Help - Search - Members - Calendar
Full Version: Rocker geo
914World.com > The 914 Forums > 914World Garage
toon1
so far the liift is good, cam card say's .426, I've got about .428.

Here is a pic. with the vave at half lift. Seems a little off(leaning back) to me.
toon1
here are somemore pics of the spacers. notice the stagered washers. This seemed necassary to get the adjusters to line up with the valvge stem.
toon1
one more
Twystd1
Did you mill your rockers about 60 thou for those 9eleben adjusters?

And yes your adjuster is not parallel to the valve stem.

And you have no adjusting room left on your swivel foot. (Bad)

What cam do you have?

Me thinks you might need rocker pad shims.

Yes you sometimes have to move washers around to make it work.

PM Craig Downs and have him look at your pics. HE IS VERY GOOD AT GEO.

He can show you some tricks to make your life easier.

Bottom line: For me it ain't right.

Clayton

Joe Ricard
Hey what kinda push rod is that?
Did you make one out of an old stock one? ya know that the ball tip is a different size.

and where it you oil for the rockers? them need to ne oiled or you will be really screwing things up.

You dial indicator is not on in the same plane as the valve stem, it makes a difference.


Just for reference my adjusters have 3-4 threads before bottoming out.

Well you aked if it looks good Honesty sucks huh?
TC.356
Shims beneath the rocker assemblies and longer (adjustable?) push rods might be necessary here. Help flatten out the rocker arm and build in some adjustability.
toon1
QUOTE(Joe Ricard @ Oct 29 2007, 05:08 AM) *

Hey what kinda push rod is that?
Did you make one out of an old stock one? ya know that the ball tip is a different size.

and where it you oil for the rockers? them need to ne oiled or you will be really screwing things up.

You dial indicator is not on in the same plane as the valve stem, it makes a difference.


Just for reference my adjusters have 3-4 threads before bottoming out.

Well you aked if it looks good Honesty sucks huh?


The truth does NOT hurt in this case. I didn't post because I was proud of what I did, I thought something was wrong and needed help. I'm getting the answers I was looking for. Thank you!

Yes, the p/r was made from a stock p/r. I drilled the ends and installed the correct tips.

You mentioned oil for the rockers, should it be on the tips of the adjusters?

I placed the dial indicator back into position for the pic but didn,t really alighn it well with the valve stem. When I am checking the lift I make sure it's alighned.

It's good to know about the amount of threads that should be exposed. I did take the .060 off the rocker for clearance.

I will try some shims this eve.

thank's again, Keith
Joe Ricard
I oil the rocker shafts with the same oil I do everything else with. left-over 10W-30 You know from a partial bottle.

Hmm good idea about the stock push rod and the Manton tips. (wish I woulda thought of that.

Might still think of of that as a matter of fact.
G e o r g e
QUOTE(toon1 @ Oct 29 2007, 08:29 AM) *



You mentioned oil for the rockers, should it be on the tips of the adjusters?




I believe Joe is asking if you put any oil on your rockers, they look way to dry





edit joe beat me to it
toon1
there is oil on the rocker shafts, I didnt' oil the rockers themselvs.

I will put oil on tip of the adjuster tonight.

Joe I will take a pic of how I moded the p/r if you'd like.
Joe Ricard
What really want to know is how much of a clearance do you have between valve and piston.

Just for reference. I am aiming for .100 but don't think I am going to make it. Using play-doh as the measuring medium.
toon1
here are some more pics. I added .030 shims under the rockers blocks. the alignment looks good to me BUT the swivel foot is still far into the rocker.

I took the .060 off the rocker, how much more can I take off?

The cam card say's.426, I am getting .436, still within 5%.
toon1
2 more
Twystd1
Uhhhh...

1) Are you setting up your rocker GEO at HALF LIFT...???????
(I don't see that in these last pics)

2) AND are you using an adjustable pushrod to check GEO?????

3) If so (see #2) Is the adjustable pushrod have the same tip as the the other 8 full length pushrods that you will be installing in your engine?

4) Have you read Jakes article on Rocker GEO at his web site? It's a long read. And it might help you figure this out.

Clayton
toon1
QUOTE(Twystd1 @ Oct 31 2007, 12:13 AM) *

Uhhhh...

