[wakesupremo]

Originally Posted by 461-69bird

Gary, there's a calculator on Wallace racing site, you can work it out.
Have you got Caltracs now? that's a much better 60ft than mine

Yes I have. I didn't realise how different they were from the old slapper bars. It felt the same but the timing tickets tell the difference!!!

[ta man]

Originally Posted by wakesupremo

Thanks again. i think I have torque converter slip but not sure how to measure it!!!! 1.4 60ft times. Its definitely no slouch!!!

With a 1.4 60ft time and 125 mph..should be 10's all day.

[Schurkey]

Originally Posted by Formulajones

I'll take a guess that chances are good you're running a 7/16-20 stud as that's super common on builds these days. You'll end up just past a 1/2 turn for that preload, maybe a pinch more if you want to compensate for aluminum heads.

As a reference, 3/4 turn should be roughly ~.037" on a 7/16-20 stud.

But the rocker arm multiplies the preload at the STUD, so that the preload at the lifter is more than the preload at the stud.

And what matters is the preload at the lifter.

You sink the nut 1/2 turn past zero lash on a 7/16-20 stud, the nut goes down .025. The lifter plunger goes down more than that. How much more depends on the rocker ratio.

[Formulajones]

Originally Posted by Schurkey

But the rocker arm multiplies the preload at the STUD, so that the preload at the lifter is more than the preload at the stud.

And what matters is the preload at the lifter.

You sink the nut 1/2 turn past zero lash on a 7/16-20 stud, the nut goes down .025. The lifter plunger goes down more than that. How much more depends on the rocker ratio.

These are generalizations so someone can wrap their head around it. Which is why I said I set up a dial indicator on the first one to be sure and mentioned rocker ratio.

See post 17

[tooski]

Originally Posted by Schurkey

But the rocker arm multiplies the preload at the STUD, so that the preload at the lifter is more than the preload at the stud.

And what matters is the preload at the lifter.

You sink the nut 1/2 turn past zero lash on a 7/16-20 stud, the nut goes down .025. The lifter plunger goes down more than that. How much more depends on the rocker ratio.

After reading this here and elsewhere and not finding anyone who gave a measurement I put a dial indicator on the rocker, inline with the pushrod. 1.55 rocker ratio. One turn on the polylock resulted in .070 preload.

[chiphead]

That means 3/4 turn will be a scooch over .050 preload with a 1.5 rocker ratio. I believe lower ratio rockers will give more preload b/c the rocker ratio is working backwards.

[Schurkey]

Originally Posted by tooski

1.55 rocker ratio. One turn on the polylock resulted in .070 preload.

One turn of the nut on a 7/16-20 stud = .050
.050 X 1.55 = .0775. Your real-life measurement is .0075 away from theoretical.

First Guess: The seven-and-a-half thousandths is easily explained by imperfect rocker ratio, and potentially imperfect measurement-tool set up.

3/4 turn = .050 x .75 = .0375 at the stud. .0375 x 1.55 = .0581 lifter preload. The rocker ratio is not "backwards".

[wakesupremo]

Originally Posted by ta man

With a 1.4 60ft time and 125 mph..should be 10's all day.

Thanks again. The shift light comes on at 5800 RPM just as I'm going over the line. No more revs to go. As I previously said either converter slip or wrong gears, but, I really don't want to go faster in a convertible.
I have 1.65 ratio rockers so, will the measurement be increased or decreased ? The polyloc is obviously not quite central.

[ta man]

Originally Posted by wakesupremo

Thanks again. The shift light comes on at 5800 RPM just as I'm going over the line. No more revs to go. As I previously said either converter slip or wrong gears, but, I really don't want to go faster in a convertible.
I have 1.65 ratio rockers so, will the measurement be increased or decreased ? The polyloc is obviously not quite central.

Can you post a timeslip?

[tooski]

Originally Posted by Schurkey

One turn of the nut on a 7/16-20 stud = .050
.050 X 1.55 = .0775. Your real-life measurement is .0075 away from theoretical.

First Guess: The seven-and-a-half thousandths is easily explained by imperfect rocker ratio, and potentially imperfect measurement-tool set up.

3/4 turn = .050 x .75 = .0375 at the stud. .0375 x 1.55 = .0581 lifter preload. The rocker ratio is not "backwards".

In that case it is even more preload than the .050 that has been said by 1 turn of the nut.

[wakesupremo]

How do I put a picture up please?

[78w72]

when you post a reply, click the "go advanced" button, that will open a manage attachments window, click "choose file" & find the pic you want to post, then click upload. after that finish typing the message & hit reply.

[wakesupremo]

Nope. doesn't want to work.
RT 60ft 330 1/8 1/8mph 1000ft 1000mph 1/4 1/4mph
0,143 1.7105 4.8643. 7.4049. 97.26. 9.5960. 111.64. 11.4427. 122.48
This is a timeslip I had but not the quickest. I cant find the quickest one.

[78w72]

should work, i post pics using the steps i posted & pics always show up...

times look great, my 467 stroker firebird does 120-123mph at 11.2-11.3 but i have crappy 60ft times due to stiff suspension not set up for drag racing & some fuel starvation issues with a mech pump.

[ta man]

Originally Posted by wakesupremo

Nope. doesn't want to work.
RT 60ft 330 1/8 1/8mph 1000ft 1000mph 1/4 1/4mph
0,143 1.7105 4.8643. 7.4049. 97.26. 9.5960. 111.64. 11.4427. 122.48
This is a timeslip I had but not the quickest. I cant find the quickest one.

Thanks. Times look great, lots of potential.