I’m running a 360 Magum Block with EQ heads that were recut and treated to mild porting. These have 2.02 / 1.6 Stainless Valves and have an installed spring height of 1.66 with a Pioneer Spring. Set up to run with all stock rockers.

Other Mods include an M1 Fuel Injected manifold, 52mm TB, Shorty Headers, 2600 Stall, stock 2001 Short Block with .042 head gasket from Mopar. Custom SCT Tune and a wide band for air fuel and rpm.

My problem area?

I used Comp Cams 1425 Rocker Kit specifically designed for these motors. Upon investigation I determined that the studs are 3/8 -24 Thread ARP studs that screw into the 5/16 head threads. The kit comes with guide plates and 6.800 5/16 pushrods. The rocker arms are CHEVY rollers part numbers. Motor was short on power.

With the 6.8 pushrods the witnesses marks are “dead nuts” in the middle of the valve tip. My tuner had to take a lot of fuel out above 4400 rpms and although the cam is small should peak in in the 4900-5200 range. (212/218 .512 114lsa. Made 258 rwhp in a Durango.

After figuring out that we weren’t floating the valves I looked at pushrod length due to serious lifter noise.
I replaced with 6.95 and made 26 more HP / 33 more ft lbs and the motor didn’t fall off until 4900. So I was short but not sure if I am optimal. The witness mark is outboard of the center towards the exhaust. So in theory too long? I am thinking the distance between the fulcrum point to the tip of the valve is not optimal for this application? Rumor mill says Ford ones have a short distance and may work.
Anyone have any thoughts on this dilemma? I'm still getting lifter noise and they were all replaced with brand new ones at time of head and cam install. It has been suggested my PR length should be 7.05 but that may roll off the tip of the valve.

 

The center of the roller should be at the center of the valve stem at max lift, is yours? This will allow all the force applied to be in a straight line regardless of where the roller starts at no lift. The noise is another issue, have you recorded roller travel across stem through full lift?

 

At max lift center of roller is NOT in the middle of the stem tip. When on the base circle roller is slightly center leaning towards exhaust side. At max lift is outside towards exhaust side.

I'm thinking the the Chevy roller is slightly longer than the mopar one when you measure from the fulcrum to the roller.

With a 6.8 pushrod I can center the sweep but there is a noticeable drop in power. And i am definitely not hanging any of the valves open with a longer rod.

 

At max lift center of roller is NOT in the middle of the stem tip. When on the base circle roller is slightly center leaning towards exhaust side. At max lift is outside towards exhaust side.

I'm thinking the the Chevy roller is slightly longer than the mopar one when you measure from the fulcrum to the roller.

With a 6.8 pushrod I can center the sweep but there is a noticeable drop in power. And i am definitely not hanging any of the valves open with a longer rod.

 

sorry for the double post. new at this stuff

 

Your problem has me really thinking. First, your noise makes me wonder about oil pressure. I ask because a couple of Magnums I've taken apart have had cam bearing problems, either split at the joint or suprisingly big chunks out of them. I can't see too much noise from the roller stem alignment unless something is binding.
Second, not alot to be said about the rocker to pushrod alignment as they don't have adjusters, which shows the shorter make tip alignment better.
Lastly that power change with only pushrod swap has me stumped, as one should not influence the other, unless there is a binding issue and valves are hanging up. One thing I have done in the past is shoot a timing light at the valve gear while running and have the strobe stop the movement. If you clamp on different wires you can catch it at different positions and see intake or exhaust. It did find wobbily valve stems, guide wear for me once.

 

Oil pressure is down, right at the "low" line at idle only. then jumps right up to middle and stays there. I agree with the oil issue and am wondering if its not a consequence of the valves always lose.

Some have stated that the noise is the lobe profile on the cam and the valve slamming shut. I don't know if i buy that but there are numerous posts out there.

I put the smaller PR back in and power is right back down and runs like its out of breath at 4400. But witness mark is dead nuts in the middle.

Guide plates have no wear or evidence of binding. Rolled all the PRs on glass. Maybe hitting in the push rod holes of the heads but i would see transfer from the metal / metal contact. I have none.

I'm setting lash at .060 as stated in the books which is 1.5 turns on a 3/8 24 thread. And the every time i pull the valve covers everything is lose. Meaning my preload is gone on base circle.

Im going to order a single ford rocker and mic the distance and set a single valve with the longer rod and see where i am.

 

One easy thing to do is get that Chevy stuff outta there and get the right stuff back in there...also get you a pushrod checker so you stop throwing money at pushrods....oil bands on the lifters coming out of the hole is probable cause of the noisy lifters...you said they were taller...thus you may be losing oil pressure and collasping them

 

You sound like a sharp guy but I have to ask, spring pressure enough, any chance of guide to retainer hitting with that .512" lift? Losing your preload, is the nut backing off? Any touching could hammer away at them to loosen them off.
When ever I have had a pressure issue I've taken a 45' fitting and 0-100psi gauge and screwed it into the back of the block where the sender is to know for sure.
If there is no touching binding issue some polylocks may be needed if you have enough stud.
If you have lost .060" of lift while running it could account for the upper RPM power loss.
Man, I'm really grasping at straws now, I wish you the best of luck and would like to know the outcome.

 

Thats a good point about springs. I have a pioneer spring with 125 closed / 310 open. BUT, I never pulled and tested these springs. This is what the machinist said. I have cycled all these and have good clearance with retainer to guide clearance. The springs mic to 1.437 wide and are really tight in the cup. I wonder if there is a binding in there? Comp says these rates will work.

