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  #16 (permalink)  
Old 01-01-2013, 12:47 AM
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Originally Posted by cobalt327 View Post
Do the valves w/the 0.250" tips have the 30 degree backcut like used on the Vortec valves? If not, it will likely be cheaper- and might run a tic better- by using Vortec valves to replace the non Vortec valves.
Just did a quick measurement on my assembled c/n 062, L31 Vortec heads (has stock Vortec valves) and found the split lock-to-valve tip measurement to be the same as on an assembled pre-Vortec 2-groove valve head (c/n 441). In other words, the Vortec valves I have do not have a longer tip than a standard SBC valve. I do not know if that was something GM changed during the production run of Vortec heads, or if this is normal for ALL L31 Vortec heads.

The Manley stock installed height 1.94" intake valves all have .250" (standard) length tips except for one 0.290" valve (p/n 11860-8) in the Race Master series.

Manley stock installed height 1.50" exhaust valves all have .250" (standard) length tips except for one 0.290" valve (p/n 10077-8) in the Budget Replacement series.

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Old 01-01-2013, 01:12 AM
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Tomorrow I'll measure ALL the valve tips on my old, bad set of #906 castings. I KNOW all those valves are the original parts. Sometimes I think "The General" just uses whats available! Especially if it was assembled on a Friday afternoon! BTW, the (my) short-tipped valve HAS the backcut. What I DO know is that for MY particular application I need the .290" tips. The carmakers sure don't make it easy, do they? Oh, and Happy New Year!
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Old 01-01-2013, 02:01 AM
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Originally Posted by flyingputz View Post
Tomorrow I'll measure ALL the valve tips on my old, bad set of #906 castings. I KNOW all those valves are the original parts. Sometimes I think "The General" just uses whats available! Especially if it was assembled on a Friday afternoon! BTW, the (my) short-tipped valve HAS the backcut. What I DO know is that for MY particular application I need the .290" tips. The carmakers sure don't make it easy, do they? Oh, and Happy New Year!
It's not as bad if you need intake valves bigger than 1.94".

BTW, if you use stock diameter springs you might want to use the stock Vortec retainers- they're made to have plenty of clearance for self aligning rockers.

BTW II, all I have been able to find regarding replacement Vortec valves (or more correctly, valves used w/self aligning rockers like Vortec and LT1/4, etc.) is:

Intake- 0.260" groove to tip length
Exhaust- 0.289" groove to tip length

Why exhausts are longer I cannot say, but the first time the intake valve tips are reground, that extra 0.010" is all but gone. And as I said earlier, this is not like my Vortec valves- they're standard length tips. So take it for what it's worth- all I can say is a stock 0.250" tip is plenty for use w/the stock valve train.

Last edited by cobalt327; 01-01-2013 at 02:25 AM.
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Old 01-01-2013, 06:46 AM
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It is the keepers, not the retainers, that interfere with the self aligning rocker arm rails or nubs when using valves with .250" tips.

I furnished my engine builder with the Ferrea 5000 Series SBC valves with .256" tips and later found the problem with the keeper to rocker rail interference. After discussing the problem with my machinist, he told me the Chevrolet heads that use self aligning rocker arms have valves with .260" tips (int.) and .289" tips (exh.). He recommended Manley Race Master Series SBC valves with .290" tips, intake and exhaust. Manley Race Master Series 11863-1 and 11860-1 valves with .290" tips provides .035" clearance between the10* keepers and the self aligning rocker arm rails, when using beehive valve springs. I am using 10* keepers which are wider across the tip of the valve than 7* keepers. When trial fitting the Scorpion self aligning roller rocker arms with the Ferrea SBC valves that have .256" tips, the self aligning rocker rails actually rode on the the 10* keeper and not on the valve!

The beehive retainers are smaller in diameter (1.055" O.D.) and sit lower on the valve stem than standard valve spring retainers and do not present a problem with self aligning rocker arms.
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Old 01-03-2013, 02:56 AM
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Well, I pulled, cleaned & measured all the valves off my bad set of vortecs and here's what I found. ALL intake valves are a bit shorter than the exhaust valves. 4.88" vs. 5.91". The lock groove to tip is ALSO shorter on the intake valves. .260" vs. .290". Looks like I can use all the exhaust valves but will have to purchase new Manley intake valves. I wonder what the reasoning was for the valve variation? This would make the valve FACE to lock groove identical. Hardened tip inserts, perhaps?
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Old 01-03-2013, 08:02 AM
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I used Manley Race Master Series SS valves that have .290" tips and are 4.951" long.

I used those valves with Comp Cams 26918 beehive valve springs, 10* keepers and retainers. We equalized the beehives at 1.750" with 144 lb. seat pressure and 330 lb. at .500" valve lift, according to a Rimac spring tester.
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Old 01-03-2013, 08:15 AM
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Just a thought I emailed one of the guys at comp to see what I needed to give me more lift on my 906's and he hooked me up with a parts list of what I needed that handles .600 lift with no machining. I know u said youy already had parts but if you cant figure it out this is another option.

Good luck
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Old 01-03-2013, 12:41 PM
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Quote:
Originally Posted by flyingputz View Post
Well, I pulled, cleaned & measured all the valves off my bad set of vortecs and here's what I found. ALL intake valves are a bit shorter than the exhaust valves. 4.88" vs. 5.91". The lock groove to tip is ALSO shorter on the intake valves. .260" vs. .290". Looks like I can use all the exhaust valves but will have to purchase new Manley intake valves. I wonder what the reasoning was for the valve variation? This would make the valve FACE to lock groove identical. Hardened tip inserts, perhaps?
Oops... I meant 4.91", NOT 5.91". Thats the plan Mousefink. The Manley race master intakes. I may not have to use the +.050 locks with them being that they're .050 longer. $119 for 8 @ Summit. Thanks.
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Old 01-03-2013, 12:47 PM
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Originally Posted by ChevroletSS View Post
Just a thought I emailed one of the guys at comp to see what I needed to give me more lift on my 906's and he hooked me up with a parts list of what I needed that handles .600 lift with no machining. I know u said youy already had parts but if you cant figure it out this is another option.

