magnum lifter preload question
 

Hey all
I have for some time now had problems with my 360 magnum mopar performance lifters being very noisy. I put a new set in and they are the same. Particularly after a 1/4 mile run they are terrible. But also noisy in every day driving. Does anyone know what the recommended preload I should be running on these?
I have read its quite a lot .060
I recently set them to .060 as I was running less but after setting them the engine wouldn't run properly. It was holding the valves open. When I reset them to about .040 it ran fine but noisy again.
When I set them to a higher preload do I need to turn the motor by hand and let it sit to bleed them down or should they just be good to go straight away?
cheers Maca

How are you setting the preload ?? They are hyd non adjustable unless you have aftermarket rockers, then you need aftermarket pushrods.. .025-.040 is a good preload range

Yep, they are adjustable rockers. Why do I need after market pushrods?
The engine shop did measure and installed some but just wondering why. Maybe factory ones too short.
I have tried soft preloads but really noisy.
Not sure why, I have 60psi oil pressure too.
Could after market pushrods oiling holes be too big?

Exactly, when you put together a custom engine you need custom parts to make everything work together. The stock pushrods were engineered for a stock valvetrain.

Yep I realise the pushrods have to be remeasured to zero lash and ad preload to get the right length pushrods but what I meant was with adjustable rockers the rockers take up any shortfall.
Does anyone know where I would find the actual recommended preload for those lifters

The rockers DO NOT TAKE UP the shortfall They must be adjusted to centered in the valve and then measured for push rod length.
.025-.040 preload is pretty standard for Hyd lifters

Hi TVLYNN
Pushrod length is fine. Its not as crucial as other rockers. These are Australian Yella Terra rockers. They are different to the normal centre adjusting rockers. They bolt down to the pedestal and don't move from there. After you bolt them down and check your whiteness mark on the valve the adjuster is on top of the pushrod. So as you screw the adjuster down to set your preload it is basically lengthening or shortening your pushrod length to get your desired preload.
here is a pic
http://www.kustombitz.com.au/p/89035...pe-st2030.html
There used to be a guy on this forum PK1 who really knew magnum engines. He told me to use .060 preload but when I did so it ran badly. I was just wondering if it was because I was supposed to let them bleed down 1st or if they should be fine straight away.

The length of the push rod DOES matter IT changes the geometry of the valve train
enough said..

We will have to agree to disagree.
I have run factory and longer pushrods with this set up with no probs.
But with my hemi 6 where the adjuster is on top of the pedestal the pushrod length was crucial as it changes the geometry.

Maybe I will try the .060 again but let them bleed down for a while as I did a quick measurement and the lifter has very roughly just over .100 so .060 shouldn't be holding the valves open.
Cheers

I don't know how you can argue that pushrod length is somehow not relevant. With the adjuster on the pushrod as your example product shows, a too long or too short pushrod will "tip" the rocker one way or the other, and at some point, valve stem contact will not be "happy."

So far as the original problem, oil pressure? Sloppy fit at the lifters bore? causing excessive oil loss? Don't know

Wish ME luck, tho, LOL. I have a 360 "roller" LA short block out here, so for the first (and probably only) time in my life, I'm about to "experience" roller lifters.

Also keep in mind that because of the extended height of rollers, seems to me pushrod length and geometry become MUCH more critical. Something that's going to "bother" my setup is the old 340 J heads.......small pushrod holes

The point here, is that unless you have a bone stock factory engine, ya better check EVERYTHING for compatibility

Yes thanks, Everything is triple checked. Have you guys ever used the rear adjustable rockers? Or have you only used the pedestal adjustable ones?
Even the manufacturer of these rear adjustable rockers will tell you the same thing that once the geometry is set with these rockers it will not change regardless of pushrod as they are bolted down to the pedestal and can not move. I am not saying pushrod length is not important with this style of rocker but just saying it is not as crucial as the centre adjustable ones because with the centre adjustable ones when you change pushrod length you change rocker height. Unlike these where rocker height can not change once set.
Let me explain it like this. Hope we agree on this point.
To get the correct geometry and witness mark the rocker height is changed up or down to get it right as shown in this video. Which I bet you guys have done it this way dozens of times. These rocker are set with shims if needed not pushrod.

With these rear adjustable rockers once you have shimmed them to your correct height they bolt down and do not change again giving you the same geometry all the time. Then you set your preferred preload over the pushrod. The adjuster is angled at the same angle your pushrod is at. So it is basically and extension of your pushrod. Longer or shorter pushrods will now not change your rocker height or geometry at all. It will only change your preload variation. Hope this helps. We may just have to disagree but does anyone know where I can find the recommended preloads for the mopar performance lifters

I wish I had the easy answer, all I've got is some examples. The "performance" Mopar lifter might be the same as other high rpm lifters that ask for 0-1/4 turn of preload, like the ones we put in my son's Ford engine.

My machinist told me about some magnum set-ups that if not correct will shoot oil across the shop when oil primed. The oil pressure at the back of the block may not be telling the whole story, I would take off the valve cover to visually see oil flow at idle.

