MyE28.com DEV

I have checked some posts regarding the collar on the stock head bolts on a B35 that hold the rocker shafts straight.

Anyway, what was the consensus regarding running ARP head studs and the alignment of the rocker shafts? Should I be worried about the few mm of lateral play?

The ARP studs are obviously not holding the shafts as nice as the stock ones.

I'm interested in this as well.

I measured the studs today (and when I say measured them, I mean the part under the bolt head on the stock and the threaded part where the nut is on the ARP studs).

Here are the ARP studs (11.90mm):

Bav Turbo Project - Day 2 by KillerPM, on Flickr

Here are the factory (12.30mm):

Bav Turbo Project - Day 2 by KillerPM, on Flickr

Is this .4mm going to make a difference in the rocker shafts? Is the head bolts/studs the only thing keeping these things aligned?

Yes. It can make a difference. the front exhaust rocker shaft on Andrew's car is sitting too far forward. The head is coming off so I can fix it but I don't know how to prevent it happening again. Given that Paul Burke put the motor together, I don't think he messed it up.

Well, in my experience its a complete non issue. That is, unless you are staring at it and thinking "isn't this a problem"?

The rockers riding on the edge of the cam lobes is a problem.

So it's not an issue at all? No compromises what so ever?
I like stock bolts. They're holding me together at 450hp.

mooseheadm5 wrote:Yes. It can make a difference. the front exhaust rocker shaft on Andrew's car is sitting too far forward. The head is coming off so I can fix it but I don't know how to prevent it happening again. Given that Paul Burke put the motor together, I don't think he messed it up.

I was having the same problem with a previous head we were using except it was the rear intake shaft.

The current head I have, the shafts seem to be stiffer and dont move as easy. Either way I think that over time they might vibrate to the point of making the rockers sit way too far off to the side of the valves. I am tempted to run factory head bolts since I know they fit perfectly. The ARP ones are obviously a superior quality bolt but I am surprised at this oversight from their engineering team.

mooseheadm5 wrote:The rockers riding on the edge of the cam lobes is a problem.

This exactly.

I could actually wiggle the cam eccentrics off of the valves on the one shaft with the ARP studs in place. While I couldn't get it to do it with the stock bolts, the shaft was obviously moving too much (I think it was worn out on the first head I was planning to use).

Even on the head with new shafts and rockers, they move much more then I would like to see them move.

^Remember to not torque past 70lb or they will stretch.

I've tried to do more as a test so just saying.
Clean the threads always.

In another thread bringing this up paul derp was saying
something about getting inserts made but never went through?

Might sounds stupid but I wonder how much it would cost
to get arp to make these specifically for m30s in 2000 materiel.
Could we raise enough cash in a group buy I wonder.

Rocker locks?

Shadow wrote:^Remember to not torque past 70lb or they will stretch.

I've tried to do more as a test so just saying.
Clean the threads always.

In another thread bringing this up paul derp was saying
something about getting inserts made but never went through?

Might sounds stupid but I wonder how much it would cost
to get arp to make these specifically for m30s in 2000 materiel.
Could we raise enough cash in a group buy I wonder.

Don't torque ARP ones past 70? I was going to torque them to 90... Or do you mean stock ones?

Maybe we can convince ARP to replace the current design with one that is the same dimensions as the stock one...

Das_Prachtstraße wrote:Rocker locks?

This looks like it might be a good option... I might have to put a notch on the shaft or something so the lock doesn't shift over time..

mooseheadm5 wrote:Yes. It can make a difference. the front exhaust rocker shaft on Andrew's car is sitting too far forward. The head is coming off so I can fix it but I don't know how to prevent it happening again. Given that Paul Burke put the motor together, I don't think he messed it up.