Good luck
Comp parts gave me what I needed as far as lift and retainer clearance. It DIDN'T give me my needed rail rocker to lock/ retainer clearance. Make sure you check this if you go that route! It probably wouldn't have been an issue with use of guide plates and NON self- align rockers.
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Old 01-03-2013, 02:03 PM
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Originally Posted by flyingputz View Post
Oops... I meant 4.91", NOT 5.91". Thats the plan Mousefink. The Manley race master intakes. I may not have to use the +.050 locks with them being that they're .050 longer. $119 for 8 @ Summit. Thanks.
If you budget can take it, use Manley 4.951" intake and exhaust valves with .290" tips. The reason the GM Vortec intake valves have .260" tips and the exhaust valves have .289" tips is because the intake valve margin is .050" and the exhaust valve margin is .080". That makes the intake valve .030" taller in the head.

My machinist uses a Serdi valve grinding machine and the finished intake and exhaust valve tip heights were identical using a .050" intake valve margin and .080" exhaust valve margin. When I picked up the heads at the shop, the first thing I did was to place a steel straight edge on the valve tips and all valve tips touched the straight edge. There is no reason to use +.050" locks with the Manley valves if the valve seats are ground with .050" intake and .080" exhaust valve margins using a Serdi machine.

I furnished a set of +.050" locks to my engine builder in case he needed them to use with shims in order to eliminate the exhaust valve rotators and achieve 1.750" spring height. Standard Vortec spring height is 1.700" . He eliminated the rotators with .090" Alex's Parts hardened valve spring shims without using the +.050" locks.
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Old 01-03-2013, 03:18 PM
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Quote:
Originally Posted by cobalt327 View Post
Just did a quick measurement on my assembled c/n 062, L31 Vortec heads (has stock Vortec valves) and found the split lock-to-valve tip measurement to be the same as on an assembled pre-Vortec 2-groove valve head (c/n 441). In other words, the Vortec valves I have do not have a longer tip than a standard SBC valve. I do not know if that was something GM changed during the production run of Vortec heads, or if this is normal for ALL L31 Vortec heads.

The Manley stock installed height 1.94" intake valves all have .250" (standard) length tips except for one 0.290" valve (p/n 11860-8) in the Race Master series.

Manley stock installed height 1.50" exhaust valves all have .250" (standard) length tips except for one 0.290" valve (p/n 10077-8) in the Budget Replacement series.
GM increased the length of all valves between the lock groove and tip starting when they went to self guided rockers, if you use valves for the older not-self-guided rocker heads there will be less distance between the lock groove and the tip there will be contact between the rocker and the retainer.

One of those damn little details to keep track of.

Bogie
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Old 01-08-2013, 02:53 PM
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Would it not be more cost efficient to install the guide plates under your screw in studs and swap out the rockers rather than redesign your intake valvetrain? I'm assuming this would be easier than the swapping valves and locks and keepers. Are your current pushrods hardened? If so this route would cut back greatly on labor as well. Another thing comes to mind is the center bolt valve covers vs. the sbc style as he non self allinging Are narrower to allow for clearance on the vortec bolt patterin.
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Old 01-09-2013, 03:49 PM
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Originally Posted by flyingputz View Post
I didn't think lash caps & rail rockers would go together, no clearance there. I was just looking at them & realized that. I'm kinda leary about shaving down the rails. I sure don't want to turn 'em into paperweights. Could I switch to guideplates if I remove the rails, or muck 'em up trying to shave 'em down? I certainly don't need any extra expense (new valves) if not absolutely necessary. Thanks for your input.
I was looking for that option but got no input on going that route. Too late now, new valves (intake & exhaust) are on the way. $240 later! My NEXT set of vortecs will be MUCH easier!(if I ever use 'em again!) No biggie, I'm opening up spring pockets anyway even though machinist I used said they were good to go. MY opinion differed.
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Old 01-10-2013, 06:05 AM
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I used 10* Super Locks designed for lash caps on my first pair of heads with SA rockers and they provided additional clearance for the SA rocker arm rails. I put about 4,000 miles on them with no problems. I did not use the lash caps, just the locks.

I replaced those heads recently and used regular 10* locks and Manley SS valves with .290" tips. That is the proper way to do it. The .290" tips provide .035" clearance between the locks and the SA rocker arm rails.
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Old 01-10-2013, 10:44 AM
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Originally Posted by flyingputz View Post
I was looking for that option but got no input on going that route. Too late now, new valves (intake & exhaust) are on the way. $240 later! My NEXT set of vortecs will be MUCH easier!(if I ever use 'em again!) No biggie, I'm opening up spring pockets anyway even though machinist I used said they were good to go. MY opinion differed.
Unfortunatly there is no in-expensive solution from where you're at with this engine. Probably the least complex are these lash locks which will add virtual length to the stem above the retainer but cheap they ain't. >>> Manton "Lash-Locks" <<<

I wouldn't get carried away enlarging the spring pockets on production Vortec heads. This can easily weaken the pocket edge where it locates above the port as it turns into the pocket. This often becomes a failure point opening a crack as the head gets some miles on it. If you need better springs the production Vortec is way better off with beehive springs that fit into the production spring pocket.

Bogie

Last edited by oldbogie; 01-10-2013 at 10:44 AM. Reason: your to you're
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