1) Are you setting up your rocker GEO at HALF LIFT...???????
(I don't see that in these last pics)

2) AND are you using an adjustable pushrod to check GEO?????

3) If so (see #2) Is the adjustable pushrod have the same tip as the the other 8 full length pushrods that you will be installing in your engine?

4) Have you read Jakes article on Rocker GEO at his web site? It's a long read. And it might help you figure this out.

Clayton



The second set of pics were taken with the rocker sitting at 1/2 lift.

I am using the adjustable p/r to check geo

The p/r does have the same tip I will be using

I have read (and re read, and re read biggrin.gif ) Jakes article.

I had to make a new adjustable p/r. It's quite a bit better than the one I was using. I went through the whole process again with the new p/r, without the rocker block shims.

Once that was complete, I was not satisfied with the 1/2 lift results so I added the shims and left the p/r locked at the same measurment.

I then added the shims installed the p/r, adjusted the swivel foot to make contact with the valve and cycled the engine.

The total lift was ok but the half lift geo was still off. I then made the corrections to the p/r and swivel foot.

after the corrections the FULL lift was good(i lost about .002 total lift but well within the 5% range) and the 1/2 lift geo was quite a bit better.

These are the second set of pics, after all the corrections, with he .030 shims and at half lift.

My p/r measures 251mm end to end w/o the tips, so 271 total length

I
toon1
icon_bump.gif el bumpo thank's guy's
Twystd1
Do me a favor.....

Throw a straight edge across ALL 4 valve stems. Tell me if they are all the same length give or take a hair.

And your last pictures look MUCH closer to correct.

Clayton
toon1
with the sraight edge on the tops of the valve stems.

the biggest gap I had was .013 on the #3 ex valve.

The other gap was .004

Twystd1
Your gaps are survivable.

If ya want it perfect. You will have to cut the stems to match height. Or get a new valve job. (not needed) (just depends on how anal you are)

It looks like you are on the right path.

Just keep it going. The first ones are the hardest. Then it gets faster. (NOT easier)

Here is a trick that Craig Downs taught me.

Grab yourself a stock pushrod (PS)

Cut it in half. (Hack saw or Lathe or arrow/pipe cutter)

Then thread the hollow end with the same thread as your rocker arm adjuster.
Then simply screw the half PS onto your adjusters. Place one on the intake and and one on the exhaust adjuster (the pair you are working on)

It will look like you just made the adjuster threaded section about 4 inches long.

Now with these extensions screwed onto the adjuster.
It is MUCH easier to visually see the alignment of the adjuster VS the stem angle as you look across the valve train.

It's kinda like trying trying to make a big wall plumb with a 2 inch level.
If you put a 6 foot level on the wall. You can stand back and really see the angles easily.

This a GREAT tool to see what the hell you are doing.

I can't thank Craig enough for this tip. KMA.gif
It works very well and saves time.

This tool should be mandatory for a first timer. (as well as us old guys with shit for eyes)
As it SHOWS the stem / rocker angles in a way that you can get your HEAD AND EYES INVOLVED IN THE PROCESS WITHOUT HAVING TO CONSTANTLY SECOND GUESS WHAT YOU ARE REALLY SEEING.

By the way. While you are in there. Just for shits and grins. After you have set your GEO on one pair of Intakes and Exhaust valves.

Run the cam up to full lift. Check how much clearance you have for coil bind. Since I have no clue what you are using for springs. This is always a good practice. Coil bind kills parts... QUICK.

It's also a good time to find out if any valves are hitting pistons once the GEO is done on one cylinder.

If you are building a known combo. This will probably not be a problem.
Just thought you might like the technical exercise.

I dunno. Is there anything else we can help you with?

If we are lucky. Jake will pop in and take us all to school.

I reiterate. PM Craig Downs for more input. He is VERY good with this and he taught me a trick or 2 I that didn't know.
But he is kinda ugly and smells bad.... Thats just some of the shit you have to put up with dealing with Craig. chair.gif agree.gif

Cheers,
Clayton
craig downs
ahhhhh I guess its time to say something and probably will get spanked but what the hell.
While I was doing mine it was difficult to see the adjuster lining up with the valve
stem. So I thought if the adjuster stem was a little bit longer it would be easier to see the angle. What I came up with was to cut about a 4" piece from a stock push rod and
chuck it up in a lathe and face the cut end so it will be square. Then tapped the end to
thread over the stem of adjuster. Then I took a valve with a flat face and set it on top of the valve stem next to the one I was measuring and lined it up with the extension I made. It really made it easier to see. If anyone is interested I can take some pics.
toon1
thank's guy's, I will give that a try.

