I recently bought a 97 dodge 1500 from a buddy of mine. I know he has quite a bit of work done to the truck. The motor has been stroked to a 408 cubic inch as well as many more mods. My problem is that the truck keeps snapping the bolts that hold the rocker arms down to the pedestal. The previous owner had the same issue and had tapped the holes out to take a 3/8 bolt. Even though I am using a 3/8 grade 8 bolt they are still snapping clean off. I work for a chrysler dealership and one of my technicians told me that he believes it is from the cam having too high of a lift and attempting to push the rocker arms up too high. is this possible??? any help would be appreciated, thank you guys

 

a very high lift cam w/o sloted rockers can cause the bolts to break. Iwould also make sure that the valve train is stable. when does it break the bolts ? high rpm? idle? regular driving? If it breaks them at high rpm I would suspect valve float.

 

STOP STOP STOP don't go any further with this motor. First off, don't use grade 8 hardware on the motor, get ARP bolts www.arp-bolts.com the tensile strength is alot better and intended for what you are doing. I also hate to say this but you have to tear the heads off and inspect the entire valvetrain before you potentially ruin the entire engine. I know this is something you don't want to do but you must at this point. There is something here that isn't right. You are eithor floating a valve and the piston is coming up and hitting it, the lift on the cam is too high and the reliefs in the pistons aren't deep enough, you are binding the coils on the valvesprings, or the retainers are crashing into the valve guides from too much lift. I suspect the later two are the most likely being PV contact would have most likely bent a valve by now. Eithor way the heads MUST come off and you must identify that you have everything right. PV contact would be obvious by little eyelash intents in the pistons aside from the normal reliefs if your pistons have any. You much check pushrod length for block deck height and how much has been milled from the heads, correct valvesprings for said cam, correct installed height on the valvesprings, performance valvesprings are not just a slap in and go. They must be installed at the correct height or big trouble can result. If the lift is too much and it is crashing the retainer into the guide, that's easy. Just have a machine shop machine the guides down alittle until the retainers clear. If it is the springs, install new springs to the correct installed height. Easy as pie. It's gonna take alittle detective work, but I'm sure you will figure it out. Let us know what you find so maybe somebody else can avoid that problem in the future.

 

That's also another real good suggestion that I didn't think of being I work on Chevy motors most of the time and the rockers are different on the newer GM motors than the Mopars (GM uses a roller bearing trunion on the newer motors so they don't have this problem no matter what lift of cam).Your rocker might be fine though, and just your geometry is way off. Too long of a pushrod will snap the bolt off like that.

 

either that or he used too much of a wild cam and the rocker ratio is too high for them.. like 1.7s on a wild cam would be too much lift

 

Valve springs could be binding. I would do some research and find out about the springs, valve lift,etc. If you drop a valve you could be looking at serious engine damage.