jalper

What would cause this a broken lifter,


will give some background on the motor and the build,
motor is a GMPP block 5.7 the newer style with the shorter head studs,


motor was all stock, but had a Schneider Race cam and broke one lifter on #5 cylinder, and had comp single springs, the lifter was missing all the rollers and was flat at the bottom,


we rebuilt the motor to a 383, uses a cam I had in my 383 for over a year, and is the same Lunati cam we use in our motors for the last 5 years, and on the dyno it broke a Ls-7 lifter on cylinder #6


can this be a issue with this block, the LS-7 lifter was purchased from the dealer not an ebay no name so called lifter,


lifter came from a major size GM Dealership, have purchased the same lifters for years, all the pushrod length was checked chromoly
pushrods and lunati Dual Springs
same as the last 15 or so motors we have done,


but this motor came to us with a broke lifter and then broke another on a different cylinder, new durabond cam bearings and new oil pump,

vettenuts

While there can be any number of issues that would result in the lifter damage, the fact that two were broke and and the second one so quickly would rule out some of the things that might cause this. Do you have a photo of the broken lifter? Any evidence it turned in the lifter bore? Have you looked closely at the cam to make sure the lobes meet roller requirements?

Rob 02

Are the springs bottoming out? By chance are you using 1.8:1 rockers?
The push rods could be too long. Otherwise maybe something is getting stuck in the valve-train.

sean.b

+1 to the incorrect pushrod length. thats the first thing I thought of and about the only thing I can think of that'd do it twice. i didnt think about 1.8 ratio rockers, but technically its the same problem - valvetrain is extruding the pushrods too hard/far into the lifter.

jalper

I checked the pushrod length, .060 plunge used my 8'' digital mic, it beat the bearings out of the rollers, cam was a cam out of my LS1 used for a year with no issues, lift was a .589, use the same springs 8 other time in past motors some still running with .665 lift,


can it be something in the block?
or can it be the Tuner he is using with bad timing causing predestination

sean.b

never heard of a tune taking out a lifter before a ring, piston, or valve. what are the cam specs?

heavymetals

I have noticed that some of the "high lift" cams achieve this by decreasing the cam lobe diameter which allows the lifter to drop farther.

This can allow the lifter skirt to fulcrum against the side of the lifter hole and it may bind.

I suggest you check the lifter skirt and the hole for wear or traces of binding.

sean.b

yea, was wondering if we're talking about a 280+ 650 lift cam or something crazy. ive heard of/seen friends cars do crazy and terrible things with the enormous cams.

jalper

Well Damn just stupid of me,


I washed up all the lifter trays, and one tray was wiped out on the flats, I can spin the lifter by hand in the tray, Totally stupid of me to try to make a dead line and rushed to get it out, and not wait for the new trays to come in,


thanks everyone for all the advise and quick response,

sean.b

have a pic of what it looks like? for posterity.

jalper

I will post a pic, it looks like the lifter tray has no flat spot in it, if you push it up all the way if feels normal, as soon as you pull it .125 down it spins free in a circle,

Rob 02

It cant be the lifter tray because that is way to obvious.

Any way sorry for your trouble and glad you found the problem. It could have been worse.

heavymetals

Now you know why they have linked bar lifters.

FASTFATBOY

Bouncing the lifter off the cam is the #1 lifter killer

Not changing lifter trays is probably #2

Bill Curlee

LOL! As I was reading the OP opening statement, the NUMBER ONE fault that came to mine was BAD LIFTER TRAYs and the rocker rotating in the bore.

ALWAYS ALWAYS replace the trays as they are only a few dollars.



ON ANOTHER NOTE,,,,,, Something else that I have found that can cause valve train issues:

Ive learned to check for abnormal wear on the two Aluminum Rocker Perches that the rockers sit on.

The small area that each rocker sits on can and does wear and that causes the rocker to sit crooked on the valve stem surface and can cause the pushrod to contact the pushrod hole in the head.

Bill

Rob 02

I had one of my rocker perches crack on the original engine. I still cant figure out how that happened.