S&S Pushrod Adjustment with Dry Lifters/ not Solids

[Tacocaster]

I'm curious what your experiences have shown you that work.

Any engine - but let's use the Twin Cam. Dry Lifters installed with S&S Adj. PR's.

Doing the math and assuming a standard Lifter depth of 1.90" ...  32tpi X .6 = 19.2 turns per inch, add an additional 5 turns (total 24) gives approximately 1 1/4" extension into the lifter and leaving just under 3/4" for "cushion".

For Dry Lifters, I've read where guys have set the target lifter on the base of the cam, confirmed Piston TDC then extended the PR into the Dry Lifter till the PR bottoms (full lifter spring collapse and corresponding valve closed).  At this point they shortened the PR as much as 1 1/2". That's equivalent to approx. 26 flats on an S&S PR using the math above. Some have said they turn them inward 24 flats ( 1 1/4").

Okay.....BUT..... shouldn't they have adjusted the PR's (shortened) by only ~15 flats? That is equal to approximately 3/4" thereby leaving the Lifter Spring at the same position as any Wet Lifter adjustment procedure where an S&S PR is extended 24 Flats (1 1/4").

What am I missing here???

[Coyote]

Not even sure where to start.

[Don D]

Bottom up top down what's the difference? Its math. 3 and a 1/4 turn will get you there if 32tpi. This is not an exact science unless you ask the guys that say a certain preload is necessary or the motor will essentially burst into flames. Set it about at midpoint and move on.

[Tacocaster]

Coyote, then don't! Pretty simple.

HD SP - thanks, I was just curious if I was missing something.

[rigidthumper]

Primary concerns are thread pitch, and total plunger movement, not lifter overall length. Most lifters have ~.2" (200 thousandths) total travel top to bottom, and you're looking to put the plunger about 1/2 travel.  The space below the lifter plunger may start out empty (when dry), but will soon be filled with oil (assuming everything is working properly), which is why they clatter on startup.  Adjustment from bottoming on a dry lifter is easy- everything at room temperature, cam on TDCC for the cylinder in question, using only fingers, lengthen pushrod to remove slack- continue lengthening, while counting flats, until you can no longer spin the pushrod between your fingers. This will tell you the depth for that specific lifter, in flats. If it takes 40 flats to go from zero slack to no longer able to spin the push rod, then backing off 20 flats will put you at half travel. Enough room left over for oil to fill the gap, enough travel to compensate for temperature shrinkage/growth.

[PoorUB]

Not even sure where to start.

Me too! not sure where 1-1/4" and 3/4" comes in with lifters with .190" plunger travel!

[kd]

I expect the OP misread the information and should have been turns not inches.  I was going to respond but was beat to the punch.

[Pirsch Fire Wagon]

0.095" or 2.28 Turns @ 24 TP @ Inch / 0.095" or 3.4 Turns @ 32 TP - ALWAYS rotate the Engine to ensure there is no contacts before starting.

[rbabos]

I've never seen a group complicate a stupid lifter to these levels.
Ron

[Ohio HD]

I've never seen a group complicate a stupid lifter to these levels.
Ron

Well i did understand the last sentence in the first post.


"What am I missing here???"


Most of HD mechanical work isn't rocket science. Everything is relatively simple.

[Ohio HD]

Not even sure where to start.

[FSG]

 

[PoorUB]

I'm curious what your experiences have shown you that work.

Any engine - but let's use the Twin Cam. Dry Lifters installed with S&S Adj. PR's.

Doing the math and assuming a standard Lifter depth of 1.90" ...  32tpi X .6 = 19.2 turns per inch, add an additional 5 turns (total 24) gives approximately 1 1/4" extension into the lifter and leaving just under 3/4" for "cushion".

For Dry Lifters, I've read where guys have set the target lifter on the base of the cam, confirmed Piston TDC then extended the PR into the Dry Lifter till the PR bottoms (full lifter spring collapse and corresponding valve closed).  At this point they shortened the PR as much as 1 1/2". That's equivalent to approx. 26 flats on an S&S PR using the math above. Some have said they turn them inward 24 flats ( 1 1/4").

Okay.....BUT..... shouldn't they have adjusted the PR's (shortened) by only ~15 flats? That is equal to approximately 3/4" thereby leaving the Lifter Spring at the same position as any Wet Lifter adjustment procedure where an S&S PR is extended 24 Flats (1 1/4").

What am I missing here???

Anyone care to clarify what the OP is talking about in the red high lighted text?

In my book 32 TPI equals 32 turns for and inch, but why are we talking inches here?

Signed,
Confused

[Tacocaster]

Ha-ha-ha! Wow! Maybe I should write Official Documents for the Government! Seems I might know how to write 'em!

Jeeze, I'm sorry I woke everybody up and started this now. Wasn't my intent. Honest! Just a simple (I thought) question after reading something and the question popped in my head, so I asked. If I'd known I was going to do this to everyone I wouldn't have posted.

In review of the above responses, Ridgidthumper, Pirsch and HD Street Performance answered my question (you know, the question that only I could understand).

To the rest, thanks for responding, please excuse my lack of clarity and again, my apologies to all offended.

[Ohio HD]

Grazie......

[smoserx1]

Tacocaster, if I read all this thread correctly I believe you were asking about preloading a lifter with a total travel of .190 inches to .125 inches using a pushrod with a 32 tpi pitch.  If my assumption is correct then the number of turns (not flats) needed to go the entire .190 inch travel would be 32 X .190 = 6.08.  Therefore if you wanted to go to .125 inches from the top down it is simply 6.08 turns X (.125/.190) = 4 turns.  Coming from the bottom up the distance would then become .190 -.125 = .065 inches, so the math in this case would be 6.08 turns X (.065/.190) = 2.08 turns backed off from the bottom.  For other pushrod threads and lifter travel values (like 24 tpi and .200 inches) just do the same math with the other values substituted.  Working with flats instead of turns is ok but IMO adds complication.  It is easy enough just to mark one of the flats on the pushrod with a dab of paint or similar and count the turns instead.  Hope this helps.

[Tacocaster]

Thanks Smoserx1. It did and does. # of Flats it is!

Thanks again to all that contributed to clarify the question.

Moving on.....