Merc 540 Bulldogs - info on them?

[Shallow Minded]

I've got my eye on a boat with Merc 500 Bulldogs. Anybody know much about them? Issues? Reliability? Decent internals? Hours before refresh? The guy stated they were the pre-runner to 500HP's, but I didn't think that sounded right given the boat is a '99. Are they just beefed up 502's or 540's? Any info would be great. Thanks. SM

[Griff]

500 Bulldogs are 540ci. Better than a regular 500HP and easier to get HP increases. They were a pretty pricey upgrade over regular 500hp's and I think were handle assembled at Merc Racing. They were built for several years at the same time the regular 500HP's were being made. I used to have the specs in a Merc manual, but don't have the manual anymore. The cam was pretty mild for a 540. Might have been the same as the 500HP cam. From what I've read, they were great engines with great relaibility and pretty mild, thus not needing freshening as often as the regular 500HP's. There was a 32 AT with them for sale about 4-5 years back that I would have loved to grabbed.
Are you looking at the 38 Scarab at LOTO maybe?????

[Ratickle]

I have the specs somewhere. They were at 470 rated propshaft HP I remember. A great motor for upgrades, the BT had them as starters. I'll find it and post it.

[Buckman_4]

They were one of the first performance products that mercury offered a one year warranty on, they have tons of great parts...

[Shallow Minded]

Thanks, guys. After making this post, I actually did a search on "another offshore website" and found several good threads. It sounds like these were a top-shelf product from Merc and at only 470HP, a pretty mild set-up.

Ratickle - any specs you could find would be great. I read where they are a tall-block set-up and a few threads about having a different bore and stroke that helped the lower-end torque, etc.

Griff - boat is not at LOTO, check your e-mail... I should have just come to you in the first place! Ha, thanks again.

[cstraub]

Shallow,
You can send this guy a PM, cjerry6036@yahoo.com he has 2 of them in a 32 AT that were modified a couple of years ago.

[RMBuilder]

Shallow,

The Merc Bulldog is an exceptional platform for upgrades. Many of these were contracted to the military, hence the overkill on the hard parts. Below are the specs on the engine.

541.9 CID
GM MK 4 tall deck (cast# 14044807)
Block clearance to accommodate 4.375” stroke
Siamese Bore, reinforced decks with blind head bolt holes.
Deck 10.2”
2 pc rear seal
Bore 4.44”
Stroke 4.375”
(With a factory recommended bore range 4.250’- 4.560” there is plenty of room for upgrades)
SCR 8.6:1
4340 Lunati crank
Piston is Wiseco (Merc part #)
Connecting rod is Manley +.400" / 6.535"
Dart Single Plane Intake Manifold

Crane Camshaft Specification Card
Part Number: 13H000036
Grind Number: H-240/329-2-10 T1.2


The cam rates on a 110*LSA, 5* advance
Lift .329” Lobe .559” Valve
Lift .340” Lobe .578” Valve

Specs:

@.0042"
................Opens..........Closes.............C/L...........Duration
Intake.....43.0 BTDC.....77.0 ABDC......105*..........300 °
Exhaust...88.0 BBDC.....42.0 ATDC......115*..........310 °
85* overlap

@.050"
................Opens...........Closes...........C/L.........Duration
Intake.....15.0 BTDC.....45.0 ABDC.....105*.........240 °
Exhaust...60.0 BBDC.....10.0 ATDC.....115*.........250 °

Camshaft Is Ground with .0012" Lobe Taper

Bob

[Mrhorsepower1]

Bob's correct. Excellent foundation to build big power with some after market cylinder heads and camshaft change.

[Thunderman98]

There was a 32 AT with them for sale about 4-5 years back that I would have loved to grabbed.


Griff,
Was this the boat that was out of OH. That is where I bought mine. This is the only 32 AT ever built with the 540 Bulldog option.

