Here is the history of my new engine.

The history on this engine is I started with a mild 'solid' camshaft that the guy in CA said would work. (There were also a couple of articles on the net about running solid cams in P90A heads) It did not work. It pumped up the lifters in about 5 minutes where the engine would stop and not restart. The valves would all be open. Makes sense to me that a hydraulic lifter will not work on a solid cam profile) I could not drive the car and we had to push the car back into the shop.

I then put a stock turbo hydraulic cam in the car with stock lash pads. This drill ensured me that the engine was sound. The engine ran beautifully. It idled at 900 rpm and had excellent power to 5500. I drove the car for the first time putting 150 miles on the engine.

I was told the Bull Frog Cams had a performance hydraulic grind. I called Mr. Gude about getting a mid-performance street hydraulic camshaft. He said he had a cam with .480 lift that he could grind for me for $350. I said, (gulp) OK.

Mr. Gude sent me the cam with .160 lash pads. I installed the cam with it set up exactly as he stated: #2 hole/5`-6` advanced. (I checked the rocker sweep and it was perfect) I drove the car about 20 miles with the new Gude cam. The engine runs for about 15 minutes and looses compression. The valves are sticking open with pumped up lifters. I did a compression check hot and got a varied report. I got all the way from 30# to 110#. I barely got the engine to start to get it back into the shop. After letting the car set for 2days, I did a leakdown test w/o the rockers installed. I had 90+% in all cylinders. Compression check showed 170-180 psi. No leakage in the valves. What is causing these lifters to pump up?

I realize I could put the stock turbo camshaft back in it and run it with no problem. I had this engine built to run higher rpm's and to produce more hp. It seemed like it needed a .450-.480 lift cam that would allow me to turn the engine up to 6800-7000 rpm. I was not happy with the 5500 cam out of the stock turbo. Mr. Bill Gude has been asked for his advice. I am now asking the forum for advice.

What is going on with this Gude hydraulic camshaft? It is doing exactly what the solid cam did: It pumps up the lifters! I have run the car with the stock hydraulic cam with NO problem. How do I get this new hydraulic camshaft to work? I need help with this engine, please.

Mr. Gude said, "Enough!" I am sending the hydraulic cam back and he is forwarding me a solid camshaft. I am converting the hydraulic lifters over to solid adjusters. I cannot wait! I have had it with this hydraulic camshaft. Whoever said that running a P90A head was the answer just simply never really ran one. What a nightmare. I'll let you know how it works. I have pics of the lifters in case anyone wants to see how to do it.

It is good if you want limited power out of a quiet head. That is about all it is good for.

Though I love the silence of my hydraulic head I will be switching to either a solid lifter head or doing the same as you and getting the necessary components to switch to a solid lifter head.

You can get the thread inserts for doing the hydraulic to solid changeover. Or, you can do some machining of the solid adjuster and H-base. If you want pics and dimensions, let me know. I can send them to you. No sense in re-creating the box!

I am doing some cam timing now to maximize the power my engine is producing. It is a bit too far retarded now. It does not have any bottom end. I am running ZTherapy modified SU's and they do not want to run below 1100 rpm's. No vacuum! It runs great at the top end but the cam is not a high end cam so I am losing power. I have an adjsutable sprocket so I will get it right. You so right in saying the P90A head is great for low output, quiet engines. Who needs it?

This was a good try that didn't work, but the one thing you guys have not yet realized is that none of the experts have used the hydrolic variety because they have a tremendous learning curve that does not exist with the solid variety-the upgrade path transfers from every other solid lifter car!.

The muddy water here is a lack of experience with hydrolic hardware, not shortcomings with the hydrolic head-it flows exactly the same volume of air as the P90, and generates far less noise and friction to do it, these are facts-that is why Nissan developed the head in the first place.

The only things you have proven here is that this try didn't work-and that anybody can use the same justification that was used for swapping SUs for a 4 Barrel kit when frustration sets in.

The facts still remain that the P90A flows exactly the same as the P90 with a much lower loss to friction.

That being said.

The upgraded cam profiles can be the same for the P90 and P90A, and even upgraded, they will still flow the same with the P90A losing less power to friction-but the way you treat the oil flow and pressure changes MUST be different.

Bring all of the variables together for a real comparason, or just say, "It was more trouble than I wanted to deal with", not that "P90A head is great for low output, quiet engines," because you have only proved that using it for a high output engine was beyond your committment to making it happen by applying solid lifter technology.

Most people, including you guys, want the simplest answer. In this case it is do what everyone else has done and avoid the frustration of being the first to do something-that isn't wrong, or a bad answer, it just isn't the only answer. How many tries does it take to get a spindle pin out?

WIll

I agree with you. No one has done the research and development of the Datsun hydraulic lifters like GM, Ford or Mopar. I remember when 'hi-ball' lifters were first introduced in the 60's. No one had done this for Datsun. Why should they? With the millions of GM, Ford and Mopar engines built and the few thousand built by Datsun in '83, why would anyone do the work? They will not and should not. I believe Gude is the only grinder of a performance Datsun Hydraulic cam grind. How many people/manufacturers have done research on GM, Ford and Mopar hydraulic cams... And for how long? Enough of this... I gave up on the Datsun hydraulic cam because the one performance cam available did not work with stock lifters. I changed springs and did all of the things I could think of but nothing worked. This engine worked well with a stock turbo camshaft and stock lifters. It would not work with a high lift cam either solid or hydraulic. The P90A head is an excellent example of a head with great volumetric efficiency. I now have it with a solid cam with solid adjusters. Until someone does the research and development, Datsun will never have a high performance P90A head. These stock lifters simply do not work with longer durations and high lift. Believe me!