393W stroker issues

[RnrdTheFox]

Ok. I understand now. We order the pushrods at the end so he could determine what to get. So I'd say yes I think they are right but I will ask again when I talk to him.

Thanks.

 

[Crude dude]

I also agree with the ARP studs. If this is common and you dont change them out that is a huge gamble. I would have thought AFR heads would use better studs too.

 

[RnrdTheFox]

Yes, I'm going to replace them while I have it apart.

 

[broncnaz]

Looks like AFR has had a lot of issues with there rocker studs breaking just like yours. It appears they dont use ARP stuff like other brands do. You'd think for the price you pay for the AFR heads they would use ARP stuff.

 

[bmc69]

Yes, I'm going to replace them while I have it apart.

Can you take a close-up pic of one of the studs from the side? I'm curious about the threads..they appear to be quite "shiny" in the pic you already posted. I would expect some of that appearance from using the crimped locking rocker nuts...but I'm wondering if those threads are cut and not rolled. The difference in stress concentration values between rolled (as ARP studs always are) and cut or machined threads is huge.

 

[RnrdTheFox]

Best pic I could get was the top of the broken stud. Also a close up of the failure and push rod.

 

[savage]

On my roller rockers I used a lock style nut that supports most the threads.

 

[NYLES]

Check the lifter, hyd roller? lifter wasnt pumped when adjusted got pumped put adjustment all outa wack pow! broken stud.

 

[KyleQ]

It's a roller cam setup. 94 351 roller block with Comp Cam 35-514-8. I ran it for 10 min at about 1200 rpm for break in.

Sorry for the troubles you experienced, way odd. Why this break-in feature? Everything I've ever been told or read said to vary the RPM's if you are even going to do that. Racers have proven that taking a brand new motor out and racing it without a break-in period seats the rings MUCH better than the factory break-in procedure. I plan to let it warm up once, cool down and then go bang gears and lay rubber.


I took a peek at your cam - I've got a 351W .030 over that I had built and that has the next cam size up in it, the 35-518-8. How do you like yours?

 

[RnrdTheFox]

Sorry for the troubles you experienced, way odd. Why this break-in feature? Everything I've ever been told or read said to vary the RPM's if you are even going to do that. Racers have proven that taking a brand new motor out and racing it without a break-in period seats the rings MUCH better than the factory break-in procedure. I plan to let it warm up once, cool down and then go bang gears and lay rubber.


I took a peek at your cam - I've got a 351W .030 over that I had built and that has the next cam size up in it, the 35-518-8. How do you like yours?

That is just what the builder told me for break in. In reality, I took me a few starts and stops to get to that point since I had issues getting it to idle.

No issues with the cam. At 800 rpm its got a slight loppines. And at 700 rpm while in gear, a little more. But, off idle it just wants to go. I pulled out the other day and didn't see an on-coming car so I goosed it and got it to chirp when the 4r70w shifted into 2nd. That made me smile. To be honest, I haven't put my foot in it yet. I'm waiting for about 500 mi on it and to get all the little kinks worked out.

 

[broncnaz]

There are lots of different ideas on engine break in. But I would go through a break in procedure for any engine I was going to run.. I dont care what racers claim. You have to figure there engines are probably have a little more effort put into the machining and blue printing process so they may take less break in time. plus if the engine takes a dump oh well they build another one for the next race. Id bet most actually do have break in procedures. Of course except maybe for drag racers that rebuild there engines between rounds. but any endurance rcre engine is broken in.
Basically on roller cam engines your more worried about seating the rings in which case I would still run it up to around 2500 and vary the RPM's between 2500 and 1000 kinda slowly. In the end its your builders experiance that you should go by if he has done top quality machining and his experiance is that break in time is short then go by his direction. But i'd reallly only expect that from high end shops.

 

[bk005]

I wouldnt use the ARP studs with those comp magnum rocker nuts. ARP has a differnet thread, and you end up with jacked threads or the problem you already have. Makes me wonder if you have similiar probs with your crrent studs.