I can certainly double nut the stud roller bolt. Appreciate that advise. Never though these could back off, but learn something new every day, THANKS!

And good call on the old valve train stuff. I sold the magnum heads with gear so will have to make a bone yard run for this stuff but it would certainly tell me where my problem area is.

 

One last thing I forgot to mention, check the radius of the stud above the hex. I've heard some with a large radius can come in contact with the underside of the rocker. It probably would have been obvious with the shorter rods. Good luck.

 

Update:

Went back to basics.

Pulled springs, retainers, locks and inspected all. Pockets look good, seals are good. Zero contact with retainers. Measured clearance again to make sure all is good. I have .544 between retainer to guide seal.

Ordered new rocker nuts to make sure the noise was not lose nuts ( 2 bucks a piece on line). And double nutted them with lock tight.

I went back to square one. Installed 6.8 PR and measured witness mark. Mark is almost .15 wide on a .310 (8mm valve stem). And "dead nuts" in the middle.

As I increase PR length my witness mark gets very small but starts to move outward.

At 7.05 my witness mark measures .805.

I was always taught that the smaller the witness mark the better and preferred in the center to reduce side loading the valve guides. BUT smaller indicates that the rocker is moving thru its normal and total range. ( not saying I'm correct, just how i was shown).

Loaded up 7.05 ( I have a pushrod checker but plenty of hardened PR in the shop) into the truck.

Not gonna dyno this but seat of the pants feel is better. And Gtech says so too

Also measured PR throw to make sure all lobes were good. All perfect.

Now for the noise.

I have no idea if comp roller rockers are supposed to be loud. Or its the cam?

I adjusted lash as per the normal procedures and oiling is very good but its still loud.

Then I adjusted with the motor running. Could get no decrease in sound. Still loud. But very good oiling through every rocker. Which confirms lifter are at least pumping up.

Conclusion: cam lobe profile is causing the rocker to leave the stem before returning to base circle? XE profile.

Rollers just loud??

Possible next steps:

Was thinking of adding lash caps to raise installed height to see if this brings the smaller sweep to the center.

Spending 80 bucks to go back to the stock valve train gear since I have PR already. I hate this option but the noise sounds like a solid roller.

Dumping this cam for a less radical lobe..

 

Update 2

The comp cams kit that they sell as a dodge fit causes a geometry issue in my application. I use a lot of their products and recommend a lot of their products and am greatly disappointed in this discovery.

I called Hartland Sharp and asked for specifics on their Mopar Rockers. I was NOT the first caller for this issue who was having issues with the comp dodge kit that uses the chevy rocker. The tech knew exactly what problem I was having. Asked me if my centered witness mark was half the stem circumference. And asked if i got a nice small sweep but were falling of the tip of the stem.

The HS rocker is .300 shorter from fulcrum point to stem than the chevy one comp says will work. There is the issue. I will post back with final results.

 

As much of a pain this has been I'm sure it's been a great education for all that follow, Thanks for sharing this.

 

Hey I dumped some 440 Source Roller rockers for the same noisy valvetrain issue..I stepped up the Harlans Sharps for the same reason...440 big block but same noise drove me crazy.

 

Noise is gone.. totally.. Motor revs incredible. I'll post an update once i get it tuned. It was extremely lean and anything above 4400 rpm went to 16/1. That comp kit must have been loaded with friction and binding..

 

Final Update.

Motor is finished and almost tuned. I had to add back a ton of fuel back in throughout the rpm range.

Here is what was discovered.

The comp cams conversion does not work efficiently in my application. Other magnum or EQ applications? I doubt it. I measured the EQ vs the magnums because i have both in the shop and they are spot on. IDENTICAL. The Comp rocker is .3 longer from fulcrum center point to valve stem over stock geometry.

When setting the valve train up you need a very small push rod length to center the witness mark on the stem and that does NOT allow the rocker to function through an efficient range of motion. So your sweep or witness mark is HUGE. I couldnt find any evidence of binding and I used dykem all over a couple of rockers and ran them to make sure..

The Harland Sharp Rockers are made in exact specification for the magnums heads. They are not made for old's or chevy's and retrofitted. The base cam circle from comp on this cam is smaller so my pushrod is slightly longer than stock. but only by .05

Also if you upgrade to 1.7 from HS i noticed they move the pushrod cup in towards rocker fulcrum. They do not just shorten the distance from valve stem on the roller side. This makes for a very efficient design. I never used HS before so I will give it time before I let you all know how they hold up. Randy from HS told me they can swallow significant springs pressures and told me to send them back if one breaks and they'll replace or repair it no charge. Cant beat that..


How efficient are they? With the chevy rocker setup the motor was done at 4700 rpm and made 276 at the wheels (dyno 276 / GTECH 274.5). And this was done with a long push rod that was clearly going to cause significant valve stem guide wear in short order.

GTECH has it at 321.5 rwhp at 5200. Im still lean at 5250 so stopped there. But this is a small cam so it wont have much more after that anyway. Engine dyno has this combo at 388 at the crank so its well within range. I'll dyno when done tuning.

These rockers did not make 50 HP! They simply let the motor operate in its full useful range of motion by significantly reducing friction. I would bet the stock stamped rockers work well too. If I had a set around I would have compared them.

Also, idle is set thru the pcm and i have it at 780 rpm. This motor hunted at 1200-1500 for almost 45 seconds to find idle after the new rocker install. Meaning that the amount of fuel and air needed to hold idle with the old rocker set up was significantly more than with the new valve train.

No more noise either!!!