well...the 'musical lifters' saga continues. It's always 'something' so I shouldn't be surprised...but this squarely falls into the 'well that's just strange' department...and I'm hoping it's a V10 vs V8 thing...

First off, I got the Comp Cams 6.800 pushrods, #7632 (289/302 Ford btw), and they installed just dandy - preload looks to be in the .030-.050 range, and in this hydraulic lifter equation I'm calling that 'good enough'.

But...(there's always a 'but'...)...I noticed there is a similar but less invasive 'interference' issue with the lifters' snap ring retainers and the pushrods...and I'll do my best to 'splain what I'm seeing, lifter functionality, and what I did.

BLUF: I'm using the V10 lifters, but with the V8 retainer clips - not the HD snap rings.

I am making the presumption that 'nothing should 'contact' anything else in the valve train equation. On the base circle everything is fine - the snap rings can rotate around in their grooves and no contact. But, with a lifter up on a cam lobe and the plunger all the way 'in' (engine not running/lifters 'bled down'/not filled with oil, etc), the angle is higher between the lifter and pushrod, and the snap ring cannot rotate all the way around without contacting the pushrod.

On a lobe, plunger all the way in, snap ring eyelets facing down - the arrow is where the interference happens when I rotate the snap rings around -


But rotate the snap ring up and around...and it runs smack into the pushrod...which can't be right...but again, these are Viper V10 lifters...


Now as I understand, with the engine running and the lifter(s) on the base circle, the lifters will fill with oil, filling the plunger area, and because the oil cannot bleed out quickly the resulting oil-filled lifter can overcome the valve spring pressure when ramping up, thus opening the valve, and repeats the process all the time (I don't really understand what the preload value is really for but one neuronal synapses at a time). But, when the engine is shut off...any lifter up on a lobe will initially hang the valve 'open'...and the lifter will very slowly lose oil prime within itself, allowing the valve spring to 'push' out the oil, allowing the valve to close all the way...which also pushes the plunger deeper into the lifter. If the snap rings end up with the eyelets facing 'down' then no problem, but, my concern is this - if a snap ring rotates in it's groove and ends up with the eyelets facing 'up', when the engine is shut off the pushrod will initially be fine...until the lifter bleeds down...and the pushrod will literally get wedged against the snap ring, like this -


In my mind that is simply unacceptable, and frankly I'm amazed the Mopar engineers allowed it to happen.

All I can figure is the Viper V10 engines (heads, rockers, valve train geometry, etc.) are different enough - something about the V10s have less of an angle difference between the centerline of the lifters and pushrods, that this is not an issue, but on a magnum V8, it obviously 'is'.

So - I removed the HD snap ring retainers and replaced them with the OE standard duty clips, and my assessment is that while the same interference issue can likely happen, the lighter retainer clips can flex a little and 'absorb' any intermittent interference issues that might happen, whereas the snap rings, cannot.

I don't know how else to do it, and I cannot see any way in which there can be 'zero interference'. It'd be great if there was a small ridge on the 'bottom' of the lifter snap ring groove to disable the snap rings from rotating in their grooves up and facing up - a 'stop' like that would prevent the snap rings from rotating more than a few degrees, but there isn't.

Out with the snap rings - didn't even unbolt everything - just popped 'em out and plyer'd 'em apart and into the trash -


...and installed the standard non-sexy clips -


Meantime, primed the engine and oil is soaking each rocker, so that's good -