1991 260 7.4 bravo speeds
 

Just bought and old Baja coming from a 35 Fountain. Yes, down sized for health reasons. Very frustrating, might add since my 35 had twin blowers. Anyways, bought boat as little project (wasa mess) with son and I and getting frustrated on some speed tests -among other small issues. Though Im no mechanic, i always try to leave the "herd "stuff to "'Guy" my mechanic...i can turn a few wrenches and diagnose on occasion. Im getting 43mph max on GPS out of this 260 with stock 7.4 thru prop exhaust. I have replaced coil (was arcing), wires, plugs, exhaust among other non related items. motor has 200 hours but wasn't used a few yrs. I did have a similar boat and size in the mid 90's that I know did in the low 60's with same set up. I get 4600 rpm and the prop is a mirage plus 21 SS. I do get a "cough at WOT some times so Im thinking Carb issues/bad gas. Timing seems ok. I cant really go to fast now, dam lung cancer, just want to make sure i can get my kids up out of hole for tubing. What ya think this boat should get at WOT? I had 1/4 gas, and only one passenger when testing on GPS. River was calm, slack tide. Boat sat a few yrs, gas was on empty and I added stabilizers..replaced fuel filter and separators a few times...btw, rides nice at 4k-42k at around 38mph...
Just bottom painted with triton and drive is clean.
http://www.gamingkrib.com/tzhs1982/images/91.jpg
[IMG]http://www.gamingkrib.com/tzhs1982/images/912.jpg[/IMG]

I had the same boat, but it had a 454 magnum which was 365hp and in perfect conditions low load I saw Max of 62 MPH GPS with a I think a 21 Mirage plus.

If yours is a 7.4L it is either a 330hp and if a magnum 365hp.

If it is a 330hp you might see speeds of 55 to 59.

According to the prop slip calculator you are at a 30% slip!! Something is wrong...have you weighed your boat? Are you sure you are getting fully trimmed up? Your engine is getting to its max rpm so you are propped correctly but your speed is way off....very odd.

http://www.go-fast.com/Prop_Slip_Calculator.htm

ya, odd, i have had many boats...trim is fine, non magnum. I did notice a slight warp in skeg about an inch and my new zinc above prop moved a bit so its not straight back, wonder if that both would limit so much mph? I do feel like its not biting the water as it should. That's new Micron paint, not triton, brain fart.

you think water logged foam between stringers? no, haven't weighted it. Transom had no rot -first thing i check when buying boat...i have the sunpad off for rework, should be even lighter without that 3/4 plywood they use...

Should get around 55 gps. I had a 91 260 for 14 years. Bought it in 1996 and sold two years ago. The 7.4 is 300 hp. Great boat with lots of cockpit space. Drawback is the 21 degree deadrise. Did lots of updating to mine including adding marine ac for overnights.

What pitch prop, make?

I believe it was a 21 or maybe even 19. I'm not one to play with props as it was on it when i bought it and never tried anything else. 4 blade Mach Sterndriver.

hmm, 4 blade might be interesting...though the last owner swawers he was getting 50 mph. Were you getting that speed with 1/2 tank? or almost empty? What speed at full tank if you recall? How ya like the 30 Boss?

I had a 91 with a 454 330 in it. With the stock 21p I would just get 50mph. I bought a 23p 3 blade prop from Overtons and could see 53. Mine did not have any tabs on it, so the only time it was fast was when it bounced.

I have a '93 260 with a 502 in it now. When I got it back in '98 it had the stock 7.4L. With a 21 degree Mirage I was getting 55mph on GPS at a little over 5000 rpm. You have to trim the drive up quite a bit to get the most out of it. I would recommend checking the timing at 3600 and see what you get. It should be 34-36 degrees before TDC. Also, a can of Seafoam in the gas tank wouldn't hurt. Something is wrong. It should run more than 4600 rpm at WOT.

I would say tank was 1/2 to full since i never let it go much lower. Love the 302 as it handles the rough water of the lake i boat at. With the 302, i still get the great cockpit space and it has an ac also for overnight crashing. Wasn't really looking to trade up when it happened, just everything worked out perfect as friend bought my 260 without ever having to put it on the market.

u sure it was over 5k, seems unlikely for 7.4 to achieve 5k w/ that prop or in general.

It's been a few years but that is what I remember. Like I said, to get that speed I had to trim the drive up quite a bit. Timing at 36* before TDC and 89 octane gas just for insurance. Motor ran great when I took it out. Just sold it last year to a guy who put it in a motorhome. Good luck.

So i replaced all gas, used 98 octane had carb rebuilt and boat runs great at 10 degrees timing, still getting 4600 max rpm. Boat still runs at 44 mph top end WOT. Not that I will run at that range, Mid range still feels too high to run at and slow. Enclosed pic of Bams Prop Calculator. Slip seems horrible at 28 %. Any ideas. Took prop to a very good prop guy, he claims prop looks fine, almost new. Though only a Mirage, not a Mirage Plus. Any help appreciated. http://www.gamingkrib.com/tzhs1982/images/prop.jpg

found a Rev 4 unexpectatly and had it labbed locally by an old timer down the street...
fyi
Stock Michigan SS 19 39mph 5200rpm max (slips, needs planing help)
Stock 21 Mirage 43mph 4600rpm max (slips, needs little tabs, maybe damaged prop)
More cupping added 21 Mirage 47mph 4500 rpm max (slips, needs little tab)
Rev 4 21 Stock 48mph 4600rpm max (no slip, nice accel, little bow lift, no tabs needed)
Rev 4 21 Labbed 53mph 4900rpm max (no slip, nice acceland and cruise, bow lift much better, no tabs needed for plane, rpm too high)