Valve Train Geometry on 66 289 - Vintage Mustang Forums
 8Likes
Reply
 
Thread Tools
post #1 of 50 (permalink) Old 05-16-2018, 11:47 PM Thread Starter
Senior Member
 
Join Date: Jan 2014
Location: South Jersey
Posts: 938
Valve Train Geometry on 66 289

I just put the heads back on a 66 289. The engine is pre-rail rockers. I had the guide holes in the heads drilled out, milled the rocker bosses and installed screw in rocker studs with guide plates. The push rods are standard length (6.800") Comp Cams hardened push rods (Part # 7632-16). I replaced the stock stamped rockers with comp cams roller tip rockers (Part # 1442-16).

I marked the valve tips with a dry erase marker on the intake and exhaust valves on cylinder 1 and set the lash. I rotated the engine and removed the rockers to check the rocker contact area on the valve tip and have a few questions.

1) The marks on the valve tips are a bit towards the exhaust side of the heads. The rocker travel on the valve tip is .075". After a ton of reading, it seems less rocker travel on valve tip is more important than the contact point being centered on the valve. Does my setup look okay or should I try to dial it in better?

2) The rockers seem to sit very close to the base of the screw in studs. I'm use to how the stock rockers sit on the previous press in studs which has a lot more space between the base of the rocker and rocker stud boss. I can turn the rocker adjustment screw about another half turn before it bottoms out on my current setup. Does this seem okay?

Below are some pictures:

1) Rockers Top
2) Rockers Front
3) Rockers Back
4) Valve Tips with marks
5) Intake Valve Tip
6) Intake Rocker Clearance
7) Exhaust Valve Tip
8) Exhaust Rocker Clearance
Attached Images
File Type: jpg R Head Cyl 1 Rockers Small.jpg (78.0 KB, 73 views)
File Type: jpg R Head Cyl 1 Rockers Front Small.jpg (55.0 KB, 71 views)
File Type: jpg R Head Cyl 1 Rockers Back Small.jpg (49.7 KB, 64 views)
File Type: jpg R Head Cyl 1 Valve Tips Small.jpg (81.4 KB, 79 views)
File Type: jpg R Head Cyl 1 I Rocker Tip Small.jpg (90.8 KB, 58 views)
File Type: jpg R Head Cyl 1 I Rocker Clearance Small.jpg (60.8 KB, 61 views)
File Type: jpg R Head Cyl 1 E Rocker Tip Small.jpg (34.9 KB, 59 views)
File Type: jpg R Head Cyl 1 E Rocker Clearance Small.jpg (50.7 KB, 54 views)
markb0729 is offline  
Sponsored Links
Advertisement
 
post #2 of 50 (permalink) Old 05-17-2018, 01:36 AM
Senior Member
 
maladezo's Avatar
 
Join Date: Jul 2015
Location: Californication
Posts: 1,080
Garage
I am no expert as I have always ran rocker shafts. But, it seems longer pushrods would put the contact area farther off center. The width of the contact area appears reasonable to me. And it is not very far off center. Did you try a pushrod length checker? I would think that would be a must. You are wise to take your time on this.

'67 coupe, 390, 4spd.
maladezo is offline  
post #3 of 50 (permalink) Old 05-17-2018, 01:46 AM
Senior Member
Supporting Member
 
zray's Avatar
 
Join Date: Oct 2003
Location: On the road in NE Oklahoma
Posts: 12,911
Were the heads milled the thickness of the guide plates ?

I've used guide plates on two sets of HiPo heads without having to mill anything, and still had more room than what you have under the rocker arm. I was using Crane Gold Race rocker arms. But my Ferrea valves (1.94 / 1.60 ) were slightly longer than stock valves, so I used push rods that were slightly longer too. That moved everything away from the ARP studs.

Z

PS. For those people adding screw in studs, but not using guide plates: Do your studs have flat bases, or do they have a raised circumference ? If they're not completely flat , like the stock HiPo studs, you are at risk of cracking the stud bosses unless they are relieved. The ARP studs are not completely flat, unless they've changed them recently.


Last edited by zray; 05-17-2018 at 01:48 AM.
zray is offline  
 
post #4 of 50 (permalink) Old 05-17-2018, 08:24 AM Thread Starter
Senior Member
 
Join Date: Jan 2014
Location: South Jersey
Posts: 938
Quote:
Originally Posted by maladezo View Post
I am no expert as I have always ran rocker shafts. But, it seems longer pushrods would put the contact area farther off center. The width of the contact area appears reasonable to me. And it is not very far off center. Did you try a pushrod length checker? I would think that would be a must. You are wise to take your time on this.
I have a push rod length checker but it has the lock nuts on it and won't work with the guide plates. Rather than buy a new checker, I'll get some washers the thickness of the guide plates and do some lengthening and shortening of the adjustable push rod and see what happens. The reason I asked about my current setup is that I currently have 6.800" push rods (stock length) and was wondering if the setup looked good as is. I'll adjust the length on the adjustable push rod and take some additional measurements. Nows the time to do it.

