residual pressure in the front brakes and no residual pressure in the back brakes. So I’d overheat my front brakes while driving, and have back brakes that took extra pedal travel to activate. That is a recipe for death right there.
So I need to order the right one from NAPA, and get some more adapters and start bending up new lines tonight.