bolt down rocker adjustment.

[Howard Jones]

SVO motors come with stamped steel rockers that are secured with a bolt running thru a fulkcrum then thru the rocker and into the threaded boss on the head. There is no locking nut and if the bolt isn't firmly torqued down it will quickly become loose releasing the rocker arm.

I called Ford motor sport and got something about 1/2 turn after the valve to be adjusted is at 0 lash clearance (at TDC). That does not work and is in fact the correct way to adjust lifter preload on adjustable rocker/ hyd tappets.

It appears to me that if the valve is still making noise after the rocker holding bolt, on my type of heads, is torqued down the only way to "reduce lash", increase lifter preload, would be to remove any shims that might be there between the rocker base and the threaded pedestal in the head.

The Question, How do you adjust lifter preload on a 302 SVO motor with alum GT40X heads that have the oem lifters, pushrods, and stamped steel rockers?

If you know that one then how do you measure lifter preload?

 

[Ron Earp]

Essentially there is no adjustment for these damn things. I fought one for months before getting it right. They have shims to raise the pedestal but that is a one direction adjustment, the wrong way in your case, I think. If you've got no shims to remvoe then do what I did.

If it is still making noise you'll have to reduce the height of the pedestal a bit. Take off the rocker and take the pedestal (which I'm calling the little metal thing that the rocker pivots on, it is just sort of shaped like a pedestal) and put it in your right hand. Then, go out back and throw it....no no no, wrong procedure.

Take the pedestal and cut it down a little bit on the flat side. I did this using a flat piece of glass and some sandpaper. I think I probably had to remove 0.060 before mine would shut up. You know, it is amazing that you figure this couldn't happen if the heads were all square, the mounting points for the rocker pedestals all the same height, etc. But it happens and I've chased this a couple of times on pedestal mount rockers - 1 or 2 that won't shut up and the shims make it worse. Thereefore you need to go the other direction. You could also cut the head down right there were that particular pedistal mounts but cutting the piece down is easier and makes more sense.

R

 

They do sell .060 over pushrods and the shim kits come with .030 and .060 shims. It is a pain, but with a dial indicator and magnetic base you should try for around .040 of lifter preload, you can also sand down the shims to help this. Especially difficult when you mill the heads for compression (I took .020 off) which I wont do again, as Ron said chased this until it was close. As far as bolts backing off, all I can say is blue loc-tite (make sure the bolts are clean (oil free). they sell checking pushrods to determine correct length, or you can do the math, with the right length it will put you in the range, shims do the rest. I for one prefer stud mounted rockers.

Hope this helps,

Chris

 

Howy,

Just an Idea,,,, I have the push rods that were used with those heads, may be not a bad idea to try them!! After all you stole those X heads from me /ubbthreads/images/graemlins/shocked.gif

Like I said, just an idea

 

[Howard Jones]

Fred, I'll take a good last look at the rocker shim status one more time, If I can't get it the way I like it then maybe we will try that. I think I will measure the push rod lenghts, they should be all the same lenght but I know they are not, and put the longest one in the noisey spot if I have to. If I do that I might want to measure yours(mine) and see if then is a difference.

Ron, what is the torque spec for the hold down bolt? And thanks for your help. I kinda though I was headed that direction or something like that.

I've said several times I did this project so I could use mine brain and learn something....Well I think I am about ready to quit the learning how to build it and begin the learning how to drive it part.

I'll get it, with a little help from my friends, thanks guys..............AGAIN!!!!!!!!!

Howard

 

[Howard Jones]

If I was to change over to roller rockers what would be your recomendations guys? I am thnking I might kill two birds with one rock.

Should I convert to stud mount or use the bolt down adjustable ones like Ford motorsport sells? Surely the new rollers should be adjustable for lifter preload. I was looking at Crain crome molly steel rollers. I was guessing, at this point thats pretty much all I am doing, that being steel they would have a longer life than alum. I seem to remember alum rollers can have a shorter life. Correct?

Anyway, anybody put roller rockers on a SVO GT40X head and would recomend I do the same? Post maker and part# please.

Oh and did they fit under you valve covers? Stock type? I have alum "powered by cobra" stock height covers now and would like to continue their use.

