Yeah I spit my beverage all over the screen when I read about this "engine expert" and his not knowing anything about the bottom end of HIS engine... Ironic indeed!

Alright let’s be technical about this. First, I apologize if I came off a little rough in the last post; I deal with similar situations everyday and they are a little annoying (I take work home with me). Lets look at this from what you want, have, and what you want/need to accomplish it.

Now, the goal here is to run the engine at 7500RPM with the hydraulic roller cam. So here are the problems that I see. First, when we normally look at running this amount of RPM we look to a mechanical tappet. The main reason for this is simple; the amount of seat pressure required to control the average valve train is too high for the hydraulic tappet to survive for any period of time. Generally they just squish down and create all sorts of fun symptoms. This leads us to the problem at hand; how do we control the valve action with light enough spring pressures to ensure the survival of the hydraulic tappet while maintaining at least some factor of safety? The answer is you don’t; you can not get around the physics involved in the process of operating the average valve train at the required rate without the pressure!

Now, valve control issues are not new and not limited to hydraulic tappets. We have problems with mechanical tappets and the absurd amount of load we want to run on them (every engine can not operate in its environment with a 400lbs at the seat set up). If you look at the vast majority of race engines that are utilizing a lot of lift and a lot of RPM (that have to survive for more than 7 seconds) you will see that they have done one major thing. They have reduced the mass of the valve train and thus, reduced the amount of spring pressure; this includes everything from the valve itself to the retainer, lock, rocker arm, pushrod and the tappet itself. They also go to great lengths to ensure that the rocker arm assembly is lubricated to the extreme (bathing the valve spring in oil to keep its temp down). They do this because you can not bend the laws of physics; either you have the mass and the spring pressure to control it or you don’t have the mass, in which case you don’t need the spring pressure to control it.

So in this case the cure is as simple as replacing some of the heavy parts with lighter ones; or changing the goal of the project. The first place to look when shedding mass is the valve, then move to the retainer, then the lock, then the rocker arms, and lastly the pushrods. Since you are running the hydraulic tappet and have the rev kit you will not be able to shave the mass that we do on the different applications but that’s ok.

So again, my apologies if I offended you; I was not calling your T&D shaft “junk”, it simply is too massive for the job (it would be at home with 700lbs open pressure). If you drop the spring pressure will you be able to rely on this engine at 7400? If you lower the operating range is the camshaft the one you want in there? If you have the funds and don’t mind the work you may (and I say may because 7400RPM is a tall order for any hydraulic tappet) be able to lower the mass down enough to use the package as you designed. Unfortunately parts that are made out of titanium are expensive, and sometimes hard to get but if high RPM out of a hydraulic is what you want, from where I sit that’s the only option. Just my .02

Hmm, a modified engine liking a lot of converter and gear? Who would have thought... That sounds a lot like ALL of the drag cars I have ever been around. You do know that a hard core drag set up will leave the line at nothing less than 6000RPM? Must just be those guys like to change parts out all the time...or that's part of being faster, who knows.

Oh and there are many good reasons to use a smaller amount of lobe separation and it doesn't stem from the port cc's; for a lot of applications that's what we install.

As a fellow engine builder with 10 years of experience working with everything from Top Alcohol drag engines to 410 Sprint Car engines I have to say Jsup is right on.

First, if you feel the need to run that many RPM you will have to buck up and buy some titanium parts (although since you don’t have enough cylinder head to make great power up there I don’t know why you are insisting upon turning it that high). You simply will not be able get the seat pressure you need when using a hydraulic lifter.

Secondly, the T&D shaft system you bought is far from the hot ticket for an application like this. The system Jsup mentioned is extensively machined to reduce the weight that the valve sees while being comprised of more durable parts (it’s lighter and can take more abuse). There’s a reason that when we (and even the Nextel Cup guys) have a choice, we run Jesel…

See that's the real point and you are missing it badly; with the flawed configuration that you chose, you have to control your valve action with compromised spring pressures. If you want to come in and play with the big boys you gotta pay at some point. I don't care if it can take a few dyno runs and not have problems; how many miles before it starts shooting parts out of the tail pipe? Have you ever heard the phrase "you have to finish the race to win it"? In this case, how many miles do you want it to go? 100, 1,000, 10,000?

Lastly, most big block engines that come through turning very many RPM have been upgraded to a larger lifter (heck, most of the small blocks are going that way as well). There are a few reasons we do this but the simple fact is the stock size has been an issue for a lot of years, so when we are allowed to get away from it we do as fast as possible! It kinda boils down to the above saying; you can’t push the limit like you are wanting to with stock type parts, and cheap ones at that.

We deal with these types of issues in the racing world all the time; I would have thought such an experienced, crack engine builder would have already known and anticipated these facts before building a time bomb. But then again, as a professional, I don’t go around asking people what I can and can’t get away with…

I'd give it some more duration @ 50 though... That would bring the meat of your power in a little later and help it digest the pump gas. Also with 113 lobe separation you are looking more for top end hp anyway.

Well generally speaking the best situation to have is the largest combustion chamber, the most compression you can work with, and an ideal amount of clearance. Now getting that takes some time and money; in your case you will not be able to open up the combustion chamber and keep compression up, so you are out there. You will also have a hard time holding your clearance down and having a truly reliable head gasket. I would run around a 0.020 compressed thickness at the minimum and get as much static compression as I could (out to 11-1); then come up with a cam lobe that put my dynamic where it needs to be. Just my 0.02

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Well it's actually done all the time... You end up with a 355 breathing through a 2 BARREL carburetor making 350hp (on gas) at 7200RPM all the way around the track (and this is the fastest way around the track for them). So what is your point? I don't want to know what you've seen or heard, I want to know what you've done. What have the engines that you've built done? Here lets do this; tell me what the difference will be between a 410 unlimited sprint car engine that is run with a set of -10X (23*) cylinder heads that flow 360cfm and the same engine that now runs a set of -12 (15*) cylinder heads that also flow 360cfm? Tell me which one will make more power and where (these engines operate from 6000-8200RPM).

Well the above was probably caused by valve float; when we do that with solid rollers we just beat the bearing out of em and drive the wheel further and further into the body of the lifter (I haven't had one disintegrate in there yet but some guys have brought them back pretty close)... Reckless, what weight of oil are you running in the engine? Also, I'm with Brian on this one, you really need to determine if this problem is related to the induction. It is suspect that the engine did not lay down on the engine dyno with a carburetor, but does now with the efi mod. All the points you brought up are valid and may be the cause; it just seems prudent to start with the only real change made from then to now.