Hey everyone, I am being a little preemptive in rebuilding my top-end of my 94 LT1 Z07. I noticed a squeak/click going on at idle and higher rpm's so parked the car, got out my stethoscope and started diagnosing.

Looks like i have a collapsed lifter or at least 1 lifter that's failing on me on the driver side rear most cylinder. I removed the rocker arm and pushrod on the troublesome lifter and the sound went away and produced a nice misfire. I checked the spring, it's not broken, the pushrod is not bent so i'm guessing the lifter.

Luckily! I purchased a set of brand new heads about 4 years ago that have brand new valves and springs. However, the studs for the rocker arms are thicker than my stock LT1 heads, which gets me thinking these could be LT4 heads..or maybe just an LT1 head fitted with LT4 springs and studs? Maybe aftermarket?

The heads are stamped with the following Numbers:

4060
10123374

I've looked around google and forums trying to pinpoint these, and it's definitely leaned more towards LT1 heads, but the thicker studs are what tossed me for a loop.

Any help with figuring out what these heads are would be great.

Now for my next issues i need help with:

Recommendations for the following:

Rocker Arms
Pushrods
Lifters
Gasket set
(anything else i should consider when rebuilding the top end)

I have no idea what my bottom end is looking like, the car has 145,000 miles on it, and still runs like a striped assed ape so i'm not too concerned. It's not blowing smoke etc, but we will see what it's like when i take the top end off and actually look at everything...

I am looking for some very light upgrades more in quality than in building horse power. I actually use this as a daily driver and have been getting up to 29-30 mpg highway so I would like to keep that.

Overall i want to freshen the top end without getting crazy, the stock engine has been very reliable and i'd like to keep it that way

I can perform all the work myself aside from if i needed to port/polish/bore anything. I'm just not as talented as some in picking the correct parts to retain a quality build.

All help is appreciated! Thanks everyone!

 

get ready for a cam change; you have all the symptoms of a failed cam lobe, or in the case of my engine...three lobes; all about the same mileage. Check how far each valve is compressed; any significant difference; i.e less travel = bad cam lobe; when you pull the lifters, ANY damage or wear at the roller = a failed cam lobe.

 

p.s. mine was running just fine too

 

Not familiar with the cam lobes, can they be changed and still retain the current cam, or will I have to pull the entire engine to swap the cam out?

Obviously I am trying to stay away from pulling the whole engine, not from a technical standpoint but from a budget standpoint. If i have to pull the engine i might as well overhaul the whole thing while i'm at it.

I can check the travel of the valves and that will let me know. Can i test the tavel of the valves without pulling the heads?

I'll need to get some pictures up for everyone once i'm doing all of this.

 

After looking around the forums, looks like i can remove the camshaft by removing the radiator and undoing motor mounts. Then i have to jack up the engine an inch or so... So at least i won't have to pull the whole thing if that's all i need to replace...

 

To be honest, it isn't all the hard to pull the engine out of these cars. Bearings are cheap as are oil pumps. If it were me, I would install fresh bearings and a new standard volume/pressure oil pump and know it was ready for another 100k. Just my .02