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I'm moving along with my engine rebuild and have a few choices to make on the covers. First, I'm curious to know if all valley pans are interchangeable. I have three different ones and would prefer to use the one with the PVC connection in the back as it is what the year (67) would have had and I have all the fittings and hoses to do that, however I have yet to set it up (motor is at the machine shop) with the HEI distributor, but I didn't think there would an issue with clearances. Second is the timing cover. I have the one that was on the motor which is for an 8 bolt water pump and is made for a dampener which has a small diameter (timing tab is closer to the seal bore) that needs work on many of the tapped holes. The second one is also for an 8 bolt water pump but is made for a large dampener and it also needs help with the holes. Then I have one which is the later style that takes the later style water pump (11 holes?) and appears to take the same diameter dampener as the second one (large). I will put a new water pump on it anyway no matter which one I use so that doesn't matter. Again, I'd like to keep it as year-specific as possible, but not to the point of wasting a lot of money, plus I have no idea if the later covers/water pumps are better for flow and cooling. An additional thing that has me curious is that the older cover which takes the small diameter hub had only one plate behind the water pump while the one that takes the larger hub had two. I ran the engine quite a bit around the house with the first cover (one plate) and never had overheating issues. Also the impellers on the two pumps were quite different (see pic). The pump with the longer, more curved veins had the two plates behind it. Opinions greatly appreciated.:confused:confused:confused
 

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Yes, the covers are interchangeable (make sure it clears your HEI). The timing cover as well. The later, 11-bolt cover uses one divider plate, and also sleeve inserts in the two passages that connect to the block passages on either side of the cam gear.
The most critical aspect of cooling is proper adjustment of the divider plate (there are many threads on this forum that discuss how to do it.) Fail to do it properly, and your engine will run too hot regardless of which pump you use.

Bear
 
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