ok so recently, for the second time, my 390 bent a pushrod. the first time was with stock rockers. i bent the intake, and on the same cylinder the exhaust wore a hole in the lifter bottom. that was on cylinder 3. the second time was with adjustables and the same situation, bent intake and worn lifter on exhaust, this time on #6.... so that is 2 cams down, im gonna ge a new one, clean the lifter bores, clean the heads and valves, drain the old gas from the tank, use some rotella oil, and try again. any ideas whats happening first? am i bending a pushrod, and that causing the other lifter to wear, or am i flatening a lifter and that bending the other pushrod? and also any ideas to keep this from happening? i have edelbrock performer heads, comp cams 268h(second cam toasted) and xe262h(first cam toasted). im thinking about trying the crn 902 next. im getting pretty tired of tearing this engine apart, and since its lifted with 38" tires so its a big production to do anything to the engine. not to mention it doesnt fit in the garage, so all the work is done out side. any help would and/or advise is appreciated.

 

Sorry for your problems. Are you following the recommendations to run the cam in properly? If not, you can easily wipe a cam lobe down. When the cam lobe goes then the rocker is not adjusted for the correct lifter preload and this could be the root cause of your problem. The first time it could have just been that things weren't right with the nonadjustable rocker arms. If you got them adjusted right on the adjustable ones then I have to suspect that the cam did not get a proper break in. You need to use the cam lube supplied to coat the cam lobes, Shell Rotella is a good oil to use at startup....and all the time imho. Also, there is an additive that can be added to the oil for startup. Then you just need to follow the time and rpm recommendations at startup. This becomes more critical as you increase the agressiveness of the cam. For the really wild ones it might even be necessary to use a standard valve spring for startup and then go back and change them out to the right springs after the cam is broken in. I don't think you need to do this but it is really important to break the cam in right.

Good Luck!

Tracy

 

On the last rebuild on my 428 I used a set of lifters from NAPA and after start up and break in, it bent 4 pushrods on peassenger side. After pulling them and replacing them with new, she ran about week and bent all 8 pushrods on the passenger side of the engine. Replaced them again and about a week later she broke the rockerarm, bent 2 pushrods and one valve spring. I pulled the intake and pull the lifters and replaced them with new lifters from differant parts house, that was 4 years ago with no problems. The lifters that I took out were all stuck at the top of there bore.

 

There's an article on this page that might help you;
https://www.ford-trucks.com/article/idx/14/0/

Scroll down towards the bottom of the page, and you'll find an article titled "FE's That Bend Push-rods, A Dirty little Secret"

 

If you floated a lifter, then it will bend a pushrod...which is what it sounds like happened. It hung the valve open enough for piston to tap it and bend the pushrod.

Eating thru a lifter is break-in or proper lube problem. Unless....it's sticking in the bore and not rotating. This will cause it to eat thru also. Make sure the bores are on size. The lifter should freely turn in bore. With it being different bores and different lifters...what's the chance? Time to really pay attention when assembling to make sure everything is free.

Alot of cam mfgr's suggest only running single spring for break in, then installing inner spring after. It's alot of work, but might help with situation. It allows plenty of oil between lifter and cam, and not alot of pressure on surfaces.

Something to think about.

 

Sounds like to me Just as mentioned above.. The lifters are sticking in the bores and not turning...Thus taking out the lifter and wiping out the cam lobs.... Or and a combination of lifters sticking in the bore's in proper break in and heavy lifter preload?

But Freightrain is right..cam manufactures would rather have you break a cam in with just the Lighter outter springs on..and the put the inners in after break in..This is a pain in the A$$ if you do your break in ...In the Vehicle...Thats why alot of us break the motor in on the engine stand where you have easy access... It Much easier than 2 or 3 R&R's......JMO........

RJ

 

A good thing to check before putting lifters in.....put them bottom face to bottom face and see if they are ROUND. They should NOT sit flat against each other..they should roll around a bit. If you have a flat lifter...this may cause it to NOT rotate and thus destroying itself.

Just something else to check before you put it together again. Ain't it a beach...but you have to check everything cause the quality just isn't there anymore with all the chinese crap that is circulating around.

 

On mine the exhaust went first. Low speed, low demand no problem. More throttle it would start popping through the carb. Go through the ignition, go through the carb, about the time I decide it must be mechanical, BANG! Limp home, pull a VC and see the exhaust rocker going half as far as the rest, the intake pushrod is bent and rocker travel pretty much matches exhaust.

