Melling Rocker Issues

[The Flying Scot]

Hello. Greetings from Scotland! New to this site and wondering if anyone can shine some light on why the pushrods on my recently rebuilt ‘68 Charger keep punching through the Melling rockers? The car has done 2500 miles on the rebuild and popped a rocker on cylinder #5 six months ago. All 16 rockers were replaced and last month a rod pierced the inlet rocker on cylinder #5.
The pushrods have both pierced rockers on the inlet valves and the first time on cylinder #5 the exhaust pushrod was also slightly bent. I haven’t manage to check the exhaust rod this time.
I’m not technically literate. I just like driving my vintage Dodge fault free!
Thanks in advance.

 

[zyzzyx]

First, I would check that you are getting oil to that rocker, then I would make sure
that the valve isn't hitting the piston ever so slightly. There's no discoloration, so
I'm pretty sure the oil is O.K. The next thing is to check the hardness of the rocker
arm. You can half-*** do this by trying to file the area closest to the pushrod cup.
If you can file one or two, but not the rest, it's a bad heat-treat. Try filing an OEM
rocker and see how hard it is! Hope this helps!

 

[gkent]

Coil bind before full lift !!

 

[RemCharger]

What's the cam specs?
I'm wondering about coil bind, guide to retainer clearance.. things like that

 

[Fran Blacker]

On a 318 I put the rocker shaft in up side down not enough oil. Above posts are good advice

 

[IQ52]

Young man came to me many years ago with the same problem. Said he was in the next town over the other night and the engine developed a miss.

So we pulled the valve cover and there was the pushrod sticking through the rocker arm.

I asked, "Did you win the race?"

"Yes", he says and smiles.

"Well quit racing and this will stop!"

 

[threewood]

Coil bind or soft rockers. If it was lack of oil there should be heat discoloration.

 

[turbine68rt]

Have you changed the cam and lifters? If so, do you have the correct length pushrods to obtain the proper lifter preload?

 

[pnora]

As said coil bind, excess spring pressure, excessive cam lift.. I assume all 16 valves have the same springs. Any ideas on closed and open pressures? Were the guides new or knurled. I ave seen knurl jobs go bad and bind the valve stem.

 

[Bee1971]

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

 

[The Flying Scot]

Wow. Thanks for the responses!
I can assure everybody that this vehicle does NOT get raced. EVER.
If y’all could see the state of the roads in Scotland you’d get some idea why. Also, the car is still on drums all round so has no real ability to stop if driven over 40mph!
The engine was fully rebuilt using all brand new internal components in mid-2019.
We retained the original 440 block manufactured in 1978, which we discovered was probably from a motorhome or pick up. It was rebored, honed and seemingly made “better than new”.
As I said, I’m no mechanical expert…in fact I’m not even novice standard…but here’s some info the rebuild engineers gave me:

Bore: 4.350".
Stroke: 4.150".
Gasket thickness: .048".
Gasket bore: 4.420".
Piston: .008" below deck @tdc.
Piston cut out volume: 6cc.
Combustion chamber volume: 78.6cc.
Head casting No: 4006452.
Valves: 2.08 inlet / 1.74 exhaust valves.
Static comp ratio: 11.24:1.

Very grateful for your input.

 

[The Flying Scot]

Young man came to me many years ago with the same problem. Said he was in the next town over the other night and the engine developed a miss.

So we pulled the valve cover and there was the pushrod sticking through the rocker arm.

I asked, "Did you win the race?"



"Yes", he says and smiles.

"Well quit racing and this will stop!"

 

[The Flying Scot]

Well, I can assure you the vehicle is driven within sensible parameters! Funnily enough, I see you’re in Idaho and I believe my vehicle may have been restored in Rexburg, Idaho around 2010 by this fella. I don’t know his name but would love to hear his story!

 

[IQ52]

Wow. Thanks for the responses!
I can assure everybody that this vehicle does NOT get raced. EVER.
If y’all could see the state of the roads in Scotland you’d get some idea why. Also, the car is still on drums all round so has no real ability to stop if driven over 40mph!
The engine was fully rebuilt using all brand new internal components in mid-2019.
We retained the original 440 block manufactured in 1978, which we discovered was probably from a motorhome or pick up. It was rebored, honed and seemingly made “better than new”.
As I said, I’m no mechanical expert…in fact I’m not even novice standard…but here’s some info the rebuild engineers gave me:

Bore: 4.350".
Stroke: 4.150".
Gasket thickness: .048".
Gasket bore: 4.420".
Piston: .008" below deck @tdc.
Piston cut out volume: 6cc.
Combustion chamber volume: 78.6cc.
Head casting No: 4006452.
Valves: 2.08 inlet / 1.74 exhaust valves.
Static comp ratio: 11.24:1.

Very grateful for your input.

Even with at least .040" milled from the cylinder heads there should be piston to valve clearance with flycut stroker pistons. The big questions still are........camshaft and valve springs. I'd really be interested on how the '452' heads were set up for a stroker engine. Generally they are pretty restrictive in that application. The fact that the valve cover rails were milled indicates something is going on out of the ordinary.

 

[The Flying Scot]

Even with at least .040" milled from the cylinder heads there should be piston to valve clearance with flycut stroker pistons. The big questions still are........camshaft and valve springs. I'd really be interested on how the '452' heads were set up for a stroker engine. Generally they are pretty restrictive in that application. The fact that the valve cover rails were milled indicates something is going on out of the ordinary.

Thanks again. Can you establish any more from this list of internal components please?

 

[IQ52]

What fuel are you using in this engine? I think you are lucky that the only problem so far seems to be pushrods punching holes in rocker arms. The cam, compression ratio and cylinderhead combination is.......uh.......politely........not optimal.

2.08/1.74 valves are factory stock sizes for that 452 cylinderhead.

 

[The Flying Scot]

What fuel are you using in this engine? I think you are lucky that the only problem so far seems to be pushrods punching holes in rocker arms. The cam, compression ratio and cylinderhead combination is.......uh.......politely........not optimal.

2.08/1.74 valves are factory stock sizes for that 452 cylinderhead.

 

[The Flying Scot]

Ok. Thanks for the info. I’m using 97 or 99 Ron unleaded fuel here in the U.K. Shell “V Power” or equivalent.

 

[Fran Blacker]

Anyone think he could use a bore scope to help with this problem. Mostly to check valve to piston contact?
https://www.amazon.com/Compatible-N...ds=borescope+for+iphone&qid=1633621093&sr=8-5

 

[The Flying Scot]

Anyone think he could use a bore scope to help with this problem. Mostly to check valve to piston contact?
https://www.amazon.com/Compatible-N...ds=borescope+for+iphone&qid=1633621093&sr=8-5

Hi Frank. That’s been done already on cylinder #5 by the engineers. They videoed it and there’s no contact. They still need to do #3 this time. Probably next week.