[TroyV]

We are building a 1997 460. Stock heads and block, refurbsihed by good local machine shop. Small ISKY cam and lifters, stock replacement pushrods 8.550 in long. Some of the stock rocker arms have 0.04-0.120 lash when torqued. We began replacing rocker arms, but not much improvement; still a gap, no preload. How do we fix this problem?

 

[The Mad Porter]

Proper length push rods.

The question is why you have such a difference and what caused it.

Using the early short valves in the later heads can cause this.

Minor differences in cam base circle, valve stem tip height, decking of block or heads etc can all contribute to needing more length in a push rod but not .120"







Scotty J. "AKA" The "Mad Porter"
"EMC 2006" 3rd place finisher
Ported BBF iron head specialist & Aluminum heads from all sources.
Custom ground cams
See our products in the Vendor for sale section
Customized crate engines
ParklandAutoMachine.com
R-H-P.biz
"Parkland Performance Auto Machine" Formerly RHP
(253)-988-6648
Parkland Auto Machine

 

[TroyV]

Thanks for the reply. We are stumped. Any thoughts, other things to consider or check would be greatly appreciated. Even worse, it is not consistent between rockers. Some appear to have proper pre-load. The new rocker kits we tried are SB International 181-1034.

 

[pedal2themetal45]

HI,
If you have NOT run the motor may be some of the lifter are collapsed under spring pressure.. If not filled with oil they well collapse really easy since some of the are good and only some are not.. If you haven't run it I'd run it then see what you got..

good luck take care be safe
tim

 

[TroyV]

Ok... update. We obviously do not understand the phrase "Not Adjustable" when referring to this 460 FORD motor. When we assembled the motor, we simply installed the rockers and torqued them to 25ft.lbs. Apparently, we were supposed to barely tighten them to 0" lash, and then tighten/torque them to 25 pounds after that, max 1 turn. Is that correct? Do the pivot blocks not bottom out? We ran the motor for 20-30 minutes. Cam and lifters are ruined. Going to require complete disassembly, clean everything, replace bearings (based on amount of metal shavings) and figure out how to build it correctly.

Sure would like a link that shows video of how to properly set these "Non Adjustable" rockers.

 

[pedal2themetal45]

HI,
?? Non adjustable means non adjustable... just TQ. them down.. there's no 1 turn after TQing them down.. If there TQed down how are you suppose to get 1 more turn???? yes the pivot blocks bottom out..
When you ran the motor did you run it at 2,000 RPM's for the 20 minutes while occasionally revving it to 3,000 rpm's?? If you didn't that would be why the cam and lifters are wiped out..
how big of a cam did you put in it?? Hydrolic cam and lifters?

good luck take care be safe
tim

 

[TroyV]

Your thought was the same as ours. Put the rockers on, torque them down, period. Followed break-in for 25 minutes with proper cam lube supplied by Isky. Used non-synthetic 10W-30. Changed the oil immediately thereafter; already see a lot of silver at that point. Mild hydraulic cam... Isky Racing Cams Camshaft Kits CL311256; cam and lifters. Stock springs; 3-angle valve job, resurface seats, with new retainers and seals; basic head work. Re-used stock rocker arms, pivots and bolts. Our assumption is that we some somehow over tightened the rockers. But, sounds like you are saying they are truly not adjustable. The only other thing may be that the Isky cam requires a custom pushrod... an obscure note in the back of their instructions noting to check it. We will call them Monday for sure!

 

[pedal2themetal45]

HI,
I looked at your cam specs. and it don't look like it needs special push rods.. it is a small lift .492 I think it was and calls for 1.74 rocker and that is stock ratio rocker. On brake in you did run it a 2,000 rpm's varing it to 3,000 rpm right?

good luck take care be safe
tim

 

[FoMoCo]

I may have missed it but did you have the .040 - .120 gap before or after break-in? If after gaps are simply wiped lobes. If before measure each push rod.

 

[TroyV]

We did the break ranging from 2,000 to 3,000 varying up and down a bit along the way. The gaps were after the cam and lifters were worn down. We don't recall any gap before start-up. Pre-primed oil pump. Oil gauge in truck had pressure immediately. I just don't know what we did wrong?

 

[FoMoCo]

We did the break ranging from 2,000 to 3,000 varying up and down a bit along the way. The gaps were after the cam and lifters were worn down. We don't recall any gap before start-up. Pre-primed oil pump. Oil gauge in truck had pressure immediately. I just don't know what we did wrong?

