Howdy moparts

I finally started breaking in my fresh 400/512 that’s been built for a while. Everything went good for a few minutes until I heard a rattle and shut it down. Turns out the last two bolts on my rocker shaft were coming loose. What was shocking was that #7 exhaust pushrod was too short to touch the rocker once I tightened the shaft.

It’s my first big block and wow what a pleasure to work on. With no water in the intake I had the valley open inside 30 mins. #7 exhaust lifter puked its piston and the little pierced sheetmetal piece underneath was ripped in half. #7 intake had its piston stuck cocked in the lifter bore. Both lifters still looked brand new on the bottoms as does the cam so I just ordered replacements. I was only a couple minutes into fire up and break in before it let go and no pieces fell thru to the pan so I think I dodged the bullet on this one and it will just be a small setback.

Is that a normal thing to have happen when rockers let go? This is stock stamped rockers and a .507” hft cam, no crazy pressures or anything. I half expected to find a whole lifter ejected into the valley I don’t see why this would have broken like this?


Thanks!
Radar in Philly

Guess I better make sure those pushrods are not bent too...

Edit: yup the one that did all the smashing #7 exhaust has a wobble you can hear but not really see when rolling it on glass. Time for some pushrods too.

After having a moment to reflect I guess the shaft got loose enough to let the pushrod out of the pocket in the rocker, then did a little smashing while misaligned in the lifter, then the shaft finished loosening up until it wasn’t even opening the valve any more.

I got a brand new set of 16. Hy-Lift Johnson slow bleed HYD Lifters. If your interested in them.

Make sure that the pushrod is not to large for the cup. It pushes down on the retaining ring and pop goes the lifter. Check for pushrod rubbing as well. (look for shiny spots where it goes through the head.
Todd

As you surmised I'd say the rocker bolts coming loose caused all the carnage. As you are doing replace the lifters (make sure they ain't too tight in the lifter bore(s)/check/replace the pushrods & #1 find out/address how the rocker bolts were/came loose. As you go together you might check/note preload.

I would make sure the rocker arm shaft bolts are at least grade 5 or better and make sure to NOT over torque them
The FSM calls for 23 to 25 Ft. Lbs. and that is what I use.(although I convert those numbers to inch Lbs. and use my 3/8 drive 100 to 750 inch lb. torque wrench on any torque below 30 Ft. Lbs. 23x12=276 inch Lbs., 12x25=300 inch lbs., correct )
I do check them at least three times while assembling the motor and again after warming up the motor to break the cam and lifters in and recheck the valve lash and inspect for F.O.D. in the heads in case of something going horribly wrong like you had
Good luck on your deal

Thanks fellas

This is stock 1977 rockers shafts and bolts out of my donor 400 screwed into brand new stealth heads. I have screwed down a ton of stock and aftermarket rocker shafts and I always worried about deforming the shaft more than pulling the threads. I will admit I never used a torque wrench on them though. When it first happened I was worried that all the threads had pulled out of the rear rocker stand. I have to go inspect the hole more carefully and decide if a stud or a timesert would be necessary or good insurance.

I’m definitely thinking about at least covering the rest of the head and spraying out the holes with brakeleen so blue loctite can get a good bite.

Ok so I went out got a really good cleaning and look at the threads on my bolt and head. Somehow the rocker stand threads still look sharp and the bolt threads down nicely. Hard to believe the last two bolts would just work loose like that with almost constant pressure on them as the rockers work the valves. Break in rpm is definitely loud though so I can see how I wouldn’t have noticed it until it realls clattered?

Still I’m surprised. While I was trying to drift off to sleep last night I kept thinking how could the pushrod have slipped far enough out of the dimple in the rocker and simultaneously wedged either to coil bind or too far toward the fulcrum of the rocker to have good leverage? The pushrods don’t contact their holes through the head but don’t have a ton of room to misalign- the holes aim at the lifters pretty well. Or did the pushrod just slip over into the lifter’s snapring/retention wire area then the cocked piston in the lifter bore broke the little sheetmetal piece underneath before it spat out the piston? And how did the intake lifter piston get cocked in its lifter bore?

And if enough force was transmitted from the rocker, which was anchored by bolts that were unscrewing fast enough to cause problems in less than 5 minutes of 2500-2700 rpm, how did it not pull the remaining threads holding the shaft bolts right out of the aluminum rocker stand?! What a freaky thing.

I actually have a video of it from my wife’s phone I posted on yootoob- you can hear a hint of a problem starting in the middle of the video but it was tough to hear in the heat of the moment at rpm before it was too late.

