Gentlemen,

its been a while for me here. divorce and moving etc have put my 540 finale off till now.

im finally about 3 weeks away and am in the process of putting my scorpion roller rockers (stud mounted) on my BBC. 540 dart and AFR heads (thanks wolfplace).

At any rate, im almost finished with the left bank and i get down to intake valve #7. well, up to this point, when i set cold lash at .019" and pull the feeler gauge out, i can rock the rocker back and forth and it will "clack"...

well, #7 intake doesnt want to clack. and as i rotate the engine around back to Exhaust 7 opening (the set point of the Intake 7 valve), it seems a little tight and again, doesnt want to clack.

so am i dumb for worrying about this or is this something to be concerned about?

so far, i have checked:

-that the pushrod is correct end up, seated correctly inside the lifter and back of rocker, that the rocker is completely spotless (no dirt to bind things up), that the pushrod is straight.

any ideas as to what this could be? could it just be the geometry of the number 7 intake?

feedback appriciated!

thanks guys

also, how bout a bent rocker stud? could that cause this?

thanks

Is the trunnion bar where the lock goes facing correctly? Could the lock be rubbing against the rocker? Mix up in push rod lengths? Just random thoughts

well, the little arrows on the lifters are pointing up and i tried different pushrods all together.

one thing that did help me catch one other error almost immediately was that on another rocker, the set screw of the poly lock was down a little further on the threads than all the others and that ended up being a pushrod not fully seated in the lifter, but that i fixed that and that particular rocker "clacked" after that

i just cant get this one (7 intake) figured out...maybe its nothing to worry about, but i like everything to be the same cause if it feels weird turning by hand, imagine what it will be doing at 7000 rpm :)

any other ideas? thanks

Will the feeler gauge still go back in? Does it still have .019"? Maybe take the rocker back off and make sure it rotates freely. And make sure you don't have the trunion upside down on that one like was suggested.

Pushrods are to short? Rockers hitting studs at bottom side of rocker arms?

AFR heads need longer pushrods.

Harry P.Hunter

yeah, the feeler gauge will go back in just like the others. and the trunnion is flat side up for the poly lock to sit on the flat part. And, i did get the longer pushrods, custom made. I spent a week verifying them a while back, and for every other valve so far, the pushrods seem ok. i swapped pushrod and rocker and poly lock and its still not clacking... thats why i was wondering about geometry...

thanks guys

So it moves like the others, but doesn't make the noise? Not sure what to tell you on that. As long as it's installed properly, and the lash is set properly, and nothing is binding, I don't see a problem.

well, its just not the noise, it also "feels" slightly different. a little "tight", like something may be binding. i was hoping someone would be able to understand the clack/no-clack distinction.

the feeler gauge will go back in, but whrn the gauge is pulled out, the rockers just doesnt move as easily. i see the clips in the side of the trunnion pivot. Can i take this thing apart and see if theres dirt or crap stuck in there that the brake cleaner didnt get? are there any parts of that rocker that once i disassemble, that i have to replace or can everything (clips/bearings whatever) be reused?

thanks

Interesting. So if you move that rocker to another valve, the problem goes with the rocker? Or does it stay with that valve?

ill check tonight, but i do know that swapping that first rocker for the second one kept the problem on that valve.

ill put that rocker on another valve tonight and see if the problem goes with the rocker

thanks

You shouldn't run it that way, something is not right. Did you check to see if the guide plate slot is too narrow, and maybe slightly pinching the pushrod. That could account for what you are seeing. They should all be clacking the same before you fire it up. Remember the old saying, "There's never enough time to do it right the first time, but there's always enough time to do it over again". Don't fall victim to that thinking. This is primitive technology (over 50 years old) that is very easy to understand, so just look everything over very carefully and you'll see the problem. :thumbsup:

totally agree. its my first motor ever. im sure not everything is perfect, but ive done the best i can. but, knowing this rocker/valve is off somehow...just dumb to ignore

keep the ideas coming

thanks

I had 1 guide plate interfere and tweeked it and got the clerance with in a few miles the guide plate broke so....don't bend the guide plate if that is a problem also look to see if the pushrod is rubbing the head or if the rocker is rubbing the radious at the bottom of the stud.

Have you checked for sufficient pushrod clearance in the head? I had to do more than a little grinding on my AFRs to gain sufficient pushrod clearance.

Its my understanding AFR has addressed this issue with their more recent castings. Mine were an early vintage.

Swap rockers with another one, if it moves, purchase a single or return it to whomever you bought it from for a replacement.....

If not, check rocker arm stud for straightness, check pushrod for binding, etc.

ok,

ive been playing with this for a couple hours. heres what i got:

when i moved the rocker and pushrod to another valve, that valve lashed fine and clacked, so it aint the rocker / pushrod

then, i put another rocker/pushrod in on the offending valve and got the same problem. i noticed that while the .019" feeler gauge went in (lash set fine), that the pushrod would NOT rotate easily even on the base circle

so, i loosened the rocker stud a little and the guide plate has a little play left-right, so i move it to the right a little, tighten the stud back down, set the lash and low and behold, the pushrod now spins in the hole and there is a clack.

but, the clack isnt as "loud" as the others, and im talking damn close, and so i look at the guide plate a little closer and notice that the machining isnt as clean on that "U" (wher the pushrod comes through).. that there is the slightest "ridge" on the "U"...just the slightest...

so, i think i found the problem. the clack is back, but should i pull the guide plate and file that little ridge off? im thinking that might make the clack perfect (just a tad more clearance) or should i leave it alone and not mess up the AFR stuff?

thanks guys

ok,

ive been playing with this for a couple hours. heres what i got:

when i moved the rocker and pushrod to another valve, that valve lashed fine and clacked, so it aint the rocker / pushrod

then, i put another rocker/pushrod in on the offending valve and got the same problem. i noticed that while the .019" feeler gauge went in (lash set fine), that the pushrod would NOT rotate easily even on the base circle

so, i loosened the rocker stud a little and the guide plate has a little play left-right, so i move it to the right a little, tighten the stud back down, set the lash and low and behold, the pushrod now spins in the hole and there is a clack.

but, the clack isnt as "loud" as the others, and im talking damn close, and so i look at the guide plate a little closer and notice that the machining isnt as clean on that "U" (wher the pushrod comes through).. that there is the slightest "ridge" on the "U"...just the slightest...

so, i think i found the problem. the clack is back, but should i pull the guide plate and file that little ridge off? im thinking that might make the clack perfect (just a tad more clearance) or should i leave it alone and not mess up the AFR stuff?

thanks guys
=
HI Jeff
Intake?
The pushrod is hitting the head
Did you align the guideplates?
They do not come aligned they are just bolted to the heads so they do not get lost
You also need to seal all the intake studs if you have not.

hmmm

how do i align the guide plate? is that a procedure or is that just loosening up the guideplate and making sure that there is clearance? is there a measurement/min clearance value that i should be seeing between the head/pushrod? i can probably knock a little out with my dremel... but obviously if i dont have to, id rather not...

yeah, its an intake valve.. number 7...and its really freaking close to the head, but does spin freely now that i moved the guideplate around.

what about that little ride on the guideplate? can i shave it off?

what do ya think i should do?

i got the sealer on there :)

thanks!

hmmm

how do i align the guide plate? is that a procedure or is that just loosening up the guideplate and making sure that there is clearance? is there a measurement/min clearance value that i should be seeing between the head/pushrod? i can probably knock a little out with my dremel... but obviously if i dont have to, id rather not...

yeah, its an intake valve.. number 7...and its really freaking close to the head, but does spin freely now that i moved the guideplate around.

what about that little ride on the guideplate? can i shave it off?

what do ya think i should do?

i got the sealer on there :)

thanks!
=
Just move the plate so you clear the head through the complete travel
Doesn't make any difference how much as long as you have clearance
They are going to hit in operation but according to Manton this can be a good thing
It helps to stabilize the pushrod, head acts like a big damper.
What you want is to center the end of the rocker on the valve tip if you can
Being in pairs you may need to compromise between them.
It can be off slightly if need be for the pushrod to clear the head but if off much you sometimes need to grind the head lightly

Not sure what you mean about the ride on the guideplate??

sorry, not ride... ridge... theres a little tiny ridge on the one guideplate. straight from AFR... that might help the clearance a tiny bit or i can leave it. right now, the clack (sound of the clearance) on this particular valve is not as loud (not as much play) and i think it might be this ridge...

should i file that ridge down a little or leave it?

thanks

I had 1 guide plate interfere and tweeked it and got the clerance with in a few miles the guide plate broke so....don't bend the guide plate if that is a problem also look to see if the pushrod is rubbing the head or if the rocker is rubbing the radious at the bottom of the stud.

Could you give us a little more detail, as to what exactly you did, and where you did it, on the guide plate, which caused it to fail? Did you hear the case hardening snap when you tweaked it? What all happened to the engine when it failed?

sorry, not ride... ridge... theres a little tiny ridge on the one guideplate. straight from AFR... that might help the clearance a tiny bit or i can leave it. right now, the clack (sound of the clearance) on this particular valve is not as loud (not as much play) and i think it might be this ridge...

should i file that ridge down a little or leave it?

thanks
=
If it is a sharp edge that is in the slot where the pushrod rides & can impact the pushrod yes, deburr or radius it
Do not make the slot wider

I am the one he is referring to the guide plate bend was angled toward the push rod and I tapped it back to get clearance so it would not rub 1 heat cycle and the guide plate broke at the bend at the base. not a good idea. all of the pieces stayed on the head but tore up 1 rocker.

Duh! I guess I need to start at the beginning!