I'm thinking that the full intake and half exhaust left pressure in the cylinder that worked against the intake. Unlike yours, mine had several thousand miles (over 10K) since the heads were exchanged: Stupid walmart oil...

 

Hypoid's got it. The exhaust lobe went south, that allowed the cylinder to fill, ignite, then when there was enough back pressure in the cylinder, the pushrod bends, trying to open the valve against the pressure. The backfire was residual pressure left when the intake valve opened. I had two do this. On both, I checked to see the lifters would spin freely when installing them, also used only a thin film of lube on the lobe and lifter bottom, no lube on the lifter sides, motor oil only there. You don't want so much lube, that the cam lobe doesn't get enough traction on the lifter bottom to spin it. On both the second time around worked. Prelube the engine before starting it. Freighttrain also has a good idea there in checking the lifter bottoms to make sure they're not flat before installing them, I hadn't thought of that before, but it also sounds like a likely scenario.

 

i dont recall checking to see if the lifter spun in the bore and i didnt use the rotella oil, but they were adjusted right, and the cam was broke in according to the manufacture. the springs on the edelbrock heads are the ones that came on them. they are athe rpm heads, would that make a difference? i dont want to have to buy new springs, but id rather buy new springs, than have to get yet another cam, ya know

 

What oil did you use in the breakin process? Did you use the cam lube? Did you use the cam breakin additive to the oil? I do not think the springs are your problem. The deal on springs is this....as a cam gets more aggressive you have higher lift rates, higher lifts, and higher rpm range on the engine. In order to keep the lifter in contact and have the valve train keep proper adjustment throughout this you need more force (i.e. stiffer springs). This really comes into play at higher rpm's. For instance, stock springs may run fine on your cam up to maybe 4500 rpm....but if you drive the rpm up too high then the spring tension is not enough to keep the lifter in contact as the cam approaches the lift height....and cannot keep it in contact on the downside....you get lifter float....possible valve to piston interference....bent or broken pushrods...etc. In your case though, you wiped a cam lobe and the bottom of a lifter....I believe that is the initiating event. Lower spring tensions would actually help you in the cam breakin process. Note the other posts about leaving out the inner springs for breakin. During breakin you're not hitting the high rpm's so you don't have to have the higher spring tensions. To me the only thing that can cause the cam lobe and lifter issue is either incorrect breakin or a lifter that does not rotate. A proper breakin means the right lube on the cam, the right oil, and the proper rpm's and time. Poor oil in the breakin process can ruin it. Most of today's oils aren't good enough for this. You need to use a Diesel rated oil here. Also, Freight brings up a good point on checking the bottom of the lifters. They need to be slightly convex....if they are flat or concave then they won't rotate properly.

Good Luck!

Tracy

 

thanks, i am pretty sure the cheap cheveron 30 oil was a factor, but like i said i didnt check to see if the lifters spun in the bore. ill make sure to do all of this stuff you guys mentioned this next time..... another question witch is better .. the only difference i see is the lob separation --- http://store.summitracing.com/partde...N-343902&N=700 0&Ntt=CRN~343904 or CRN~343902&Ntk=&rsview=sku&Ns=
or
http://store.summitracing.com/partde...N-343904&N=700 0&Ntt=CRN~343904 or CRN~343902&Ntk=&rsview=sku&Ns=

 

ok so i got the cam changed. when i pulled the old one out i noticed that it had eaten up almost half the lifters? so when i put in the new one i took a break hone to the lifter bores to make sure they were clean. then i made sure that all of the new lifters spun freely in the bore. i used the cam lube that came with the cam on all of the lobes, bearings, and the bottoms of the lifters. for the break-in run i keep it between 1800 and 2300 rpms for about 25-30 mins. this is my third cam this year.... what are the chanced this one will last? i used rotella-t oil. i used cheveron 30 the last two times, and didnt check to see if the lifters spun.... do i have a better chance this time... i really dont want to have to do this again. thanks mike

 

When you start it up, do it with the valve covers off, so you can watch the pushrods for spin. No spin= cut the ignition. Also prelube the oil system before firing it off.

 

ok so i quit!!!!(not really quit) this is the third cam this year!!! i cant afford to keep pulling cams and putting a new one in. the first one (with the non-adjustables) lasted the longest jan -august. the one i put in this weekend lasted about a total of 1 1/2 hours, the same as the last one. i have changed cams before, and never had this happen (till now). could there be something wrong with the block? i am totally out of ideas. ive tried adjusting the rocklers to zero + 3/4 ... zero + 1/4 and even just zero lash...