Since the geo is getting better with the spacers under the rockers should I try another spacer( I have .030under them now) under the rockers or remove a little more material from the rocker( say go to .080 )?

Should I do a geo on every valve and have a custom length p/r for the individual differences?

Joe Ricard
That extension thing on the Rocker adjuster is pure genious.

OK you mentioned piston to valve clearance. What do you guys shoot for. I have had replies on other boards stating he thought .100 depth and .050 edge was a good number.

If I go that far I will be through the thickness of the dome and into the crown of the piston. I need to measure how much meat there is on these Arias Pistons. Don't want to go too thin (what would too thin be exactly)?
Joe Ricard
Bump for the evening crowd.
Obviously the day surfers on this board don't know.
HAM Inc
The geometry in the last photo looked a lot better.

Clayton is correct that the valve stems all need to be level. If they are off it will effect valve timing. The biggest impact will be on the cross-over point. This is the point during intake and exhaust valve overlap when the exhaust is closing and the intake is opening, but both are off their seat the same amount. This is an extremely critical point in the engines cycling. Sharp race engine builders will check the cross over points on each cylinder (requires a dial indicator on each valve) to ensure that they occur within a * of each other, that's + or - 0.5 *. No point spending the bucks on the cam and all of the other innerds if the valve stem ht's are all whacked. I guarantee the stem ht's on every head that leaves my shop are + or - .005" of each other.

Here's a trick for setting geometry that de-confuses the relationship between pushrod length and rocker shims. Remove the valve springs. Purchase a couple of shaft collars that are the size of your valve stems. Set the head on a bench with the valve stems up. Slide the collars over the valve stems (one for intake and exhaust) and set them so they will hold the valves open at half lift. A caliper works fine for this. With the valves in the half lift position set your rocker assembly in place with the valve adjuster locked where you want it. Now just keep adding shims until you have the proper geometry, which is the adjuster in line with the valve. If the intake and exhaust have different lifts you may have to make adjustments to one of the adjusters to level them both out. You may also have to make adjustments to your screws if the first positions you try are in-between what you can level with the available shims. Once you have that worked out, set the head on the engine and bring your adjustable pushrod in, adjust it to take out the slack. Now you have the correct shims for proper geometry and pushrod length to fit the space.
This works because the pushrod has nothing to do with proper geometry. The proper geometry is a function of the relationship between the rocker arm and the valve, period. This would be easier if the adjusting screw was in the pushrod side of the rocker like HP domestic rockers and some hi-lift rockers.
toon1
thank's for the reply and the good info.

How many shims can I add?

There is already a .030 shim there, this made the geo much better. Can I add more or is it going to get too high?

Is the geo in the last pic. good or does it still need adjusting?

After laying the sraight edge accross all the valve tops and finding one was lower by.013 than the rest, what can be done or will it bee ok if the geo on that valve is done correct?

should I get a * wheel and check the valve timing you suggested?

thank's, Keith
Twystd1
Do not take any more than about 60 thou off the rocker.
NOTE: I typically polish the underside of a cut rocker to help mitigate stress risers in the metal.
Shot peening is also necessary of ya have big spring pressure IMHO.

NEXT:
I helped a guy last year with GEO. It was an unknown combination to me. It took 60 thou + under the rocker stands to make the GEO work.

This engine is still running in his race buggy. No problems and he has a full season PLUS on this engine (So Far)
And he has around 200 pony's to have fun with.

In truth. I don't know what the max is. Me thinks you will have to shim until you get it right. PERIOD.

Irrelevant of the shim thickness.

Thats my .02 worth.

And THANKS for chipping in Craig and Len.

I learn something every time one of these threads come up.

Clayton
Twystd1
CRAIG.....

Post up pics of your PS tool / arrangement.