[Ratickle]

HP500 Bulldog Specifications

Propshaft Horsepower: 470 (350 kw)
Displacement (Liter/CID): 8.9/542
Cylinders: V-8
Bore (in/mm): 4.44/113
Stroke (in/mm): 4.375/111
Compression Ratio: 8.6:1
Fuel Requirements: 87 Posted Octane (R+M)/2
Full Throttle RPM Range: 4800-5200
Ignition Type: Thunderbolt V
Alternator (amps/watts): 55/776
Length (in/mm): 47.5/1207
Width (in/mm): 32.75/648
Height (in/mm): 25.5/648
Weight (lbs/kg): 1540/699
Warranty: 1-year limited, 3-year limited corrosion

[Ratickle]

Here is a link where the manual and parts list is available. You may want to call first to verify.

I've also heard the 500 Bulldog is the base motor for both the 800SC and the 900SC.



http://www.crowleymarine.com/mercury_parts/5356/270.cfm

[Shallow Minded]

Thanks for the info, guys. I actually convinced the dealership to fire them up on the muffs and couldn't believe how smooth they sounded. From everything I've read, they sound like an excellent package. While we're at it, the motors have about 300 hours on them... anything I need to be concerned about from a maintenance standpoint? Gaskets, valve springs, etc? Thanks again.

Thunderman - is that you, Chris? If so, thanks for all your input via e-mail... I got the boat!

Quint

[Griff]

There was a 32 AT with them for sale about 4-5 years back that I would have loved to grabbed.


Griff,
Was this the boat that was out of OH. That is where I bought mine. This is the only 32 AT ever built with the 540 Bulldog option.

I don't remember exactly where it was located, but it did have 500 Bulldogs. Probably the same boat.

Thanks for the info, guys. I actually convinced the dealership to fire them up on the muffs and couldn't believe how smooth they sounded. From everything I've read, they sound like an excellent package. While we're at it, the motors have about 300 hours on them... anything I need to be concerned about from a maintenance standpoint? Gaskets, valve springs, etc? Thanks again.

Thunderman - is that you, Chris? If so, thanks for all your input via e-mail... I got the boat!

Quint

Congrats Q!!!!!!!! Can't wait to see it in person this Summer.

[Thunderman98]

Thanks for the info, guys. I actually convinced the dealership to fire them up on the muffs and couldn't believe how smooth they sounded. From everything I've read, they sound like an excellent package. While we're at it, the motors have about 300 hours on them... anything I need to be concerned about from a maintenance standpoint? Gaskets, valve springs, etc? Thanks again.

Thunderman - is that you, Chris? If so, thanks for all your input via e-mail... I got the boat!

Quint

It is me. Glad to hear that you got the boat. I have not heard from you in awhile and was going to email you to see what was going on. As with all the Merc " Blue " motors, Valve springs should be replaced between 200-250 hrs. This also depends on how the motors were run. If they were babied, the springs may be fine at 300hrs. If they were run hard, They would need to be replaced around the 200hr mark. Either way, I would change them out, if they have not already been done. Also do a comp test. You should be at 150psi for a stock motor. You do not want a reading that is less then 15% of your highest psi reading in a cylinder. Also do a leakdown test. This will determine if the problem is in the valves. You should not be less then 10% of your highest reading. I usually only like to see a difference of 5% with this test. The stock springs are rated at 120lbs closed and 350 lbs open with a installed height of 1.843. These motors use a Hyd Flat Tappet cam. You will want to use a oil that is high in zinc to help with wear on the cam and lifters. Run the boat this year and enjoy it. Next winter, get with me and we can discuss some upgrades for your motors to get some more power out of them. Not trying to scare you into thinking that anything is wrong with the motors in your boat, I am sure they are fine, but these couple tests will let you know what is actually going on with them and if there may be any problems down the road.Have the mechanic do these 2 tests before and after the springs are installed. He will also be able to tell you what the spring pressure is on the old springs. Give me a call anytime. I will help you out the best I can.

Now lets see some pics of your new ride.

[VetteLT193]

I don't know about the old 250 hour rule of thumb on the bulldogs.

The cam on the bulldog is totally different than the regular 500. The bulldog has a flat tappet cam Vs. hydraulic roller. The overall lift is lower and the duration at .050 is higher.