I wonder when PB assembled that motor? When he was assembling my head (2011?) he advised NOT to use ARP studs but rather use NEW OE bolts and torque them properly and in the proper sequence to include heat cycling. WRT rocker arm locks he advised against them, again stating if the head is assembled properly there is no need for locks, they are a crutch for improper assembly, adding that they will oval the shafts. Perhaps Paul will chime in with further insight but he's been scarce lately. I was ready to burn the additional $$$ for the studs and locks but he talked me out of it. The fact that the ARP's are 0.4mm smaller in diameter than the OE bolts is a major nonstarter. Glad I followed expert advice.

I am facing the same dilemma. I am building a turbo motor for my 83 745i (sorry, not an e28).

Just getting all the parts together. Bought pistons from Paul, and his T11 camshaft.

He did caution me agains ARP unless I found some way to stabalize the rocker shafts. They will not likely move, but they definitely could move.

However, I don't remember him telling me what the alternative would be, i.e. what I could use to lock the rocker shafts in position.

I have not ordered studs yet, and won't unless I know there is a way to do this.

I have thought of two ways. Can't wait for someone to tell me why they won't work.

1. Small sleeve around the stud, id the same as the diameter of the stud, od same diameter as the factory head bolt. This is too easy, so I am sure there is something I am overlooking.

2. Drill four small holes, each going through the top of the head and into the rocker shafts AFTER making sure they are in perfect aligment. Thread each for small screw. Disassemble and clean. Reinstall using four small screws with loctite.

LynnBilodeau wrote:I am facing the same dilemma. I am building a turbo motor for my 83 745i (sorry, not an e28).

Just getting all the parts together. Bought pistons from Paul, and his T11 camshaft.

He did caution me agains ARP unless I found some way to stabalize the rocker shafts. They will not likely move, but they definitely could move.

However, I don't remember him telling me what the alternative would be, i.e. what I could use to lock the rocker shafts in position.

I have not ordered studs yet, and won't unless I know there is a way to do this.

I have thought of two ways. Can't wait for someone to tell me why they won't work.

1. Small sleeve around the stud, id the same as the diameter of the stud, od same diameter as the factory head bolt. This is too easy, so I am sure there is something I am overlooking.

2. Drill four small holes, each going through the top of the head and into the rocker shafts AFTER making sure they are in perfect aligment. Thread each for small screw. Disassemble and clean. Reinstall using four small screws with loctite.

Number 2 wont work. The rocker shafts supply oil through pin holes underneath the rockers.

Number 1 would probably be the way to go. I dont know how fragile a .2mm think insert would be but technically we would only need 4 of them, one for each rocker shaft...

I agree, if the right size bushing can be found, that would work best assuming there is no impediment to getting it in place.

I don't see why the screws wouldn't work. I understand the shafts carry oil. I am not talking about a large screw. Something like a 10-24 which does not protrude into the rocker shaft. It wouldn't take much.

I have a junk head and some old shafts out in the garage. May do some expirementing. Will post pics if I do.

How does .4mm difference even allow an unsavory amount of movement? Even if a rocker shifted over the full difference of .4mm ( in my mind it would actually only be .2mm possible) Does that actually ride the rocker off the cam lobe? That is like a 64th of an inch or something at best.

I would need to check, but I think the rocker shaft rests against the shank of the bolt, not right under the head. If this is the case, the ARP stud is much smaller in the area where the rocker shaft sits.

GI jonas wrote:How does .4mm difference even allow an unsavory amount of movement? Even if a rocker shifted over the full difference of .4mm ( in my mind it would actually only be .2mm possible) Does that actually ride the rocker off the cam lobe? That is like a 64th of an inch or something at best.

Biggest problem isn't the rocker in relation to the cam lobe (although that can be a problem).

Biggest problem with potential shift is the rocker eccentric in relation to the valve stem. It needs to be off center so the eccentric will rotate the valve. I have seen heads that rookies put together where the eccentric was dead center on the valve stem and it causes premature wear, cupping the valve stem. You want it to rotate.

