VETDRMS

As the title implies I finished up my week long project of rounding up parts and getting everything back together.

First off I"ll say that this setup was a very noticeable improvement over the prior hydraulic roller and unmodified AFR 195's. Simply awesome. :reddevil:

The bad part is that the same day I got it back from the exhaust shop it had a mishap. First the exhaust. I had a tubular crossmember fabricated for the transmission as mine was bent and there was no way to run a straight 3" exhaust with it. The tubular setup turned out great, and I had a driveshaft loop fabricated at the same time. Pictures of the exhaust and crossmember to follow.

Anyways I had just come back from the shop and reset the timing and got the carb dialed in when I went to take it for a test run.
Drove a ways to get it warmed up and decided to get on it a little.
3/4 throttle from a 5mph roll and the tires went up in smoke, just about at 5000rpm in 1st I hear a loud BANG, and no power, a few pops and i hit the kill switch i installed that shuts down the ignition and the fuel pump without locking the steering wheel (pics to follow).

I rolled to the side of the road (luckily at my friends shop), and tried to diagnose the problem. I noticed my fuel pressure regulator was not working and was flooding the carb with 14psi. I thought this could be my problem and it was just loading up. There were no leaks or holes(thank God).
I turned it over a few times and it turned over fine, but was laboring on one compession stroke...not good.

I pulled the passenger side valve cover to check the lash and everything checked out (thinking it was a poly lock that had backed off).
I had an appointment and had to leave so I pushed the car into my friends shop and decided to come back and check it out later that night.

Wow, this is long winded (sorry). I came back and pulled the driver side valve cover to find the problem: a broken rocker stud.



This was the least of my problems. From what I can figure out the poly lock that broke off fell between the springs on the #3 cylinder and bound up the intake rocker. I noticed the intake rocker was off a bit and was bound up.
After taking it off I noticed it had chewed up the top of the valve, and in the process it chewed up the roller rocker:



After pulling that I noticed the pushrod was bent:



Just as soon as that was noticed I saw this in the lifter valley:




I pulled it home last night and pulled the motor. Upon tear down I was able to confirm nothing else had been damaged and the screens I had installed in the oil returns caught the chunk missing from my lifter (cheap insurance!)

I took the head to my machinist today to have the valve replaced/fixed.
I also picked up a new lifter, some ARP pro series studs and have a rocker arm and pushrod on order.

With any luck I will have it running this coming weekend. :)

The moral of this very long story: ADJUST YOUR LASH CORRECTLY.
After talking with my machinist I made a common mistake when trying to "lock" the poly lock.

I set the lash with the hex, tightened the lock, backed it off ~1/4 turn, retightened the lock and used the hex to crimp down the lock in the stud.
This ends up twisting the stud and weakening it.

lesson learned

:cheers:


[Modified by VETDRMS, 11:27 PM 3/15/2004]

SmokedTires

Man that is quite a lesson :sad: Sorry to hear it broke so soon, but it's good to hear the power was definitely there beforehand :) Are you using stud girdles ? The unfortunate thing about building an engine like this is that there are all kinds of "cheap insurance" parts that show up adding to the overall cost :rolleyes: .

Good luck getting back up & running. :cheers:

Jack71

It sounds like it could have been much worse. Must have been nice to see that chuck of metal in the screen. Hopefully you'll be back on the road soon...

mandm1200

Sorry to hear about the problem. Now that you learned that you tightened the poly lock the wrong way, did you learn how to tighten it the right way? And are you going to share that knowledge with the rest of us. I haven't started assembling my engine yet, just a few more pieces and and a few more months to go.

Mike

comp

:smash: thanks for the lash reminder :thumbs:

norvalwilhelm

I hope you are right and it is only a problem with how you tightened down the valve. I would be sceptical.. I would look further into the head to something binding. Have you honestly checked all clearances in the head?? Install a checker spring and check installed height, then maximum lift and see if there is enough retainer to valve seal clearance???

Check everything now that the head is off. Twice I have run into this same problem and both times it was caused by the retainer to seal clearance.

Good luck

gkull

Norval - Yesterday I told him that the stud break might be caused from to much flex and that he needs a stud girdle.

