Arc racing 1.3 ratio billet rockers blowout?

[adamjankowski51]

So had my arc 1.3 ratio rockers on the exhaust side fail on me. Luckily it was just while at low rpm. Nothing else went wrong just the rocker. Is this a known issue with them?

I'm running a dyno 308 cam, chromoly pushrods, arc rod, arc flywheel, flat top piston, shred head, 5.5 stainless valves +.150, 18lb valve springs, aluminum dual valve springs retainers.

Pushrod length was adjusted and showed the roller contacting the middle of the valve where it should be. Lash was at .003.

I want to use arc rockers again but now I'm worried this is a common thing with these. Anyone know for sure?

 

[Whitetrashrocker]

Most racing parts don't come with warranty but you might call ARC and see what they say.

That's a cool looking bike.

 

[Darren]

The rockers problem comes up infrequently, I've got gage billet ali roller rockers. Rockers normally fail for two reasons, excessive spring force and an excessive rocker angle.

 

[Denny]

Check also for coil bind or a sticky valve.

 

[adamjankowski51]

Check also for coil bind or a sticky valve.

No coil bind. The shred head is designed for high spring rate springs. Thanks for the suggestion though.

 

[adamjankowski51]

The rockers problem comes up infrequently, I've got gage billet ali roller rockers. Rockers normally fail for two reasons, excessive spring force and an excessive rocker angle.

Yes I agree, most people do not know how to properly set up geometry on rocker arms. I tried to give as much info as possible regarding how things were but we are what we are. Coil bind was a suggestion as well but that was checked as well as the shred head is designed for high spring rate springs (pre pocketed). Valves are also +.15 just for this reason.

 

[adamjankowski51]

Most racing parts don't come with warranty but you might call ARC and see what they say.

That's a cool looking bike.

Yeah, was figuring asking them is a waste. Maybe I get a set of free rockers out of it but doubt it.

 

[panchothedog]

Even though the rocker is sold ( or made ) by ARC, other than the roller tip, it looks and functions just like a stock Chinese rocker. The real roller rockers made by Gage corp. are the way to go. Yes they are expensive, but you get a quality part. You are pushing .400" valve lift with that cam and that ratio. In my somewhat ( learned ) opinion you are asking an awful lot from a fulcrum ( stock) style rocker. I'm also somewhat surprised you aren't running a little more spring pressure with that much lift. Get a set of the Gage rollers and some 26 lb springs, and have a setup you'll never have to worry about.

 

[adamjankowski51]

Even though the rocker is sold ( or made ) by ARC, other than the roller tip, it looks and functions just like a stock Chinese rocker. The real roller rockers made by Gage corp. are the way to go. Yes they are expensive, but you get a quality part. You are pushing .400" valve lift with that cam and that ratio. In my somewhat ( learned ) opinion you are asking an awful lot from a fulcrum ( stock) style rocker. I'm also somewhat surprised you aren't running a little more spring pressure with that much lift. Get a set of the Gage rollers and some 26 lb springs, and have a setup you'll never have to worry about.

Good answer. I was debating in EC roller rockers as well. Any opinion ?

 

[adamjankowski51]

Even though the rocker is sold ( or made ) by ARC, other than the roller tip, it looks and functions just like a stock Chinese rocker. The real roller rockers made by Gage corp. are the way to go. Yes they are expensive, but you get a quality part. You are pushing .400" valve lift with that cam and that ratio. In my somewhat ( learned ) opinion you are asking an awful lot from a fulcrum ( stock) style rocker. I'm also somewhat surprised you aren't running a little more spring pressure with that much lift. Get a set of the Gage rollers and some 26 lb springs, and have a setup you'll never have to worry about.

Also you were right about the valve springs. I am running 32lb dual valve springs. I have no idea where 18lb came from.

 

[panchothedog]

Have never used the E C rockers. Just went on their website. They look great. A shaft mounted roller fulcrum and a roller tip. Look almost identical to the Gage rockers. I wouldn't hesitate for a second to use them. I'm sure you'd be happy with them. Yeah, 32lb. sounds more reasonable with that cam.

 

[bob58o]

I don’t know enough about your head.
.400 seems like a lot of lift on the exhaust side.
32 lb spring (with 0.895” install height) should allow .400” lift. Seems like the pockets were cut wider and deeper to get proper installed height.

No clue on piston to valve clearance in your engine.

GPS description says it is set up for 0.400 lift so I assume it is just a part failure?

Maybe just double check the installed spring height next time.

 

[ezcome-ezgo]

I would like a cookie.

 

[Denny]

Iced oatmeal!

 

[BaconBitRacing]

Classic chocolate chip would be best for me.

 

[Whitetrashrocker]

Macadamia for me.

 

[Crappy212gokart]

raw dough's the only way to go