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lifter preload procedure.

TEK310

TEK310

New member
is it the same as lets say on a chevy 350 sb, where you turn the engine over to intake starting to open to set exhaust preload and exhaust opening to set intake preload? zero lash plus 1/2 turn for the 350 sb

if i remember correct it was 16ft lbs plus 90*
 


matt5112 said:
I'm not sure people follow that.

They get reusable bolts and torque to 23-25 ft lbs and move on.
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so it does not matter which valve is closed or open on our engine? you just torque down the rocker bolts to the tq spec and go on down the line?
 
It depends on the setup but you are close enough, zero lash with the other valve open then .5 to 1.5 turns. The stock lifters are supposed to be a little more forgiving than the comp cams in that the stock lifters are good for 1/2 turn to 1 1/2 turns and the comp cams around 3/8ths to 1/2 iirc. Most just try to keep the lifters, pushrods, rockers etc. in the same layout as they are going to put them back in, torque the rocker bolts and thats about it.

When you start changing the hg thickness, rocker, head milling, valves, cam then you have to account for a little more.
 
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Stock valve train = torque to spec
Modified valve train = torque to spec - providing correct spacers are installed to achieve correct geometry.

This is nothing like the old engines that required pre-load adjustment and rocker nuts with locks.
 


im kind of confused.

so on our engines, we do follow that procedure(with stock lifters) by tightening down the rocker bolt to zero lash and then 1/2 turn?

or

just the 16ft. lbs. plus 90*


also during the torque down procedure, is it on the closed valve? i have heard of people just tightening them down to the torque spec whether they are open or closed.
 
Just torque them to spec. There is no pre-load procedure. It doesn't matter which valve is open or closed.
 
Rico said:
Just torque them to spec. There is no pre-load procedure. It doesn't matter which valve is open or closed.
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gotcha, how would the torque be to full spec, if the spring is pushing against the rocker when it is opening the valve?


rico, are you by chance the guy who needed new heads bc your rockers grenaded?
 
TEK310 said:
gotcha, how would the torque be to full spec, if the spring is pushing against the rocker when it is opening the valve?


rico, are you by chance the guy who needed new heads bc your rockers grenaded?
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Spring tension will not effect the torque.

Funny guy, aren't you? I wanted the heads to do some porting.

Over 30K on my rebuilds with stock valve train and no problems.
 
Rico said:
Spring tension will not effect the torque.

Funny guy, aren't you? I wanted the heads to do some porting.

Over 30K on my rebuilds with stock valve train and no problems.
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lol, did not mean that as a joke, i have a set of used L67 heads for sale on craigslist and someone from ft worth had been interested in them a while back. says you are in ft worth so i was not sure. im in mesquite/dallas
 


I'm northwest of Fort Worth...it's called Blue Mound near Saginaw.

Are you the guy that never sent me the pictures?
 
For torquing rockers with reusable bolts. I torque them down to the spec. Turn the motor a couple of times by hand and retorque to ensure none were bound by being partially open. Ideally you'd TDC each cylinder and torque it w/o any pressure on the rockers. It's just not happening in my world though.
 


BillBoost37 said:
For torquing rockers with reusable bolts. I torque them down to the spec. Turn the motor a couple of times by hand and retorque to ensure none were bound by being partially open. Ideally you'd TDC each cylinder and torque it w/o any pressure on the rockers. It's just not happening in my world though.
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Bill

We're in the same world. It probably takes less than 1/4 of a ft-lb to compress the spring. :th_thumb-up:
 
BillBoost37 said:
I've had one or two bind a little somehow..so turning the motor a bit helps my peace of mind.
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what about with TTY bolts? say mine have already been torqued down, and ran for about 3k miles, can i retorque them without them loosening up on me?
 
Reuse TTY bolts at your own risk. Torque them to 20 ft-lb and stop.

If I were you I would just get some reusable bolts...peace of mind.
 
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