silent1

iTrader: (3)

Here's a rundown of my setup and the problem I am having:

Darton LS1 Block 4.125" bore
Callies 4" stroke
Stage III 6.0 heads 2.08/1.60 valves
Comp 252/258 612/613 112LS
Comp "R" lifters
Jesel 1.7 adjustable shaft mounted Mohawk rockers
LS6 ported oil pump

Problem:
At about 1500 miles the intake lifter on cylinder 1 collapsed/broke, sending my pushrod through the rocker.

What I did:
Removed heads and replaced lifters with a new set of comp "R" lifters and replaced the broken Jesel rocker along with new pushrods.

What's happening now:
After driving for around 15 minutes or so and the engine reaches operating temp I get a tapping noise from the #1 cylinder area. The tapping comes and goes while driving. I've double checked all my lifter pre-load setting and bolt torque settings.

After talking to few guys at my shop they seem to think I may have a hairline crack in the lifter bore causing a loss of oil pressure to that lifter under certain conditions. That would explain the failure of the first lifter and why the tapping doesn't occur until after the engine reaches operating temp.

This explanation makes sense, but I'd like to get as much input as possible. Is this a likely cause of my problem? If so, could this be a stress crack caused during the re-sleeving process? Also, if there is a crack in the lifter bore, can IT be re-sleeved like other SBC's?

Again, any suggestions or input of any kind are greatly appreciated, thanks!

SAM98WS6

what is your preload?

mikey

iTrader: (6)

Was there any p-v contact on that cylinder? Did you check for a bent valve?

silent1

iTrader: (3)

I have -7cc dish in the pistons and the heads are only milled .030" so P/V isn't an issue. I did check the pistons when I had the heads off and they were all clean/ no dings. I do not have a loss of compression nor is there cylinder leakage.

Steve - Race Eng

iTrader: (1)

The machining for MID sleeves does not come near the lifter galleys.

Did you pull the camshaft and inspect it? That lobe may have been damaged when the lifter broke.

Steve Demirjian
Race Engine Development

Chris@AP-Engineering

iTrader: (-2)

When lifters break parts from them go every where. Like Steve mentioned, did you check the cam? Also did you change your oil and look at it to see if you had any parts from the lifter reach the pan?
What part of the lifter actually broke, the wheel?

silent1

iTrader: (3)

What broke from the lifter was the top cup. I found 2 large pieces of it in the head(approximately half of the cup) and pulled the rest of it out of the oil pan. The roller on the lifter did not show ANY signs of damage, it was very clean and smooth. As for the cam, I just checked it through the lifter bore as I turned the engine over. I didn't see any damage.

JC5

Silent-1 you didn't answer the question from mikey. A marginally bent valve stem, bad guide, or tight stem to guide clearance could have caused all of the above problems! Best of luck solving this!

silent1

iTrader: (3)

I would have thought that a bent valve would cause somewhat excessive cylinder leakage? I know this may sound stupid but, is there a way to check for a slightly bent valve without removing the head?