How Much Pre-load When Adjusting Hydraulic Lifters (using 273 rocker arms)?

[dibbons]

I have Lunati hydraulic lifters and bushed 273 adjustable rocker arms on the 340 build. What is the recommended pre-load after taking out all of the free play? Thank you.

 

[Dana67Dart]

I would contact Lutani.

 

[dano]

Who is now Edelbrock.

 

[MOPAROFFICIAL]

I have Lunati hydraulic lifters and bushed 273 adjustable rocker arms on the 340 build. What is the recommended pre-load after taking out all of the free play? Thank you.

.030 is good. No more than .060 for sure.

 

[dibbons]

.030 is good. No more than .060 for sure.

So the question is how far apart are the threads on the factory 273 adjusters? If we know that, we can figure how many turns (or partial turns) to make on the adjuster to get let's say .030 to .050. I guess I can try to measure with dial caliper (not sure how accurate I can do it though).

 

[MOPAROFFICIAL]

With the pushrods out or in..
can spin the pushrod to check for zero lash. Measure from the bottom of the rocker Adjuster side to the tip of the adjuster And count the turns.

 

[crackedback]

24 pitch threads

1/24 = .041

JMO Depending on use. Hard runner, maybe 1/4 turn.

Street car 3/4 to 1 turn max.

 

[LO23M8B]

I always zero lash them. You can rev them forever. Been doing it that way for about 55 years and never had an issue. But I do check them once in a while.

 

[Darter6]

I always zero lash them.

50 years ago I installed a hydraulic Crane Cam in my 340 along with the 273 rockers. Crane's instructions said set zero lash as LO23M8B stated.
But I do agree with crackedback in the 1/4 turn over zero. The lifters are quite forgiving and can go as much as 1 full turn.
My last project had a Lunati hydraulic and the instructions said bottom the lifter adjustment then back off 1 to 1 and 1/2 turn.

 

[RustyRatRod]

So the question is how far apart are the threads on the factory 273 adjusters? If we know that, we can figure how many turns (or partial turns) to make on the adjuster to get let's say .030 to .050. I guess I can try to measure with dial caliper (not sure how accurate I can do it though).

You're thinkin too much.

 

[dibbons]

24 pitch threads

1/24 = .041

JMO Depending on use. Hard runner, maybe 1/4 turn.

Street car 3/4 to 1 turn max.

My dial calipers are in mm and roughly I got 1 turn as about 8.25 mm which would be equivalent to .032". But crackedback probably has it correct as one turn equivalent to the .041". I initially used 1/4 turn with the motor on the engine stand but now with the motor installed and run for 10 minutes I will re-check and perhaps preload a bit more. Looks like I could split the difference for now and use 1/2 turn which would help account for any inaccuracies on my part in either direction.

 

[Bewy]

You need to consider three aspects of the adjustment:
- the hyd lifters have adjustment from zero to about 0.180". Anywhere within that range will work.
- the large range of adjustment will also affect final valvetrain geometry.
- with those particular rockers, you need to check the thread position....& range....on the adjusters to ensure the prods get oiled.

 

[RustyRatRod]

I always zero lash them. You can rev them forever. Been doing it that way for about 55 years and never had an issue. But I do check them once in a while.

The only reason I would not do that would be if the lifters only have the small, retaining wire holding the plunger. With zero preload, the plunger "COULD" come against the retainer and pop it out. I've seen it happen more then a few times and it was always because of too little preload. Now on a TRUE anti pump up lifter, they always have the good, heavy duty snap rings holding the plungers, so I wouldn't hesitate with those.

 

[Master of Mopars]

Half a turn.

 

[Bodyperson]

Like Bewy said. Is it a regrind? You need to hit the sweet spot for shaft oiling. Might need custom push rods.

 

[mygasser]

don't forget most suggest 1/2 to 3/4 turn from zero for hyd' tappets but that's most always with a stud mount factory rocker. with 273 rockers, like most aftermarket rockers the adjustment is at the pushrod. 1/2 turn at the stud will be more like 3/4 ish at the pushrod. basically you need less turns if the adjustment is at the pushrod end of the rocker rather than in the 'middle' at the stud. hope that all makes sense.
neil.

 

[PRH]

With std lifters(small round lock wire), I’d set them at 3/4 to 1 turn.