I have the same rockers just put on some edelbrock heads, and I galled one rocker stud taking the nut off, I became a bit leary of them. They go on super tight, lots of heat generated. I coat them in oil, and work them on slowly. Id still bet money the cause of failure was the nut nicking the bolt or setting it up in tensile for failure.

Im rebuilding my motor now for the second time due to a crank bolt fiasco, and Im going back with some differnt rockers with poly locks this time.

 

[bk005]

Can you take a close-up pic of one of the studs from the side? I'm curious about the threads..they appear to be quite "shiny" in the pic you already posted. I would expect some of that appearance from using the crimped locking rocker nuts...but I'm wondering if those threads are cut and not rolled. The difference in stress concentration values between rolled (as ARP studs always are) and cut or machined threads is huge.

^^^^^ What he said!

 

[rguest3]

Not to be expected from AFR, but maybe they took a shortcut with the studs.

ARP for everything in my builds. May be considered overkill, but it's a little insurance to me.

Have the same Rockers and Cam in my 351w. Great Cam! You will love the torque once it is broken in and you can stand on it.

 

[73azbronco]

The only critical issue with breaking in motors today is not unlike yesteryear, you want to make sure all the surfaces wear into normal operating position without overheating or galling the parts.

While racers will take a stone cold motor and hit it, guess what, that's about the guys 50th motor he built with those specs, so he has lots of faith it will all come together. Can you imagine if you decided one minute after start to go tooling down the highway at 80 and that stud let lose? Unless you have an old school camshaft, starting up a motor and varying rpm for 1st hour is all you really need, that and getting varying loads on the motor both under load and under decal to seat the rings and valves. All your really doing is verifying everything works so it doesn't come apart on the interstate.

 

[broncnaz]

I wouldnt use the ARP studs with those comp magnum rocker nuts. ARP has a differnet thread, and you end up with jacked threads or the problem you already have. Makes me wonder if you have similiar probs with your crrent studs.

I have the same rockers just put on some edelbrock heads, and I galled one rocker stud taking the nut off, I became a bit leary of them. They go on super tight, lots of heat generated. I coat them in oil, and work them on slowly. Id still bet money the cause of failure was the nut nicking the bolt or setting it up in tensile for failure.
.

Those nuts are that way by design there locking nuts that do have some thread interferance. Better type to run is poly locks. From the pics it appears that the stud broke below the nut so I highly doubt that the nut even if it did gall the threads caused the issue.
As I mentioned earlier its seems AFR cheaped out on the studs many people have had the same exact issue

 

[bk005]

Those nuts are that way by design there locking nuts that do have some thread interferance. Better type to run is poly locks. From the pics it appears that the stud broke below the nut so I highly doubt that the nut even if it did gall the threads caused the issue.
As I mentioned earlier its seems AFR cheaped out on the studs many people have had the same exact issue

Agree, but ARP even states do not use stock type nuts on ARP studs. I have been trying to findout what is reason exactly, I have heard one has class 2 threads and the other class 3. Or that that the lock nut nicks the high tensile stud and makes it prone to crack. I have same set up as OP is only reason I bring it up.

 

[barronj]

Have the same Rockers and Cam in my 351w. Great Cam! You will love the torque once it is broken in and you can stand on it.

lol, I bet a broom handle would make gobs of torque in a windsor stroker with decent heads. No slight to your cam choices though, obviously.

 

[EricLar80]

Best pic I could get was the top of the broken stud. Also a close up of the failure and push rod.

It did not fail in pure tension; as expected, there looks to be some element of cyclic crack propagation from the top left hand edge of the bolt. The real question is whether the issue is material related, or if there was damage that caused a nick during manufacture or assembly. If you want to send me the two halves that broke, I could provide a more in depth perspective.

Personally, I would go to the ARP stud and change out the crimped locknut for the kind with the allan screw on top since I am not a fan of the damage the crimped kind can do to the screw.

Eric

 

[justjoe1]

ARP Studs and poly locks are the way to go. I have been running them in three different motors for over 15 years, and never had any problems, but I am also running full roller rockers in all three motors.