I'm sure this has been addressed before many times. But I've never remembered seeing it. People that are running roller cams with high spring pressure, what studs are you using that don't break. I've ran grade 8 bolts, studs and broke both over time. Currently I have some stainless bolts. Deal is I'm not running that much pressure but going to a roller. Before you'll start telling me I have coil bind or bad geometry, I don't. And I'm not over reving it.
Get the rocker pedestal adapters from Rob Giroux. He has a post selling them on here. Definitely helps alot from breaking shafts and the studs.
Not to mention just plain weaker. Surprised they didn't break. They aren't Grade 8....may not even be 5.
They are only 5/16,..but the stretch strength of a 5/16 is pretty high,... sounds like it's pushing them back as the lobe come around,....kinda uncommon to break the bolts or studs from my experience,....you have an anomaly imo
Get arp studs not hardware stuff,...I'm thinking that's your issue,...the factory bolt is shouldered,...the ARP studs are shouldered ,..if you're running hardware store studs they aren't shouldered,... slightest movement allowed will shear them everytime,..
Hi Jim, you'll need to support those cantilevered rocker shafts at the ends with that much spring pressure. Gary Kubish had a nice support using a bracket that used the end head bolt that connected to the shaft. Rob G.'s system looks like it may provide the necessary support too. I went with a Jesel rocker system. Costly though.
Thanks, I'll do something as I don't feel good about not having something. That will be for the engine you did the rotating assembly for. Waiting to get block girdle done. Have the 470 girdle fixed. Waiting on getting a crank/rod bearing issue solved.
There is a lot of misinformation about stainless bolts being advertised as grade 8. They are NOT and should not be used for any high-stress applications. Great for valve covers,intakes and other pretty stuff,but that’s it. I know you mentioned that you do not have coil bind,but how is your geometry and contact on the valve? That can cause additional stress to break studs/bolts,pushrods and premature wear on guides and everything else.
Thanks for the info. Engine jad over 1152 1/4 mile passes. Like i said only broke 2. All valve train that much too, just think a fatigue deal
Jim, I assume you have the heavy duty shafts, and as such, the force is now being transferred to the studs, on the unsupported outer rockers. Get the rocker supports mentioned, you should be good to go. The standard TA shaft stud kit should work just fine. And Gary.. I have broken too many Jesel/T&D individual shaft rockers to believe they are any stronger.. they just give you more room, an issue we no longer have with the advent of 1.300 dia HD valvesprings for the LS engines. I only mention this to advise you to keep a couple of those cute little rocker shafts on hand.. One for the intake, and one for the exhaust, to prevent losing a race weekend.. They do break.
Interesting,thanks for the advice. Never had one break yet but theres always a first time.What was the over the nose spring pressure.?
Just so you guys know, stainless steel was developed against corrosion. There is a one type of stainless that is heat treatable, used mostly for kitchen knifes. It's called, 400 series stainless steel. I know most of you are aware stainless knifes don't hold a shape edge for long. That's because it doesn't have enough carbon in it or isn't able to take enough carbon to reach the Rockwell hardness to match carbon steel alloys. However, it is flexible (not brittle) so it will appear to be strong because it didn't break or shear-off like a hard carbon steel will. Also stainless will gall very easily with loss of oil lubercation and when high pressures are applied, especially with lost of oil. When using stainless screws, you should coat the threads with anti-seize. Remember the old carbon steel knifes your parents used (they rusted) they held a sharp edge for a long time. I worked in Tool & Die work and did a lot of heat treating. Read some of the cam and lifter failures, due to poor heat treating in a lot of cases and a poor tapper grind on the cam lobes or sometimes none at all. DO NOT use stainless except for bright work or sheet metal work. 316 alloy stainless great for high polish appearance. Very soft. 304 alloy stainless, very tough material, good for making brackets. Bad on shears, dulls the blades on a shear very quickly. Best to use 316 alloy. Hope this info is helpful. VET (Navy)
