i have crane aluminun roller rockers on my 400. im having a problem with them loosing up. im running a solid cam and i understand that i have to adjust the lash every couple hundred miles or so. i adjust them last night and i put about 5 miles on the car today and they loosened up already. is there any special trick to this? do am i supposed to use lock tight? this really sucks because i just got the car running and i can drive it. any help or suggestions would be great. thanks alot

 

Sounds like you're not getting the Poly-Locks tight enough....

The first thing you have to do, is to get the lash right in the first place. I usually do that by using a dial indictor and finding the max opening of a valve, any valve, whichever is convenient. Let's say I walk up to the motor, pop the valve covers, and find that #6 intake is opening, and is about to reach max.

Remember that cylinders that are 4 positions away from each other in the firing order, are one full crank revolution apart when comparing the same events, and therefore 180° (one-half cam revolution) apart. So, if #6 intake is exactly at peak opening, then #1 intake is exactly on the base circle. So, in the previous example, I find #6 peak open, and adjust #1 intake. Then I rotate the crank exactly 90° with a crank socket, and adjust #8 intake. Then 90° more, and adjust #4 intake. etc. etc.

Then once I've done all the intakes, I go back and find an exhaust that's about to reach peak opening; and do the exact same thing.

No other method has any cheance of working, except for loosening them all ¼ turn and going all the way around the engine and adjust all 16 to spec, then turning it like 1/16 turn and adjusting them all again, never loosening a valve after the intitial loosening, only tightening, and making a little more than 2 complete crank revolutions. The method of adjusting the intake just as the exhaust starts to open and the exhaust just as the intake starts to close, is not precise enough for a solid with lots of duration (although it works entirey well enough for most hydraulics).... too much chance that the valve you're trying to adjust is on a ramp. And certainly none of the "set motor here, adjust 8 valves" methods will work.

Then, when you're done, tighten the Poly-lock itself and the lock screw, at the same time. Box wrench on the nut, allen on the screw. If you've tightened the allen as tight as you can get it by itself, you'll get a good 1/16 turn of the nut farther, tightening them both together. Make sure they move equally, together, and that you don't tighten the nut but leave the set screw still; that will over-tighten the valve.

Once you master the technique, you should be able to get 12,000 miles easily out of one adjustment. I certainly have no problem with that, and alot of other people I know who are similarly meticulous, get similar results.

And, you'll be amazed at how smooth and quiet and perfect your engine will run.

 

ok thank you very much. the way i was adjusting was rolling the motor over to tdc on #1 cylinder and adjusting 3,4,8 exhaust and then 2,5,7 intake. then turn it to tdc #6 and doing the rest. and i don't think i was tightening them correctly. i would asume that your method would have to done while the engine is still warm for the best result, am i correct. thanks alot.

 

Another method of positioning the crank in the proper position to adjust the valves lash is a s follows:
Unplug the 12v power wire to the distributor or remove the coil wire from the cap to disable the spark.
Bump the starter over little by little with the starter
till an intake valve has opened and is just about all the way closed (intake closed) set the exhaust valve lash for that cylinder. Now bump the starter over till the exhaust valve just starts to open (exhaust opening)
Adjust that intake valve lash to spec. repeat for the rest of the cylinder's valves.
easy: no fireing sequence to remember.

Poly locks were never designed for street motors and continous use or easy adjustment.
Good for all out race motors, a pain on a street motor.
Setting them and getting them to lock is a bit tricky.
RB's advice sounds pretty good. Takes a bit of practice to master it.
If after setting them *correctly*; they still come loose it indicates a valvetrain problem (interference, exessive spring pressure , cam wear etc)
Should only have to adjust the valve lash ever 3 months or so. Over reving the motor into valve float will mess up the lash adjustment.

Setting valve lash correctly is an aquired skill. Once you master it its easy and does not take long.
On your next *street motor* consider using a quality rocker that uses a conventional ball and jam nut adjustment. makes life a lot easier. Both Crane and Comp cams make good ones.

 

your sig doesn't say anything about heads.
Do you have screw in studs?
Cause if they're pressed in, they might be pulling out.

 

i really don't understand how to set these poly locks. so far i had to adjust them twice in one day because the poly lock keep coming loose. i took off the valve covers and the one side was fine. the other had one rocker laying on its side with the poly lock next to it and was another rocker was loose. if i had known that these poly locks are not for sreet use i would have never bought them. its a shame that summit doesn't doesn't say that in there ad. is there a way to get rid of the poly locks and use something else. i spent a decent amount of money on these rockers and i want to use them. i have afr heads with screw in studs.

