IF it is mechanically possible to hydraulically over-extend a 4G63 lifter without breaking it, then I will have learned something new today. Report your findings.

 

I don't have much experience with the Evo valvetrain so I was applying general theory. If the Evo lifters are mechanically limited to prevent overextension, then the lifters are obviously exempt from lifter pump.

With my leakdown at the valves, repeatable, mind you, I'm looking for explanations. The motor was never overrevved so I'm going through all logical possibilities. My leakdown results will be repeatable with the cams out of the head if lifter pump is impossible.

-Jon

 

Well sorry fellas but I can't give you any info as I've ran into a slight snag.

It seems my intake cam has suffered some damage on the lobes and will need replacing. On the #2 cylinder one lobe has an eraser tip sized chunk missing all the way across the lobe and two more lobes have pencil lead sized chunks missing. The rest of the lobes have spider web cracks on the roller surfaces. The cam has been in my car for a little over two years.

Once I get the cam replaced and the car up and running again I'll give my run-down of the JAM lifters.

 

On the cylinders with the greatest leakdown, there was also a greater indication of wear across the base circle. I cannot go so far as to say they were pumped, but I can say the force with which they were pushing back against the cam was greater than those in the cylinders that are testing good. I'll be bleeding my lifters to see if there is any stickiness or indication that the lifter is bad.

To further expand on the JAM lifters, it looks like the inlet and outlet have been bored slightly larger. The instructions also say to bleed the lifter by compressing it in a vice where the factory lifters should be bleed with a tool inserted into the top to move the check valve.

-Jon

 

I bled mine the same way you bleed the stockers. Using a vice just sounds like a good way to blow the seals in the lifters.

Anyways, I got my new cams today. Hopefully I'll have them installed this weekend but the car won't be running till next weekend (getting valve cover powder-coated).

 

UPDATE:

I finally got the car running (minor issue with cams, valve cover and available tuner) and the JAM lifters fixed my phantom knock issue.

Before I was spiking nearly 30 counts of knock between 2-3000 RPM on pump and race gas no matter how much timing was taken out. Eventually I started to hear the valve tick and it got worse.

So today I finally got a chance to get together with my tuner and run some logs. The phantom knock is completely gone. We were able to add timing to compliment the rest of the map and the car feels completely different down low.

I definitely recommend upgrading to JAM lifters if you experienced the same issue I had.