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Discussion Starter · #1 ·
Trying to learn by the book; when I need help I've always found it here with you guys/gals.

Here's the deal: basically building up new from the 5.0L H.O block except keeping stock crank/pistons'connecting rods (all measured, within specs). Have Twisted Wedge heads/E303cam, FMS roller lifters and rockers.

Trying to follow Trick Flow's instructions for "Checking Piston to Valve Clearance and Valve Train Geometry". Have done the molding clay deal several times at the max adjustable pushrod length (6.75", +/- 0.050") and still cannot get a valve impression in the clay. I'm doing this with the guide plates installed; have tried with zero lash and with the measurement from the rocker fulcrum center-to-guideplate @ 1.150". Have done this 8+ times. I built my own mock solid lifter from an old donor lifter (same size as new lifter) by removing the internals and filling with BB's (after several attempts, finally have it "solid").

What am I doing wrong?
 

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Discussion Starter · #2 ·
Also, am I interpreting "Zero lash" correctly: tighten by hand until no play in pushrod?
 

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First off, checking push rod length is a completly different animal than checking valve to piston clearance. Do them as seperate animals and save some grief. With the valve at 1/2 total height, the roller should contact the valve tip smack dab in the center. Now leave the push rod length alone.

Place a glob of clay across the entire top of the piston without touching the cylinder walls. It should be about 1/2" deep or so. Spray a little WD-40 on the glob so the valve won't stick to it.

Now assemble the heads and valve train for that cylinder just like you would in final assembly. Spin it over a few times. Take it apart and measure.
 

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Discussion Starter · #4 ·
Bob, thanks for the advice; when I put the clay on as you suggest, this is to check piston-to-valve clearance, right? When I do this (with 1/4" thick clay - I'll use 1/2" now)how do I adjust the roller rocker? And I do use the target pushrod length to do this?
 

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FFCobra Fanatic
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Dale,

Those trick flow heads and a stock shortblock should use stock length push rods and valve clearance won't be an issue. Even with the e303 cam. My brother has that setup on his car. Tightening rollers is a whole different story and I'm sorry but I forgot how I did mine but I do remember using a feeler gauge for the correct gap instead of doing it the 3/4 turn way. Try looking in the chilton mustang book for valve train instructions.

good luck,

chris.
 

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Hydraulic lifters get adjusted the same way, whether they are roller or not. Set them to zero lash, and add 1/8 to 1/4 turn. Hot or cold, doesn't matter.

The same thing goes for the push rod length. Hydraulic or solid lifters, roller or non roller rockers, it's all the same concept. As the rocker arm tip moves up and down in it's arc, it will move laterally across the valve tip. You want to center that movement as much as possible to prevent side loads on the valve stem.

They clay on the pistons is purely to check piston to valve clearance.

Chris is right, with your combo you should have plenty of clearance. But I would check it anyway. It takes a little time, but no special tools and it's almost free. And it keeps you from sweating so much on the first start up.
 

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Discussion Starter · #7 ·
Thanks Bob & Chris. That sorts it out. However, Trick Flow specifically says I need pushrods ~ 1/2" longer than stock. I'll start after the coffee run this morning. G'day!
 

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Check with Trick Flow and you will find they specify a longer pushrod, which it sounds like you already have done. Stock length pushrods with Trick Flow heads will work, but will cause accelerated valve guide wear, which was a problem that plagued these heads when they first came out ( for that reason ).

As for checking for PV clearance with an E303 and 1.6 rockers, you'll have plenty of room and then some.

Check your piston top to deck height at TDC and if it's around .010, the block has probably not been decked. Even if it was zero decked, you should still have plenty of clearance with an E303.
 
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