(I'm sniffing a Craig sticky in the making)

Len, Do you have any pics for the setup you suggested earlier?
I understand it. But others may not.
(Might have to make another sticky for this as well)

Clayton

Clayton
toon1
I took another .020 off the rocker. I got your post too late. Oh well, I think it will bee ok, it's a stock 1.7 an will rarely ever see more than 5000rpm.

I was able to get a good 1/2 lift alignment but the top of the swivel foot is still close to the bottom of the rocker.

I think i will shim it to .050 and do it all again, this will get the foot away from the rocker.

I was able to get .441 lift form the #3 int. and .416 on the ex. the p/r measured 251.66 on the int. and 251.55 on the ex w/q the tips

On cyl. #4 I got .438 int. and .416 ex BUT the p/r measured 251.78 and 252.05 on the ex.

Should I avaerage all the measurements from all 4 cyl's and then cut the p/r to the avarerage?
Twystd1
Since your engine was't machined perfectly to a known spec.

I suggest you measure ALL 8. No if's and butts...

No averaging here. You have too many unknown tolerances.

Like I said. It takes me a whole day to get it right if there are ANY discrepancies from cylinder to cylinder..

I like to learn. Thats just part of the payment to learn......

Cheers and go kick some rocker geometry ass...!!!!!!!!!!!!!!!!!!!!!!!!!

Clayton
toon1
QUOTE(Twystd1 @ Nov 1 2007, 10:45 PM) *

Since your engine was't machined perfectly to a known spec.

I suggest you measure ALL 8. No if's and butts...

No averaging here. You have too many unknown tolerances.

Like I said. It takes me a whole day to get it right if there are ANY discrepancies from cylinder to cylinder..

I like to learn. Thats just part of the payment to learn......

Cheers and go kick some rocker geometry ass...!!!!!!!!!!!!!!!!!!!!!!!!!

Clayton


I will be doing all 8. If they are within .5mm, that's real close. My thought was to take an average of all eight instead of making a custom p/r for all.

I added shims to take it to .050 of shims, the swivel foot is comfortably farther away now and the geo looks REAL good, I think I got it aktion035.gif .

I will do all eight tommorow and see how it goes from there.

Does anyone have 1 chro mo. pushrod and 1 tip, the style Jake sells?? I need 1
craig downs
Ok I'll try to get some pics tomorrow.
Hmmm putting a straight edge across my stems shows my stem heights off quite
a bit also.
Twystd1
TOON,

A half a MM is way to much to average

Do each pair of rocker pads with shims that get you what you need.
Then measure EACH pushrod for length.

You may end up with 8 different pushrod lengths. So be it.

There is no reason to leave lift on the table. Get all you can get.
This also helps EACH cylinder run the same. If the GEO is out of whack. The engine is fighting itself to get RPMs. It's kinda like having an engine that is out of balance. I am not sure how this works. A guy named Smokey Yunick wrote about it many years ago. I never forgot that.

Do it once. Do it right.

It is this kind of measuring and re-measuring that makes for a great engine. A Type IV takes me Soooooo long to build. Perfection takes time.

AND THE RESULT IS SO WORTH THE TIME AND CARE YOU GIVE TO YOUR ASSEMBLY.

A well assembled and machined engine even SOUNDS different than a typical engine. They sound kinda of like a sewing machine at full song. No rattles, No weird noises. Just this beautiful mechanical sound that is very consistant and harmonious.

Taking the time to do it right has so many benefits.

The exhaust note will be perfect... Just wait and see....!!!!!!!!!!!!!!!!!!!!!


Craig,

Who did your heads...??????

Was it one of my guys??? if so. Send it back and get it done right if possible. I will personally follow if needed.

If'n it's somebody else. Make a phone call and see what they say.

Cheers,
Clayton
purple
I guess it's kindof a newbie question and all, and I dont know what stage your engine build is at. Aren't you missing your pushrod tube retainer spring?
toon1
QUOTE(Twystd1 @ Nov 2 2007, 01:27 PM) *

TOON,

A half a MM is way to much to average

Do each pair of rocker pads with shims that get you what you need.
Then measure EACH pushrod for length.

You may end up with 8 different pushrod lengths. So be it.

There is no reason to leave lift on the table. Get all you can get.
This also helps EACH cylinder run the same. If the GEO is out of whack. The engine is fighting itself to get RPMs. It's kinda like having an engine that is out of balance. I am not sure how this works. A guy named Smokey Yunick wrote about it many years ago. I never forgot that.

