Melling Rocker Issues

[The Flying Scot]

I don’t know about “fundamentally wrong”....... but my guess is if the rockers weren’t failing, you’d still be happily motoring along.

Yes, probably. I had previous concerns with “pinking” but aside from that it was ok, although I felt performance was a little bit flat overall.

 

[RemCharger]

The comp cams rockers can be a bit of a headache to get the proper size pushrods..

 

[RemCharger]

Yes, probably. I had previous concerns with “pinking” but aside from that it was ok, although I felt performance was a little bit flat overall.

you mean pinging? As in detonation?

 

[The Flying Scot]

you mean pinging? As in detonation?

Yes. Known as “pinking” here in the UK although I suppose “pinging” works also.

 

[The Flying Scot]

The comp cams rockers can be a bit of a headache to get the proper size pushrods..

That’s useful to know. Thanks!

 

[PRHeads]

The comp cams rockers can be a bit of a headache to get the proper size pushrods..

I guess it depends on what you’re used to.
I don’t find them to be difficult in that regard at all.

In fact, I feel like they’re actually easier........ since you’re not guessing about how many threads should be showing below the rocker to facilitate proper pushrod oiling.

With the Comps, screw the adjusters up into the rocker as far as they’ll go, then back it out one full turn..... snug the nut down.
Now use the pushrod checking tool to figure out the correct length and order them up.
Done.


As for the pinging....... too much compression with poor/no quench for the octane you’re running.
That’s (a lot)more complicated/expensive to solve if you’re trying to make it work with the same gas you’re running now.

The first step would be to take a couple of degrees of timing out of it and see if that helped.

A slower, factory styled advance curve........ and employing vacuum advance might solve it, or make a noticeable improvement.

But..... that’s a topic for another thread.

 

[Bee1971]

This is not a 268 cam.
It’s a XE275HL, .525/.525 lift.



Not balanced?
Hopefully that’s not really the case.

A cranking compression test might shed some light on whether or not the claimed CR is accurate.

No one has mentioned it....... but since it appears the motor should have a fast rate cam in it(based on the part number), perhaps the Melling rockers just aren’t up to the job.

Edit- I see Beanhead touched on the rockers as being suspect.

Same Cam and Lifters I am running with the Sealed Power Stamped Rockers , like I mentioned earlier in this thread

Five summers now , and zero issues

Going to pull the valve covers , rockers/shafts when the car goes into Winter Storage
Look everything over for a second time

I see the Scot started looking at adjustable rockers - Seeing where both in the same boat sort of speak

What’s considered a durable / good quality STREET adjustable type rocker system
Without breaking the bank
These Comp XE275 HL and Comp Lifters are only good for about 5400/5500 RPMs from what I have seen anyways

If I find anything suspect , will bee time to change over to adjustable

Peace

 

[The Flying Scot]

I guess it depends on what you’re used to.
I don’t find them to be difficult in that regard at all.

In fact, I feel like they’re actually easier........ since you’re not guessing about how many threads should be showing below the rocker to facilitate proper pushrod oiling.

With the Comps, screw the adjusters up into the rocker as far as they’ll go, then back it out one full turn..... snug the nut down.
Now use the pushrod checking tool to figure out the correct length and order them up.
Done.


As for the pinging....... too much compression with poor/no quench for the octane you’re running.
That’s (a lot)more complicated/expensive to solve if you’re trying to make it work with the same gas you’re running now.

The first step would be to take a couple of degrees of timing out of it and see if that helped.

A slower, factory styled advance curve........ and employing vacuum advance might solve it, or make a noticeable improvement.

But..... that’s a topic for another thread.

Timing was set originally at 13* and pinking badly. Adjusted it to 10* and that seemed to cure it…or at least improve it considerably.

 

[RemCharger]

I guess it depends on what you’re used to.
I don’t find them to be difficult in that regard at all.

In fact, I feel like they’re actually easier........ since you’re not guessing about how many threads should be showing below the rocker to facilitate proper pushrod oiling.

With the Comps, screw the adjusters up into the rocker as far as they’ll go, then back it out one full turn..... snug the nut down.
Now use the pushrod checking tool to figure out the correct length and order them up.
Done.


As for the pinging....... too much compression with poor/no quench for the octane you’re running.
That’s (a lot)more complicated/expensive to solve if you’re trying to make it work with the same gas you’re running now.

The first step would be to take a couple of degrees of timing out of it and see if that helped.

A slower, factory styled advance curve........ and employing vacuum advance might solve it, or make a noticeable improvement.

But..... that’s a topic for another thread.

I agree Dwayne, the first ones I did on a 383 with edelbrock estreets and a comp hyd went well,, ended up using a stock size 351 Cleveland pushrods (exh I think).
My problems started with a 440 trickflow dyno mule clone.
Sent the customer down with the pushrod checker to the performance parts guy ,,(I know, I know) he came back eventually with comp 9.100's. Well, they were maybe 20 is thou to long.. so to avoid having to order a specialty size rod again (covid/canada/parts shortage) I made these work. That's where it became a PITA, the morel had rollers asked for 30-35 thou, so in the end I had to adjust them by feel and eyeball as some had preload when I bolted the rockers down
There was no way to reasonably measure plunger depth. But I'm confident they will be ok. One part that was concerning was seeing guys here snap the adjuster off at the recessed part. So the whole thing was a little disconcerting lol.

But ya... they can and do work.

 

[RBCharger]

Guys I think everyone is missing the point - so what if components aren't "matched". Sill doesn't explain the rocker situation. To me it looks like too much lifter preload with stock pushrods. Heads were milled and I don't see any rocker shims or measured pushrods. Did I miss something? Cam specs were .525 lift?

 

[12icer]

The first thing I would check is the oiling if more than one rocker gave up. I have run a 305 525 CC cam for 40,000 miles of daily use and it has 440 6 bbl stock gear on it all oil holes were indexed for maximum flow with a high pressure pump.

 

[12icer]

Just to add, it has dual springs and a dampener on the original 67 440 hp heads

 

[BSB67]

…….it has 440 6 bbl stock gear on it all oil holes were indexed for maximum flow……..

Can you share with us what “holes were indexed” means?

 

[Cartel]

Not good to see , considering good quality stamped steel rockers are a thing of the past

Mopar Performance - Gone

Sealed Power - Gone - Discontinued in the last year

Elgin - Pure Junk

Melling - Still made

I run the Made In The USA Sealed Power R828/R829 Stamped Steel Rockers and Shafts on my 383/432 Stroker
Edelbrock E-Street Heads
Comp XE275 HL

Five Summers now

I measured the thickness of these (Sealed Power) and they where thicker in the cup area and surrounding metal over my factory rockers that I honestly thought about using when i rebuilt the motor

Anyways had the valvetrain off last summer looking everything over and was very happy from what i saw

But these Melling Rockers look almost identical with the Sealed Power from what i seen on a friends motor this past summer
Did not measure though

are elgin junk for sure?
I'm in the market for stock type rockers and 440source has some made in the USA but they say they are made by elgin so now I'm really confused.
also apparantly elgin is made by sealed power?

​

 

[dvw]

Rocker failures like this aren't uncommon. If it had to much preload the valves would be hung open. Inspect the rest of the rockers. If the pushrod area isn't balloning I'd try another rocker and pushrod.
Doug