I have already composed an article about tuning a Spyder but since there seems to be such mystery about the Maddman Rocket valve, I may as well elaborate a little further into the tuning process with this particular valve since it is a bit different in design than any of the other Spyder valves.
The Design
The Rocket valve design is a bit different than the others because of the integral valve spring that's attached to it on the striker side of the valve. It also has a very thin valve pin, large cone shaped cup seal and an adjustable spring retainer plate(SRP) which is part of the dwell duration adjustment. The front portion of the valve has been extended and there is only one o-ring at the front portion of the valve body. Seems to me that Maddy and Mike have changed the design a bit since the Rocket valve was first released a couple of years ago. The greatest change being that the valve pin appears to be longer than it used to be and they've gone from white to black plastic which may mean they're using a different type of plastic now. It used to have a larger hole to the bolt and the striker pressure slot was orientated to the bottom. All of that has been changed now.
Things To Know Before You Start
Tuning the Rocket valve can become a bit much for some since it's not a simple drop-in like other valves available for Spyders such as the New Designz, 32*, Taso and AKA high flowing valves. You have to be running the pressure below 500psi with this valve or it will ruin the valve because of some of the materials it's made of and it's design.
You'll need to keep removing and reinstalling the valve when adjusting the SRP. You cannot leave the end of the valve pin uncut once you have the SRP set because leaving it uncut could in time drive the metal threaded valve pin through the plastic threaded SRP material. I left mine uncut for a few days of play when trying different SRP locations though and had no such problems. I would definitely discourage just setting it and cutting the end off as soon as you get it because I have seen plenty of cases of people making the setting too short, cutting and filing the end and wondering why it continually jack hammers afterwards. You can always purchase a cup seal kit but be patient when finding the correct SRP setting for your Spyder.
I would discourage using a dremel to cut the end of the pin because the heat from cutting it will most likely melt the plastic SRP material. Once you get it set you can clip the end with some wire cutters and file the sharp edge down. Don't file the end holding the valve steady and pulling the file across the pin but rather hold the valve in your hand and scrape the pin end over the stationary file. You may bend the pin by scraping the file over the end of the pin. Once it's set, use some red or blue Loctite to hold the SRP in place and let it cure completely before using it afterwards.
If you have an older Rocket valve as I do, they used to be made with a larger valve body hole at the top and the pressure slot to the striker was to be orientated at the bottom. The newer versions are suggested to be orientated to the side and all of the holes in the side of the valve body are of the same diameter. I was looking down the back of the lower body tube in my Spyder one day and discovered that when the pressure slot was at the bottom, the valve screw that holds the valve body in place could restrict the flow of pressure going through the slot because it's so close to it. To avoid this you can simply orientate the slot to the side as instructed to do on the current versions. Having the smaller diameter hole on the top really has no affect on the flow to the bolt since the through hole in the body to the bolt is not that big anyways.
Some Modifications That Can Aid Recocking
There are a few modifications you can perform that can help aid recocking when using the Rocket valve.
Blocking Off The Striker Exhaust Port: I would not suggest this for any other valve outside of the Rocket valve because it will create a suction between the valve body and striker and your marker will not recock. I believe it works OK with the Rocket valve because there is no o-ring at the rear portion of the valve body and the valve itself is so high flowing.
For those of you that aren't aware of what this is, there's a small hole in the bottom of the body by the valve screw that relieves excess pressure to the striker. This can be blocked off in a couple of different fashions. The most simple being, just filling the hole with a good grade silicone RTV. If you choose this option just be sure none of the RTV enters the inside diameter of the bottom tube so the striker o-ring won't be catching on it. If you can just put a piece of masking tape in there temporarily til it's dried, that should do the trick. Another option is to tap the hole for a small set screw that is 1/16" long and use some blue Loctite to hold it in. Further info on this subject can be found here.
Cupping the striker: Cupping the face of the striker will aid recocking for the fact that it will be more susceptible to catching the pressure in the cupped shape over the normal flat surface of the stock striker configuration. If you don't have the proper tools this can be a bit difficult. If you do it in the incorrect fashion the cup can be a bit uneven and unsightly. I've made a few of these and found that I got a much lower pressure and recocking response from the one that I left the raised boss at the end of the striker on. Seems that the one that was fully cupped out should have gotten a better recocking response since it is closer to the end of the valve when thrust forward which leaves less space between the valve and striker but it didn't on mine anyways. This proves my views on theory: sometimes theory is foiled by reality. SPPS offers a cut & carved, cupped and polished striker by the name of the Dragonfly striker in the SPPS Products section of our website for those that may not have the means or skills of making their own.
