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Rocker Adjustment Help

  • Thread starter Thread starter hulk_lil87gt
  • Start date Start date May 13, 2012
H

hulk_lil87gt

Member
Aug 24, 2009
47
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May 13, 2012
#1
  • May 13, 2012
  • #1
Hey haven't posted anything in a long time I am looking for help my rockers as they might be causing my misfire.
Here what I am running...

306 with forged DSS flat tops stock crank and rods
F-303 cam with stock heads .530 springs stamped steel roller tip rockers and stock length push rod but brand new.
Cobra intake with 1" spacer 70mm T/B
19lb injectors
BBK fuel rail
BBK shorties
All emission removed and plugged

Now my issue seems to be a misfire, I went to set my timing the other day and started with 10 dagrees the motor was shaking like no tomorrow as if it where misfiring on 4 cyl. So I turned the timing up and only got worse so I turned it down and it seemed to smooth out more but still shaking. Right now it's set at 0 dagrees and is smoother but still shaking. If I rev up it seem to be very clean no hesitation, bogging, stumbling. I was going to replace my plugs but talk to my mom friend he said maybe my rockers are too tight and holding valves open the rockers I got aren't suppose to be adjustable. When I put them on I went by they torq spec of 25lbs I don't know if this was the smart way or not I never checked my gap for rocker to valve. If anyone can give me a spec or help in general that would be awesome I've been working on this car for a few years and have a total of 6 months driving time. I would really like to get out and drive it this summer thanks for the help guys
 

95Vert383AOD

15 Year Member
Jun 10, 2008
1,133
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69
New Bedford, MA
May 13, 2012
#2
  • May 13, 2012
  • #2
Did you turn the motor to make sure each lifter was on zero lash before tightening? Zero lash is when the lifter is on the backside of the cam lobe. Zero Lift.
 

jrichker

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May 14, 2012
#3
  • May 14, 2012
  • #3
Michael Yount’s valve adjustment procedure

Here's an easy way to determine this. Start with the #1 cylinder. Rotate the engine with a ratchet on the crank bolt clockwise. Watch the #1 pushrods. First the exhaust pushrod will rise and fall signaling what would be the exhaust valve opening and closing if the rocker were on. As it closes the intake pushrod will rise -- keep rotating clockwise until the intake pushrod falls and is level with the exhaust pushrod - both at the same height. Both lifters are now on the base circle of the cam - both valves would be closed if the rockers were on.

Now, install both rockers. Tighten the bolts with one hand while rocking the rocker with the other hand - continue until you reach the point where you can't 'rock' the rocker any more because there's no gap on the valve stem end or the pushrod end. You are at zero lash - i.e. - no gaps. Stop tightening just as you reach this point.

Now, put your torque wrench on the bolt and tighten it to 18-20 ft-lbs while counting the number of turns it takes to reach the torque. You should hit the torque within 1/4 to 1 turn of the bolt. If it takes more than 1 turn, use a shim to raise the rocker -- each .030" shim will reduce the number of turns to torque by about 1/4 turn. If you reach the torque in less than a 1/4 turn, or you have trouble reaching zero lash even at full torque, then you'll either need longer pushrods, or to CAREFULLY remove some material from the bottom of the rocker fulcrum. Using the procedure described above, you will work through the remaining 7 pairs of rockers. If you follow the firing order, it will minimize the manual cranking you have to do to get the lifters on the base circle of the cam prior to installation of the next pair.

When I first went through mine, 13 of them took no shims; 3 of them took 1 .030" shim. Upon cranking it up, one or two of them sounded a bit noisier than I thought was right, so with the engine hot, I pulled the upper off, and the valve covers, and went through the installation procedure again. That time, 11 of them took no shims; 4 of them took one .030", and one of them took one .060" shim. And they were very quiet running.

Good luck with it.
__________________
Michael Yount - K'ville,TN 82 Volvo 242w/5.0L; 2000 Suzuki Bandit 1200
 
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