|
#2 pushrods keep bending I think I found the problem
#1030954
07/12/11 01:14 PM
07/12/11 01:14 PM
|
Joined: Apr 2005
Posts: 1,505
TN
SCATPACK 1
OP
pro stock
|
OP
pro stock
Joined: Apr 2005
Posts: 1,505
TN
|
OK here is the deal, 904 heads with an old set of Isky/Crane cast adjustable rockers. Pushrod Cups allow 2 threads to show on the adjuster, so I think this is correct for getting enough oil to the cups.
Running 60 pounds of oil pressure when hot and all of the pushrods look great except the exhaust rocker for #2 cylinder. Last week it was burned black and the cup was broken. This allowed it to come out and bend the intake pushrod. I replaced the adjuster ball and put in a new set of pushrods. I pulled the head and no problem with the valves, they are not hitting the pistons and nothing bent or out of line. Same valve springs pressure on all cylinders. No coil bind, not even close. I am running spacers with 60 thousands clearance instead of springs between the rockers, could this be a problem?
I was running a roller cam with over 700 lift and swapped to a smaller roller cam with 640 lift. Never had any issues with the bigger cam.
The rocker shaft had some scratches the last time this happened. I pulled the rockers off, re honed each of them, polished the rocker arm shafts again, cleaned everything up to make sure nothing was inside the shafts and reinstalled them. This week, the #2 exhaust pushrod cup is noticably smoked and both the intake and the exhaust pushrods are bent which allowed the lifters to come out of their bores. The adjustor ball still looks good and is smooth.
What am I missing? Is it just coincidence that it is the #2 cylinder each time? The only thing I have not checked is the valve guide clearance again. But I am not sure what would have changed on the heads with the cam swap that could affect the guides.
Old Geezer Racing
|
|
|
Re: #2 pushrods keep bending and breaking WHY
[Re: SCATPACK 1]
#1030955
07/12/11 01:24 PM
07/12/11 01:24 PM
|
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
|
Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
|
Is the cup hitting the rocker when the valve is on the seat... that will be the closest to the rocker... you might want to take that rocker off and prime the engine while turning the crank to see if that oil hole is pumping oil out to the rocker 
|
|
|
Re: #2 pushrods keep bending and breaking WHY
[Re: MR_P_BODY]
#1030956
07/12/11 02:23 PM
07/12/11 02:23 PM
|
Joined: Apr 2005
Posts: 1,505
TN
SCATPACK 1
OP
pro stock
|
OP
pro stock
Joined: Apr 2005
Posts: 1,505
TN
|
The cup is about 1/4 inch below the rocker when the valve is closed. I will try priming it with the rocker off that cylinder and see if any oil comes out. The rockers are grooved for oil supply, but are the oil holes supposed to be on the front facing the pushrods or facing the valves. Just starting to question everything at this point. FRUSTRATING  I know it is probably something simple or silly.
Old Geezer Racing
|
|
|
Re: #2 pushrods keep bending and breaking WHY
[Re: SCATPACK 1]
#1030957
07/12/11 02:35 PM
07/12/11 02:35 PM
|
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
|
Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
|
Quote:
The cup is about 1/4 inch below the rocker when the valve is closed. I will try priming it with the rocker off that cylinder and see if any oil comes out.
The rockers are grooved for oil supply, but are the oil holes supposed to be on the front facing the pushrods or facing the valves. Just starting to question everything at this point.
FRUSTRATING
I know it is probably something simple or silly.
Its not the top thats close... its the back of the
cup and the radius of the rocker and the higher ratio
will move it in closer yet.... its been a long time
since I used the shaft rockers BUT I think it should
be down and inward.... there was something about the
notch on the end of the shaft but I forgot
|
|
|
Re: #2 pushrods keep bending and breaking WHY
[Re: sixpackgut]
#1030960
07/12/11 06:52 PM
07/12/11 06:52 PM
|
Joined: Mar 2006
Posts: 9,910
Eighty Four, PA
B G Racing
master
|
master
Joined: Mar 2006
Posts: 9,910
Eighty Four, PA
|
Bending usually isn't an oil problem unless they are getting super hot then you would see them blue from heat,bending is caused by interference or binding.Check all your clearences,valve,springs, rockers,block,head,gaskets.Some common areas are coil bind,retainer to guide,side loads or block/head interference. 
|
|
|
Re: #2 pushrods keep bending and breaking WHY
[Re: B G Racing]
#1030962
07/12/11 07:37 PM
07/12/11 07:37 PM
|
Joined: Oct 2004
Posts: 1,752
detroit area
moderncylinder
top fuel
|
top fuel
Joined: Oct 2004
Posts: 1,752
detroit area
|
if the exh pushrod or rocker gets messesd up to the point of failure, so it will not open th exh valve on that cylinder, the piston will compress the exh gas which should have exited, then the int valve is supposed to open, but with the massive amount of pressure in the cylinder, it will bend the int pushrod or break the int rocker. im sure your pushrod bending issue is the result of the burnt exh pushrod,, you need to find out why there isnt enough oil to the #2 exh pushrod,, once you fix that,, youll be ready to go
|
|
|
Re: #2 pushrods keep bending and breaking WHY
[Re: moparniac]
#1030963
07/12/11 07:38 PM
07/12/11 07:38 PM
|
Joined: Jan 2003
Posts: 75,092
A Banana Republic near you.