Do it once. Do it right.

It is this kind of measuring and re-measuring that makes for a great engine. A Type IV takes me Soooooo long to build. Perfection takes time.

AND THE RESULT IS SO WORTH THE TIME AND CARE YOU GIVE TO YOUR ASSEMBLY.

A well assembled and machined engine even SOUNDS different than a typical engine. They sound kinda of like a sewing machine at full song. No rattles, No weird noises. Just this beautiful mechanical sound that is very consistant and harmonious.

Taking the time to do it right has so many benefits.

The exhaust note will be perfect... Just wait and see....!!!!!!!!!!!!!!!!!!!!!


Craig,

Who did your heads...??????

Was it one of my guys??? if so. Send it back and get it done right if possible. I will personally follow if needed.

If'n it's somebody else. Make a phone call and see what they say.

Cheers,
Clayton



QUOTE(purple @ Nov 2 2007, 02:33 PM) *

I guess it's kindof a newbie question and all, and I dont know what stage your engine build is at. Aren't you missing your pushrod tube retainer spring?


Thank's Clayton, I had a person in santa clare do the heads.

I finished all the geo and it turned out good. The lifts are all within .002 of eachother for intake and .001 on the ex.( 3 came out exactly the same). I will say there are differences in the p/r lengths.

I will get some .015 shims and add them to the shorter length p/r that should even things out.

There where a couple sets of valves that had the same p/r lenths for the int. and ex.

My p/r sets measured cyl#1 252.48 both lift.435int .417ex

cyl. #2 252.5 ex and 252.3 int lift .439int. .417ex

cyl#3 251.98 both lift .439int .415ex

cyl. 4 251.8 both lift .439int. 417ex


Purple, the p/r tube springs are missingbut i'm not ready to button it up yet.

Thank's again, Keith
Twystd1
Excellent job Keith.....!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

What else do you need help with.?????

Clayton
toon1
DO those #'s look good?

Thank's for the offer, right now I am on hold. I want to add the .015 shims to the rockers that have the shorter p/r's and see if I can get things a bit closer. All that is left is to cut the p/r's.

I am getting new pist and cyls. this week, I tried to make swome old pistons work but I'm not comfy with them. I will bite the bullet and get a new set.

I am mounting the VR sensor for the 36-1 wheel

Thank's for all the help, Keith

Twystd1
Keith,

YOU WILL HAVE TO START OVER ON YOUR GEO WITH NEW CYLINDERS.

DON'T CUT YOUR PUSHRODS YET....!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Yo, if the cylinder heights (lengths) are ANY different from what you are using now. (and it will be different)

Your engine will either shrink or grow with different cylinders. Therefore different PR lengths.

By the way. Since you are getting P&Cs. Here is a notion for you.

I hope the following makes sense. It is difficult to write what I see in my mind and on the bench.

Check the length of the new cylinders for length. Write that measurement down. If they are different lengths. Machine them for equal INSTALLED length.

Else your back to odd ball GEO issues.

Now mock up your engine to make sure it all fits correctly.

If your cylinders are EXTREMELY close in length. And your GEO is still wacky. It's possible your cylinder registers are collapsing. Thats the area of the block where your cylinders sit.

Thats is a somewhat common problem for the POST 1973 2.0 cases.
I think the date is right.

I learned this data from Jake Raby over at his web site. I hope I have accurately stated it here.
He has taught many of us how this all works. Thats a grateful plug for Jake.

SO: Just for shits and grins. When you pull your cylinders. Find a dead nutz flat steel and see if you can find any depressed points on the cylinder registers.
X and Y this area and use a feeler gauge to check clearances. You should be able to eyeball this area if there is any demonstrative depressions in the block.

If it looks depressed from the outside of the register to the innermost of the register. Fix it.

If so. You will have to pull your studs and have your case machined flat. (Unless you have already done so) And hope the problem doesn't repeat itself. Or toss the case and start anew.

If you have this issue. And you don't rectify it. Your PR lengths MIGHT be all over the place. And your rocker adjustment will change for no known apparent reason. And the propensity for the heads to loose their torque settings is possible.
(Block is shrinking)

Maybe I am giving you too much to think about. You block probably has no issues with this..... Then again... While your there........

