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Springs replaced, seemed to have done the trick. 0-100 in the high 7s. In recent times the car had slowed down to 9 sec +

Engine sounds a little different too, far less raspy from 4k onward, which I actually preferred the old sound.

Pulled apart one of the new lifters, cleaned out the protective oil which had glued up the plunger with solvent and lightly oiled it with gun oil. I had easy full travel and it measured exactly 5mm, nothing even close to the BS figures thrown around the net.

That had me wondering if the official figures I had from a GM bulletin that lists the specs from first gen roller lifters all the way to the 490 lifters and mine being first gen is meant to be 6.03mm total travel and I measured 5.3mm and in fact the 12648846 lifters looked identical externally and internally and have virtually the same travel. Even the one way valve was exactly the same. That said the 490s I got years ago did have the 4.22mm travel that is advertised in the bulletin.

Not exactly what I expected. Only thing I noticed is the plunger is much tighter in the new lifter and I think that is what makes the newer gen lifters perform much better. Better tolerance control these days.

The lifters are probably full of test fluid. Normally you just put them in and the valve springs will do their job and bleed them down but in your case it will pay to pull the inards out and drain the oil out then do your measurements.

vlad01 wrote:Pulled apart one of the new lifters, cleaned out the protective oil which had glued up the plunger with solvent and lightly oiled it with gun oil.

Charlescrown wrote:The lifters are probably full of test fluid. Normally you just put them in and the valve springs will do their job and bleed them down but in your case it will pay to pull the inards out and drain the oil out then do your measurements.

It's a sticky thick dark yellow/brown stuff. I'd say it's anti-corrosion oil. I tried pushing them in as hard as I could with a pushrod and they did not move one bit. There wasn't much inside them so it wasn't just hydrolocking the plunger, they were just stuck from the oil itself.

Easy enough to pull apart and clean. Some aftermarket lifters state you need to open and clean them as they are filled with similar stuff.

vlad01 wrote:It's a sticky thick dark yellow/brown stuff. I'd say it's anti-corrosion oil. I tried pushing them in as hard as I could with a pushrod and they did not move one bit. There wasn't much inside them so it wasn't just hydrolocking the plunger, they were just stuck from the oil itself.

Easy enough to pull apart and clean. Some aftermarket lifters state you need to open and clean them as they are filled with similar stuff.

In response to me ??

No, to Charlescrown.

I haven't fitted new liftersw for a long time but I have never seen ones that you need to pull apart and clean them out before use. The test fluid is a very light viscsity fluid that easily bleeds out under a valve spring force.

Yes, that's what it was like with the 490s I bought back in 2015, light wd40 like oil. These were more like the anti rust liquid grease that parts and tools come covered in.

The crow cams lifters have always been like that, they state they are filled with grease.

Seems excessive to use that type of coating on hydraulic lifter internals.

I remember cleaning it off new equipment, could be a right PITA.