Thanks guys
Howard Jones

 

[Ron Earp]

Howard, I think it is 25 ft/lbs but it doesn't matter. That is what took me awhile to realize - there is no adjustment besides shims and milling the pedestal. The torque spec is only there because of the bolt size and head, they don't want you stripping it out. I'd convert to stud mount if I were you, but, if this is your only problem a slightly longer pushrod or milling the pedestal will fix it.

R

 

[Howard Jones]

Ron, If I was to convert to stud type rockers can I buy the studs and simply screw the studs into the orginal rocker bolt down hole and use a roller rocker that has a adjustable lock nut? Or should I use a bolt down roller rocker that has a adjusment at the pushrod tip for preload.
I want to get away form any kind of shimming or milling the heads (pedestal).

Do you have the information (part numbers or makers) of the studs and any recomended rockers.

I would like to do this without pulling the heads off again.

Thanks, Howard

 

[Lynn Larsen]

From Ford Rocker Arm Guide (full document attached)

Turn the bolts by hand until there is no clearance between the roller and the valve stem (make sure the pushrod is seated in the rocker arm cup). Slowly torque the bolt to 18-20 FT-LBS. Since you are pushing down the plunger in the hydraulic lifter as you torque the bolt, it will probably take a minute or two to complete the procedure. The bolt should have turned between one-quarter to one full turn to reach the torque setting. This will give the correct lifter preload of .020" to .060". If the bolt turned more than one turn, you will have to shim the pedestal (use Ford Racing Performance Parts shim kit M-6529-A302). NOTE: M-6500-A301 anti-pump-up lifters only need .020" to .030" preload. If the bolt turned less than ¼", you will have little or no lifter preload. The solution for this is longer pushrods. These are available from a number of companies, such as Crane Cams Tech Line (904) 258-6174. There are many modifications that may have been made to the engine which will change the lifter preload, such as valve jobs, different cams, different thickness head gaskets, head milling, etc. It is a good idea to check the rocker arm pattern on the valve stem tip. Use a felt tip marker to “paint” the tip. Then, with the rocker arm in place, turn the engine through two revolutions. Remove the rocker arm and inspect the pattern. It should be nearly centered on the tip. If it appears to be too close to the edge of the tip, call the Ford Racing Tech “Hot Line” for assistance. Note: The lifter preload may be different between the intake and the exhaust or between one side of the engine and the other. Therefore, you must check lifter preload on each rocker arm. Step 6: Repeat this process on the remaining cylinders.

 

[Howard Jones]

Lynn,Ron,others. What a nice thing to do. Thanks for the help guys. That Ford instruction sheet is just what I need. I'm sure I'll be able to sort it out now.

I am still interested in replaceing the stamped steel rockers with a roller type but I can wait on that if I can just get the stock rocker set up properly. I have so much to do just finishing up the body so I can paint it. It would be nice to leave the motor alone for now.

Thanks again
Howard

 

[Ron Earp]

Burn that sheet - it made me struggle for weeks with a loose rocker. If it is loose, and it should be if it is making noise, then sand that pedastel and call it a day.

 

[Howard Jones]

Sh** I am just finishing up 6 months of sanding the whole damn thing. OK If it doesn't come in with the next go around I'll sand the fu***** rockers too! Thanks again Ron. I'm sure I'll end up there anyway. I'm thinking of taking off 5 thou at a time and then check it. Or should I go ahead and measure everything and then remove what it takes to achieve 40thou of preload. How did you figure how much to remove?

 

[Ron Earp]

I left the rocker over off. Sand pedestal. Install rocker. Start engine. Listen. Repeat until it shuts up. This is a fast and simple process that will work.

If you do this enough the oil that the rockers throw out on the headers WILL catch fire. I know. Use a cardboard box to block the oil splash.

 

[Mark Clapp]

To catch the oil splash while adjusting the rockers, I took a junk valve cover to a muffler shop and had them torch a wide slot in the top, they charged $5. You can then set it on and adjust through it with an extended socket/rachet.

 

[Howard Jones]

Ron, Cool you think like I do. I had visions of getting out the dial indicator and filling a whole page with measurements only to end up with take off a little at a time until they quite down.

Ya see all you got to do is ask and the forum shall provide.