Overall the ramp is less aggressive and it's generally speaking a mild cam so the top end issues that the HP 500 have should not happen to bulldogs

[Shallow Minded]

VetteLT193 - thanks for the input, I have actually heard the same thing from another well-known marine mechanic. Other than both motors being rated at 500HP, I think the Bulldog and 500HP's are quite a bit different and didn't have the valve spring issues like the 500HP's.

To be safe, I'm sure I'll take Thunderman's advice and have some basic tests done just to see where things are at. Thanks again for all the info guys, I really appreciate it.

Here are a few pic's of the new ride, if I can do this right...

[RMBuilder]

SM,

The issues that plagued the Mercury were isolated to the (99896-16) HP500 spring. Back in the late 90’s, early 2000’s, there was a batch problem with specific spring wire (used in the 99896 spring) that suffered from improper heat treat. Because there are only three companies in Kobe that supply 95% of all spring wires worldwide, this wire made its way into the system of multiple suppliers, one of which was the supplier of valve springs for Mercruiser. By the time the issue was identified the defective springs made there way into some production engines and subsequently failed. It brought significant notoriety to Mercury, and many thought this was solely a company issue, due to the fact it appeared to be isolated to the HP500. It was, however, a material supply issue, not that of Mercury.

The Bulldog spring part #99893-16 is designed for flat tappet applications and has not experienced any reliability issues.
Bob

[screamineagle]

VetteLT193 - thanks for the input, I have actually heard the same thing from another well-known marine mechanic. Other than both motors being rated at 500HP, I think the Bulldog and 500HP's are quite a bit different and didn't have the valve spring issues like the 500HP's.

To be safe, I'm sure I'll take Thunderman's advice and have some basic tests done just to see where things are at. Thanks again for all the info guys, I really appreciate it.

Here are a few pic's of the new ride, if I can do this right...

She is a beauty! Might see you on the water. Congratulations!!!

[Thunderman98]

SM,

The issues that plagued the Mercury were isolated to the (99896-16) HP500 spring. Back in the late 90’s, early 2000’s, there was a batch problem with specific spring wire (used in the 99896 spring) that suffered from improper heat treat. Because there are only three companies in Kobe that supply 95% of all spring wires worldwide, this wire made its way into the system of multiple suppliers, one of which was the supplier of valve springs for Mercruiser. By the time the issue was identified the defective springs made there way into some production engines and subsequently failed. It brought significant notoriety to Mercury, and many thought this was solely a company issue, due to the fact it appeared to be isolated to the HP500. It was, however, a material supply issue, not that of Mercury.

The Bulldog spring part #99893-16 is designed for flat tappet applications and has not experienced any reliability issues.
Bob

Bob,
Im not trying to step over your knowledge on this. The reason for my statement is because when I bought my boat, The motors only had 225 hrs on them. At that time they were popping every now and then an did not idle real well. When we pulled the valve springs, Some were only showing 80 lbs. Im not saying that Quint is going to have the same problems that I had when I purchased mine, or that this is a known problem with the Bulldog package, but this is what I ran into and for him to do a few checks to be safe. My valves were also tuliped badly at 350 hrs. This is why I did the rebuilds. The main reason I wanted the Bulldogs was because of the high quality parts that were used and also being a tall deck block.

[Thunderman98]

I don't know about the old 250 hour rule of thumb on the bulldogs.

The cam on the bulldog is totally different than the regular 500. The bulldog has a flat tappet cam Vs. hydraulic roller. The overall lift is lower and the duration at .050 is higher.

Overall the ramp is less aggressive and it's generally speaking a mild cam so the top end issues that the HP 500 have should not happen to bulldogs

Vette,
You are correct that the cam is a flat tappet and that you should not have any problems with the upper end, But the question that I have, is that we do not know how the previous owner drove or maintained the boat. I do know that when we changed over mine to a Hyd Roller cam, we measured the old cam and found alot of wear on the lobes and even a busted piece of lifter sitting in the pan. Quint purchased a beautiful boat with an awesome engine package. Its better to do a few simple tests while its winter time and take care of any problems now, then find out in the middle of the summer and be down for the rest of the season.