rocker arm shaft torque

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cudabear67

cudabear67

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does anybody know iof there needs to be a sequence to removing the rocker arm shaft. I need to replace push rods. As i understand the toque soecs are 17 ft lbs but I just want to make sure there is no specifice sequence to removal and retightening
 
I'd just break them loose very easy and start in the middle and work your way outward gradually ! Just the reverse of torqueing them !
 
cudabear67 said:
does anybody know iof there needs to be a sequence to removing the rocker arm shaft. I need to replace push rods. As i understand the toque soecs are 17 ft lbs but I just want to make sure there is no specifice sequence to removal and retightening
Click to expand...

My factory service manual (1964) says 30 foot pounds. Not 17. Is that wrong? I JUST torqued them down to that figure and had no issues. I started in the middle and worked toward the end, alternating, side-to-side. I brought them down in 5 foot pound increments. This is a solid lifter setup, if that matters.

I don't think it matters what sequence you use when dis-assembling the shaft from the head.
 
What are you working on?

Shouldn't matter at all how you remove them.

I have a 74 manual and its 25 for slant or BB and 17 for SB, but that may be different for other years. As for sequence I did not see any recommendation. I started at center and alternated sides out kinda like head bolts. Basically on anything you tighten you just dont want to bind it from outside in. Snug them all first then torque.
 
That torque spec has been misprinted countless times in several different manuals.
There is one that says 45 ft. lbs. It's just a blessing that the broken bolt is easy to remove.
There is a reference chart showing standard torque specs for the various standard bolt sizes to be had also.
Per that chart 5/16 bolt runs from 11 ft. lbs. minimum to 27 ft. lbs. maximum depending on bolt grade and thread count. I think you have 5/16 NC in grade 6 or 7 which per the chart is 17 ft. lbs.
 
RedFish said:
That torque spec has been misprinted countless times in several different manuals.
There is one that says 45 ft. lbs. It's just a blessing that the broken bolt is easy to remove.
There is a reference chart showing standard torque specs for the various standard bolt sizes to be had also.
Per that chart 5/16 bolt runs from 11 ft. lbs. minimum to 27 ft. lbs. maximum depending on bolt grade and thread count. I think you have 5/16 NC in grade 6 or 7 which per the chart is 17 ft. lbs.
Click to expand...

You would THINK that a technical specification, (such as a torque spec.) when incorrect, and could result in something as grievous as a broken bolt (or, several,) that the person responsible for editing out mistakes, PARTICULARLY in a "factory shop manual" that will be used by "line mechanics," at dealerships, would closely proofread the copy and make every effort to eliminate mistakes like this, mistakes that could prove costly in the real world.

I mean, if you can't trust a factory shop manual, what CAN you trust???

THANKYOU, RedFish, for the good information. I, for one, really appreciate it!:hello2:
 
That bolt is 3/8. I checked several FSM from 1969 to 1978. The speck listed, is a low of 24 ft/lbs to a high of 30 ft/lbs. The older manuals had the higher spec.

Personally I just tighten them to the German spec.(goodentite)
 
Slant has 3/8" grade 5 bolts except for the long one at back end. That is reduced to 5/16 at the threads, but it is grade 8, I dont recall if they are coarse or fine thread.. So, still not sure where they come up with 25, 3/8 would actually be higher, but maybe they did not want that much pressure on the shaft? Of course, a little oil on the them down grades the torque setting...
 
zkx14 said:
Slant has 3/8" grade 5 bolts except for the long one at back end. That is reduced to 5/16 at the threads, but it is grade 8, I dont recall if they are coarse or fine thread.. So, still not sure where they come up with 25, 3/8 would actually be higher, but maybe they did not want that much pressure on the shaft? Of course, a little oil on the them down grades the torque setting...
Click to expand...

Is there any other difference in that back bolt, other than it being 3-inches long? Is the threaded portion really 5/16", so it would not thread into any of the other holes, and is it hollow, or different in any other way? I just want to make sure my rocker arm shaft gets the oil it needs.

Any information will be appreciated....
 
Charrlie_S said:
That bolt is 3/8. I checked several FSM from 1969 to 1978. The speck listed, is a low of 24 ft/lbs to a high of 30 ft/lbs. The older manuals had the higher spec.

Personally I just tighten them to the German spec.(goodentite)
Click to expand...

Charrlie, you're funny!!!!:blob:
 
Bill Dedman said:
Is there any other difference in that back bolt, other than it being 3-inches long? Is the threaded portion really 5/16", so it would not thread into any of the other holes, and is it hollow, or different in any other way? I just want to make sure my rocker arm shaft gets the oil it needs.

Any information will be appreciated....
Click to expand...

First, I am working on a 1975 slant 'peanut head', but acording to my 74 FSM it looks like this info is right for the older style as well.

Correct, the back bolt is 5/16-18, and will not tighten in any other position (they are 3/8-16). No, there is not a hole through it. The oil comes up through another hole on an angle next to it and goes into the shaft around the reduced shank of the bolt. Other than that, be sure the small holes in the shaft point toward the springs and down. Also be sure to use the wider hold down 'washer' in the center position and that none of them pinch a rocker.
 
zkx14 said:
First, I am working on a 1975 slant 'peanut head', but acording to my 74 FSM it looks like this info is right for the older style as well.

Correct, the back bolt is 5/16-18, and will not tighten in any other position (they are 3/8-16). No, there is not a hole through it. The oil comes up through another hole on an angle next to it and goes into the shaft around the reduced shank of the bolt. Other than that, be sure the small holes in the shaft point toward the springs and down. Also be sure to use the wider hold down 'washer' in the center position and that none of them pinch a rocker.
Click to expand...

