When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Current setup: Xtreme Energy 268H Hydraulic Flat Tappet Camshaft & Lifter Kit Lift: .477" /.480" Duration: 268°/280° RPM Range: 1600-5800
K 180 Series Cylinder Heads 180cc Intake Ports
Cast Steel Roller Tip Rocker Arms for 1955-1986 Small Block Chevy 1.6 to 1[Set of 16]
I re-did the top end of my L48 about a year ago and it's been running perfect. Today I noticed a miss in the engine and when i took of the valve cover I saw that one of the 3/8 inch studs had snapped. After taking things apart I see significant damage to the rod tips on most of the rods. I think I may have F'd things up by using the stock pushrods since the length was fine instead of going to new hardened rods.
See pics below.
Questioon is:
1. Do you guys think this issue is likely a problem with the use of old stock push rods? Or could I have an oiling issue at the top of the motor?
2. Oil pressure was fine when I turned off the car and I don't see any metal in oil pathway on the heads. I plan on draining oil, flushing with oil with care off and then adding fresh oil and filter. Do you think that's enough or can I expect further damge from that metal that came off rod tips?
metal sinks if it's big. You can buy oil filter magnetic wraps that do a good job with the fine suspended metal. magnetic drain plugs always help.
Hardened push rods are for guide plates and maybe stronger, but tip chipping is most often incorrectly set valve lash and or valve float from too weak of springs for the rpm
Interesting, I run that same cam. But the stock pushrods were definitely not the correct length in my case. Perhaps because of different heads? Not certain. Are you certain those stock pushrods measured out correctly?
lack of oil to the top end would be obvious. Your lifters wouldn't be pumping up.
I tend to agree that your issue is in a miss match of parts. (Springs, pushrods). Or just incorrect lash.
How about a pic of the valve stem tips. Would be good to see the wear pattern.
Interesting, I run that same cam. But the stock pushrods were definitely not the correct length in my case. Perhaps because of different heads? Not certain. Are you certain those stock pushrods measured out correctly?
lack of oil to the top end would be obvious. Your lifters wouldn't be pumping up.
I tend to agree that your issue is in a miss match of parts. (Springs, pushrods). Or just incorrect lash.
How about a pic of the valve stem tips. Would be good to see the wear pattern.
Here is a pic of the wear pattern. Looks like it's centered.
You need hardened push rods , most likely .10 longer than stock since the heads are .10 thicker than stock. The rocker stud threads can be fixed with a helicoil .
When you use rocker studs or studs and guides it's best to glue them in. Use something like sealant gasket maker or even silicon black. your studs were getting loose and that would tear up the tips.
Your ware pattern is nice. But do you know if the springs are made to do the additional lift od the 1.6 ratio? They do make hardened tip push rods
Yeah. I ordered hardened push rods , 1.5 ratio rockers and new rocker studs just in case. Most of the material that came off the rod tips was still in the rocker cups so I'm hoping I'll get most of the gargabe out of the engine with a good flush and oil/filter change.
and while in there, replace oil pump. i check the mains and replace the rod bearings, but i don't like recommending that to those who are not comfortable with opening up the bottom end.
and while in there, replace oil pump. i check the mains and replace the rod bearings, but i don't like recommending that to those who are not comfortable with opening up the bottom end.
I thought about replacing bearing by lowering the pan. Don’t think the rod bearing would be that tough. But not sure I could do main bearings without taking out engine. Has anyone been able to remove top half of main bearing by tap it to rotate around the crank journal and using same method to install new one?
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
That wasnt making a clattering noise?......it looks like you snapped the ball ends off all the rods, they look so jagged. If you havent ordered new rockers yet consider 1.6 rockers since you need new rods anyway, just measure everything first with a rod checker and checking springs.
Any pics of good rods...both ends
My rockers were 1.6 so that is probably why the stock push rods were the correct length since the wear pattern on valve stems looks like its right in the center.
The pushrod damage occured on the rocker side of the rods but I do see the lifter ends of the pushrods are also starting to show wear.
I don't think the stock pushrods were able to put up with the pressure of springs. The springs that came with the heads were CC981's. They have 100 lb Closed, 300 lb Open with 1.850 Installed Height, and .525 Maximum Lift. My lift with the 268H cam is .512 (with 1.6 ratio rocker) so I think CC told me by open pressure was around 280lbs. That may have been too much for the stock pushrods, especially since they aren't hardened. The rocker cups are pretty beat up as well so those are going to be replaced by full rockers. I had roller tips,.