 

what cam are u useing? how much spring pressure.?
a rocker like the ones I posted above may be more suitable for your needs.
Might want to inspect the tops of the rocker studs.
If they are not flat on the top , the poly lock set screw won;t lock down on them well.
Don't know if AFR heads come assembled with good ARP studs or cheapies.

re-facing the tops of the rocker studs may help.
could run over them with a flat file.

 

Ditto what F Bird said
I have some cheap Cat poly locks and they stay put, but that's with a hyd roller.
The studs should be squared off on the top.
Another thought... The trunions on roller rockers have a flat side and a rounded side, the flat side is for the nut to seat against.
Is the flat side up on all the trunions?

 

Does this method apply to either type of solid cam..solid roller or solid flat tappet?Good method to know when I swap over.

 

my cam is a crane cam 280/288 duration and 518/536 lift. i had afr do there spring upgrade because i heard that there stock springs are crapping. i don't know the specs but i know that they can handle 600 lift. i'll see if i can fine some specs for them. i'll check the rocker studs tommorrow and see if they are flat.

 

It applies to all cams. You can use it on hydraulics even, just pay attention to the lifter plunger instead of rocker lash, and look for it to just barely begin depressing, and then add your desired preload.

As a hint: Go visit a car assembly plant. You'll see the cars roll down the assembly line, engines get installed somewhere along the way, and at the end somebody gets in and starts them up and drives them off. Off to the side on pallet racks or in containers or something, you'll see a large stack of engines in inventory, that got delivered from an engine plant. They're fully assembled, with spark plugs, wiring, hoses, etc.; all gaskets installed, torqued down, sealed, etc. AFAIK the engine assembly plants don't test-run the engines, but I could be wrong about that. Yet, at the assembly plant, they simply drop the engines in, turn the key, and drive them off. No valve adjustment required. No head bolt or intake bolt retorquing. Ready to crank up, drive away, and not have to be touched for the life of the car, unless something breaks.

Now, that means they have some way of getting the engines to that point, infallibly. With no guesswork, no errors, just accuracy, down to a failure rate with lots of zeros to the right of the decimal point before any other numbers. All we, as hot-rodders, have to do to get the same results, is to figure out how to duplicate that technique. Right?

AFAIK, that's how the factory does it.

 

That cams lift is not likely to create exessive spring pressure with ".600lift springs" so should be ok.

If you just can't get the poly locks to stay tight after trying RB's advice on adjusting them,
you could switch rocker arms to a conventional ball
and jam lock nut style with a roller type.
(require a 3/8" stud dia.)

May not be as sexy as a full rollerized rocker but they work well, last the life of the motor, are easy to adjust
and will stay put.

I use the Crane cams brand PN #11806-16 1.5:1 ratio
they are available in 1.6 and split sets.
These are way better than stock GM rockers in every way. I moved them from my old motor to my new motor.

I'd also recommend Comp Cams Magnum rocker
#1412-16 1.5:1 ratio. They are also available in 1.6 ratio

 

RB83L69 i THINK im doing what you're saying, but i might be confused....



when i set mine i tightened the nut ALMOST where i wanted it.. within about 1/8th of a turn... (and never loosened....just turned till i figured its within about 1/8th.)

then i snugged up the poly tight

then i turned the allen key and the nut at the same time to where i wanted it to stay.... i think its locked in there VERY tight.





is that what you were saying about turning both at once, or are you refering to a alternate method?

 

Yup, that's pretty much it....

Except, if you think about it, the act of tightening the allen moves the Poly-lock itself away from the rocker, which increase the lash; so it works better to stack up the couple of thousandths of error in favor of slightly over-tightening the valve. The head will expand more than the push rod anyway, so you'll gain a couple of thousandths of extra lash in operation even if you get them perfect when it's not running; so I'd rather set them a hair tight than perfect or a hair loose.

 

ialright guys. i adjusted my lash today while it was hot and i tightened the poly lock the way RB83L69 explained. i'll let you know how everything works out. thanks for all the help.

 

actually, most modern engines use NON-adjustable valve trains, all lash/preload is in the design/maching of the components

 

I've always adjusted them with the motor running...

-- Joe

 

And this would alter the facts about how SBCs are/were built somehow?He has solids. You can't adjust them with the motor running and get anything remotely resembling accuracy, although as we all know it works fine for hydraulics in the field.... even though that's not how the factory does them.

 

whats really funny is... most modern pushrod motors are converted to adjustible valvetrains when the engine builders get serious........


like one big circle. :lala: