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-   -   Rockers are hitting Retainers....?? (http://www.hotrodders.com/forum/rockers-hitting-retainers-141142.html)

nastynova 06-28-2008 07:43 PM

Rockers are hitting Retainers....??
 
Well... as the old saying goes... if it isn't one thing... it's 247 of em...
The problem now is my rocker arms are hitting the retainers. I have Crane Energizer Rockers and Crane CRN-96877 Valve Springs, Dual, 1.460 in. Outside Diameter, 404 lbs./in. Rate. with 1.5" retainers...

Is this a common problem with 1.5" retainers? Do i have to buy even higher priced rockers to clear them? The Energizers are suppose to work with springs up to 1.5"...?


If it helps...more motor specs:

383 sbc 12.9:1
Dart Sportsman II heads with Milodon Mega Flow Valves +0.100 length
Crane Energizer Roller Rockers, Edelbrock Super Victor Intake with Holley 750 DP

Crane Solid Cam #110981
Duration at 050 inch Lift: 252 int./260 exh.
Advertised Duration: 288 int./296 exh.
Valve Lift with Factory Rocker Arm Ratio: 0.536 int./0.554 exh. lift
Lobe Separation (degrees): 106

Moroso Pan w/crank scraper and windage tray
MSD Probillit Dist.\MSD Digital 6 Plus Box w/timing locked out @ 34-36 degrees
Hooker Super Comp's 1 3/4" tubes

Mike H 06-28-2008 09:16 PM

Those rockers are pretty thick in the trunion area so if you want to grind them for clearance you would not be the first to do it. I have done it and have broken a few over the years but if you don't have allot of spring preasure I would not be scared to give it a try. A forged rocker will have a little more clearance around the spring (Crane gold, Lunati etc.)

Try running an 1.625 spring on a SBC you have to pull the 2 center springs to put the heads on, rocker clearance is a joke compaired to the 1.50 spring.

Stroke 06-28-2008 09:17 PM

How is your geometry? What length push rod are you using now? Can you post a pic?

nastynova 06-28-2008 09:33 PM

push rods are 7.765" (recommended length)
geometry is fair...
will try and get a pick tomorrow...

some rockers seem better than others, but all very close or hitting enough to hold the roller off of the stem...

would not take much to clearance the rocker, but with all the trouble I have had and with over 400lbs. they would no doubt break with my luck...

thanks

j.d.brown.042964 06-28-2008 10:22 PM

Do you think Stainless Steel roller rockers might hold up better that aluminum after "massaging" for clearance? Generally considered a stronger material.

ericnova72 06-29-2008 03:14 PM

Rockers hitting
 
Sounds like maybe a geometry problem, since you have .100" longer valves. This would normally require adding to the pushrod length, you have shorter than stock length.
Why are you running 1.5" retainers with a 1.46" spring? Retainer for these springs would be in the range of 1.38"-1.44" dia. The retainer only has to cover 1/2 of the spring's wire diameter, anything larger is just excess weight.
Another possible fix is to use lash caps on the end of the valve stem, especially if a geometry check shows that the pushrod is somewhere close to the correct length currently.

oldbogie 06-29-2008 03:54 PM

Quote:

Originally Posted by nastynova
push rods are 7.765" (recommended length)
geometry is fair...
will try and get a pick tomorrow...

some rockers seem better than others, but all very close or hitting enough to hold the roller off of the stem...

would not take much to clearance the rocker, but with all the trouble I have had and with over 400lbs. they would no doubt break with my luck...

thanks

What is meant by "geometry is fair". Unfortunately you can almost ever buy pushrods before the engine is nearly complete. At the point where the heads are bolted on with valves, springs, retainers, and rockers; the cam and lifters are installed: at that point you can use an adjustable push rod to determine proper geometry which will establish the proper push rod length. If you have 400 pound springs at this point you may well have to remove them and reassemble the heads with light springs for checking as the adjustable push rod isn't intended to open valves against that kind of pressure.

With the top of the valve stems marked with grease, Prussian Blue, or a felt tip pen; the crank is turned to cause the valve to fully cycle. You're looking to see that the roller starts at about 1/3rd the width of the valve stem from the exhaust side of the head when the valve is closed. As the valve is opened, it will travel back toward the intake side where at max opening it will be at 1/3 rd the width of the stem on the intake side. At mid lift it will sit in the middle of the valve stem. The "thirds rule" is at the extreme, if you're set up is inside this, favoring the middle of the stam as much as possible, all the better.

There isn't any "fair" in this term; the push rod length will establish this absolutly. The manufacturer of the rockers can only give an approximate push rod length, they have no way of knowing if the head and or block has been milled, what the real distance of the cam is to the crank. Nor how accurate the rocker studs are located compared to the valves nor if the valve stems are of different length or if stem caps are being used. The check I just sighted is to discover what's really needed in push rod length to establish proper operating geometry at the valve stem by compensating for all the machining and part disparities that can accumulate. All this has considerable influence upon where the trunnion ends up compared to the retainer.

Whew, it get worse. 1.5 inch springs and retainers are always troublesome with aluminum rockers. Beehive springs make this much less of an issue. However, with std springs and retainers one can grind a little off the trunnion face to clear the retainer if this is necessary after getting the push rod length dead on. For as crude as it looks, such grinding doesn't seem to endanger the strength of the rocker. The ratio of the rocker doesn't have anything to do with this clearance problem, it can contribute to other clearance problems but not this one.

If you decide to kiss a little off the rocker, be sure to run the die grinder so the cuts are in the direction around the trunnion rather than across the width. This keeps any stress risers or gouges in line with the major stress instead of across them. The latter condition can lead to fracture formation.

Bogie

woodz428 06-29-2008 04:08 PM

Many rockers have that issue. It has nothing to do with geometry in most cases. It's merely a manufacturing convenience( read; cost). Many rockers are the same contour for different ratios. That way they don't have to make several bodies, they just bore the center at a different place to get the ratio they want. I have seen it on scorpion's on a SBF , so it's not just a SBC problem. As was pointed out the more pricey, less broad application rockers usually don't have the problem.

SSedan64 06-29-2008 06:47 PM

Quote:

Originally Posted by woodz428
Many rockers have that issue. It has nothing to do with geometry in most cases. It's merely a manufacturing convenience( read; cost). Many rockers are the same contour for different ratios. That way they don't have to make several bodies, they just bore the center at a different place to get the ratio they want. I have seen it on scorpion's on a SBF , so it's not just a SBC problem. As was pointed out the more pricey, less broad application rockers usually don't have the problem.

I thought the pusrod cup was moved closer to the trunion for higher ratio?

nastynova 06-30-2008 08:26 PM

thanks for your posts... haven't been able to get back to my engine do to work... but will try and answer some of your questions...

spring... retainers... push-rods... are all matched to the cam by Crane...
+0.100 valve were to get close to the correct spring installed height...
I have an adjustable push rod to check for length but there is no way to get it in the friggin hole with the guide plates to use it... so I ordered the recommended ones to start with and go for there... that was when I ran into the rocker problem... It looked do-able on the first cylinder I checked... tight but not a hard interference... I'm going to see if some other racers around here have an extra set of rockers to just check with...

thanks

Stroke 06-30-2008 09:01 PM

Quote:

How is your geometry? What length push rod are you using now? Can you post a pic?
The reason I asked these simple questions is because I saw your +.100 valve, and, they are in fact relevant and have everything to do with proper set up. The common misconception is that 'recommended' is correct. If installed as 'recommended' and it 'works' many think they're all good. I'd hazard a guess and say that 99% of the time that would be wrong :smash: Pushrod mfrs make custom length pushrods for a reason, not so somebody can say they have 'em. IMHO, Proper valve train geometry is as important as any of the components of the valve train - from under the shelf to top of the line. Many readers of this and other forums would do themselves a huge favor if they did a little study into proper valve train geometry, and the reasons why it is important. What some people think is right, is all wrong :eek: I will not rant on this subject as it is like beating a dead horse :boxing:

racecar100 07-01-2008 08:35 AM

Just grind the rocker enough to clear. I've done so many and lost count. Never had any failure.

nastynova 07-01-2008 03:55 PM

don't disagree at all on geometry and am trying to get it right... I had all the cam and valvetrain components bought before I found out i had a spring height issue and had to buy longer valves...

nastynova 07-01-2008 05:54 PM

2 Attachment(s)
alright got a couple of pics to add...
travel on valve stem is centered more towards exhaust side...
first pic should be of valve closed position... second, valve open...

coldknock 07-01-2008 06:05 PM

My man, your pushrods are WAY too short. I have a stock pushrod in my hands right now that measures 7.794". With an aftermarket cam, and 0.100" longer valves, you should need at the very least a 7.9" pushrod.

Like everybody said, the only way to get it right is to measure it. You might have to take a couple of rockers, and studs, off to get a guideplate out of the way so you can drop the adjustable pushrod into place. It's worth the effort.



Larry


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