entropy
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posted August 07, 2007 03:29 AM
 Edited By: entropy on 16 Aug 2007 04:27
Q: valve angle: new - Barbies back from rehab
Anybody know the angle which the valve stem makes with respect to the head?????
I used a VERY cool 90 year old Starrett angle measuring thing (vernier to 5minutes of arc) to determine the angle of the face of the valve pockets to the flat of the piston dome.
With that angle, i'd like to check against the valve stem angle to make sure the valve face is parallel to the face of the valve pocket (does that make any sense???)
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entropy
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posted August 07, 2007 04:53 AM
well entropy, why TF don't you just google it??
OK  its 12 degrees intake, 13 degrees exhaust
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Texas12R
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posted August 07, 2007 05:20 AM
I thought I was the only one that answered my own questions 
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woppi
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posted August 07, 2007 06:42 AM
no !!
quote:
I thought I was the only one that answered my own questions
no, no
i dont think so !!
me to !!!!
woppi
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dougmeyer
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posted August 07, 2007 07:52 AM
No that doesn't make any sense.
Why not put some blueing on the pocket and dry assemble the head with a valve in it. Push the valve down on the dome @TDC and spin the valve with your fingers, then look at the marks in the pocket. Highly unlikely that the pockets are machined at teh wrong angle, but I have seen it happen (usually on a custom piston).
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tcchin
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posted August 07, 2007 08:09 AM
I've had both Wiseco and JE pistons that were machined at the wrong angles Quite annoying. Lost compression plus no valve clearance - what a great combo.
WTFWGF (what will Google find)??
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rgeorge
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posted August 07, 2007 01:23 PM
Edited By: rgeorge on 7 Aug 2007 14:31
Just use the modeling clay method and check piston to valve clearance as usual. Dissect the clay in several places. If the valve face and the pocket are parallel the clay will be the same thickness from the front to the back of the pocket.
I wonder, does JE intentionally add a little extra angle to allow for piston rock? I doubt it, the angle would be tiny and is probably negligible if you have decent piston to valve clearance.
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TRNorBRN6001
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posted August 10, 2007 06:18 AM
How goes it Karl?
How did the valve angle and piston match up?
Give us an up date on the motor when you get a chance.
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VincentHill
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posted August 10, 2007 12:19 PM
quote:
I've had both Wiseco and JE pistons that were machined at the wrong angles Quite annoying. Lost compression plus no valve clearance - what a great combo.
WTFWGF (what will Google find)??
Both basically the same company! I use CP and the first set they made were made with the wrong relief and I called them / sent a e-mail at 4 AM EST and about 7 AM PST they knew what the problem was and were making me another set of Pistons and I had them in a week. Until I got real Stupid they lasted 3 years! I have another set and plan on the Schnitz NOS Controller to avoid my self inflected Stupidity!
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tcchin
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posted August 10, 2007 02:38 PM
CP only has forging blanks down to 75mm. The pistons I need are in the 73mm range. I understand that CP is staffed by former JE employees. I guess it's a pretty incestuous industry...
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entropy
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posted August 10, 2007 10:16 PM
quote:
How goes it Karl?
How did the valve angle and piston match up?
Give us an up date on the motor when you get a chance.
Gary,
the domes of the custom JE pistons are 12 degrees, just like they should be.
With the new pistons the CR was excellent (16:2 : 1 ) but the Intake PTV was just too tight for comfort .037-.038 @ CL = 8.
On Thu Andy modded the intake pockets by .014-.015 and i'm gonna see what my VTP is in an hr or so.
 scrossed
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entropy
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posted August 10, 2007 10:28 PM
quote:
Just use the modeling clay method and check piston to valve clearance as usual. Dissect the clay in several places. If the valve face and the pocket are parallel the clay will be the same thickness from the front to the back of the pocket.
I wonder, does JE intentionally add a little extra angle to allow for piston rock? I doubt it, the angle would be tiny and is probably negligible if you have decent piston to valve clearance.
Rob,
I use "TimChin'sTool" to determine VTP. The clay method certainly works (and also gives you lateral clearance) but Tim's tool is MUCH easier and i know my lateral clearance is fine.
interesting thought on dome angle and clearance to account for rock, but upon checking the JE dome angle is same as OEM design (12 degrees).
The "wedge" i saw when i used the clay method last summer was almost certainly due to piston rocking.
Thanks!
BTW,
you ARE coming down to the mile in Oct, n'est-ce pas??
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entropy
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posted August 10, 2007 10:33 PM
quote:
No that doesn't make any sense.
Why not put some blueing on the pocket and dry assemble the head with a valve in it. Push the valve down on the dome @TDC and spin the valve with your fingers, then look at the marks in the pocket. Highly unlikely that the pockets are machined at teh wrong angle, but I have seen it happen (usually on a custom piston).
Doug,
i pulled the motor down last tue and saw a beautiful circle of the valve face on the dome. Since these custom pistons have a dome with a peak (no flat part), i could see the entire imprint of the valve.
