Rocker geo, hoe does this look to you guy's Options

[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]

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 (IMG:style_emoticons/default/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]

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

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]

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.