Not sure if the stat is true but read somewhere that 50% of the HD cams wipe lobes on break-in. Even with all the safe guards in place it happens.

 

[The Mad Porter]

Did you use a flat tappet specific oil or better yet break in oil?
ZDDP is a component of these types of oils.

With bolt down non adjustable rockers you have to establish appropriate push rod length upon reassembly.

Changes in cam base circle, valve stem tip heights, decking the block or heads all have an effect on final length.

When installing the rocker and tightening it by hand a proper length push rod will require about 3/8 to 3/4 of a turn to SEAT THE ROCKER IN THE rocker pedestal AFTER you've taken out the slack between the rocker and lifter plunger.
This is what preloads the lifter plunger.
Torque down after this does not change preload.

If it takes more than 1 turn to seat the rocker in the slotted pedestal while preloading the lifter plunger the push rod is too long.
Less than 1/4 turn and the PR is too short.

We typically get the push rods a bit long when doing final assembly and then fine tune the preload with hardened steel shim that goes under the sled fulcrums.


Finally. When you replace the cam get a proper dual pattern cam.

OEM is 193 / 206 @ .050"

That isky cam is 202 with no exhaust split and is only appropriate if your focus is peak and throttled torque in an HD towing or hauling application. The lack of exhaust duration will clip the last 1000 rpm of the power band.









Scotty J. "AKA" The "Mad Porter"
"EMC 2006" 3rd place finisher
Ported BBF iron head specialist & Aluminum heads from all sources.
Custom ground cams
See our products in the Vendor for sale section
Customized crate engines
ParklandAutoMachine.com
R-H-P.biz
"Parkland Performance Auto Machine" Formerly RHP
(253)-988-6648
Parkland Auto Machine

 

[thomasa]

Did you use a flat tappet specific oil or better yet break in oil?
ZDDP is a component of these types of oils.

With bolt down non adjustable rockers you have to establish appropriate push rod length upon reassembly.

Changes in cam base circle, valve stem tip heights, decking the block or heads all have an effect on final length.

When installing the rocker and tightening it by hand a proper length push rod will require about 3/8 to 3/4 of a turn to SEAT THE ROCKER IN THE rocker pedestal AFTER you've taken out the slack between the rocker and lifter plunger.
This is what preloads the lifter plunger.
Torque down after this does not change preload.

If it takes more than 1 turn to seat the rocker in the slotted pedestal while preloading the lifter plunger the push rod is too long.
Less than 1/4 turn and the PR is too short.

We typically get the push rods a bit long when doing final assembly and then fine tune the preload with hardened steel shim that goes under the sled fulcrums.


Finally. When you replace the cam get a proper dual pattern cam.

OEM is 193 / 206 @ .050"

That isky cam is 202 with no exhaust split and is only appropriate if your focus is peak and throttled torque in an HD towing or hauling application. The lack of exhaust duration will clip the last 1000 rpm of the power band.









Scotty J. "AKA" The "Mad Porter"
"EMC 2006" 3rd place finisher
Ported BBF iron head specialist & Aluminum heads from all sources.
Custom ground cams
See our products in the Vendor for sale section
Customized crate engines
ParklandAutoMachine.com
R-H-P.biz
"Parkland Performance Auto Machine" Formerly RHP
(253)-988-6648
Parkland Auto Machine
[/QUO

Ok... update. We obviously do not understand the phrase "Not Adjustable" when referring to this 460 FORD motor. When we assembled the motor, we simply installed the rockers and torqued them to 25ft.lbs. Apparently, we were supposed to barely tighten them to 0" lash, and then tighten/torque them to 25 pounds after that, max 1 turn. Is that correct? Do the pivot blocks not bottom out? We ran the motor for 20-30 minutes. Cam and lifters are ruined. Going to require complete disassembly, clean everything, replace bearings (based on amount of metal shavings) and figure out how to build it correctly.

Sure would like a link that shows video of how to properly set these "Non Adjustable" rockers.

See the post from Mad Porter.

Set up adjustable push rod - I adjusted length at zero lash making sure pivots were fully seated. Measured adjustable push rod, added .050 to length and ordered push rods.

Shimmed pedestals as needed for final adjustment to achieve 25ft lbs. of torque at 3/8-3/4 turn when installed.

Works!