LynnBilodeau wrote:

GI jonas wrote:How does .4mm difference even allow an unsavory amount of movement? Even if a rocker shifted over the full difference of .4mm ( in my mind it would actually only be .2mm possible) Does that actually ride the rocker off the cam lobe? That is like a 64th of an inch or something at best.

Biggest problem isn't the rocker in relation to the cam lobe (although that can be a problem).

Biggest problem with potential shift is the rocker eccentric in relation to the valve stem. It needs to be off center so the eccentric will rotate the valve. I have seen heads that rookies put together where the eccentric was dead center on the valve stem and it causes premature wear, cupping the valve stem. You want it to rotate.

That and there is already play built into the tolerances of the assembled head.

By throwing more play into the mix is why its getting goofy.

If there was a fine tolerance between these parts to begin with, it probably wouldn't be a big deal. The fact is that there is already play from the factory. The factory amount of play + the added play from the ARP studs (which is easily close to 4mm by the time they are installed, the amount of contact of the rocker shafts to the studs is minimal to begin with) will cause a big problem in the long run. At least that's what I am thinking.

I am going to ask ARP for my money back. I will probably go with stock bolts.

Can any guys with 350+hp turbo M30 builds chime in? Id like to hear if anyone can say they've been running this set up with no issues.

I've been running arp studs for at least 6 years now. I have broken 2 rockers prior to getting heavy duty rockers and springs (ireland engineering), since then I've had no issues. I think the springs that keep the rockers pushed back are a bigger issue than the shaft moving a little. I'm getting about 325-350 out of an 84 m106
marc

heinrich535i wrote:Can any guys with 350+hp turbo M30 builds chime in? Id like to hear if anyone can say they've been running this set up with no issues.

Stock head bolts are fine for 350 and a bit more.

The engine I am building won't be much more than that.... for now. However, I am building the engine to be bullet proof up to about 500. I want the option of changing out the exhaust manifold and turbo, changing the tune on my war chip and not having to get back into the engine.

So... I would like to use arp studs.

I really don't believe the MAIN issue here is movement. Once everything is in place, how much can these shafts move? I believe it is initial alignment. The shoulders on the bolts make you get the shafts at least close. Personally, I have never relied on that for perfect aligment. Like I said earlier, you want the eccentric off the center of the valve stem.

Still, I believe there is a chance for slight movement. It wouldn't take much to insure the shaft don't move.

Anyway, I believe I have found a suitable solution. Here is my solution. Just drilled and tapped 4 holes on an old cracked junk head, one for each shaft. An 8-32 screw gets a good 6 to 8 threads to catch. I see no need to drill the shafts themselves. Just install 8-32 set screws with heavy duty thread locker.

If I can figure out how to post a pic, I will do so.

I don't know if the collar on the stud will work. The hole is almost exactly 13mm, and the shoulder on the factory head bolt is less than 13mm. Can someone post a good clear pic of the arp stud along with the measurement of the shaft?

At 450hp my stock bolts are doing just fine
I don't need these added complications with arps and
sloppy rocker shafts.

Even m50s guys have studs made specifically for them
in 2000 material. We get skinner chopped down from a pinto that don't really fit right. what the heck.

http://e28-535i.com/upload/shaftlock.web1.jpg

Very simple solution.

If you want a little more peace of mind, you could drill into the shaft about .020" to sink the set screw. Probably not necessary.

I've been running arp's for over 3 years without any rocker shaft movement. They are TQ to 90ftlbs.

Good & Tight wrote:I've been running arp's for over 3 years without any rocker shaft movement. They are TQ to 90ftlbs.

And I hope you don't.
The point is, they CAN move.
If I were in your shoes, and everything was stable after 3 years, I probably would do nothing other than pay very close attention during routine valve adjustments.

However, my engine is in pieces. If I can take remdial steps before assembly, that is the best approach.

It took me maybe 5 min. to drill and tap for those set screws.
I see no downside.

Here is a bit more of my discovery.

So as it turns out, a B35 head has a 2 piece rocker shaft.

<<<SNIPPED FOR WRONG INFORMATION>>>