Thats just the way I am about these engines. And I don't know shit compared to some others. Yet I have checked one of my 1.8 blocks and one of my 2.0 blocks and found they had this collapsing problem. Not bad mind you. But enough to possibly build a very expensive boat anchor if I didn't address this possible issue.

If there is any other way I can help confuse your build.. Please ask.......

Measure...measure....measure. Mock it up as many times as you have to and make it all fit right.

Cheers,

Clayton
orange914
QUOTE(toon1 @ Oct 29 2007, 08:29 AM) *


I placed the dial indicator back into position for the pic but didn,t really alighn it well with the valve stem. When I am checking the lift I make sure it's alighned.


where axactly does the indicator go? wouldnt anywhere on the spring retainer do the same?
toon1
Thank's Clayton, I'll wait till the cyl's come in before going on.

Mike, there is a flat spot onthe top of the spring retainer that you can put the tip of the indicator on. It is imprtant to get the indicator shaft lined up with the valve stem. For fun , I missaligned the ind. and rotated the motor and did notice a couple thu. difference.

Keith
craig downs
where axactly does the indicator go? wouldnt anywhere on the spring retainer do the same?
[/quote]

It can go anywhere on the top of the retainer just make sure its at the same angle as the valve. I found it was getting a little crowed with the dial indicator there so I made a little foot to go on the bottom of the dial indicator to offset the indicator off the retainer. I cut a piece of sheet metal bout 1/4" wide X 3/8 long and drilled a little hole at one end. Then I unscrewed the little point on the bottom of the indicator and put the foot I made on and screwed it back on the indicator.
Twystd1
To the guy that just PMed me about how to INSTALL the dial indicator

Bolt a piece of flat stock to the intake manifold studs. Use your existing nuts to hold the flat stock down.
(EEEwww.. That might hurt a little)

Use that and a magnetic base.

Or clamp to fins. Or anything else you can make up.

Just make up shit till it works. Ingenuity is the tool of choice here.

Also go back and reads Len Hoffman's response on this thread. He has a REALLY trick idea you might use.

Can't wait to try it myself.

Clayton
toon1
QUOTE(Twystd1 @ Nov 3 2007, 12:00 AM) *

To the guy that just PMed me about how to INSTALL the dial indicator

Bolt a piece of flat stock to the intake manifold studs. Use your existing nuts to hold the flat stock down.
(EEEwww.. That might hurt a little)

Use that and a magnetic base.

Or clamp to fins. Or anything else you can make up.

Just make up shit till it works. Ingenuity is the tool of choice here.

Also go back and reads Len Hoffman's response on this thread. He has a REALLY trick idea you might use.

Can't wait to try it myself.

Clayton


Lens trick of putting the collar on the valve stem is trick
HAM Inc
Been out of town for a few days, so I just got up to speed on where the thread has gone.

Clayton I think you'll like this method of setting the geo. I wish I had photos, but I don't.

A couple of things I should have pointed out were; that once the rocker spacers are set you need to reinstall the springs before setting the heads on, and rotate the cam lobe so the heel of the cam is in position (180 cam *'s from max lift). This works if the cam lobe is symetrical. If the cam lobe is asymetrical (not so comon on street cams) then what you'll want to do is bring the lobe to half lift, (taking a measurement directly at the lifter) and lock the crank in position. In this situation you are not going to install the springs before setting the head back on the cylinders. Leave the lock collar in position on the valve. Now when you run your adjustable pushrod up you are doing so with the cam lobe at half lift and the valve at half lift as well.

The lobe doesn't have to be asymetrical to use this particular step, but is neccesary on asymterical lobes. You can take the half lift reading on the lobe with any cam and lock the crank down.

If you use the symetric lobe method and don't end up with the same geo you had with the lock collars holding the valves at half lift then you may have an asymetric lobe. Just rig up a way to measure lift at the lobe and eliminate that variable. If the lobe is at half lift and so is the valve when you set the pushrod length, then no additional variables can effect the outcome.

I hope this makes geo easier, as I know what a pain it is to go fishing for it using other methods.
This is a "lo-fi" version of our main content. To view the full version with more information, formatting and images, please click here.
Invision Power Board © 2001-2024 Invision Power Services, Inc.