Oh boy. Valvetrain geometry issues.

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JoePole1

JoePole1

A dude in a B body
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Hi Guys. Yet another stumbling block in my build. I'm at the point where I need to measure for pushrods and I am noticing that, using a straight edge, my valve stem tips are at different heights. I am running EQ heads with Hughes 1199 valve spring kit and stamped steel rockers and roller lifters. The heads are used but the seats look excellent. I replaced a few intake and exhaust valves because a couple were bent and I chucked all the others in my drill press and had slight runout on some. Thinking that the replacement melling valves may have been longer, I pulled the "taller" valves and some are the original on the heads so not associated with the new valves. Rough measurement with feeler gauge and straight edge has worst at about .012".
Is there an acceptable amount of difference between valve tip heights?
 
Jus' sayin' I don't know too many drill presses that are accurate enough to be 'the standard' to check runout.........
 
I wouldn't worry about .012 difference, personally. I have a set of heads where the exhaust are about .015" different than the intakes. I'm sure it was a setup issue, but they will be run as-is.
 
I've seen worse than that. Since I run mainly hydraulic flat tappet cams a set of adjustable rocker arms can compensate for that little difference. 65'
 
Thanks guys. As far as the pushrod measurements....use the lowest valve as the length reference because that will lift the most.
Correct?
 
E8521156-85FC-45E3-9980-7C2EFB5E0A3A.jpeg
I’m running the same setup, even the used EQ heads :)
 
JoePole1 said:
If you want to pick up the tab....I'm in. Are those Hughes? Have you run them yet?
Click to expand...

They are Hughes, the only thing I changed were the Locks for the rockers, they just had the old Teflon threaded lock that will back off over time.
They are small block Chevy 1.6 rockers that Hughes just puts in a kit, I didn't buy mine from Hughes, I got mine on a trade for some MP Performance BB Valve covers.

I'm using these Hardened push-rods from Speedway

Small Block 302 Ford Push rods, 6 7/8 Inch
Part #: 91514100

After I installed them and did a geometry check, they are working pretty good.

I have not ran the motor yet, but so far they are rubbing the permanent marker on the valve like they're supposed to. When I tried to use the original stamped rockers, they were way off even with the original push-rods.
 
ideally, they should all be the same, especially if you run rocker shafts, but for your Magnum heads and the small difference in valve heights, I wouldn't worry too much. If you really wanted to, and had access to a valve grinder, you could grind a little off the stem ends of the longer valves.
 
JoePole1 said:
Hi Guys. Yet another stumbling block in my build. I'm at the point where I need to measure for pushrods and I am noticing that, using a straight edge, my valve stem tips are at different heights. I am running EQ heads with Hughes 1199 valve spring kit and stamped steel rockers and roller lifters. The heads are used but the seats look excellent. I replaced a few intake and exhaust valves because a couple were bent and I chucked all the others in my drill press and had slight runout on some. Thinking that the replacement melling valves may have been longer, I pulled the "taller" valves and some are the original on the heads so not associated with the new valves. Rough measurement with feeler gauge and straight edge has worst at about .012".
Is there an acceptable amount of difference between valve tip heights?
Click to expand...
Do you know for sure the reason these used heads had some bent valves? The Engine Quest heads were really castings, but a lot of them were sold assembled with guide clearance that was too tight. That caused a bunch of stuck valves that resulted in all kinds of bent pushrods and valves and some broken valves with additional damage.
Also, if you slid in replacement valves without checking the clearance, you could have induced a guide clearance issue that will have the same results.
None of this has anything to with the varying heights of the valve tips, but needs to be asked before you start it up and run it, just to make sure it has been checked. If the guide clearances are NOT known to be in an acceptable range, it would be strongly suggested to remove the heads, have a competent shop check it and adjust as necessary, then while it's in you can have them check the valve job and correct the valve stem tip heights.

Now, if you know for sure the guide clearance is right, and the heads are already on, just get pushrods that give around .030"-.040" or so lifter plunger preload for the shorter tips, and make sure the plungers on the longer tips do not compress more .060" and you should be all set. That will get you to about the middle of the plunger travel safely.
 
Thanks. I had read about the EQ guide clearance issues and not know the history I took the heads to my machinist and he gave the thumbs up. With my reground cam and . 028 head gasket I checked and it looks like the factory pushrods are pretty close for the taller valves so many just get custom for the shortest valves. I am using a checking pushrod to verify.
 
Unfortunately no valve grinder either. Thought about that or even shimming the pedestals where possible. I am also checking the valve contact pattern.
 
I have read different process for measuring pushrod length.
First is to lengthened the checking rod so that it spins wit a little resistance using 1 finger to spin it and lock it, measure an add desired preload.
The second is to lengthen until you can no longer spin it using 2 fingers, then tighten, measure and add desired preload.I
I'm pretty sure the first is correct.
 
The best way is to physically measure the clearance between the lifter plunger and the retainer ring or snap ring. That is what you are actually setting. If the intake is installed and you cannot measure the clearance directly, you must choose one of your procedures. If the pushrod still spins easily with two fingers, add another .005" or .010" to your measured length AND extra length for plunger preload. If the pushrod is tight and is hard to turn, do not add anything to your measured length except the extra amount for your desired preload.
There is a a few thousandths difference in length between a pushrod that easily spins and one that does not spin easily.
 
Valve length is not what you measure but the INSTALLED height. This changes with valve face wear or too much ground from the face when grinding the angles of the valve seats, valve face seating area. High is generally good, low is usually not.
 
sully.....those are priced really good. Dang lucky chebby guys. That said did you use the factory 5.9 guide plates? Did you have to replace the pedestal studs?
 
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