No missmatch in angles. Thus i needed a lil machine work which is done. today i will find out if it worked.
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VincentHill
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posted August 11, 2007 05:38 AM
quote:
CP only has forging blanks down to 75mm. The pistons I need are in the 73mm range. I understand that CP is staffed by former JE employees. I guess it's a pretty incestuous industry...
Disgruntled ones that wanted Better! When I spoke to Mahle about Pistons, they mentioned CP and Cosworth but no others as their Competition! WIerd how JE is owned by Wiseco and it is not the other way around!
Too Bad they do not have less than 73 MM
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entropy
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posted August 11, 2007 06:03 AM
For those interested in this kind o' stuff, here are the morning results VTP vs cam CL's:
Int cam CL @ 103, VTP min .040" @ 10degrees aTDC
Int cam CL @ 105, VTP min .050" @ 10degrees aTDC
Int cam CL @ 108, VTP min .062" @ 10degrees aTDC
Exh cam CL @ 105, VTP min .084 @ 7.5degrees bTDC
Exh cam CL @ 110, VTP min .106 @ 7.5degrees bTDC
Exh cam CL @ 115, VTP min .122 @ 7.5degrees bTDC
If i measured stuff right, these VTP's will allow some cool cam timing tests
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dougmeyer
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posted August 11, 2007 07:41 AM
Nice , Karl
If those circles were caused by "no deposits" rather than actual contact, you've found the optimum set up. This is just what I love to see. Pistons looking like that put a smile on my face (is that weird?).
I've used Cosworth and Mahle pistons whenever possible and I think they are probably the best in the world. They are expensive and not always available quickly or in the design you need (because of their large European market) but they are unmatched in quality.
I installed my first set of JE's (4" bore in 283 Chev to build a 301) in 1962 and even through all the various ownerships always preferred them.
Doug
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tcchin
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posted August 11, 2007 07:06 PM
Nice work, Karl! Did you have a chance to cc the piston after Andy machined it? I'm curious to see what CR you have now. Also, I can't wait to see where your cam timing ends up. Those dyno runs should be a lot of fun to watch.
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entropy
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posted August 11, 2007 10:42 PM
Tim,
i always cc the assembled combustion chambers, did all 4 of them before the Andy machining, and all 4 afterwards. Unfortunately, 1 of the 4 always seems to leak thru the valves no matter how carefully i try to grease em 
Anyway, CR was 16.2:1 before machining, 15.6:1 after.
I lost about 0.5:1, which i don't like, but i am really happy with the flexibility the added VTP gives me for cam CL testing
BIG THANKS to YOU, Mr Chin! That VTP tool works flawlessly, and with the cam ends turned down to .750, the dial indicator probe has a nearly straight shot and readings are almost always 100% reproducible.
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entropy
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posted August 11, 2007 10:44 PM
quote:
Nice , Karl
If those circles were caused by "no deposits" rather than actual contact, you've found the optimum set up. This is just what I love to see. Pistons looking like that put a smile on my face (is that weird?)..
Doug
Doug,
the circle is just from contact, doing the VTP determination, but i am hopeful i am making progress.
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TRNorBRN6001
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posted August 14, 2007 12:23 PM
Yep, Karl will have hours of entertainment with the new cam degree capabilities.
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VincentHill
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posted August 14, 2007 01:39 PM
Since Stock is as low as 100 for the Exhaust, why did you not look farther?
DM, have you ever seen a Porsche 911 Piston? Even though Mahle the ones I have, the Bottom Ring land cannot be any thicker than 2 MM! I never understood why because when the Pistons failed, I WOULD Always see that part broken!
What did you have in your WOrld famous ZX11?
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dougmeyer
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posted August 14, 2007 09:34 PM
Cosworth
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entropy
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posted August 14, 2007 10:48 PM
Edited By: entropy on 14 Aug 2007 23:50
quote:
Since Stock is as low as 100 for the Exhaust, why did you not look farther?
.084 is about as tight as i want to go on exhaust,
exh CL @ 100 would be about .065+/-.
I didn't test exh CL at 100 cause that .060's is too tight and i don't want to take any more off the piston and lose even more CR.
I'm already "down" to 15.5:1 +/- to get CL flexibility on the intake side.
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tcchin
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posted August 15, 2007 10:19 AM
I run .060" on the roadrace bikes (where downshifting can cause the engine to exceed redline) and Muzzy recommended .050" on that 1375 that I cobbled together last year. Since you're going to be measuring anyway, you might as well check it at 100 just for giggles.
BTW, I noticed that all of your minimum PTV numbers happened at the same crank position regardless of which LC you were using. Is that just coincidence or did you only check at that crank position? The cam profiles I use make the crank position that's coincident with minimum PTV a function of LC.
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TRNorBRN6001
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posted August 15, 2007 10:21 AM
Are you headed to Andy's this weekend to enjoy the new cam variables?
Any pictures of the magic new pistons? I always enjoy looking at shiney
engine stuff, maybe a Garage Barbie as well!
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