Valve/lifter adjustment - Pontiac GTO Forum
User Tag List

 1Likes
  • 1 Post By bigD
 
LinkBack Thread Tools Display Modes
post #1 of 10 (permalink) Old 04-16-2019, 06:52 AM Thread Starter
 
Join Date: Jan 2017
Posts: 161
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 36 Post(s)
Valve/lifter adjustment

Hi everyone. If you have a completely stock '71 400 engine, how do you adjust the valves/lifters?? The book calls for 20 lbs. of torque on the rocker nut, but does this have to be with the lifter on the base circle of the cam?? Or do you just tighten down to that torque requirement regardless of where anything is?? I put a Lunati Voodoo cam in my engine and put everything back together and the motor runs well. Now I'm hearing something different about where the lifter should be on the cam when torquing. From what I recall, I might have been close to running out of threads about the same time I reached the 20 lbs. of torque. Guess it seemed right to me. Thanks, Nicholas.
Nicholas is offline  
Sponsored Links
Advertisement
 
post #2 of 10 (permalink) Old 04-16-2019, 09:44 AM
 
curtis.smith68's Avatar
 
Join Date: May 2018
Location: Syracuse, NY
Posts: 96
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Garage
I hope this helps but I'm not sure if you have the same setup as I do. I used the method described in the below link. Never had a problem that way. There are way more knowledgeable people on the forum and am not sure how others adjust their rockers...

Pontiac Rocker Arm Adjustment
curtis.smith68 is offline  
post #3 of 10 (permalink) Old 04-16-2019, 10:09 AM
 
Join Date: Jul 2016
Location: North Louisiana
Posts: 524
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 54 Post(s)
Rather than trying to do all the right valves, I always just start with the #1 piston at TDC of it's comp stroke, and do both #1 cyl valves.

I then rotate the crank 90, and do both valves on the next cyl in the firing order, which is #8 .

Then rotate another 90, & do both valves on #4 cyl.

Continue rotating 90 for each cyl, right on down the firing order. Since the crank makes 2 turns while the cam makes only 1 turn, it takes 2 complete crank revolutions to go thru the entire firing order. I have my balancer marked every 90, to make it easy to find the 90 intervals.

You go thru the firing order once, & your done.

Not saying the other way don't work. Just posting the way I've always done it, which has worked for me. No chance of confusion. I don't have to look at a reference to see exactly which valves I can & can't adjust, at the same crank position.
PontiacJim likes this.
bigD is online now  
 
post #4 of 10 (permalink) Old 04-16-2019, 02:59 PM
64-67 Expert
 
geeteeohguy's Avatar
 
Join Date: Feb 2008
Location: Fresno, California
Posts: 8,457
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 98 Post(s)
Quote:
Originally Posted by bigD View Post
Rather than trying to do all the right valves, I always just start with the #1 piston at TDC of it's comp stroke, and do both #1 cyl valves.

I then rotate the crank 90, and do both valves on the next cyl in the firing order, which is #8 .

Then rotate another 90, & do both valves on #4 cyl.

Continue rotating 90 for each cyl, right on down the firing order. Since the crank makes 2 turns while the cam makes only 1 turn, it takes 2 complete crank revolutions to go thru the entire firing order. I have my balancer marked every 90, to make it easy to find the 90 intervals.

You go thru the firing order once, & your done.

Not saying the other way don't work. Just posting the way I've always done it, which has worked for me. No chance of confusion. I don't have to look at a reference to see exactly which valves I can & can't adjust, at the same crank position.
Used to do it this way on my '63 VW Bug every 3,000 miles. Foolproof and accurate method. And SAFE.
geeteeohguy is offline  
post #5 of 10 (permalink) Old 04-18-2019, 05:30 AM Thread Starter
 
Join Date: Jan 2017
Posts: 161
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 36 Post(s)
Thank you everyone with your responses. I probably didn't explain myself properly because I'm still looking for an answer, or perhaps it's there and I don't understand it. I'm not looking to adjust the valves. My question is, on an almost stock engine, can you just torque the rocker nut to 20 ft. lbs. and leave it?? I believe this is the factory method. Thank you, Nicholas.
Nicholas is offline  
post #6 of 10 (permalink) Old 04-18-2019, 11:15 AM
 
Join Date: Jul 2016
Location: North Louisiana
Posts: 524
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 54 Post(s)
If you don't think that the extra spring pressure of having the valve in the max lift position, with the cam you have in it, would affect your 20lb torque reading, then just torque 'em all to 20lbs & forget it.

BUT, if you think having the cam lobe in a max lift or near max lift position MIGHT affect your torque reading, then you need to torque the nuts when the lifter is on the lobe's base circle. It's your decision.

If you choose the latter, both lifters are on the base circle when that cylinder is at TDC of it's compression stroke.
bigD is online now  
post #7 of 10 (permalink) Old 04-18-2019, 09:24 PM
 
PontiacJim's Avatar
 
Join Date: Dec 2012
Location: Gastonia, NC - Born & raised in Connecticut - 31 years
Posts: 3,451
Mentioned: 0 Post(s)
Tagged: 1 Thread(s)
Quoted: 347 Post(s)
Garage
Quote:
Originally Posted by Nicholas View Post
Thank you everyone with your responses. I probably didn't explain myself properly because I'm still looking for an answer, or perhaps it's there and I don't understand it. I'm not looking to adjust the valves. My question is, on an almost stock engine, can you just torque the rocker nut to 20 ft. lbs. and leave it?? I believe this is the factory method. Thank you, Nicholas.

