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Old 09-30-2012, 09:10 AM
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push rod length

hi guys i can't find any info about rod lengths for this engine it's a first gen engine sbc 383 with roller hyd lifters bought it as a short block...i just bought pro comp 190cc heads for it and i have no idea about the lifter rod length are they standard lengths and what would that length be thanks so much if you need any more info on this engine to help out just ask thanks again

Vince

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Old 09-30-2012, 09:28 AM
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Length depends on type of lifter. Push rod seat height in lifter. Deck height, Valve position/length in head. The only way to quickly measure with some accuracy, is to purchase a length checker. Several sources sell a handy one that sets on stud like a rocker arm. Measure from pushrod seat to checker to get length.
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Old 09-30-2012, 10:54 AM
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get a pushrod length checker that screws in and out for different lenghths mark top of valve with marker rotate engine several times and check pattern go for the narrowest pattern not necessarlly in the middle of the valve.
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Old 09-30-2012, 11:08 AM
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Quote:
Originally Posted by 1932bantam View Post
get a pushrod length checker that screws in and out for different lenghths mark top of valve with marker rotate engine several times and check pattern go for the narrowest pattern not necessarlly in the middle of the valve.
FYI you want it in the valve center.. and not hard to get with adjustable valve train.. with roller rockers and poly locks..
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Old 09-30-2012, 12:01 PM
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Quote:
Originally Posted by E.Furgal View Post
FYI you want it in the valve center.. and not hard to get with adjustable valve train.. with roller rockers and poly locks..
Having the narrowest pattern in the valve center is actually damn hard to do, and more often than not requires relocating the stud, rollers and locks have nothing to do with it.
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Old 09-30-2012, 01:13 PM
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I've had less failures with a when given a choice on a tad wider pattern that is centered, than a narrow one thats off to one side..
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Old 10-02-2012, 07:42 AM
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Its an intresting debate. that has been talked about a lot on here. Read about jim miller pretty good stuff. In the past I have always went for center. But I have been wrong before. Do a little studying make your own decision everybody gets set in there own way of thinking, sometimes not right.
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Old 10-02-2012, 09:14 AM
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A page on valve train geometry including a link to valve train points to check (at the bottom of the page) is here.

An adjustable pushrod like shown below can be easily made.



Good luck.
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Old 10-03-2012, 02:46 PM
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ok got my a adjustable push rod checker got my new heads in my god they look pretty my wife says I'm eating top roman for the rest of the month though i just might like it......anyway now the lifters do they have to be pumped up with oil to do this? don't know how i would do that if they do? any help there......
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Old 10-03-2012, 03:55 PM
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Just my two cents.
Yes the lifters need to be close to the same dimension that they would be after valve adjustment(approximately 1/2 turn). If your using 3/8"-24 studs
that would be just over .020" down from the retainer ring(1 divided by 24=.0416" per revolution, divided by 1/2=.0208").
If you take a lifter apart, and replace the valve disk and spring with some small washers that will bring the plunger up to the retaining ring, or better yet .020" below the ring, you can use that as a tool for finding the correct pushrod length. Just remember to put it back together the way it was, before final installation.
Instead of washers I made a single spacer to do the same thing(see pic).
I don't know if you can measure the distance from the plunger to the top edge of the lifter(lifter fully extended as if it were pumped up), then measure the distance from the plunger to the edge of the lifter when the lifter is fully collapsed, and subtract the difference from your length checker when using a collapsed lifter to check with. It may harm the lifter(spring/valve) when its
under load. Perhaps someone else will chime in.
FWIW
ssmonty
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Old 10-04-2012, 08:43 AM
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Fwiw

Quote:
Originally Posted by ssmonty View Post
Just my two cents.
Yes the lifters need to be close to the same dimension that they would be after valve adjustment(approximately 1/2 turn). If your using 3/8"-24 studs
that would be just over .020" down from the retainer ring(1 divided by 24=.0416" per revolution, divided by 1/2=.0208").
This has come up before. I posted basically the same info that you just did, then had another member come along to say that the rocker arm ratio has to be added to the equation.

Then there was this theory... At the very least, the decimal point placement is way off.

I've not had the occasion to check if the rocker arm ratio comes into play or not on an assembled engine, but my feeling is that the ratio will have an effect on the preload.

If that's the case, the preload would be 0.625" per full turn, or 0.312" for 1/2 turn.
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Old 10-04-2012, 10:13 AM
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Quote:
Originally Posted by gaurdian101 View Post
hi guys i can't find any info about rod lengths for this engine it's a first gen engine sbc 383 with roller hyd lifters bought it as a short block...i just bought pro comp 190cc heads for it and i have no idea about the lifter rod length are they standard lengths and what would that length be thanks so much if you need any more info on this engine to help out just ask thanks again

Vince
Try this for some reading:

Rocker Arm & Valve Train Geometry - Circle Track Magazine

Bogie
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Old 10-04-2012, 02:18 PM
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Quote:
Originally Posted by cobalt327 View Post
If that's the case, the preload would be 0.625" per full turn, or 0.312" for 1/2 turn.
Talking about decimal placement, I'll give myself an F. Obviously, the passage above should read "If that's the case, the preload would be 0.0625" per full turn, or 0.0312" for 1/2 turn".

More on valve train geometry can be seen here.

Good luck.
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Old 10-04-2012, 03:25 PM
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"I've not had the occasion to check if the rocker arm ratio comes into play or not on an assembled engine, but my feeling is that the ratio will have an effect on the preload.
If that's the case, the preload would be 0.625" per full turn, or 0.312" for 1/2 turn." by Cobalt

I stand corrected. I didn't think about the rocker arm coming into play. My bad. I used to know that, but I'm not as young as I used to be. I'll try to keep that in mind.
Thanks
ssmonty
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