Hemi Rocker adjustment
#2944545
07/18/21 12:37 PM
07/18/21 12:37 PM
|
Joined: Feb 2007
Posts: 217 New Port Richey, Florida
Wolfe440
OP
enthusiast
|
OP
enthusiast
Joined: Feb 2007
Posts: 217
New Port Richey, Florida
|
1969 426 Hemi. Have a Comp Cam Hydraulic Thumpr roller cam and lifters, using stock rockers, have 40lbs of oil pressure at idle.
Problem is I am getting some lifter tapping across engine. Talked to Comp Cams, need .020 to .040 preload. Turned engine to correct position to adjust each rocker, first they said go to zero lash and half turn.
That helped a bit but still have tapping, then they recommend adjustment zero lash and go one full turn, I tried that and still have some tapping, it was a small improvement.
Now they are saying with this particular cam and lifters I have go to zero lash and then go at least one and a quarter turn.
I'm getting a bit nervous going that much. I myself in the past with other motors (other then Hemi) never had to adjust preload on a hydraulic that far, usually half a turn max.
Are the factory adjusters on a Hemi a finer thread and require that much turning?
Thanks, Wolf
|
|
|
Re: Hemi Rocker adjustment
[Re: NITROUSN]
#2944564
07/18/21 02:11 PM
07/18/21 02:11 PM
|
Joined: Feb 2007
Posts: 217 New Port Richey, Florida
Wolfe440
OP
enthusiast
|
OP
enthusiast
Joined: Feb 2007
Posts: 217
New Port Richey, Florida
|
Are the adjuster screws 3/8 fine thread? If so that would equate to .0416 per turn. So 1 1/4 turns come out to .0520 preload. They claim most lifters have up to .200 of adjustment for preload. If the Cam and lifter company is suggesting this I guess it is worth a try. Thank You for that info. I will pop the covers off and find out what the adjuster thread is. I noticed I didn't do the sequence correctly, I should be doing exhaust closes and intake starts to open on cyl 1 and then adjust both rockers on cyl 6, then do the same on 8 & adj 5, then 4 & adj 7 etc...etc. I'm going to do this over again with the correct sequence and see what 1 1/4 gives me. Thank You!
|
|
|
Re: Hemi Rocker adjustment
[Re: NITROUSN]
#2944577
07/18/21 02:50 PM
07/18/21 02:50 PM
|
Joined: Feb 2007
Posts: 217 New Port Richey, Florida
Wolfe440
OP
enthusiast
|
OP
enthusiast
Joined: Feb 2007
Posts: 217
New Port Richey, Florida
|
I would adjust them one cylinder at a time just like comp cam suggests. Mopar had a lash setting chart. I used to do it by the chart however they claim cam profiles have changed and you need to be sure you are setting the lash on the base circle of the cam. This should be your lifters and instructions. Adjustment Ok, I will stay with the Comp instructions and do one cylinder at a time like I have been. Finding the thread pitch on the adjusters is first thing tomorrow. Good stuff...thx!
|
|
|
Re: Hemi Rocker adjustment
[Re: Wolfe440]
#2944582
07/18/21 03:19 PM
07/18/21 03:19 PM
|
Joined: Jan 2003
Posts: 25,785 Rio Linda, CA
John_Kunkel
Too Many Posts
|
Too Many Posts
Joined: Jan 2003
Posts: 25,785
Rio Linda, CA
|
That helped a bit but still have tapping, then they recommend adjustment zero lash and go one full turn, I tried that and still have some tapping, it was a small improvement.
Could be a bad lifter right out of the box.
The INTERNET, the MISinformation superhighway
|
|
|
Re: Hemi Rocker adjustment
[Re: John_Kunkel]
#2944583
07/18/21 03:40 PM
07/18/21 03:40 PM
|
Joined: Jan 2003
Posts: 18,415 UPPER MICHIGAN, MARQUETTE COUN...
NITROUSN
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 18,415
UPPER MICHIGAN, MARQUETTE COUN...
|
That helped a bit but still have tapping, then they recommend adjustment zero lash and go one full turn, I tried that and still have some tapping, it was a small improvement.
Could be a bad lifter right out of the box. I was just going to suggest that. He needs to re-lash all of them and run it. If it keeps making noise again re-lash and write down which ones changed. If this keeps happening on the same one or more there could be a cam and lifter failure.
|
|
|
Re: Hemi Rocker adjustment
[Re: John_Kunkel]
#2944594
07/18/21 04:20 PM
07/18/21 04:20 PM
|
Joined: Feb 2007
Posts: 217 New Port Richey, Florida
Wolfe440
OP
enthusiast
|
OP
enthusiast
Joined: Feb 2007
Posts: 217
New Port Richey, Florida
|
That helped a bit but still have tapping, then they recommend adjustment zero lash and go one full turn, I tried that and still have some tapping, it was a small improvement.