The strange thing is I discovered this issue when one of my rocker studs snapped off causing engine not to run well probably becuase rocker came off vave as a result of the pushrod damage. A minute before that rocker stud broke the engine was running perfectly and I assume the damage to the pushrods was already there.
I'm adding picture of the lifter end of the rods, the rocker cup and busted stud as an example. Here is busted stud. It broke where the rocker pivoted. I assuming the ROD was damaged causing the lash to increase to the point where the roker tip came off the valve putting sideways pressure on that stud. If you zoom in you can see the damage to the rocker cup The rods ends on the lifter side show that they are starting to fail as well but no where near as bad on opposite end that was pushing rockers.
Most aluminum cylinder heads state in the owner's manual that a longer pushrod of 0.100 is required but always double check with a measuring tool.
It's not so much that aluminum heads are thicker, but rather the rocker stud pad is 0.100 higher than stock location. And you may or may not have guide plates that raises the stud also.
There are pushrods available for $19.95. And there are units for $90 on up. Guess which ones you want?
Top quality rods have a thicker wall to fight flexing, are chrome moly for very little wear on guide plates, but most importantly are one piece design. No ball ends.
i would think one could adjust rocker up or down even a quarter inch regardless of rocker stud base. i would think the geometry is about the height of the top of the valve. and does anybody make 1.55 rockers that are not full roller? . i see summit has comp 1.52 roller tip arms. i think 1.6 is a little big for 3/8ths stud thread. maybe go with 7/16ths studs and rockers.
My oil pressure is around 40psi when cold, idles around 20-25 when hot and goes up to around 38-42 while driing at RPM using VR1 20-50W. I have dakota digital setup with digital pressure display. Not terrible but not great. Since I'm dropping the oil pan to clean out any crap that might be there I'd like to change oil pump as well. Would I be better off replacing with high volume oil pump to help get a little more oil to the top of the engine espcially at higher RPM?
i would think one could adjust rocker up or down even a quarter inch regardless of rocker stud base. i would think the geometry is about the height of the top of the valve. and does anybody make 1.55 rockers that are not full roller? . i see summit has comp 1.52 roller tip arms. i think 1.6 is a little big for 3/8ths stud thread. maybe go with 7/16ths studs and rockers.
Hadn't considered that the 3/8 stud wouldn't stand up the pressure with 1.6 ratio rockers. Since stub snapped inside the nut just above where the rocker was pivoting i thought it was due to lateral pressure on stud as the rocker came off the valve stem. If it were an issue with the stud not supporting the linear back and forth pressue during regular operation I would think the stud would snap closer to it's base where that pressure would be hightest.
Hadn't considered that the 3/8 stud wouldn't stand up the pressure with 1.6 ratio rockers. Since stub snapped inside the nut just above where the rocker was pivoting i thought it was due to lateral pressure on stud as the rocker came off the valve stem. If it were an issue with the stud not supporting the linear back and forth pressue during regular operation I would think the stud would snap closer to it's base where that pressure would be hightest.
You have such a mild cam that 3/8th studs should have NO problem. I ran 3/8th studs over 100K miles with .600 lift 1.6 ratio and shifting at over 7000 rpm. !.6 might be perfectly fine in your case unless you have springs that are too short and you have exceeded the max recommended lift or you are reving the motor into valve float
But when you are beating up the tips and have loose rocker studs..... That's a real problem!
You have such a mild cam that 3/8th studs should have NO problem. I ran 3/8th studs over 100K miles with .600 lift 1.6 ratio and shifting at over 7000 rpm. !.6 might be perfectly fine in your case unless you have springs that are too short and you have exceeded the max recommended lift or you are reving the motor into valve float
But when you are beating up the tips and have loose rocker studs..... That's a real problem!
None of the rocker studs were loose including the one that snapped. I had to really wrench them to get them loose.
So YMMV but due to comments on this forum that two piece rods were no good for my application, I replaced my cheap ($45) ball end elgin pushrods this summer after running them a year (and only about 1000 miles) and they were perfect even with the comp double springs for the retro roller cam and 1.6 roller rockers im running...
I went with stronger single piece crower rods I found as NOS on ebay... That said it surprises me that the stock rods would fail so badly like that. my first instinct would have been that they were overtightened somehow, even before hearing of the snapped stud.
Push Rod damage