Thanks for that information.

Here's a couple of pictures I came across on another site that are enlightening, I think.

Seems like, when the design was changed to hydraulic lifters, the design of that rear bolt was changed as well. They are not interchangeable, apparently.

I think it also said that the rear hole in the shaft was smaller on the hydraulic lifter motor.

Thanks again for the good information.
 

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Don't know what they used the left bolt on. I have solid 'barbell' lifters and the bolt on the right is what I have. The picture is accurate for mine as well. Any idea what year that pic is from?
 
zkx14 said:
Don't know what they used the left bolt on. I have solid 'barbell' lifters and the bolt on the right is what I have. The picture is accurate for mine as well. Any idea what year that pic is from?
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My engine is a solid lifter (1964) engine and that (left-side bolt) is what the rear bolt looks like that came out of it (3/8"-16, not turned down to 5/16".)

I'm thinking your engine might have a head that came off a hydraulic lifter motor, and that's why the different bolt.

That picture came from a note in the slant six forum, that was written in August of 2011.

There may be a casting number on your cylinder head that could tell us when that head you have was manufactured. Casting numbers can sometimes identify what year the parts they are on were built.

That head may be a late-model slant six head. The hydraulic lifters were in all slant sixes after about 1980, I think.

Check it out...:coffee2:
 
Been doing some research... I have a casting # 4027600, which is correct for a 1975 (or 76) mechanical. I found numerous posts with indecisive years on the change in the back bolt, apparently all were small after 78 or 79. But like mine, there were earlier ones and mechanical ones that used it. That said, I don't think you will find any factory hydraulics with the large bolt in the back.
 
zkx14 said:
Been doing some research... I have a casting # 4027600, which is correct for a 1975 (or 76) mechanical. I found numerous posts with indecisive years on the change in the back bolt, apparently all were small after 78 or 79. But like mine, there were earlier ones and mechanical ones that used it. That said, I don't think you will find any factory hydraulics with the large bolt in the back.
Click to expand...

I think you are right on all counts...

You know Ma Mopar, though; never say "never..." LOL!:banghead:
 
I don't know what year Chrys changed to the step down rear bolt, but it was prior to the switch to hydraulic lifters. The consenses of the reason for the change was more to make assembly of the rocker shaft "idiot proof". With the step bolt and the corresponding rocker shaft, the shaft can only be installed in the correct position.
 
Funny thing is, I am pretty sure I had my rocker shaft on upside down when I started to reassemble. And, it does not have a flat spot for reference, just had to orient the oil holes correctly. Mine would obviously be one of the earliest with small bolt, so maybe shaft changes were not done yet. I assume they made the bottom hole smaller so the bolt wont go all the way in (and none of the other bolts would fit either) on the 'idiot proof' shaft?

Charrlie_S said:
I don't know what year Chrys changed to the step down rear bolt, but it was prior to the switch to hydraulic lifters. The consenses of the reason for the change was more to make assembly of the rocker shaft "idiot proof". With the step bolt and the corresponding rocker shaft, the shaft can only be installed in the correct position.
Click to expand...
 
zkx14 said:
I assume they made the bottom hole smaller so the bolt wont go all the way in (and none of the other bolts would fit either) on the 'idiot proof' shaft?
Click to expand...
That is correct.
In your case, after this many years, the shaft might have been replaced with the earlier style, at some point in its life.
 
so now that I finally got password and username issued solved I did figure out the torque on the rocker shaft. went with 17. My slant now purrs like a kitten although does anyody recommend readjust while running. Its pretty quiet ad have only adjusted cold. i think I need to adjust again hot?

by the way its a 67 Barracuda FB. Purchased it for 2K. not in bad shape for sitting in a barn for 13 years. it s an original colorado car. usual rust spots
 
also looking for disc brake set up for this car. Drums are wasted and I want to convert.

I am also looking to put 15x10 in the back. i think i can do it but am unsure of the backspacing? I measured from the inner whell weel to drum base, 6". does this sound right and if so does this mean i can buy any wheel with less than 5" backspace to acommodate for whatever tire I use?. It has the original mopar OE's 14x6x4 on it now.
 
Always adjust slant valves while running, when hot. A quiet valve is one that is too tight. You should hear some clatter.
 
You don't need to adjust valves "running."

Get the engine warmed up, all your tools ready, and look for obstructions such as wiring clamps or hoses that prevent you from removing the valve cover fairly quickly

Then use EOIC and remember that

This little "ditty" will allow you to adjust valves on anything from a Briggs and Stratton to a P&W radial. Anything with poppet valves

EOIC means you

Wrench or bump the engine until the EXHAUST just starts to OPEN and then adjust the intake for that cylinder

Then rotate the engine until the INTAKE has opened and is nearly CLOSED and adjust the exhaust for that cylinder.

You can "start at the front" or the rear, and go right down the head, no matter.

The reason you use this method is that this insures that the tappet is on the backside of the cam of the valve you are adjusting.

Take care to slide the feeler in "straight" and use the specified feeler and one .002--.003" larger. You can then have two, a "go" and "no go"

Google it. This method has been used before I was born (I'm 65) and it works for any engine

https://www.google.com/search?num=40&newwindow=1&q=EOIC%2C+valve%2C++adjustment&oq=EOIC%2C+valve%2C++adjustment&gs_l=serp.3..0j0i22i10i30.451685.456663.0.456893.24.24.0.0.0.0.401.3042.3j20j4-1.24.0....0...1c.1.26.serp..2.22.2769.EPAg5K7ugzk
 
Reaching into a running anything is a big no no in most cases. As a mechanic, rarely do we get to play surgeon.
Once you get the knack of riding running rockers, the ride ends too soon.
 
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