Valve question

william · Post by **william** » Mon Mar 13, 2006 9:14 am

When I adjusted the valves on the GTE I noticed that some of the valve stems are not center on the rocker arms? Are there caps that go over the valve stems to make for a larger contact area? If so my car does not have them. On some of the valves it appears that not much contact is being made this concerns me.

Jim Riff, Kerry, anybody?

Thanks

Post by **330GT** » Mon Mar 13, 2006 12:17 pm

No caps. The rocker arm adjustment screw is designed to be off-center on the valve stem. This causes the valve to rotate keeping the wear on the valve seat equal.

One needs to carefully inspect the adjustment screws for wear and damage. If any are suspect, replace them. Much cheaper than replacing a valve because the stem got damaged by the adjustment screw. I also remember reading that the adjustment screws are case hardened and shouldn't be ground or re-finished, just replaced as needed.

Jimmyr · Post by **Jimmyr** » Mon Mar 13, 2006 3:33 pm

William, ditto what Kerry said. It is a good idea to inspect the contact surfaces on all screws and junk any that do not look smooth. Also, caution if you need replacement adjuster screws as there have been some poor heat treating on some suppiler parts. Ask for info on this site about who has had any supplier problems. Jim

Bryan P · Post by **Bryan P** » Mon Mar 13, 2006 4:05 pm

Instead of starting a new thread, I'll ask my question here. I took off my cam covers for blasting and new wrinkle paint and to do a valve adjustment. I removed one of the rocker arm carriages and found (1) the adjustment screws to be worn and rough at the edges and (2) some very small scarring on the tip of the valve stems. The "scarring" looks like a few scratches, not very deep - I can barely feel them w/ my fingertip, but they're shiny so they can easily be seen.

I ordered a replacement set of the screws from Rutlands this morning. I was offered the "roller-tip" type which I declined. (I've heard bad things about these). I also found a link on F-chat to this - http://www.roelofsparts.com/bolt.html - does anyone have experience with this product? I already ran it by Zac and he was not familiar w/ this mfg.

I'm looking for opinions from the group here - with the National show coming up soon, I don't want to do a valve replacement job at this time. My plan is to replace the adjustment screws, adjust, and run the car. This is a tight motor - other than start-up, it does not smoke; so I don't think I have advanced valve guide wear. I also know from the previous owner's receipts that some valve work was done in the 90s on this car. My gut says this is a recent problem w/ the existing adjust screws that I have caught in time before some real serious valve stem damage has occurred. Am I missing something? Am I making a fatal error w/ this plan? W/ the beginings of problematic wear on the valve stem ends, I figure I'll need to do a complete valve replacement in the next couple of years - maybe at that time, I'll do the Roelofs screw replacment.

thoughts?

william · Post by **william** » Mon Mar 13, 2006 5:10 pm

Thanks Kerry, Jim,

I also spoke to John Hajduk today he had some more advice. I will do a through inspection of the adjustment screw.

Thanks

afwrench · Post by **afwrench** » Mon Mar 13, 2006 6:20 pm

While I have no experience with the roelofspatrs devices a couple of things come to mind. For one you are adding another moving part , actually 24 moving parts ,to the system .Also it is not hard to imagine what sort of havoc would occur if one or more of those tips siezed or fell apart. If it froze in one position it would no doubt wear the valve guide to one side very fast. If someone has used them with no problem I guess my fears are not justified . Mike PS if the scratches are as you say you should be able to polish them out with a stone or emory cloth.

Jimmyr · Post by **Jimmyr** » Mon Mar 13, 2006 10:49 pm

Siick with the standard adjuster screws, the problems described above with the other kind are real. Your observation and program sounds like the right way to go. Pass along my hi to John, have not seen him in a long time. Jim

treue · Post by **treue** » Tue Mar 14, 2006 9:46 am

Guys:

I just happen to be looking into this as 9129’s engine is starting to go back together. I contacted Roelof about their “Improved Valve Adjustment Bolt for Ferrari Engines”. They have an informative website and Herald ten Hove wrote a quick reply to my queries. It is a kit containing the articulated adjusting screw AND a new roller sleeve (hardened?), snap ring and roller with 14 bearing needles that replace the original bushed roller. They claim a smaller angle between the adjusting screw and the valve stem centerlines. This appears to be due to a smaller cam roller diameter. Another benefit is that contact between the adjusting screw is changed from point to area. This should substantially reduce side force on the stem and the tendency to make the little dimple in the end of the valve stem. A little pricey at $1881 an engine set, but appears well thought out.

On disassembly of my engine, I found one of the little, hard caps on the end of an OEM valve stem had left the valve and traveled to the crankcase, so, even the OEM design is not trouble-free. I am going to a set of custom-made Manley one-piece stainless steel valves.

Tom

william · Post by **william** » Wed Mar 15, 2006 11:25 am

Kerry, how much off center on the valves are we talking on the adjustment screw?

Jim, I'll say hello to John for you. I may stop by his shop next Friday.

JonBrent · Post by **JonBrent** » Wed Mar 15, 2006 1:33 pm

To me, the Roelof's design certainly looks very sound. I'd like to hear about how well it holds up in service though, before I'd use it in my engine. I'm not in a position to be an early adopter.

Fwiw, the Porsche guys have been using this design, so it would seem:
http://www.pelicanparts.com/catalog/sho ... is_pg4.htm
http://www.pelicanparts.com/techarticle ... adjust.htm
so perhaps there is a decent history on the adjustment screw part.

Hth, Jon

tim · Post by **tim** » Sat Mar 18, 2006 3:43 am

Greetings... If the ends of your valves are looking a bit knackered, Crower Cams sells a device called a lash cap. It's like a little top hat for your valve stem. It was originally developed to provide a larger surface for the rocker to work on allowing higher lifts. (Some prostock drag racers run .75 inch lift but then they also run titanium springs good for maybe 8 passes) Tim

william · Post by **william** » Wed Apr 12, 2006 1:12 pm

When I started this thread I don't think my question was very clear. My valve adjustment screws are off center foward and back on the valve. That is foward of the car and back of the car. Not Intake valve to exhaust valve.

I stoped by John Hajduk shop and looked at some heads off a SWB and a set of heads just delivered for repair. John said that the rocker arms just need a little more bushing to get them where they need to be. The heads that were delivered had the Roelof adjuster screws. pretty cool stuff.

John Vardanian · Post by **John Vardanian** » Thu Apr 13, 2006 12:08 am

William,

Sometimes you may have too much lateral slop of the rocker arm.

The outside plug engines have two copper washers on either side of the alum spacer bushing that the rocker arm pivots on.

Too much wear can cause the adjusting screw to dance sideways on the valve stem.

john