Author Topic: Pushrod length confirmation  (Read 1057 times)

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Offline earthwalker

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Pushrod length confirmation
« on: December 12, 2017, 09:46:31 PM »
Hi All
Getting a fair way into my engine build (build thread to come shorty) but wanted to get some feedback on pushrod length determination. While I have build many an engine as a diesel mechanic  (mainly 60lt V16 3000hp jobbies) this pushrod measurement is a new one for me. I've done the procedure as follows
Fit valve testing springs
Torque down head
Fit adjustable pushrod and rocker gear
Adjust rocker nut to just take out lash, but no preload on lifter, rotate a couple of cycles
Adjust pushrod to obtain a good roller contact in centre of valve (as pic shows)
Measure up rod length - 6.360 inch obtained

As the head gasket used in the procedure has a compressed height of 0.047in, the final gasket to be used has compressed height of 0.041in, So subtract the difference 0.006 inch

Add preload distance as advised by AFR (0.030-0.035), in this case 0.031 (3/8 24tpi stem at 3/4 turn)

So we have 6.360 - 0.006 + 0.031 = 6.385 inch rod needed

Is this on track?



[/u]

Offline boofhead

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Re: Pushrod length confirmation
« Reply #1 on: December 13, 2017, 09:23:31 AM »
it looks to me to be way to wide of a mark. you want it as thin as you can get.

Offline shaunp

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Re: Pushrod length confirmation
« Reply #2 on: December 13, 2017, 09:28:01 AM »
Did you use light checking springs so you don't crush the lifter or a solid lifter the correct height .You'll find most places will only have rods in 50 thou increments ,some times  25 if you are lucky . So just in case in your testing pick 50 & 25 thou sizes either side of your your perfect number to see which is best.

Offline earthwalker

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Re: Pushrod length confirmation
« Reply #3 on: December 13, 2017, 10:12:35 AM »
Did you use light checking springs so you don't crush the lifter or a solid lifter the correct height .You'll find most places will only have rods in 50 thou increments ,some times  25 if you are lucky . So just in case in your testing pick 50 & 25 thou sizes either side of your your perfect number to see which is best.

Hi Shaunp, yes I used the crane cams checking springs, can I buy single rods?,

Offline earthwalker

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Re: Pushrod length confirmation
« Reply #4 on: December 13, 2017, 10:14:48 AM »
it looks to me to be way to wide of a mark. you want it as thin as you can get.
Hi Boof, ok will try to get narrower mark, I assume this can be achieved by shorter rod length, ill bolt her back up and continue, how wide should I be aiming for?

Offline shaunp

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Re: Pushrod length confirmation
« Reply #5 on: December 13, 2017, 10:32:42 AM »
I generally buy rods from performance wholesale in Brisbane . Cronulla st  slacks creek . Like I said they don't always have them in 25 thou sizes. 

Offline boofhead

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Re: Pushrod length confirmation
« Reply #6 on: December 13, 2017, 10:43:24 AM »
Hi Boof, ok will try to get narrower mark, I assume this can be achieved by shorter rod length, ill bolt her back up and continue, how wide should I be aiming for?

thin is more important than totally on center. slightly off center ok. About 30 thou so atleast half of what you have.

Offline earthwalker

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Re: Pushrod length confirmation
« Reply #7 on: December 13, 2017, 10:55:47 AM »
I generally buy rods from performance wholesale in Brisbane . Cronulla st  slacks creek . Like I said they don't always have them in 25 thou sizes.
Great, thanks mate, I might even try lighter springs from the hardware,

Offline earthwalker

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Re: Pushrod length confirmation
« Reply #8 on: December 13, 2017, 03:06:53 PM »
Okay have managed to get the contact narrowed down to about 0.030 (pics), and have remeasured and taken into account the head gasket difference and preload allowance to get a final length of 6.413, could only get rods in 0.050 increments so have ordered one rod in each 6.350, 6.400, 6.450  to check for best fit

Offline earthwalker

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Re: Pushrod length confirmation
« Reply #9 on: December 13, 2017, 03:09:41 PM »
I generally buy rods from performance wholesale in Brisbane . Cronulla st  slacks creek . Like I said they don't always have them in 25 thou sizes.
Got the rods from these guys, thanks for the contact :thumb:

Offline barnett468

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Re: Pushrod length confirmation
« Reply #10 on: December 14, 2017, 12:36:49 PM »
xlnt job.

Offline earthwalker

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Re: Pushrod length confirmation
« Reply #11 on: December 14, 2017, 01:16:06 PM »
xlnt job.
Thanks mate, its a learning process, ill start an engine build thread so we can all see why she explodes on the first dyno pull  :bolt:

Offline barnett468

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Re: Pushrod length confirmation
« Reply #12 on: December 14, 2017, 05:24:54 PM »
Thanks mate, its a learning process, ill start an engine build thread so we can all see why she explodes on the first dyno pull  :bolt:

That's the spirit!  :lmao:

Offline boofhead

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Re: Pushrod length confirmation
« Reply #13 on: December 17, 2017, 10:02:43 AM »
That is much better. good job.

 

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