Jet Boat Tech Notes

Also, I’d like to thank all of the guys on the various discussion boards, whose advice I always valued, even if I didn’t use it. You all know who you are. Thanks!

The purpose of this article is to provide someone thinking of about installing a blower some kind of an idea what it will take to complete the installation. I won’t get into tuning as there are a lot of people with a lot more experience on the subject than me who are more than willing to share their info.

When I first decided to buy a blower, I started looking through the classified ads on several different web sites. I would find a blower here, drive parts there, and a manifold over here. I came across an ad for an outfit in Whittier; Ca. called Dragparts.com for "New and Used Blowers and Parts". I contacted Dragparts.com by email. Dragparts.com is the Internet arm of Good Vibrations Racing. The owner, Jim Maher, called me the next day. I explained what I had and what I wanted to accomplish to him. He told me that he could set me up with all kinds of used parts to put this thing together, but in his opinion that wasn’t really the way to go. He said that a lot of times when a guy tries to save a few bucks by scabbing together a bunch of used parts for this sort of thing, he ends up spending just as much as a new kit. And with added hassle and less than expected results. Maybe Jim is just one heck of a salesman, but what he said made a lot of sense to me. I thought about it for a while and then I called him to order a new complete polished Stage II BDS 8-71 kit. In retrospect, I think it has saved me some time, money and a lot of hassle to buy new.

The "Big Brown Truck" delivered my boxes of goodies within a couple of weeks. Now I had to put together the rest of the package. I figured I would need a pair of carbs, an ignition upgrade, and modify my fuel delivery system. That was a good start, but there would be more, lots more. After wheeling and dealing for a few months, I had finally worked myself into a matched set of carbs. I scored a pair of pro-rebuilt Holley 4223 850 Center Squirters. I decided to start a mock up of the entire package to see what else I was going to need. One of the first things I knew I needed was throttle linkage.

My original plan was to fabricate my own. But after I started realizing what I was going to need to do it, I decided to call Jim (the first of many calls to Jim during this exercise) and had him send me out an Enderle linkage kit (I ended up replacing all the rod ends with stainless later.). While I had everything mocked up, I took measurements for a belt guard. I fabbed the guard (the first of two I made) from some nice stainless sheet. Next thing I noticed was there was no pop off valve provision in the manifold. I promptly called Jim again. Because I was installing this set up on a boat, he sent me a "competition" manifold. There is no pop off or thermostat (or temperature sender provision, as I later realized) provisions on a comp manifold. The standard backfire protection for a comp set up is either aluminum studs with restraint straps or burst panels. Because this was going to be a low boost application, Jim told me I could mill a relief opening and drill and tap a couple of holes for a standard pop off valve. I had him send me a pop off valve.

Since this was to be a low boost/low RPM set up, the fuel pump I had installed(Holley "blue" with a regulator) when I previously installed the nitrous system was going to be sufficient. I needed to get the fuel to the carbs from there. I fabricated an aluminum fuel log and mounting bracket. I also was going to need fuel lines from the log to the carbs. Another call to Jim brought a set of slick looking hard lines for the carbs. I ordered from Summit all the AN fittings and braided stainless hose needed to feed the log and a liquid filled fuel pressure gauge.

I bought a Mallory Comp 9000 from a guy on dragboats.com. I bought a Mallory Hyfire box and a new set of Accel plug wires on ebay.com. I figured I had everything I needed to get this baby assembled. Of course I was wrong!

One thing I can’t stand is polishing aluminum. My answer to polishing all this new aluminum was clear coat. My first idea was Powder Coating. I called a local guy and he advised me that manifold heat and Powder Coat wouldn’t mix too well.

At the local parts store, I found an engine enamel clear coat. It has some kind of ceramic resins in it and claims to be able to stand up to 500-degree temps. I decided to give it a shot.

Before I could start applying the clear coat, I had to do the machine work on the manifold and plug all the unnecessary plumbing holes on both the manifold and the blower top. I bought all stainless pipe plugs and plugged everything up. I mounted the manifold to a mill table and, using the horizontal spindle, milled the relief opening and drilled and tapped the boltholes. The next step was clear coating. I spent the next several days spraying the various components.

I bought the blower in April 2001. I was planning on having it installed on top of my stock 454 for that season. When the boxes arrived, I knew it was going to be a bigger project than I had anticipated. The blower sat boxed up (except for a couple of mock-ups) in my garage until the following November. This prompted some negative comments from my wife. "You spent $3200 on that thing just to box it up?!!!" was one of her favorites. While it was boxed up, I started asking questions on the boards. One thing I heard a lot was that a stock 454 would blow up under boost. "Build it right the first time" and "Only cry once" were some of the popular comments. I got worried. I made yet another call to Jim, who assured me that with this set up, the engine would live with low boost and sensible use.

The victim was an 18 year old stock 330 HP cast/cast 454. I had ran her for four seasons with a 100 HP Nitrous kit without a hitch (I was told a 100 HP nitrous shot would break the crank, too). Hit the key, fire in the hole. The only two breakdowns I ever had were ignition related, one of them my own fault (never leave your distributor loose and hammer the throttle!!!).

I started the teardown phase. I pulled the carb and valve covers first. Then I dismantled the front of the engine, removing the lower pulley, the harmonic balancer and all the cooling lines. The only things left were the distributor and the intake, so off they came. I cleaned all the mating surfaces, readying them for the installation. It was time to break out those boxes!

The blower kit came with a counter balanced hub that is used in place of the harmonic balancer. Installation of the hub was no different than installing a standard harmonic balancer. Next I installed the supplied spacer and lower drive pulley. At this point, I realized I had no way to set/check the timing. The supplied timing tape was to be applied to the spacer. I was going to have to come up with some kind of timing tab for reference. Another call to Jim brought me a BDS adjustable timing tab. There was still a problem. The tab required the use of an aluminum disc to be attached between the spacer and the lower pulley. I figured I could machine one myself. Then I realized I didn’t have any suitable material on hand. To get around this, I drilled a small hole in the tab, in line with the tab’s existing pointer. I then pressed in a pointed piece of stainless welding rod. To see where the timing is, I have to line up the tab’s pointer with pointer I installed while looking at the timing tape. Not the easiest way to go, but it worked.