My ProMags a quiet as can be. I don't understand everyone who complains about them being noisy.

 

Different ramp speeds on different cams play a big role in how much noise the rockers will make. My cam has fast ramps so they are much noisier than they were on my stock cam. Just varies from cam to cam.

 

If you use zero preload by just taking the pushrods all the way out your valve train will be extremely quiet. Shoebox is correct. don't attempt to tighten your valves that much, you will break something. And looser is definatly faster.

 

I don't know much about ramp speeds, but I have an 847 if that says anything.

 

I have run them on big blocks with 750lb open pressure and nearly 8000rpm time and time again and they survive just fine.

When I had them on my lt1 they were originally on an 846 with the crane duals which are not weak by any means. They were then run on a much more agressive grind that had high ratio solid roller lobes with hydraulic lifters and even beefier springs. Then I moved over to shaft rockers, I sold them to a friend on the cheap and he has driven them for another 30k miles.

Beehive springs and self aligning rockers dont work together with stock valves unless you are not running much lift because you need +0.50" locks and that will put the SA guides right into the valve lock... no good. Not saying that was the case with you but high rpm possible valve float and SA rockers doesnt sound good to me. I'd be more afraid of the beehives than the rockers if they were from comp. I broke one of those on a 434 idling in the effin driveway 5 min after initial startup .

The pro mags despite thier large bearings also experience a failure, its just not catastrophic. When you run pro mags very hard with wild cams and alot of spring after a period of time the trunion gets a little funky and gritty feeling, and slop developes in there. I used to trade them out every season and sell the old ones. I know i've seen Ellis talk about it over on ls1 tech and he is the only other person I have seen mention it he swaps them out pretty regular just like me iirc. Then again most people are happy to have the valve covers off once, and I am constantly tinkering with mine and checking things out closely when I am doing head/cam swaps. Yes I may have a problem .

 

You guys may well be correct. In the more than 40 years I've been screwing on these suckas, the factory recommended preload is the only 1 full turn preload adjustment I can recall ever seeing.

However, based on the responses and such strongly held views, it's peaked my interest to learn more.

Thinking back on what I read in TPIS' tests, they wrote that going as far as TWO COMPLETE TURNS from zero lash showed even more of an improvement. Now how's that for flying in the face of contemporary thinking!?

So my next step is to research those articles, read what the reasoning was and actual test/dyno results so I can better understand what's actually going on here. I'm open-minded that way.

But rather than continue to kick this around on someone else's original thread (which isn't about lifter preload), I'll start a new thread when I find and read the articles.

Jake

West Point ROCKS!

 

Well some people aren't quite as good at picking up sounds like that. I'm sure some people could listen to my motor and say everything sounds quiet, but put it in front of someone who builds motors for a living and they will tell you they sound loud right away. I'm not saying that is true for your case, just throwing that out there.

 

A cam lobe with a "fast ramp" which are usually associated with high lift cams, snap the valve open and closed much faster than a slower ramp cam. Fast ramps are harder on the valvetrain and make for more undesirable noise sometimes. Fast ramps tend to produce more power ASSUMING the valves stay under control and dont float or bounce. A comp XFI lobe is considered to be a fast ramp as well as other cams that are shorter on duration and higher on lift.

The 847 (still a great cam due to duration) does not have very fast ramps so that is likely why yours are more quiet. Your valves are being opened and closed with a bit less intensity compared to the fast ramp cams.

 

Well I completed the head swap, the old heads had some valve guide play, but not as much as I was expecting. Got the new heads on, and stayed with the aluminum rockers, and these are still noisey as hell...its not the same noise as before. Before it sounded like 1 or 2 valves were making noise, now they all are but not as loud from a single valve.
I'm beginning to think its the LPE cam which has a pretty aggressive lobe, and the fact its on a small base circle, which makes it even more aggressive since the distance around the lobe is less...start I new thread on this idea...

 

Well I thought I found an issue....the rocker poly locks I used with the aluminum rockers were the ones that had came with the promags. It turns out they are about .020" wider giving only about .010" clearence on the alumnum rockers in the slot where the bolts goes. I swapeed to the thinner ones that came with the aluminum rockers but still noisey....
So I swapped back in the heavy dual springs but had to go back to the Steel Promags since the SA tabs are smaller, the Crane Golds would not work....different tone of noise, but still noisey, so I'm throwing in the towel and will just learn to live with it for now and turn the radio up Next time I'll go with a less aggressive lobe cam...

 

Did you check for any other areas that may be causing the noise?

One place to check is the underside of the rocker arm to retainer. If the rocker is tapping the retainer, ususally there will be witness marks on the rocker arm.

You could manually cycle the engine while checking for any spot where the pushrod may be causing the noise.

Just my thoughts.

Jake

West Point ROCKS!

 

Yep, I did have that issue on 2 valves on the old previous set of head as each of the valve step tops sat a bit lower towards the locks/retainer than the others. None on this new set have that issue. PRs have plenty of clearance. Poly locks have plenty of room now also. As of now, everything on the valve train has been replaced at least once, some 2 or 3 times.

 

I wonder if that small base circle cam has anything to do with it. Sure seems like lifter tracking would be more of a challenge again on that cam compared to the larger base circle.

 

yeah, thats the conclusion I'm coming to, but I figured the heavy dual springs would have cured some of that. The smaller base circle means you would have even steeper angle to achieve the same lift as a larger base circle unless they change the complete cam lobe profile...yet the surface of the cam lobe is actually spinning at a slower speed then a larger base circle...like on a merry-go-round, the further out you get from the center the more distance you are covering per rpm....so maybe it makes no difference...
But at this point, thats the only difference between the TA cam and the truck's cam, and the truck is fairly quite with guide plates and steel pro mags.

 

FWIW. You might remember the valve float issues I had last year with a small BC cam. Went to the large BC cam and no more float.