After 2 years of periodically working on the block to try to configure the preload on my rockers I have given up and have decided to say uncle on this and to look for experts to do it for me.
Went around to shops in "Chucktown" and they all got that deer in the headlights look.
And everyone of them said you need to do what?
No one had ever heard of doing it.
I even talked to an old guy who use to work for Rover in the UK for 20 years.
Once I explained it to him he kind of got it, ....
But still looking
I'm tempted on taking it up to Woody in Ma ,an 13 hour drive, and have him do it for me
Once that's done all the rest is butter.
2 years I have been struggling with this and I want to keep this ball rolling
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Ok I'll bite.
Preload on Rockers? Lifters sure but.....
What exactly are you trying to do?
Measure for the shims under the rockers
Don, Most use an adjustable pushrod to figure geometry. I'm a believer of mid-lift theory as you have less wipe on valve stem. A lot of guys just deduct the amount milled off deck or head and use shim for that difference.
Jim,
About to get on a plane to the Emerald city in 4 hours.
Stock 4.0 block with nothing milled off heads or block.
Just a semi aggressive cam that have
Don, I'm in AZ now but enjoy your Seattle trip!
http://bullfire.net/TR6/TR6-19/TR6-19.html
Nothing milled, then the only thing could be Valve Tip wear, Valve recess into seat, wear in Rockers, different head gaskets. RPI has some info on their site, use different thickness welding wire to measure preload. Willing to bet that you need nothing in the way of shims if you have not decked heads or Block. Now if the cam is that aggressive what have you done for piston relief, Valve spring bind?
Jim's Link is interesting. Guess it depends on just how aggressive the cam is, if its worth going into so much depth. Just assumed you were using standard rockers etc.
Standard rockers, rebuilt.
New push rods
New lifters
The welding wire is funny.
You have only one measurement and then that is Greater than and less than
I have old style wire feeler gauges that go from .02 to.08 in about 10 steps.
My original measurement I couldn't even guess as it was quite a bit bigger than .08.
So I put some SS washers under the rocker arms so I could at least get a better read and figure in the washers.
I get readings of less than .02 and greater that .64.
I just can figure how come they are all over the map like that.
I also noticed that I get completely different measurements if I wait and do it a second and third time
Don,
First place a straight edge along the tip of all valves to make sure they are all at same height.
Lifters may not be full of oil so are compressing more easily? Used to be we were told to soak new lifters in oil over night but that seems to have gone away.
About to head out the door.
Straight edge done
Lifters dry
Hey Don,
Where are you taking your measurement?
With stock length push rods and your valve stem heights already set, the only adjustment that is available is the lifter preload.
And that is done the easiest with the use of pedestal shims.
The stock lifters have roughly 0.220" of plunger travel. So that should leave a lot of room for measurement.
With everything stock except the cam. I can't imagine running out of room to the point of having to shim the pedestals to get a baseline.
The variability is a big concern. You need to have repeatable measurements. If not something is very wrong.
Possibly you're not getting the lifter on the base circle of the cam. You can see the cam lobe through the slot in the block. The lobe should be pointing 180' away from the lifter such that the lifter is as far into the block as it can go. You can then measure the preload.
This is the distance between the circlip in the lifter and the surface of the push rod cup in the lifter.
The specs are 0.020" to 0.060" My personal opinion is that 20 thou is too little in a fully aluminum pushrod street motor. With all the flex in the system and the growth of the aluminum when up to temp you are very close to or at zero preload. Great for a race engine with better circlips, not so much for a street motor.
So aim for no less than 0.040" and live happily ever after.
Hope that helps
Cheers
Fred
Ted Eaton has information on his web site about rockertrain geometry. http://www.eatonbalancing.com/
I usually shoot for something in the .060"-.080" range and have not had a lifter tap problem since I began doing that. The downside is that it can cut your redline a few rpms if your springs are marginal, but I'd rather chance that than lifter tap. It's a trade off, but as Fred said there is a lot of room to work with. I would never even consider anything under .040" under any circumstances for hydraulic lifters.
I've found the easiest way to measure is with adjustable pushrods, and the easiest way to set it is to order custom length pushrods from Smith Bros. If you are that concerned about rocker arm geometry, then yeah you can mill the pedestals and shim them, but it's usually just more work.
Jim
Gentlemen, Gentlemen. Thank you for all the responses.Sorry I have taken this long to do it.