You explained yourself properly. The info supplied is not used to adjust the valves - just torque the rocker arm nuts down as factory.

You got several responses on how to set the valves in an unloaded, no pressure on the rocker arms, position. You can either rotate the engine for each cylinder and get each cylinder into its compression stroke at top dead center (TDC) and do each 8 separately and individually OR, rotate the engine 90 degrees at a time to save a little extra spinning of the engine and adjust the numbered cylinders as bigD has pointed out.

Some will simply torque the nuts down regardless as to whether there is any pressure on the rocker arm (like at full lift) or both valve closed (rocker arms on compression stoke, no spring pressure). However, spring pressure could affect torque readings as the spring pressure is pushing up against the rocker arm pivot point and up against the rocker arm nut as you are trying to torque it down - ie 2 opposing forces. This may not be quite the concern with stock cam/springs, but may be of concern when you begin to increase lift and/or spring pressures. So, best to torque the nuts while the rocker arms have no lift/spring pressure being applied to them - which is TDC/Compression Stroke where both rocker arms/valves are closed.

"From what I recall, I might have been close to running out of threads about the same time I reached the 20 lbs. of torque."

Thread count has nothing to do with torquing the nuts down. The rocker arm studs have a 7/16" base and 3/8" threaded top area. The base of the stud tapers into the 3/8" threaded stud, thus the Pontiac term "bottleneck studs." The rocker arm nut is designed to clamp to the "neck" of the stud at the transition. Torque to 20-25 ft lbs and your done, period.
PontiacJim is offline  
post #8 of 10 (permalink) Old 04-19-2019, 06:46 AM Thread Starter
 
Join Date: Jan 2017
Posts: 161
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 36 Post(s)
OK everyone. Got it. Thank you again. I'd like to think I have stock valve springs, but I'm not sure. I did take out what I considered to be a radical Voodoo cam and replaced it with a much milder Voodoo one. I torqued the rocker nuts to 22 ft. lbs. because that's what the repair manual called for (I think their range was 20-25 ft. lbs.) I left it that way and was never concerned about it. The motors runs well. I recently read an article on adjusting Pontiac hydraulic valve lifters which surprised me. It really piqued my interest. Never knew that was possible or recommended for a stock or near stock motor. That's why I came here and asked my question. I was concerned over whether or not I had done the adjustment/tightening correctly based on what I had. As I mentioned, the motor runs well. Very smooth at idle. Doesn't seem to be tight if that's the word. I've run it up to 4800 or so rpm's several times and never broke up. Unless someone suggest something else, think I'll leave it as is for now. Thanks again to all, Nicholas.
Nicholas is offline  
post #9 of 10 (permalink) Old 04-19-2019, 04:49 PM
 
PontiacJim's Avatar
 
Join Date: Dec 2012
Location: Gastonia, NC - Born & raised in Connecticut - 31 years
Posts: 3,451
Mentioned: 0 Post(s)
Tagged: 1 Thread(s)
Quoted: 347 Post(s)
Garage
Sounds like you got it, not too difficult, but do understand when you begin to research you will get conflicting ways to do something and then your brain goes into confusion mode.

The Service Manual for your car is always one of the best references to use - no confusion there unless you are modifying something or the photo/diagram really lacks explanation which sometimes they do.

Most of the stock Pontiac cams (discounting the HP cams like SD or Ram Air) are designed to have a nice smooth idle and broad flat torque/HP RPM band. They will pull to 5,200 RPM's and beyond. It is when you begin to go aftermarket that cam specs invariably change as each manufacturer has their spin on a cam.
PontiacJim is offline  
post #10 of 10 (permalink) Old 04-20-2019, 06:43 AM Thread Starter
 
Join Date: Jan 2017
Posts: 161
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 36 Post(s)
OK. Thanks everyone. I always leave learning something new which I am very appreciative of, Nicholas.
Nicholas is offline  
Sponsored Links
Advertisement
 
Reply

  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, LeMans & GTO Engine Tuning and High Performance

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Pontiac GTO Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Valve adjustment 69 Lrdurbin 1964-1974 Tempest, LeMans & GTO Technical and Electrical Wiring 4 11-13-2012 06:16 PM
Lifter Replacement / Rocker Adjustment mgfliby Engine Discussions 2 07-08-2012 12:18 PM
Valve lifter pan question Al T 1964-1974 Tempest, LeMans & GTO Technical and Electrical Wiring 3 09-11-2010 05:56 PM
2005 GTO LS2 valve adjustment? rnoswal Service, Maintenance and Technical Discussion 8 05-31-2009 08:18 AM
Valve Lifter Noise Mean Goat Service, Maintenance and Technical Discussion 2 10-18-2005 07:38 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome