got my comet going, my 351w is a killer. its so powerful that it has popped off a polylock on one the passenger side, got me a new polylok, a couple days later it busted a rocker stud in half, got a new stud, last night i'm not sure but back on the passenger side i think my roller rocker is off on one of my cyl. again.. i have chevy valves, thanks to a friends suggestion, chevy springs, alumin roller rockers. my max lift on my cam is 496/520 and i'm using slightly taller pushrods to compinsate for the shorter valves ( and yes they were cheaper) any ideas on why i might be busting studs and loks?
Push rods too long...rocker slots not large enough for cam lift...Valve springs stacking up before cam lobe runs out of lift...rocker ratio too big for your set up... just to name a few.You really need to check your rocker arm geometry and correct this before really bad things happen.my initial guess? push rods too long/cheap rocker studs or too much lift for valve train.Good luck.
My guess is you used a shorter valve and didn't change to a shorter spring,with the required tension. the spring had to be partially compressed to put in the keepers.when the longer pushrod come up it totally compresses the spring and the rest of the valve train is still coming up. if spring totally compressed then the rest of the valve train has no where to go but to push out on the side.Why go chev valves, when there are ford valves to do exactly the same thing. Also you dont state what the ratio is on your rocker arms. Hopefully 1.6.
printed the the pages and thanks, unfortunatly the guy that was doing the work for me at the start had suggested the cheaper valves and at the time, like the present i was low on cash and he had a set of valves already i had the heads cut for chevy valves. the roller rockers are 1.6. i appreciate the help. i am almost tempted, even though i've spent money and time porting the heads ect. i may just find some used heads off of a 5.0 explorer or something if i can't get this thing right, i know it not all right but man when i've driven it i have no traction because 1. the power and 2. um my stock open rear 8". so if i can solve my rocker problem i'll be diffently looking for better traction..... and i used the chevy springs to match the valves .. of course this is all guess work on my part cuz unfortunatly i'm not an expert... maybe in my next life lol
If the valve springs arent stacking up on you at max lift...you may be able to remedy the problem with proper push rod length.Dont give up!!!
You need shorter pushrods, not longer. You didn't check the geometry correctly. Taller valves= taller pushrods. Shorter valves would need shorter pushrods.
This sounds familiar. I had similar trouble building a 355 Chevy, and yes I needed shorter pushrods. BUT - I discovered that at a cost. Saw tiny stress cracks in my roller rockers, and all that tension wiped my cam. When you change those studs, I would take a look at the lifters and make sure they don't look ground down. It might not be too late, but I sure wouldn't run it much more until you get to the bottom of this.
i took it to someone more knowledgeable, first thing he says is " looks like your pushrods are to long" he's got a length checker and varies push rods and ect. so Lord willing i'll have it going strong by next week, cash allowing of course
yes i am, i'm running guide plates. once i find the right length , i'll have to order the hardened push rods.