I got back late last week from a week in Vancouver and came home to a refrigerator emergency. YIKES
I'll try to respond in order of responses
1. Where are you taking your measurement?
At the lifter piston retaining ring
2.With everything stock except the cam. I can't imagine running out of room to the point of having to shim the pedestals to get a baseline
I wasn't running out of room I didn't have a tool to measure that big
3. Possibly you're not getting the lifter on the base circle of the cam.
I am pretty sure I was
Somebody told me to measure at a cyl at TDC, then a different at90 then another at 180....
I just went down to my bench and I think I threw the directions away, dang it.
4. I've found the easiest way to measure is with adjustable pushrods, and the easiest way to set it is to order custom length pushrods from Smith Bros
I think I might try the adjustable push rods. the rods I have now are brand new from Smith bros , hollow ones. How do I use the adjustable ones? I take it you use it to figure out the correct length?
Looking forward to you responses
Yes, install the adjustable pushrod, set it so it just takes up all the slack, then remove it and measure it. Add your preload to that length and order your new pushrods. Measure both intake and exhaust that way, and to be complete you can do all cylinders, but they should all be within a few thousandths. I usually take the average and add .060"
Jim
Jim, Thanks
A couple of dumb questions (I'm flush with those)
Is slack when it won't spin in your fingers ...or when there is a slight drag?
Do I use a long caliper to measure, I would guess so.
In my long response above. My answer to #3, is that sound correct?
Thanks
New title
You can find charts that tell you which valves are open when you are on the base circle, but in general, it will be during 1/2 rotation of the cam or 1 full crankshaft rotation, so 1 crank rotation past where the valve is fully open will do it.
Adjust so that the play is gone but you are not compressing the lifter. Most easily seen if the intake is off of course, but you should be able to feel it also.
If you have long enough calipers that would be best. Otherwise you'll have to get creative, such as for instance a drill press and a stack of blocks.
Jim
Next question. The cup size on the Rover motor is 3/16 and the Smith catalogue doesn't show that size for a measuring pushrod.
Don't have to worry about the intake being on as this is thae way it's been for a while
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Must be a misprint Don.
The actual size is 5/16"
Super common size, so should be easy to find.
Cheers
Fred
Yeah. The push rod on my 215 is just over a 1/4".
OK, this is weird. Will need to call them.
The original invoice shows 5/16.
I had to send them back as they sent me the wrong length.
The new papers show 3/16.
Never mind they both show 3/16
That's the size of my 3.5 Factory TR8 used
Don't get the size of the cup confused with the diameter of the pushrod.
The rover pushrods neck down to 1/4" after the ball end.
And yep should have put my glasses on! the ball end is in fact 5/16ths"
There is no cup...just balls
This is even more confusing, I sent them them a rod from the old engine to match and they made the ball 5/16 on the new ones...
Though it doesn't say that
It says 3/16
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The push rods have balls, the rockers and lifters have cups. All the same size. 5/16 for sure.
Was doing some checking on the web to see if I could find ball specification.
Real Steel in the UK has this
3/16 for the Rocker end
and 5/32 for the Lifter end
Interesting
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They are quoting radius vs diameter 5/32" rad. is 5/16" dia.
5/16ths is the measurement from the pushrod that I have in my hand right now.
Christ...how they heck did I miss that
Then I will order 5/16 balls for the adjusting rod tool.
Length? Will 8"-9" work?
The factory rod is 8.00" exactly so you will want a little on either side of that.
Say 7.50'' to 8.50"
Mine measured out at 8.028 so ...7 1/2 - 8 1/2 it will be
I appreciate the patience and the help
Stay tuned for more questions (Probably) when I get the push rod and it isn't to hot
Hey, when push comes to shove...you just gotta grab it by the balls.
Otherwise you don't measure up!
Oh god, it must be scotchy scotch time.
Cheers
Don't stop now Fred, you're on a roll.
Jim
Adjustable PR has arrived and the question I have is how much tension should it have as I lengthen it.
Not a lot.
The hydraulic lifter has an internal piston and a spring. If you take one out you'll see that the cup is held in by a wire clip. Under that is the piston. You can push it down with a screwdriver, and depending on how much oil it has in it, it will probably go down easily for a bit and then stop. If it has no oil in it it will go down quite a ways, maybe as much as 3/8". If it is full it will hardly go down at all.
So the trick then is to get an accurate measurement against that light spring pressure and it isn't easy.
I solved the problem by using a spare lifter and substituting an adjustable bolt and nut for the piston and spring, adjusting it so that the cup was all the way up against the spring clip, then used that for measurement. But it has to be the same length as the lifters that you are using.
Jim