Skip to 2:45 through to hear the carnage happen. I think after that it was still running on 7 cyls pretty well with the one cylinder only slightly opening the intake and the exhaust valve staying closed! The rpm didn’t change a ton and there were no additional horrible noises. On the other hand a healthy 448” V7 motor should make enough power to drag a dead hole along for the ride.

https://youtu.be/pyZlQqcrNkI

If it were mine, I would be checking the rocker shafts as well to make sure they are not bent.

I agree you dodged a bullet, it could have been much, much worse.

The shaft bolts get loose, then you have some clearance between the pushrods and the rockers/lifters, pushrods are jumping around in the lifters & rockers, hammering all the pieces involved....... and you’re gonna end up with a few broken pieces.

Stuff happens........ you caught it before it got real ugly.

To me it sounds like at approx 36 seconds in on your vid it dont sound well. Sounds like its already laboring imo.

Hope its a easy fix.

Does the Stealth head use heli coils for the rocker arm shaft threaded bosses ?

Never installed a Stealth head


Was nice to see that the Edelbrock E Street used heli coils and supplied studs for 2 and 4 bosses

However

Was not nice to see the some what broken off heli coil tangs left in the bottom of the holes in three spots when I was trying to torque everything down

Avoided a messy situation there

You might want to use some old NHRA "stock class" racer tricks with the stock rocker arms to check the lifter preload on every rocker arm and lifter, you may need to swap some of them around to get between .015 to .045 preload on all of the lifters on the base circle of the cam lobes , all 16 of them :wrench

I had my thumb on the throttle and couldn’t understand why my buddy wouldn’t spin the curb idle screw until I could let it go. Turns out he was trying to be smart and run back and forth to look at the tach but that dip in rpm was me checking to see if I could let the throttle go yet or not and yelling at him to zing up that curb idle asap.

My floats were way high and it was running super duper rich. I’m still not sure if I did it again if I would have heard it starting to let go and know to open the valvecovers. I’ve had adjustable lifters on solids open up before but always heard a tap and shut her down.

Guess it was my torqueing negligence mixed with a freak thing. The stealths have room to run 1/4” longer bolts without flirting with the bottoms of the blind holes. I’m gonna spray out the holes with brakleen and shop air a few times then blue loctite them in next time.

I got new pushrods, just waiting on lifters and gonna order some new grade 5 or 8 bolts off mcmaster.

I do NOT recommend loctite on the bolts

Don't do that

X2 no loctite & my Super Stealths have inserts so I would highly assume the Stealths do also. Not sure about grade 8 but I will defer to others on this. EDIT yes spray em out with brake kleen & eyeball em to see if the threads look good then run a bolt in there & see if it threads in/out good then we will see about advise on a lube. I usually dip threads in 30 oil then blow em off with shop air. On a side note I would pick a cyl that is on TDC compression & see what the preload is (not that I think it caused this) but it is important.

did you fill the lifters with oil before you started engine? Do you have adjustable rockers?

I soaked the lifters overnight but I didn’t take them apart and fill them or anything crazy. I also let the drill run for a minute when I primed the oil pump- dunno if it was clocked right to feed the lifter galleries but it didn’t noticably clatter on fireup.

I’m running a comp .507” hft cam with extreme energy lifters and I bought comp 5/16” pushrods that are nice fartory low deck replacement deals- 8.555” iirc. The rockers and shaft are stock late 70s truck pieces out of the 400 donor motor I stroked.

Haha I spelled factory ‘fartory’ oops thats a hilarious typo

When you check the lifter preload make sure and do that on the firing stroke on each cylinder, not when the intake and exhaust valves are on the overlap cycle

I could see a bunch of loctite crumbs causing problems in the oil pump maybe but why not clean the threads and bolts nice and dry and smear a drop of blue loctite on the first few threads?

Also I’ve used adjustable pushrods to preload hydraulic lifters on harleys a million times and set lash on tons of solid flat tappets in v8s but all I ever did on a non adjustable setup was make sure the pushrods had no lash but still could be spun in my fingers on the heel of the cam.

I guess with the valley open I can spin it around a little and look at the lifter bodies and make sure the lifter pistons are uniformly depressed an appropriate amount from a fully extended lifter? The motor didn’t really have any lifter clatter or anything before the poo hit the fan.

I just want to put it back together and feel confident- I’m not really sure why this happened unless I just didn’t properly torque the rear bolt in the first place.

For one, the 2nd bolt from the rear has an oil passage for the rockers, 2. if you remove the bolts after you have put on loctite the Heli Coil will likely get uscreewed out of the aluminum cyl head, not what you want, 3. why do it, there is no reason to, not done from mamopar, or ANYone that I know of, none on my stealth heads, yours came loose because they where never tighten down correct.