Quote:
Originally Posted by zray View Post
Were the heads milled the thickness of the guide plates ?
Yes, the rocker bosses were milled. I have some before and after pictures of the heads and I can tell they were milled. I'm assuming they were milled the thickness of the guide plates but I wasn't there when it was done so I can only hope that was what was done.
markb0729 is offline  
post #5 of 50 (permalink) Old 05-17-2018, 09:44 AM
Senior Member
 
pollock's Avatar
 
Join Date: Sep 2003
Posts: 217
One sentence in your post jumped out at me: "I can turn the rocker adjustment screw about another half turn before it bottoms out..."

Maybe I am missing something, but the nut that holds the rocker down is really used to adjust your lifters. You are familiar with that procedure, right? Make sure the valves are fully closed (piston at TDC of compression stroke). Run the nut down finger-tight until the roller contacts the valve tip. Then turn it another 1/4 to 1/2 a turn and tighten the lock nut.

But that makes me notice another thing. It seems like your rockers should have lock nuts, maybe like the ones in this photo?
Attached Images
File Type: jpg image1.jpg (11.2 KB, 38 views)

pollock

Go Mean Green!
pollock is offline  
post #6 of 50 (permalink) Old 05-17-2018, 09:49 AM
Senior Member
 
pollock's Avatar
 
Join Date: Sep 2003
Posts: 217
Quote:
Originally Posted by maladezo View Post
But, it seems longer pushrods would put the contact area farther off center.
This is correct. The photo indicates a shorter pushrod would tend to move the contact area to center.

pollock

Go Mean Green!
pollock is offline  
post #7 of 50 (permalink) Old 05-17-2018, 09:51 AM
Senior Member
 
pollock's Avatar
 
Join Date: Sep 2003
Posts: 217
Quote:
Originally Posted by markb0729 View Post
I have a push rod length checker but it has the lock nuts on it and won't work with the guide plates.
I ran into this too. I was able to flip the checker over so that the nuts were in the lifter valley. I may have had to drop in there prior to bolting the guide plates down - can't remember.

pollock

Go Mean Green!
pollock is offline  
post #8 of 50 (permalink) Old 05-17-2018, 10:04 AM
Senior Member
 
Join Date: Nov 2014
Posts: 225
I think you need longer studs. Ideal sweep is .060 or less and reasonably centered.

A Pushrod Length & Rocker Arm Geometry "Must Read"
markb0729 likes this.
funnelcake is offline  
post #9 of 50 (permalink) Old 05-17-2018, 10:17 AM Thread Starter
Senior Member
 
Join Date: Jan 2014
Location: South Jersey
Posts: 938
Quote:
Originally Posted by pollock View Post
One sentence in your post jumped out at me: "I can turn the rocker adjustment screw about another half turn before it bottoms out..."

Maybe I am missing something, but the nut that holds the rocker down is really used to adjust your lifters. You are familiar with that procedure, right? Make sure the valves are fully closed (piston at TDC of compression stroke). Run the nut down finger-tight until the roller contacts the valve tip. Then turn it another 1/4 to 1/2 a turn and tighten the lock nut.

But that makes me notice another thing. It seems like your rockers should have lock nuts, maybe like the ones in this photo?
I知 familiar with the procedure for adjusting the valve lash. I did exactly what you said with one difference. I tightened the rocker but 3/4 turn at zero lash which is what most here say to do. You have a good eye. The nuts on the rockers I知 checking are just regular non locking nuts. I have locking nuts but using regular nuts for this procedure is easier to do and is easier on the rocker stud threads.

The bottoming out I mentioned happens after I adjust the preload on the lifter 3/4 of a turn at zero lash and then go another 1/2 turn after that. I知 not with the car at the moment (gotta pay the bills) but I知 not sure if the lifter is bottoming out or I知 running out of threads on the rocker shaft that痴 why I was asking about the space between the rocker and the bottom of the rocker shaft.
markb0729 is offline  
post #10 of 50 (permalink) Old 05-17-2018, 11:20 AM
Senior Member
 
pollock's Avatar
 
Join Date: Sep 2003
Posts: 217
Cool.

