Update on "This motor's for you..."

[Pat Bush #35083]

Alright fellas, I tore it apart and low and behold the lifter sort of came undone.... Two pieces (the ball and a circular plate) were in the valley but surprisingly the retaining clip was still in place.

Before doing this though, I cranked the engine over to make sure I had not wiped the cam. Plenty of lift there. I believe it is OK but I will not really know until I put the new parts in and put a dial indicator on the rocker. I am going to measure the inside bore on the "suspect" and compare against tolerance. I must say, the lifter is not at all sloppy in the channel and it fits exactly like the others.

I am intrigued on the oil channel.... Is there any way to check this supply in the motor? I too believe it is too coincidental that this occurred on the same valve. I have put a straight-edge, measured, and re-measured. Do not see anything out of the ordinary in there.

Bringing in the heavy guns tomorrow (two other 30 yr engine machinists) to look at this conundrum before reassembly. More tomorrow....

Pat

[Ed Jennings]

Re: Update on "This motor's for you..."

PAt, I had a similar problem with a collapsed lifter on a 327/360 with about 5K miles since rebuild. I ended up doing nothing but replace the lifter. After about 1K miles, all is still well, but I'm still a little concerned about it. Could find nothing wrong with the lifter. I reassembled it and it seemed to work fine. I trashed it anyway, of course. Hope you find something you can point a definate finger to. (something cheap and easy, of course)

[Clem Z.]

check the valve for binding

i would check to make sure that the valve moves freely in the guide. put the piston at TDC in that cly,then remove the valve spring and see if the valve moves freely and rotates with no binding.

[Clem Z.]

PS

if this was a exhaust valve i would check to make sure the intake lobe on that cly is still ok. this is because if the exhaust valve does not work as it should you will build up excess pressure in the cly causing excess pressure on the intake valve and cam lobe when the intake valve tries to open against the pressure in the cly.

[Duke W.]

Re: Update on "This motor's for you..."

You must have replaced the Duntov cam with a hydraulic cam. I don't see how a 585 lifter could collapse.

Duke

[Pat Bush #35083]

Re: PS

Clem -

Given that it ran great and got ugly fast and I shut it right down, I suspect it will be OK, but this too I will do tomorrow when I pop the exhaust spring. Clem, I replaced this exhaust valve, seat, and guide when I rebuilt the heads. When I reassembled them, all was free and easy. I just don't think its the valve or guide now. Spared no expense to make sure this was done right. Has me really perplexed.

Tell me, have you ever experienced the casting being off enough on the pushrod or rocker boss to cause this type of problem? I noticed when I was adjusting the valves, the rockers on cylinder 5 weren't quite parallel on the valve stem. Didn't give it much thought then as it didn't seem too odd and a couple of the others on different cylinders rode that way too, but I suppose it could be the stud boss or the pushrod casting on this cylinder is off a bit too much. However, nothing is binding and everything rides clean and clear.

I checked the lifter oil passages on both sides -- clear as a bell and no signs of starvation on the old lifter or on either side of the "suspect". All that's really left is the lifter bore and I need to get a smaller inside mike from my Dad than I have in my case to check that....

I don't know, just seems very odd. Think I own stock in Felpro now. Off and on, off and on....

Pat

[Ed Jennings]

Re: Update on "This motor's for you..."

Duke,
I didn't, but the guy ahead of me did. I wish hew had used a 151 cam instead of the Comp Cams model he put in, but I'm sort of fond of hydraulic lifters. All except that particular one, that is.

[Clem Z.]

Re: PS

both the rocker stud hole and the push rod guide hole in the head are machined in a precision machine from the factory so i do not think that would be the problem. i have never seen a lifter come apart like you discribe even in race engines.i have taken apart engines that the retainer clip has come out of the lifter but the lifter was still in one piece. if you do not have screw in studs make sure that the stud is not pulling out of the head and letting the clearance get too big and let the rocker arm jump off. i have seen engines stick a valve and do what you have seen. after the engine cooled down the valve was free but the stem showed traces of spalling even with chorme plated stems. the exhaust valve stem needs .0015 or more clearence to prevent this. also i never use positive teflon seals on the exhaust because they do not let enought oil pass to lube the stem. good luck.

[RUSS#36338]

Re: PS

Just an idea, I had a Pontiac 400 bought and already built, I started it and it bent 3 pushrods etc... checked and pondered for days and finally discoverd that at full lift it had coil spring bind due to improper shimming and stem cut, visually it looked ok but it was not and when running it will break and bend parts.. good luck