HP500carb. and Bravo X
 

Hei, I am going to throw out my -99 7.4 MPI/Bravo One and put in a HP500 carb with Bravo X and have some questions:
1. do the drives have the same cut out and bolts?
2. is there any difference on the inner transom?
3. the drives do they have the same measurements/dimensions ?
4. anybody have a pdf of the original brochure?
5. anything spesial to look for before I innstall this engine?

Thanks...

Re: HP500carb. and Bravo X
 

No major diffrences between the two, it is a plug and play swap unless you go with the offshore front mount wich you probably should.

Re: HP500carb. and Bravo X
 

Hi Hydrolift:
That's the exact same engine swap that I did!! You will LOVE IT!!!!

I'm still running the 1999 Bravo drive, so far without problems, but I do baby it out of the hole, and my boat is small.
===
If your HP500 has close to 200 hours on it or more, you really need to change the valve springs. I did mine at 180 hours, just before the swap, and the springs were all very weak, none broken. 1999 was a bad year for the Crane springs, and they will weaken and break. I went back with the Comp 929-16's.
I went ahead and pulled the heads and had a valve job done and had them planed a touch, but they didn't need it. Everything else was perfect.

Mine just dropped right in.
===
I always understood that an X drive will bolt right up to the Bravo housing.

Kent

Re: HP500carb. and Bravo X
 

I will go for the offshore style engine mount. This 500 was replaced in 01 on warranty not shore but I think it was only the short block. Does this engine use "gil" manifold, same bolt pattern? I will for a short time have to use the std. cable steering, will this fit the inner transom?

Re: HP500carb. and Bravo X
 

OK, just to get this right. Is the cut out in the transom the same on the Bravo One and Bravo X?

Mudball do you have the spec for the HP 500 no EFI? What parts did MC use in this engine when it was new?

Re: HP500carb. and Bravo X
 

The HP500 carb in 1999 had all the good stuff!!!
The HP/torque is almost identical to the EFI. I personally like the carb version much better. No computers to screw up...

I don't have a spec, but the carb version used Crane valve train components, good steel cranks and rods, forged pistons at 8.75:1, built to withstand offshore racing at WOT all day long!!
The weak link in these engines was the valve springs. The cam is very radical with a very steep ramp, and the earlier Gil exhaust risers were too low, creating reversion problems. Moisture in the valve covers kills springs. Many people reported RUST on the valve springs!!
The valves are the good big stuff. Inconel exhausts and stainless intakes.
These use the Dart single plane intake with a Holley 800cfm double pumper w/electric choke and mechanical secondaries (Note that I removed my choke).

The Gil's were stock. I am lucky to have the taller risers.
Here's a picture of my motor just before installation.
The reason for the crossover is the stock circ pump was leaking. I recommend NOT using a crossover. I had a nightmare of a time getting it to work right with a thermostat.
The billet pulleys were because the stock pulleys looked pretty bad, rusting in several spots...
The stock flame arrestor had most of the silk screened lettering rubbed off (cheasy job by Merc!).

Re: HP500carb. and Bravo X
 

I forgot to mention that everything will work with the new power!
I also had the stock cable steering when I swapped engines.
I do now have full hydraulic steering though...
Kent

Re: HP500carb. and Bravo X
 

And, the exhaust outlets of the Gil's are exactly the same as the 7.4mpi through hull!!

Re: HP500carb. and Bravo X
 

This sounds good, which prop do you use, and what gear 1.5?

Re: HP500carb. and Bravo X
 

Here's the info for my setup:
Boat: 1999 Donzi 22ZX with the step.
Engine: 1999 HP500 carb, top end freshened and installed 15 hours ago.
Drive: Stock Bravo 1, 1.5 gears.
Prop: 28p Stock Bravo 1
RPM: 5,100
Speed: Best of 78.2 GPS (Garmin eTrex) 76-77's every day.
Steering: Full hydraulic single ram XS marine.
Tabs: NONE!
Handling: Rear end moves around above 75 or so when trimming up. (A little scary!) I don't know if this is chine walk....It doesn't feel like it, but it could be.

Plans:
1. Add 19s Victory Tabs (thank God Brian is back!)
2. See what that does for handling.
3. Do prop work if handling improves with Throttle Up!
4. Hope to hit that magic 80 mark!!
Kent

Re: HP500carb. and Bravo X
 

Thank you for the info. Need to go to bed now, it`s nearly 2:00 in the night here, but it`s hard to sleep it`s nearly as light as the day!

Best regards from the land of the midnight sun!

Re: HP500carb. and Bravo X
 

Mudball, What were your numbers prior to the swap? Power,Prop,Rpm,ect? Very nice. Thanks, Doug

Re: HP500carb. and Bravo X
 

Before HP500:
Engine: 1999 7.4mpi.
Prop: 24p stock Bravo.
RPM: Don't remember exactly, but around 4600-4700.
Best speed ever was 63 gps. Normally around 61-62.

Re: HP500carb. and Bravo X
 

Kent, How much taller is the 500HP than the 7.4mpi? Doug

Re: HP500carb. and Bravo X
 

The HP500 is taller on the intake, but the exhaust is about the same as the 7.4mpi with the riser spacer, like this pic, after it was pulled...

Re: HP500carb. and Bravo X
 

Hei, found this in a old brochure:

1999
HP500 carb.
Length 38,19
Width 32,68
Hight 23,23
Depth 9,62 single / 13,38 side by side
Weight 1090lbs. Bravo1

1999
7.4MPI
Length 39,02
Width 32,02
Hight 24,02
Depth
Weight 1148lbs. Bravo1

Length=Taken at transom at crankshaft centerline to forward most part of the engine

Height=Taken from engine crankshaft centerline

Re: HP500carb. and Bravo X
 

Wow, that shows the HP500 as 3/4" shorter!!!
Fascinating!
My HP500 intake was taller than the MPI intake. I remember that because I measured everything before the swap to make sure it would fit. I wonder if they are talking about the exhaust risers? I would believe that the exhaust might be a little shorter.
Kent

Re: HP500carb. and Bravo X
 

Maybe, on the picture it shows the exhaust ca. 1/3 up on the flame arrestor...

Re: HP500carb. and Bravo X
 

I would have thought the HP was higher. You guys are good! Hydrolift, Do you have the numbers for a carb 7.4L and a 500HP EFI? My 7.4L is tight in there, in every way. Thanks Doug

Re: HP500carb. and Bravo X
 

HP500EFI Bravo1 (1999)
Length 87,2cm 34,33in
Width 85,7cm 33,74in
Hight 56,0cm 22,05in
Weight 516kg 1137,59lbs

Havent got any data on the carb 7,4L

Re: HP500carb. and Bravo X
 

Thanks Hydrolift, I will measure the 7.4 from crank center to compare to the HP. Doug