Why the solid lifter recommended valve lash varies?

[rstreet]

Was just thinking about lifter lash and wondered why so many recommended various clearances In simple terms please!
Also years ago at least in NASCAR “mushroom” lifters were prominent. When assembling did the lifters have to be pushed up from the bottom and somehow held up during cam assembly?
Robert

 

[La Hot Rods]

My guess on the valve lash is the clearance ramp design. On the mushroom lifters the block has to be machined from the bottom of the lifter bore for clearance, and yes the lifters go in from the bottom.

 

[63409impala]

lifters went in from the bottom. For them to stay in all you do is flip the block upside down when installing the cam

 

[55Brodie]

Y block Fords had mushroom solid lifters from the factory. Having owned several in the past my opinion of them is quite low.

 

[427John]

While they are no sbc,they do have their following.I always found them to be torquey little engines for their displacement fairly economical and reliable if you could keep the sludge out of the oil.If you were in a hurry you were better off picking something else,but they were still way ahead of a 6 cylinder.Also there weren't many engines that sounded better with a glasspack dual exhaust.There were a few very talented guys back in the day that could make them run hard,Karol Miller probably being near the top of the list.But my Starliner which was originally a Y block car hasn't had one since 1981.

 

[427John]

As far as the lash variations, LA is spot on about the clearance ramps.Sometimes the ramps were tailored to certain types of valves too,an example is when some manufacturers were using hollow stem valves back in the days before the wider availability of titanium,they had to use a gentler closing ramp to maintain reliability of the valves.The hollow stem valves worked great as long as you used a cam designed for them,but as soon as you stuffed an Isky or Crane or whatever into it, it started popping heads off of valves because the cam slammed them on the seat.Thats why it is so important that your cam grinder have such pertinent information when recommending a profile for you if you are running something outside of the norm.

 

[rstreet]

I get it as to the ramps profiled to create a desired effect but the wide variety of lash clearances doesn’t seem to fit.
Robert

 

[55Brodie]

I get it as to the ramps profiled to create a desired effect but the wide variety of lash clearances doesn’t seem to fit.
Robert

Not sure I understand your question. The lash for Ford Y blocks I mentioned earlier was .019" for both intake and exhaust. The chevy 097 cam was .012 intake and .018 exhaust, I believe. Then there was the 30-30 cam...guess what the lash was.
These were the clearances determined by engineering based on design and intended usage.

 

[427John]

When they are a developing a profile their looking at things like acceleration and inertia and using all kinds calculations to determine opening and closing rates and ramps if needed.They know what want to see under the curve but have to work backwards to determine what they need to do to achieve it reliably and safely,I would say that lash specs.are part of that.Its really quite scientific, its not like they just whittle out a lobe copy and paste and give it a try.But I think the best part was some of the marketing terms and names they came up with,Isky was probably the best at that.