Thread: Valve Lash

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Our 383 is getting close to coming out of machine shop and so my Dad and I are going to be starting the build with the parts we currently have. Had a few questions.

1. I’ve got a comp pushrod checker. Thanks to Richard and others, I’ve got a decent idea on rocker geometry. My question is, when I set valve lash (using solid lifters) for purposes of using the pushrod checker to get a length so I know what size to order, do I set valve lash to zero or actual lash per the cam card? I’ve heard it both ways.

2. If I do set lash to cam specs for purposes of testing for length with the checker, obviously the engine will be ‘cold,’ and I’ve read to subtract .006 from lash spec to get an approximate lash while engine is ‘cold.’ Is this acceptable?

Thanks

Strongly advise using this procedure.....
https://www.youtube.com/watch?v=o5is9BsH5OU

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That is an excellent video.

Let me ask this question since I need to ask it before I get into our build. I have Dart Pro 1 aluminum heads that came with guide plates and rocker studs (figured that was a bonus at the time as I did not expect heads to come with them). I am pretty sure the plates are not going to do me any good as I believe they are 5/16 (have yet to put caliper on it but think that spec is on the build sheet) and I plan to use 3/8 rods. So here's my question. How do I know the rocker studs that came with the heads will even work with the roller rockers I plan to get? In other words, do I need roller rockers, pushrod, and guideplate on head just to figure out if these rocker studs that came with head would work? Or is there another way?

Remove rocker studs. Order 3/8" guideplates. Put 5/16" plates on craigslist. Measure total length of stud, then measure from bottom of hex nut to top of stud. Call Crane, give them the measurements and cam specs and order rockers to match. Being a race motor, you may want to change the whole shebang over to 7/16", so I'd wait to talk to Crane before ordering guideplates. Badda Bing, Badda Boom.

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The Dart studs might already be 7/16, and are (if from Dart) some of the finest you can get(probably ARP)

As Richard suggested, I'll definitely take those measurements and call the vendor. Now this is real rookie question from me. I requested 7/16 stud holes, for the heads, from Dart so would I be safe to assume the rocker studs they gave me would also be 7/16 as well? I'd not think they would machine 7/16 holes for the head studs and machine something different for the rocker stud holes, but like I said this is a rookie question on my part. If the answer is yes, then I have a question, just to satisfy my trivial curiosity. Could I still run 3/8 guide plates and rods on 7/16 rocker studs (I would think so).

yes- most rocker studs these days will have 7/16 threads for the end that goes into the head.
Most Darts will have 7/16 on the tops--------these are High Performance/race heads and you would be nuts to use a 3/8 stud.

Use whatever guide plate/pushrod size you want-----remember that the ball end radius must match the lifter and the rocker arm socket

Sorry-just looked in Dart cataloque and it says they are 3/8 screw in studs