Alright I got some new parts. Gotta get some replacement bolts or studs. New lifters are soaking in oil till I get a chance to button it back up.

I have used a pushrod in the lifters with them fully submerge in oil and pump them(the pushrods in the lifter cups) up and down until all the air stop coming out of the sides of the lifters to make sure they where full of oil and not the factory anti rust stuff that is in them
I have also soaked them like your doing and then used a drill motor to spin the oil pump over to prime the motor and then used the starter to spin the motor over with no spark plugs in the motor 20 to 40 RPM several times to fully lube the rocker shafts and rocker arms

My personal preference is not to soak or pump up a hydraulic lifter until it has been installed/adjusted. When filled or pumped up, setting pre-load it will open the valve not pre-load. This makes it very hard to set proper pre-load. For me anyhow

that'd be my guess (it happens to all of us at one time or another). To do lifters to the nth degree (which I do now after my recent lifter fiascoes!) is take em apart & clean thoroughly then reassemble dry then install em & set preload individually if I have adjustable rockers & if not then I before hand on mockup individually checked preload (it should be about the same on all of em but cant assume anything for everything being the same length/dimention) then get #1 cyl to 15 BTDC compression then preoil. I also toss the flimsy clips & use hardware store 11/16 internal snap rings in their place & a guy said to have the sharp edge side down which I thought was backwards but I am going with what he said. It might be better to lightly lube internals with WD40 as opposed to dry & I am open to changeing that but that is where I am at now. Holler how it turns out

I’m done collecting parts- the 1/4” longer bolts for the end and middle stands fit perfect. The extra thread engagement will give me a little reassurance, plus the loosening shaft beat up the threads on the stock bolt so that’s garbage anyway. Gotta work a long day today, hopefully tomorrow I can report with good news.

Also I don’t see a helicoil in the rocker stands on my stock stealths- maybe the ported model has them? Or marbe I need a flashlight. The exhaust bolt holes definitely have steel inserts which is nice.

And thanks for all the help and for not beatin me up too bad for soft torquing that bolt😘

Heck my life of working on cars is FULL of mistakes & I know there will be many more for me LOL, Keep us posted !!!

The only way I learn to remember to NOT REPEAT mistakes is to have to learn how to fix them

I wonder if it was an assembly line slip up on their end, I would think if alum stands needed em that it would be the same across the board on all of em.

When I built my first small block (318 w/360 heads) way back in the early 1980s, I tried torqueing the shaft bolts to 25 lb-ft and some of the bolts would stretch before getting to that torque. Also it seemed like they were an odd length, 2-1/8" or something that wasn't readily available at the nut and bolt stores.

If my memory is correct I think all the SB rocker shaft hold down bolts are 5/16, not 3/8 like the BB and Hemi motors use

the 1,3,5 holes have the heilicoil, 2&4 do not

These are aluminum heads?

Either way, grade 8 bolts are wrong for the application. You can't stretch the bolt properly without risking damage to the threads in the head. If the heads are cast iron, then I would feel comfortable with grade 5 uncoated bolts. Coated bolts change the torque requirement.

If the heads are aluminum, then I am a strong proponent of studs. Because you don't have the high friction on the internal threads while torquing with studs, the studs torque better, and you have a lesser chance of damaging the threads. Remember that when torquing a bolt the bolt is twisting during the torquing process - studs don't have that problem. Also remember that if you over-torque the bolts you can yield the bolt or internal threads or both and then not have proper clamping force. Once yielded its not possible to have proper clamping.

Most pf the time you can get away without proper clamping/bolting practices, but eventually it can bite you when you have a more difficult clamping application. I consider rocker clamping more difficult than most bolting on an engine. In my work life, I have been involved in quite a few bolting failures, and some were super expensive. Because I'm anal, I try to follow clamping/bolting best practices on everything I put together.

I get that for sure but I always felt like I’d oval the shaft before any stretching happened? I thought the rocker shaft roundness was the weak link in this operation, at least with stock hold down spacer/washers which don’t apply force to a whole 180 degrees like a fancy billet hold down.

You are correct on the stock shafts and their weaknesses
I've had to file more than one shaft ends to get adjustable rocker arms off of them when someone else had over tighten them

Ok so this morning I reassembled the valvetrain and top end and gave her another shot at the break in period.

Here’s a video. A couple minutes after this it started getting real hot so I shut her down, waited a bit, and added more antifreeze. Hopefully it just needed more burping.

I started it back up after waiting for it to cool some more and I saw the temp climb then come back down as the thermostat opened, then start slowly climbing again. It got to around 210 before I shut it down again. The RPMs were starting to hunt a little bit which was worrying. The AFR was reading around 9-10 which is PIG rich- I dunno if it even matters with no load on the motor? I did fix the floats so they’re not high any more. Dunno if twiddling the 4 idle screws would even make a difference with the throttle open to het 2500-3000 rpm.

