73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: swilliams on October 18, 2014, 07:19:32 pm
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I have a 350 with hydraulic lifters stock length push rods and a 249 cam. My lifters after a head change and re tightening the head bolts are still ticking. If i wanted to add 1/4 of a turn to the poly locks can i do this without getting each valve on the base of the cam lobe like just pull the valve cover and add the 1/4 turn to each valve.
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I don't quite understand why you wouldn't want to do it correctly. Why not follow the valve adjustment procedure and do it the right way?
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I do plan on doing it correctly. It is one of thoes things where someone knew this great engine builder and they did it this way bla bla bla. I just wanted to check it out..
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To answer your question directly yes you can add 1/4 turn on the rocker nuts without the lifter on the base circle.
But I'm with Vile, I would do the adjustment by the book unless there was some extenuating circumstance that prevents it.
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It is a good thing i went through the the process instead of trying the shortcut I found 2 push rods that the guide plates were not adjusted correctly.
(http://i36.photobucket.com/albums/e42/swilliams19733/B45C5B5F-F1C0-46F4-BC07-39C33E94C909_zpsigaab2mo.jpg) (http://s36.photobucket.com/user/swilliams19733/media/B45C5B5F-F1C0-46F4-BC07-39C33E94C909_zpsigaab2mo.jpg.html)
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When you installed heads with guide plates, did you also install hardened pushrods?
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Yes i got them from jegs. I have gone to 1 1/4 turns past 0 valve lash because i still here tapping. I got it all back together and it does not want to start not like before you can tell it wants to start. Have i gone to tight and the valves are not closing.
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Sounds like you might have messed up your adjustment. Rotate the engine until you see the #1 intake rocker open and start to close. Put it on TDC and start from there. Measure zero lash up and down, not by rotating the pushrod. You can easily misjudge zero lash and over tighten them.
Another method is to follow the firing order in 1/4 turn increments. Mark the balancer every 90° and starting at #1 TDCC adjust I-E, rotate 90° adjust #8 I-E and repeat through the firing order sequence. 1-8-4-3-6-5-7-2
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That sounds good I will do that. Is 1 1/4 turns to much all i here about is 1/4, 1/2, 3/4 or 1.
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I'm having a similar problem with my Fresh'ish 350. Sounds like a diesel idling. Not a knock but not rocker chatter. COMP cams recommended 1/2 turn.....most books and YouTube vids said 3/4-1 turn. I've never heard anyone say 1 1/4 turns.
*Long story short turns out that design of lifters are just noisy. Read lots of posts on various forums all the same. You basically have two options 1. Change the lifters out or 2. Live with it.
I ended up tuning mine to 3/4 turn and it quieted down but still noticible. I may go 1 full turn to see if it helps any more but I think 1 1/4 is a little much.
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I think the Chilton manual says 1.25 turns. I have always done 3/4 turn.
Ideally you want the push rod, valve, and an imaginary line drawn from the push rod seat in the rocker arm to the top of the valve tip to be at theoretical 90° angles to one another (90°/90° is not really possible-more like 110°/110° with the Chevy small block's 23° valve angle) at 2/3rds cam/valve lift. This minimizes the rocker tip scrub at the highest point of valve spring pressure.......
......try accomplishing this on a Big Block Chevy race engine with a solid lifter cam and separate exhaust/intake angles where the only way to adjust rocker arm tip scrub is by changing the valve installed height and/or push rod length.....eek.
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Thanks for the help. I got it running again.