That's all I got. Your rocker stands when shimmed for proper stem contact are just right, I don't think you have any rod length issue causing this noise. If you were thorough I'm assuming there is no contact of under rocker to spring retainer.

Thanks coronet 500
Good call. The clearances are good. I will give it a run with the covers off like you suggested.

I don't have the money for "fancy stuff" but I use factory 273 cast adjustable rockers. These type rockers have been on at least 4 engines I've put together. These of course are LA heads I'm using.

Hey Guys
Looks like preload is the least of my problems.
I removed the cam to install another one and for some reason I am not sure of one of my cam bearings is worn right through. Only one is worn the others look fine. Anyone else had one cam bearing worn heaps more than the others?
These bearings are only about 10,000 miles old. It has been a tough 10,000 though.




Attachment 11903

That would somewhat explain the noisy valve train....
Check to see if the cam was bent. Or was machined wrong..
Might have the cam bores checked for alignment. You know, the old core shift problems of the mopar blocks... :(
After you get the new bearing installed, Make sure the cam turns freely..

the cam could be bent.

I will run a straight edge and see if it looks bent. Prob need to stick it in a lathe though I would think. It was a brand new cam from comp not too long ago.
I will be running a different cam now but will still check. Hope it is the cam and not the block.

I had a bent cam from Comp years ago, brand new. Maybe it was the UPS guy?

So you have had a new bent cam. That gives me hope that its the cam and not the block.
I am running a LA sump on my magnum to fit it in my old charger. I was told because I am using the LA sump to use the LA rear main seal and sump gasket. I am on my second LA rear main in my magnum and it is leaking again.
I did not fit the rear main so I guess my question is:
Has anyone else had LA rear main seals leak in magnums and I should use the magnum rear main or have I just been unlucky twice that the shop didn't fit them right?
cheers

I run the rear sump also without any problems.....
I run the Magnum rear main in my Magnum block without any issues...I have not tried it the way your talking about. But as a side note. I also got a new rear sump pan kit (5.9 Rear Sump Truck) to fit the Magnum block.
No Problems... 50,000 on this junk yard dog right now....:)

Thanks Bob


Sorry for the silly questions but we don't have magnums in Australia. Only LA 360s. I bet in the States you have heaps and they are prob cheap.


I think I will use a magnum rear main this time. I think something like this.
http://www.summitracing.com/int/parts/fel-bs40651
When you used the magnum engine with an LA sump did you use the LA pan gasket or can I still use the magnum gasket on the LA sump?


Also I was burning a bit of oil. I am not efi, I am carby and I noticed when I took off the manifold gasket that it looked to be sucking some oil from the bottom of the intake ports as there was oil on both sides of the gasket around the intake ports. I was just using a graphite flat gasket. like this.
http://www.summitracing.com/int/parts/dcc-4876049
Is there a better gasket you recommend or do these usually do the job and I may need to get my manifold machined. I was thinking of using a gasket with some raised sections like this.
http://www.summitracing.com/int/parts/edl-7277
or
http://www.summitracing.com/int/parts/pfs-55601
Any help appreciated

Before thinking about what gasket I would be setting the manifold on with none lined up with threaded rod on each corner and try feeler gauges top and bottom of ports at each corner.

A bit of putty squeezed between, cut and measured like checking piston to valve clearance could work too.

I,m curious what cam journal it was. I have read and heard guys with not bent but too big of journals on new cams, having to get them ground down.

I made a cam bearing shaving tool once that had flutes cut in an old cams journals like a reamer to size one or two that were tight. It would be best to have a bare unassembled block to do this.

Yep I agree, I will be checking the manifold to head for sure.
It was the second to rear one that wore.
Any suggestions on gaskets is appreciated
Cheers

The only thing different was the lip seal for the timing cover. One takes the thin and one take the thick. Both come in the pan gasket kit.
I agree you have to check the manifold to head clearance. There maybe to wide of a gap? I like using poster board from the art store to check the impression.
Are you running the Magnum heads on the LA block? Or am I off base here?

I am running the full magnum engine. I have only changed the manifold, dizzy and sump pan.
So with the LA sump and magnum engine which sump gasket do I run?
The magnum one looks to be one piece?
Cheers

The pan # should be a P5249060AB Mopar Performance
I'm not 100% positive of the gasket # But If I recall rite, The Fel-Pro OS34409R Should fit....

:)

Thanks I appreciated the help.
I run the factory flexplate and have had a slight vibration for a while now. I was thinking of changing my factory one for a b&m one. Are there any advantages to running the b&m one over the factory one?
Also I noticed that they list it as a 2 piece plate. Why is it a 2 piece?
My ring gear in on the converter so not sure why its a 2 piece
Cheers

One plate has the gear, an additional plate is sandwiched with or without a cutout for internal or external engine balanced engines.

They have them for all the manufacturers, great idea I think.

The problem will be one of two things.....
1. Wrong or Spun Dampner
2. Wrong Convertor balance

Also one more thing to add on the oil pan area....
Careful with the oil pump you use with the Pan. You can get the wrong pick up, and the pan to pick up clearance will not be proper. The pan kit i listed has the pick up with the pan, but it's to be used with the Magnum oil Pump and has the rite clearance....
:)