JohnRR
I Win
|
I Win
Joined: Jan 2003
Posts: 75,092
A Banana Republic near you.
|
Quote:
im gonna say 60thou is way to wide! dont think Ive ever been wider than .030 side to side... also do you set lash using EOIC! I used to use the mopar chart and set lash with my roller stuff then came right back around and checked it using EOIC and couldn't believe how much lash was in there COLD! good luck figuring it out though
|
|
|
Re: #2 pushrods keep bending and breaking WHY
[Re: B G Racing]
#1030964
07/12/11 07:39 PM
07/12/11 07:39 PM
|
Joined: Apr 2005
Posts: 1,505
TN
SCATPACK 1
OP
pro stock
|
OP
pro stock
Joined: Apr 2005
Posts: 1,505
TN
|
Quote:
Bending usually isn't an oil problem unless they are getting super hot then you would see them blue from heat,bending is caused by interference or binding.Check all your clearences,valve,springs, rockers,block,head,gaskets.Some common areas are coil bind,retainer to guide,side loads or block/head interference.
BOB
It is possible there is too much side play between the rocker arms on this cylinder and this could be the problem. I am going to try to fix the excessive side clearance and spin it over to make sure there is no interference with anything. I have turned it over slowly with a wrench on the crank bolt but did not see any issues. Thanks for the info.
Old Geezer Racing
|
|
|
Re: #2 pushrods keep bending and breaking WHY
[Re: SCATPACK 1]
#1030965
07/12/11 07:46 PM
07/12/11 07:46 PM
|
Joined: Jan 2003
Posts: 75,092
A Banana Republic near you.
JohnRR
I Win
|
I Win
Joined: Jan 2003
Posts: 75,092
A Banana Republic near you.
|
Quote:
Quote:
Bending usually isn't an oil problem unless they are getting super hot then you would see them blue from heat,bending is caused by interference or binding.Check all your clearences,valve,springs, rockers,block,head,gaskets.Some common areas are coil bind,retainer to guide,side loads or block/head interference.
BOB
It is possible there is too much side play between the rocker arms on this cylinder and this could be the problem. I am going to try to fix the excessive side clearance and spin it over to make sure there is no interference with anything. I have turned it over slowly with a wrench on the crank bolt but did not see any issues. Thanks for the info.
I'd also check the guide clearance and the rocker to pushrod clearance , the rockers walking a little aren't causing the overheating issue .
|
|
|
Re: #2 pushrods keep bending and breaking WHY
[Re: SCATPACK 1]
#1030966
07/12/11 07:56 PM
07/12/11 07:56 PM
|
Joined: Mar 2006
Posts: 9,910
Eighty Four, PA
B G Racing
master
|
master
Joined: Mar 2006
Posts: 9,910
Eighty Four, PA
|
Quote:
Quote:
Bending usually isn't an oil problem unless they are getting super hot then you would see them blue from heat,bending is caused by interference or binding.Check all your clearences,valve,springs, rockers,block,head,gaskets.Some common areas are coil bind,retainer to guide,side loads or block/head interference.
BOB
It is possible there is too much side play between the rocker arms on this cylinder and this could be the problem. I am going to try to fix the excessive side clearance and spin it over to make sure there is no interference with anything. I have turned it over slowly with a wrench on the crank bolt but did not see any issues. Thanks for the info.
Check for any witness marks on the pushrods,retainers(top and underside)And check springs at open height and travel to coilbind.
|
|
|
Re: #2 pushrods keep bending and breaking WHY
[Re: pittsburghracer]
#1030971
07/14/11 12:09 AM
07/14/11 12:09 AM
|
Joined: Jan 2003
Posts: 3,048
Richmond, Tx. (Houston)
GTSDave
master
|
master
Joined: Jan 2003
Posts: 3,048
Richmond, Tx. (Houston)
|
I just set up my vintage Isky rockers this past weekend. I was going from PRW aluminum rollers to these Iskys that I have had new in the box for as long as I can remember.
I had a problem with the Isky's during setup. What I found was that on #1 and #2 the bottom of the rocker and side shim was hitting the side of the rocker stand not allowing the rocker to center on the valve. The stand starts off narrow and gets wider as it gets closer to the head (452's). It was hitting where it gets wider. It was a very small section at the bottom of the shim/rocker that was touching. I ended up grinding a small bit off of side of the stand to allow the rocker to move far enough over to have the shim butt up against the hold down. Now they are centered on the valve and do not bind.
Also, I didn't use the springs from the kit on the shafts. I used spacers with shims set up at .030 side clearance. I would have rather set them up at .025 for better oil control, but I was a little nervous running it that tight on the street.
I am running a solid roller with .545 gross lift and a very aggressive ramp. The fulcrum bearings in the PRW aluminum roller rockers were starting to come apart and I caught it during reassembly. I had 4 burnt pushrod cups (Smith BRS) and was looking at everything closely when I found the rocker issue. I had probably 5-6K miles on this engine when one of the plenum bolts inside my Wieand tunnel ram decided to back out and go through #1 destroying the piston, breaking the block and all sort of other damage.
I haven't fired it up yet (waiting on my headers to come back from coating) I hope these Isky's are up to the task. They are the original style before Crane bought them out.
If you figure out what the problem is PLEASE post it! I have never run ductile iron rockers on a Roller cam before and quite frankly am worried about it.
-Dave
PLEASE Pray for our brothers and sisters in harms way. If you are the owner of a GTS us at the GTS Registry www.gtsregistry.com
|
|
|
Re: #2 pushrods keep bending and breaking WHY
[Re: Cab_Burge]
#1030973
07/14/11 12:44 AM
07/14/11 12:44 AM
|
Joined: Jan 2003
Posts: 3,048
Richmond, Tx. (Houston)
GTSDave
master
|
master
Joined: Jan 2003
Posts: 3,048
Richmond, Tx. (Houston)
|
I don't have a way to check it here at the house, but I believe they originally specked out at around 580 open. I am not enjoying senility as much as I should be.  -Dave
PLEASE Pray for our brothers and sisters in harms way. If you are the owner of a GTS us at the GTS Registry www.gtsregistry.com
|
|
|
|
|