Of course on shutdown I was treated to a little dieseling and a couple nice loud tailpipe backfires. I’m gonna call that normal for the throttle being open that far.

The rpm hunting does have me worried though. I’m going to re-check the rockers before continuing the break in. I did get to hear the idle for as long as it took me to jump out after it started and zing up the curb idle screw- if I ever get this monster running right it is gonna sound nasty!

https://youtu.be/ihPa2vJz7Ag

what do the plugs look like now?

How is the dist timing set up, initial & total, vac adv hooked up ?

Did you run the motor enough before the lifter failure to know if this problem is new since then, or could these issues have been there before too? RPM hunting can be a vacuum leak

^^^ that is what I was getting at, that the 9-10:1 rich reading could be a gauge "reversal" from actually way too lean. Not my area, just thinking out loud

Hi fellas!

I posted another thread with a clip of the idle sound. My valvetrain is sorted out for now. Break in almost done (5 mins left but had to fix a water leak)

I never worried about unloaded free rev afrs but I did go ahead and screw in the four corner idle screws to see if they still had any noticable effect at break in rpm. I started out with a B guitar string in the ifrs and the corner screws out 1.5 turns. I’ve found that restricting the IFR until best idle was achieved around 1.5 turns out has tended to give me a good balanced leanish cruise at light throttle with bigger motors. I don’t usually do much with the air bleeds unless the curve needs tweaking.

Anyway, it did respond to the corner screws and seemed much happier and didn’t hunt rpms anymore. It was reading 9s and now it’s up in the high 10s/low 11s on the meter. That’ll do the trick for break in. Once I get it to idle for more than 10 seconds I’ll really find out where the corner screws end up, then decide if I go looking for thicker guitar strings to restrict the IFRs. If I wasn’t so lazy I’d tap them and make little jets or just buy billet ones...

By adding the IFR (if your installing them into the air bleeds and not the idle fuel feed channels)you are enrichening the mixture, remove them and shoot for 14.5+ AFR at high idle above 1500 RPM, use the secondary throttle blades also to get the RPM you want, not just the primary throttle blades
I drill and tap both the idle fuel feed channels and the power valve fuel feed channels to #6x32 and use blank allen headed brass set screws that I drill out to the size I want to fine tune the AFR at idle and at slight power valve opening and then tune the high speed air bleeds sizes for the WOT AFR tuning
What year is your Dodge Pickup, 1954,55,56 or what year?
I had a 1955 D500 flatbed that I converted into a car hauler and sold it to a friend and later buying a 1957 D300 whup car hauler that I ended up replacing the entire cab with fenders from a 1960 pickup, motor and a D60HD rear end out of Class B motor home chassis
If your carb is a four corner idle carb try from 1/4 to 1 full turn out from bottom on all four mixture screws and see what that gets you on the AFR, if it is primary only idle mixture blocks try from 1 to 1 1/2 turns out from bottom with the secondary throttle blades barely opened at idle
You really need to set the total timing as soon as possible, that can have a big effect on the idle quality and heating issues due to not enough advance, I shoot for 34 to 36 degrees total at or above when the mechanical advance is all in

No I never wire down the air bleeds I am talking about wiring down the idle feed restrictions. My oldschool 950 has jets in the bleeds but non adjustable ifrs. At least they’re in the low position which is what I’m used to.

Like I said above I only mess with the bleeds after doing the fuel and only to mess with the delivery curve like if it gets richer with rpm.

It’s a 54 dodge 3/4 ton that I shortened to 104” wheelbase.

Setting timing at 34° with a light was the first thing I did as soon as it fired and we brought the rpm up. I will see where initial falls after I get done break in and start to tune the idle.

I’ve been eying those fully adjustable metering blocks but I get along fine with my guitar strings- haven’t met a double pumper that wasn’t too rich for the street yet.

Interesting on the four corner tip- I thought 1/2 a turn out was an indicator that the IFRs needed to be smaller

your correct about that
We learn by doing, correct

Ok so other than being tricky to start with no choke on my carb I have a strong idle dialed in at 900. Throttle response is good. I have an exhaust leak at #2, my oil pressure gauge has a tiny leak and the rear main seal is weeping. Not too bad of a list to start working on. The valve train is quiet now too!

Thanks all for the help! Now I’m dealing with my non functioning transmission in another thread but it’s all good forward progress and now I have a running 512 which fits my custom chassis which is a leap in the right direction.

Radar I'm glad that things are takeing a good turn for you cuz you certainly have had a run of bad luck here (eng & now trans).