540 Bulldog Motors

[ozarkdevil]

I haven't heard to many bad things about the 540 Bulldog motors but I was wondering if they have the same issues that the older 500hp carb. motors had with the valve train at around 200-250hrs?

[glassdave]

Not sure if that would be considered an issue, its more something that should be considered scheduled maintenance. Thats about when you should be looking at the valve train anyway, springs at least. I have heard good things about the Bulldog as well. I have a friend with a pair with several hundred hours and no probs

[Ratickle]

Take a peek at this thread from awhile back.

The base motors in the BT were Bulldogs. They are strong bottoms. After reading it, let us know if you have any more questions.


http://www.seriousoffshore.com/forum...ead.php?t=1440

[Chris]

Over 200 hours on valve springs on anything over 400 horse is asking for trouble. They're cheap, why take a chance?

[ozarkdevil]

Take a peek at this thread from awhile back.

The base motors in the BT were Bulldogs. They are strong bottoms. After reading it, let us know if you have any more questions.


http://www.seriousoffshore.com/forum...ead.php?t=1440

Thanks for the link, great info.

[ozarkdevil]

Over 200 hours on valve springs on anything over 400 horse is asking for trouble. They're cheap, why take a chance?

So true and I am not a gambling man.
Just curious as to what lies in the horizon if a guy was to buy a boat with 540's that has 200hrs on them.

[VetteLT193]

They are way better than the 500's. it's a simple math thing. 540 cubes making the same power as 502 cubes the 540 is going to be more reliable. The cam is less aggressive.

To put it in perspective, The stock 502 Mag made roughly .82 HP per cubic inch.
The 540 bulldog is roughly .87
496 HO is roughly .86
The HP500 is roughly .94

Most people just run the crap out of 502 Mags and never worry about valve train issues after 200 hours... hell, they put them in express cruisers. The 496 HO is even closer.

The HP 500 nears the 1:1 mark with regular gas. If it required premium it would make the power with compression instead of a big cam... that is the key. if you look at even the automobile world as things get to and surpass the 1:1 ratio octane goes up first... in the marine world it can be a PITA so the power is made through the valve-train which lowers reliability.

[PatriYacht]

The Bulldog uses a mild flat tappet cam and softer valve springs. I would say the lifters and valvesprings are good for as long as the heads. Change them when it's time to do a valve job. Even better, change to a roller cam and lifters now and get 600 hp easy.

[LITTLE TOMMY]

mercs best motor to date!

[Geronimo36]

They are way better than the 500's. it's a simple math thing. 540 cubes making the same power as 502 cubes the 540 is going to be more reliable. The cam is less aggressive.

I agree but with one small caviat.. The 540 has more recipricating mass than a 502"' or 454" which can reduce the longevity of the bottom end.

It's a minute point but thought it was worth mentioning.

I'd buy it and drop a 741 or 651 cam in there!

[Nordicflame]

Also a wonderful platform for a 4.0L Whipple package