antman89iroc

I'm running a Dart SHP block in my 414 (check sig) It's a street motor with hyd roller cam and rockers. I run all Comp valve train with short travel roller lifters, comp pro mag 1.6 rockers and push rods.

The problem I am experiencing is a repeated galling of the #2 cylinder exhaust pushrod/rocker joint and lifter plunger cracking. I don't know which is happening first but the rocker starts making a little noise then I inspect and notice the damage.

This was a new built combo and the first time around got about 20K miles. I replaced the damaged parts and things seemed fine for a few more thousand miles. At first I had a ~600 lift cam and AFR heads with their up-graded springs. I pulled the motor out to go through some things and do a cam change. The heads were checked out and checked for the new cam which was shorter duration but a little more lift a 616. This time I got about 1500 miles before the same thing happened to the same valve.

Any ideas? When I put it back together it was oiling all rockers. Not a stream shooting out but a good dribble on each rocker. The only thing I can think of that would have done this on two sets of lifter/pushrod/rocker is insufficient oiling (it's the furthest valve on the passengers side) or possibly the valve spring going to near bind or binding and the machine shop just missed it. It is frustrating because the motor is running great, I was just checking the valve adjustment after getting some miles on the latest update when I noticed it again. ????

sofakingdom

iTrader: (1)

Might want to pop out the plug on that side at the front of the oil passage, behind the cam sprocket, and just look down it, while rotating the cam; and make sure the lifter's oil band and feed orifice makes it far enough down (or up, as the case may be) to get oiled well.

It's a common problem with small-base-circle cams. They make special lifters for that situation, for that reason.

https://www.thirdgen.org/forums/atta...lifters-std-vs

Small-base-circle design on the left...

antman89iroc

That's a good point and something I can check if/when I pull the motor. I do run a small base cam. The first one was .840 and the current one is .950. I have not verified it but from measuring parts and block the passage is within the lifter ring.

What do you think would be the effects of having a valve spring going to bind or near bind? Could it crack the lifter plunger and then the lifter problem causes the lack of lube at the pushrod/rocker?

sofakingdom

iTrader: (1)

Absolutely: an overstressed ("under-selected") valve spring choice is a recipe for any number of parts breakage, mystery failure, oddball wear, etc. scenarios. Valve float could also be an issue: what springs did you use? What's the installed height? What's the seat pressure?

Another issue with the oil band is, with a SBC cam, it can fall completely below the bottom of the bore; literally, out of the block. The "more" cam it is, the worse it is, since the "peak" of the lobe is pretty much always as tall as it can be and still be able to install the cam, and lift is produced by making the base circle smaller which of course creates a larger DIFFERENCE between min and max lift. Although, that's a REALLY MILD cam especially for a motor that large.

I'm not really seeing where there's any obvious need for a SBC cam. That would depend on your rods of course, if they're bolt & nut rods you still might, but if they're cap screw rods everything should fit without that.

antman89iroc

The springs are AFR's 8019 upgraded hyd roller spring on the 210 heads. I don't have the specs in front of me but I spoke with the machine shop today and was told they checked out with .080 clearance for .625 lift and I am running ~603. The oil bands are within the lifter bosses.

They're hypothesis is since it is the last lifter in the passage it may not be getting enough oil up top, especially during cold starts. With the dart block priority main oiling and lifter limited flow making it all worse. They have suggested opening up a passage on the outside of the lifter between the oil band and the oil hole. I really thought the oil hole is within the band so I'll have to check that out.

I am wondering if I would be better off with LS7 type lifters and dog bones on my build. It is mostly street driven and rarely goes to 6k so the short travel race lifter may not have been the best choice.

skinny z

Somewhat unlikely seeing as you haven't mentioning any other problems (such as prematurely wearing valve guides), however the incorrect pushrod length could cause some binding issues and perhaps interfere with oiling. Did you revisit your valve train geometry when you swapped lifters? The Comp short travel lifters have a different seat height than the standard counterparts and require a different length pushrod to maintain correct geometry.
Just throwing that out there.

antman89iroc

The lifters were in the motor when it was built. I have swapped cams and pushrods. I checked pushrod length very carefully and had oiling when it was idling. Now it wasn't squirting like stock lifters but was dribbling evenly on all rockers.

ASE doc

Pushrod length doesn't seem so likely an issue since the problem is only affecting one lifter.

I will put it out there that pushrod length isn't going to affect oiling, that is all in the lifter, its hydraulic piston and check valve, and its relationship with the lifter oil gallery, along with correct lash adjustment.

I gather you already know this but, pushrod length will affect the loading of the pushrod tip and the socket of the rocker. Incorrect pushrod length will also reduce actual valve travel. For best conversion of lifter motion to valve motion and to center the loading of the pushrod tip in the rocker, you want the rocker tip roller/pushrod tip centerline to be level with the valve at mid lift.