I set mine with a box end and T handle Allen. Place the feeler gauge between the roller tip and the valve stem. Back off the Allen lock and turn the 9/16ths box till the correct drag on the feeler gauge (Lash) tighten the Allen lock while ensuring that the feeler gauge drag stays the same.

I can do the whole motor in just a few bumps of the starter.

Then retighten the stud girdle on the rocker nut and then it won't move for thousands of miles :steering:

VetDRMS - Who is the manufacturer of those roller lifters and rockers?


[Modified by gkull, 9:38 AM 3/16/2004]

zwede

I can't believe that twisting the stud with a wrench would break it! What about when you torque the stud down into the head? Is that supposed to break it also? Like Norval said, something else is going on here and like Norval, my money is on interference/coil bind/seal clearance etc. Also, if the stud snaps for no real reason (i.e. no binding), why would the pushrod bend?

Edit: GKull also makes a good point. If you are running high spring pressures you may need a girdle. How strong are the springs (seat and open pressure)?


[Modified by zwede, 10:24 AM 3/16/2004]

VETDRMS

SmokedTires No I was not using a stud girdle, and i'm not so sure i'm going too. But yes, the many "cheap insurance items" CERTAINLY add to the cost. :lol:

mandm1200 Gkull explained it correctly below. Set the lash with the hex, hold the hex still and use an allen wrench to tighten the lock. Don't use the hex to "Lock" it.

norvalwilhelm I am almost certain it is only an issue with a weak stud. The valves are +.100 and are set at 1.850 installed height. I had all the clearances checked and there was no binding/interference. The head is at my machinist's and I will have the valve and the clearance checked again. No need to repeat!

gkull I also use an offset box end and a T-handle allen. The roller lifters are COMP 818's, the rockers are Blue Racer.

zwede The twist can weaken it. When you torque it down into the head you are "twisting" the hex and the 7/16" threads IN the head, not the shaft. You may want to re-read my post, but the rocker that had the stud break did NO damage to the pushrod or lifter. The loose poly lock bound up the rocker/spring beside it, causing that one to bend the pushrod and break the lifter. The rocker that broke the stud has no damages.

I am not running that high of spring pressure: 155seat 420open.

Thanks for the condolences, hopefully it will be running again this weekend. :)
:cheers:

norvalwilhelm

Norval - Yesterday I told him that the stud break might be caused from to much flex and that he needs a stud girdle.

I can't argue with that either George. I never ran my motor without a stud girdle. It went right along with the roller cam.
I just would make sure, absolutely sure that seal to retainer clearnance is right, at least .060 at full lift. Twice I found one valve out of the 16 on 2 different motors to run into seal to reatainer clearance.
While assembling heads I check EVERY valve for proper clearance. It doesn't take long if you know what you are doing, I do use checker springs and make gauges to suit the installed and fully open height.
If anything breaks assume something touched, check to make sure. Doesn't cost nothing but time and gives peice of mind.
I run a crane stud girdle and adjust the valves the same as you. 2 complete turns and all valves are set.

Fevre

That sounds wrong to me, will work with a hyd cam but you will be tightening the rocker down a touch using that method. Try it and see if you can still get the feeler gauge in there after. Seems once you get the nut where it needs to be you lock it in place with the hex head esp with a solid cam.

norvalwilhelm

my money is on interference/coil bind/seal clearance etc

Zwede brought up another good point. Coil bind. You know the installed height, the cam lift so you known the closed height of the spring.
Take a spring and completely compress it in the vise using the proper retainer, right down until the spring goes solid, now measure the length from the vise face to the underside of the retainer.
This is the coil bind length, add .060 to this value and your open length can never be less then this.
Thanks Zwede for reminding me a coil bind. Mind focussed on retainer to valve seal and never got over it.
I too can not believe tightening the nut caused this.

VETDRMS

norvalwilhelm I am going to check the clearances again, but I think it was nothing more than a weak stud/flexing. Coil bind is at 1.190" which is .660" lift. NET valve lift on the exhaust is .560". This is .100" before coil bind. These numbers were confirmed on a spring compressor.
The spring pressures and RPM range i'm running in should work fine without a girdle, however I may use one just for the added insurance.

Fevre Use the hex to set the height, if you tighten the allen without moving the hex your lash should not change. It may be useful to "lightly" lock the allen using 1/16 turn or so on the hex. All my lash settings were right on when checked cold/hot.