Could be a bad lifter right out of the box. Its crossed my mind. The motor was built and ran on a dyno, the shop says they didn't hear any lifter tapping. The motor then sat for a year in the shop, I turned it over by hand a couple of times a month. I got to identify adjuster threads so I at least know how much preload is one turn. In the end if it takes me to 1 1/4 turn and I still have problems, I will go for a new set of lifters. Thx..
|
|
|
Re: Hemi Rocker adjustment
[Re: Wolfe440]
#2944615
07/18/21 05:55 PM
07/18/21 05:55 PM
|
Joined: Jan 2003
Posts: 18,415 UPPER MICHIGAN, MARQUETTE COUN...
NITROUSN
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 18,415
UPPER MICHIGAN, MARQUETTE COUN...
|
Thank You for that info. I will pop the covers off and find out what the adjuster thread is. I noticed I didn't do the sequence correctly, I should be doing exhaust closes and intake starts to open on cyl 1 and then adjust both rockers on cyl 6, then do the same on 8 & adj 5, then 4 & adj 7 etc...etc.
I'm going to do this over again with the correct sequence and see what 1 1/4 gives me. You need to stay on the same cylinder and adjust the valves on that cylinder and move on to the next. Do not observe the valve closings/openings on one cylinder and adjust a different cylinder.
|
|
|
Re: Hemi Rocker adjustment
[Re: TJP]
#2944675
07/18/21 09:10 PM
07/18/21 09:10 PM
|
Joined: Jan 2003
Posts: 15,348 Omaha Ne
TJP
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 15,348
Omaha Ne
|
The method I was taught many years ago to has never failed me. EO/IC rule (Exhaust Opening and Intake Closing). using a remote starter button/ switch to bump the motor around Set the intake valve when the exhaust valve is beginning to open. This will put the intake lifter at the base circle which is where you want it to be. Then set the exhaust valve when the intake valve is almost closed. I have trouble remembering the above, so I wrote it on a piece of cardboard and prop it up for referencing as I adjust each valve If adjusting hydraulics, loosen the adjuster until there is noticeable play between the rocker and pushrod / valve While rolling the pushrod between two finger tips, begin slowly tightening the adjuster. Just as you hit Zero lash you will feel a slight but distinct resistance. You can loosen a 1/4 turn or so and retighten to confirm several times until you get the "hang" of it. The above resistance will be felt even with empty lifters. You will also note the " free play" is gone. From that point, depending on adjusters threads per inch determines how far to tighten. Most are 3/8 x 24. So if one divides 1inch by 24 =.0416" per turn. All camshaft Manufacturers' I am aware of recommend. 0.020" to .040" preload. With the above, I have always used 1/2 turn beyond zero lash. I also agree with starting at the front of the motor, and do each valve working towards the back. Then repeat the process on the other side
|
|
|
Re: Hemi Rocker adjustment
[Re: cudachas]
#2944716
07/18/21 11:18 PM
07/18/21 11:18 PM
|
Joined: Jan 2004
Posts: 8,249 fredericksburg,va
cudaman1969
master
|
master
Joined: Jan 2004
Posts: 8,249
fredericksburg,va
|
I had similar issues with mine , turned out four adjusters were tapping the baffles in my stock covers. Not sure what covers you have but if there stockers look for witness marks on the baffles.Good luck! Hemi covers don’t have baffles I ran mine (440 & 383) at zero lash + 1/4 turn, no tap,
Last edited by cudaman1969; 07/18/21 11:23 PM.
|
|
|
Re: Hemi Rocker adjustment
[Re: cudaman1969]
#2944726
07/18/21 11:58 PM
07/18/21 11:58 PM
|
Joined: Dec 2007
Posts: 18,157 Mass
DAYCLONA
I Live Here
|
I Live Here
Joined: Dec 2007
Posts: 18,157
Mass
|
Hemi covers don’t have baffles Uhhhh....yeah they do....
|
|
|
Re: Hemi Rocker adjustment
[Re: DAYCLONA]
#2944784
07/19/21 10:39 AM
07/19/21 10:39 AM
|
Joined: Jan 2003
Posts: 15,348 Omaha Ne
TJP
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 15,348
Omaha Ne
|
Hemi covers don’t have baffles on Uhhhh....yeah they do.... and have re-tacked more than one spot weld on them. Another thought couple of thoughts? Are you sure it's a lifter tick and not an exhaust leak ? a small one can sometimes mimic lifter noise I am not sure how pronounced the noise is but some hemis are known to make a bit more valvetrain noise keep us posted
Last edited by TJP; 07/19/21 10:39 AM.
|
|
|
|
|