The most proficient way to do this would be to chuck it in a lathe and turn the cup off the face of the striker with a carbide bit since the striker is made of case hardened steel. Since we all don't have a lathe handy in our garage or basement there is another proficient manner to cut the cup. You would need a dremel, 1/2" cutting disks and a variable drill. Find a dowel rod that will fit in the spring hole of the striker and insert it all the way in. Cut the dowel rod just long enough to fit the striker as closely as possible to the end of the drill. Make sure that there is no wobble in the striker while turning it in the drill or the cup will turn out uneven. While slowly turning the striker in the drill, start at the center of the striker and pull the cutting disk towards the outside, deeper in the center and tapering upward to the side. Make sure not to cut it too deep/close to the outer edge of the striker because you may end up cutting into the o-ring slot. You will most likely end up using 3-4 cutting disks before you're done since the striker is made of case hardened steel. After you're satisfied with the cup, while turning it in the drill use some 1000 grit sandpaper to smooth it out and some metal polish for the final smoothed surface.
Filing the pressure slot: Filing the pressure slot to the striker in the valve body will help alleviate recocking issues but you may lose a bit of velocity in doing so. If you resorted to this it would be suggested to only file a little at a time until you got the results that you're looking for. You would need a pin file set to accomplish this since the slot isn't that wide.
Tuning Your Spyder
Thought I'd never get to this part eh? For the most part it will be very much similar to the 'Configuring and Tuning Your LP Spyder' article in the tech section with a few variances. As stated in the other article; have a chronograph handy, tune it with a full tank of propellant and write down the results, especially if you get into detail with your tuning. If you don't write it down chances are you'll kick yourself for not doing it when possibly retuning it at some other point and time in the future.
When installing the valve, the spring goes in the striker area rather than the VA area as it was before with your old valve. It's somewhat a pain to have to take the valve in and out every time you want to change the dwell duration/gap as compared to just simply changing out the valve pin spring as before. People that have little patience and find tinkering a bit mundane might end up fiddling with it a couple of times and just be satisfied with what they ended up with once their patience ran short.
Setting the SRP: I have the SRP of my older version Rocket valve all the way opened along with a light Shocktech striker spring. I'm not sure you could do that with these newer versions because as I stated earlier the valve pins look a bit longer. If so the cup seal may run into the end of the VA that is inserted into the front of the bottom tube. Next time I remove my valve I may put a dimension in this article but for now I'll just generalize.
You could start out by turning the SRP in one turn at a time with different valve springs and checking the results of pressure and velocity. I would say to stay with a light to medium striker spring if possible. Chances are the more you turn the SRP in the heavier striker spring you'll need to accomplish velocity depending on the pressure setting used. To accomplish a lower pressure it will require higher flowing parts and either a wider dwell opening or longer dwell duration.
One theoretic technique to set the SRP is to turn it in a little at a time with whatever striker spring you choose to use until it finally refuses to recock, Once you hit this point turn the SRP out a little until it consistently recocks. This point is the shortest dwell opening you can use for the striker spring that you are currently using. This will be most efficient if you're using a lighter striker spring.
Another technique is to put the front o-ring slots of your old valve and pin assembly and the Rocket valve side by side. With both valves in the closed position, turn the SRP in until the end of the SRP is at the same length as the end of old valve pin. This is simply duplicating the dwell opening of the old valve which I'm not too sure is very practical since these are two completely different valves with different flow rates and configurations. I suppose it may be a good starting point anyways. If you're easily satisfied with anything as far as tuning goes, I suppose either of the aforementioned techniques will suffice.
Now........for you techno-heads; if you want the best settings and efficiency from your Rocket valve you're just going to have to slave away at turning the SRP in a couple of turns at a time, trying different pressure readings on the reg and using different striker springs. Trial and error your way to perfection. If you really want to get crazy techno, use all of the different striker springs from a couple of different spring kits. Don't forget those stock striker springs because I've found that a brand new stock spring is much heavier than any heavy spring I've seen in an aftermarket spring kit. If you plan to get super technical you may consider spending an extra $10 and get the Rocket Valve repair kit as a spare just in case. Another thing to consider is that cutting off and filing the end of the valve pin will create a slight variable because the striker will hit it at a slightly different point of length. Whatever you do, write the results down so you can go back and refer to them for possible future tinkering ventures of perfection.
There's not much more that I can say about this that I haven't mentioned in the 'Configuring and Tuning Your LP Spyder' article. Maddman has a great high flowing well designed product for any LP Spyder. There are pluses and negatives to it's design and one negative is the difficulty some may have in understanding and performing the tuning process. The positive is the results that you can accomplish by installing one of these in your LP Spyder if tuned in the correct manner. I've noticed a price hike since the recent change of hands of the Maddman the company. Hopefully that doesn't get out of hand because I'm sure that's one reason that many where purchasing the Rocket over the high flowing, high priced AKA valve in the past.
Purchase a Maddman Rocket valve now
Technical Information