Fevre

Youa re correct, my bad, had it switched around in my head. :thumbs:

norvalwilhelm

Coil bind is at 1.190" which is .660" lift. NET valve lift on the exhaust is .560". This is .100" before coil bind.

If you are convinced all clearances are right and I do not trust others to do this checking. Often the machine shops young kids who might have put 100s of motors together still don't understand high performance.
My friend a licensed mechanic and front end alignment guy comes to me a nobody to learn about bump steer and how to correct it.
Just because someone said it is ok I still check.
The example you gave does have .100 clearance at maximum lift so that is fine, how about retainer to seal clearance??

If all checks out OK buy better studs.
Just trying to come up with MIGHT BE??
Have a good day

MotorHead

Sorry to hear about that, I am going to use the same cam with 1.6 rockers I was planning on a stud girdle, didn't really think I needed one but now................... are you using 7/16 studs, 3/8 won't cut it and was the one that broke ARP ? :D


[Modified by MotorHead, 11:30 AM 3/16/2004]

gkull

Norval is on to something with the bronze guide to spring retainer clearance. It takes allot of pressure to do what you did to those parts.

This is a picture of my bad roller when the wheel bearings went out after 20,000 bad miles.

Solid LT1

I can't say that I agree with your conclusion. I always back the poly lock out about a 1/8-1/4 turn and set the set screw THEN re-check the valve lash. This method was taught to me in the mid 1970's by a machinist friend who ran modified and gas eliminators in NHRA. The Mod and Gas motors were mostly small displacement high revving 287 cu/in small blocks turning towards 8700 RPM (dosen't seem like much today but was a major challenge back then!) I have crewed on Trans Am, cicle track and Drag cars and always employed my method of setting the poly lock set screw then doing final lash set and NEVER had problems. The damage to the side of the roller lifter tells me the valve either seized up or made physical contact with the piston (looks to me like the valve and piston met one another) and caused the push rod to bend and exit the side of the lifter, you will need to check the cam for damage if the lifter bar was bent during this mis-hap. My LT-1 has ARP 7/16" rocker studs and I would never use old or stock rocker studs but, would still continue to use the method taght to me by a NHRA World Record holder in the 70's. Sorry to see that misfortune, I hope it goes well in the next round, Eric B.


[Modified by Solid LT1, 10:36 AM 3/16/2004]

VETDRMS

norvalwhilhelm I did not try to come across defensive about it. I too suspected this and that is the reason I pulled the motor and removed the head. My machnist is a good friend of mine and I trust HIS work. I was there when they were assembled and there is plenty of clearance. With a 2.00" installed height I have nearly .500" of retainer to valve seal clearance.

The head is done and the valve was not bent and the guide was not hurt. It just needed a light grind on the stem to clean up. Its a perplexing problem as all the numbers check out. The only thing that "could" of bound it up would be interference with the loose poly lock. I will be running ARP PRO SERIES studs WITH a stud girdle this time around. I think it was a combination of tweaking the stud, and it being a cheap piece.

Thanks for the helpful insight, always appreciated. :cheers:

MotorHead Your gonna LOVE it. And, after some tuning I was pulling 10-11" of vacuum at 750rpm. Actually better than my HR. I was using the 3/8" studs that came with the heads, I will continue to use 3/8" with a girdle. The stud that broke was whatever AFR sells with their heads.

gkull I think the pressure came from it binding with a foreign object (poly lock). The poly lock was between the springs when I found it. It has some scars, and it is a very tight fit to get between the springs.

Solid LT1 I'm sure it is an acceptible practice if your using a quality stud, and you don't over do it. I may have just tweaked it a little too much, along with having a sub-standard stud. These studs weren't "old", and were only used for 2500miles with my HR. I can't say much for AFR's quality control, as quite a few things have been "fixed" on these heads.

:cheers:

norvalwilhelm

I never took offense. I am just trying to impress upon you what could happen if not checked. I have learned the hard way with one blown motor because of this.


With a 2.00" installed height I have nearly .500" of retainer to valve seal

This is not right??? In another post you had an installed height of 1.850??
Both are alright.
Install new studs and a stud girdle and hopefully everything will be fine. You did do alot of work finding the problem.