Yeah, the bottom of your rockers looks a little too close to the fillet at the bottom of the studs. 1/2 a turn on a 3/8-24 thread is only about .020, so that seems a bit too close for comfort. A longer pushrod would help but it would make your roller/valve tip situation worse. Longer studs, as suggested, would not help. The easiest fix I can think of is to have the stud bosses milled down a bit more.

Another thing to watch out for - make sure your rockers don't get misaligned by the guide plates. In other words, the slots aren't lined up properly between the lifter and the valve, and the rocker ends up a little crooked. That happened to me and over time the roller tips cut into the aluminum rocker bodies. I see that yours are steel so it would be slightly less of a concern. Comp Cams sells a split/adjustable guide plate now, just for this reason.

pollock

Go Mean Green!
pollock is offline  
post #11 of 50 (permalink) Old 05-17-2018, 01:10 PM
Senior Member
 
Join Date: Oct 2009
Location: far east north corner of Texas
Posts: 6,642
Garage
Probably not the answer you want but I would not leave that. It will wear the guides faster. If it was just a hair off center it is ok as long as the pattern is tight but I think yours is a bit over an acceptable offset of the pattern.


65 2+2, 331, C4 presently apart for complete a restore
1979 Ford F150 custom, 302, C4, AC, tilt wheel, main transportation
macstang is offline  
post #12 of 50 (permalink) Old 05-17-2018, 05:12 PM Thread Starter
Senior Member
 
Join Date: Jan 2014
Location: South Jersey
Posts: 938
Quote:
Originally Posted by pollock View Post
Cool.

Yeah, the bottom of your rockers looks a little too close to the fillet at the bottom of the studs. 1/2 a turn on a 3/8-24 thread is only about .020, so that seems a bit too close for comfort.

My thoughts exactly.


A longer pushrod would help but it would make your roller/valve tip situation worse.

And a shorter push rod would require turning down the adjustment screw on the rocker more. Correct?

Longer studs, as suggested, would not help.

I'm not sure how a longer stud would help. But I welcome being enlightened. Threads going further down the stud would help but it would that would require a different stud design. Something like this: https://www.summitracing.com/parts/m...6/applications

The easiest fix I can think of is to have the stud bosses milled down a bit more.

Crap! I was afraid of that. $44 in head gaskets down the drain. I wonder how much got milled off in the first place? I'll see if the shop remembers but I have my doubts.

Another thing to watch out for - make sure your rockers don't get misaligned by the guide plates. In other words, the slots aren't lined up properly between the lifter and the valve, and the rocker ends up a little crooked. That happened to me and over time the roller tips cut into the aluminum rocker bodies. I see that yours are steel so it would be slightly less of a concern. Comp Cams sells a split/adjustable guide plate now, just for this reason.

I haven't payed close attention to the rocker alignment yet and nothing has jumped out with respect to cylinder 1 but will check to make sure everything looks good. Hope I don't need adjustable guide plates.
Mark
markb0729 is offline  
post #13 of 50 (permalink) Old 05-17-2018, 05:26 PM Thread Starter
Senior Member
 
Join Date: Jan 2014
Location: South Jersey
Posts: 938
Quote:
Originally Posted by macstang View Post
Probably not the answer you want but I would not leave that. It will wear the guides faster. If it was just a hair off center it is ok as long as the pattern is tight but I think yours is a bit over an acceptable offset of the pattern.
This is in reference to the rocker contact pattern on the valve tip. Correct? Are you are saying the pattern is off center too much and the pattern should be tighter?
markb0729 is offline  
post #14 of 50 (permalink) Old 05-17-2018, 05:44 PM
Senior Member
 
Join Date: Oct 2009
Location: far east north corner of Texas
Posts: 6,642
Garage
The width looks ok to me but it is off center just a bit more than I would want.

Photo below courtesy of Lunati is the ideal but give take a hair either way off that would pass if it is not any wider.



65 2+2, 331, C4 presently apart for complete a restore
1979 Ford F150 custom, 302, C4, AC, tilt wheel, main transportation
macstang is offline  
post #15 of 50 (permalink) Old 05-17-2018, 06:24 PM
Junior Member
 
Join Date: May 2018
Posts: 2
Hello,
New to the forum. My Stage II 302 has a burned valve and I'm looking to go with new heads rather than going through these again.
The Edelbrock E Street PN 5025 is my choice, so far.
Any thoughts on aftermarket heads? Experience? Advise?
Thanks!
todd m is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Vintage Mustang Forums 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










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



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 On
Trackbacks are On
Pingbacks are On
Refbacks are Off

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