Nordicflame

iTrader: (4)

Looking at a budget rebuild for a tired 1997 Bulldog and was wondering if anyone had been down this path.
Looks like a valve job is necessary for sure and the rings/pistons are suspect after a leak-down test. I will know more upon tear down.
Other than some mild porting, I’m looking at installing a 741 cam and hydraulic roller lifters for a start. There may be better cams available but I have access to this particular cam and I have had nothing but excellent results with it in the past on other 540s.
If we are able to reuse the existing pistons I will check the deck height and see if any additional compression can be gained through the use of a thinner Cometic gasket and/or decking the block and/or heads. However, I’ve heard that the Bulldogs are already near zero deck from the factory. If this is the case then pistons and head milling would be the only alternative to get additional compression.
If I can get the CR up to around 9.25:1, install the 741 cam and do a mild port the heads I’m thinking we’ll be getting near 600 hp.
Has any one performed this rebuild and have there been any reversion issues with the cam upgrade and the Gils?
I don’t think any carb mods will be necessary because she’s pretty rich right now at our high altitude. Obviously a check it and see situation.
Any experience with this out there?

Thanks,
Dave

US1 Fountain

iTrader: (1)

I had the 741 cam on a 502 using Gils with my silent choice and never a sign of reversion.

mrhorsepower1

Dave,
what type of budget do you have? I have used a bunch of the Crane 741 camshaft in your cu.in. engine builds. Reversion is definetly not an issue. Camshaft works very well. Depending on your budget, Mildly porting the factory heads will pick you up about 35-40 HP when done properly. The biggest area to focus on here is the exhaust port short turn. A nice radius needs to be formed here. If your budget it allows a cylinder head change will net you HUGE gains. We have a cylinder head package that we developed in "A" and "B" class offshore racing that I use in my N/A 1X4 applications. A increase of 80-90 HP would be seen in this case. The other thing you can do is lean out the carbs 2-3 jet sizes . The carbs from Mercury are jetted extremely rich! I have seen a couple MPH just in tuning from factory specs. Richness can do as much if not more damage on an engine , especially when it is a new build. Thanks,

Dean Gellner
Gellner Engineering Marine Power

Bulldog

A tired 1997 Bulldog? I am a 1957 bulldog, but not too tired.. What carb is on the 540? If I recall the mercs originally came with 850 DP's. Lots of people run 1050 Dominators on 540's- so you might want to go a little bigger. Maybe someone can provide some dyno comparisons.

Mr. Gellner- Welcome to OSO.

Just a warning- there are a lot of opinionated a-holes on this board. Among others, Dennis Moore bailed out after getting ragged on repeatedly by a few troublemakers. Please, please ignore these people. You can also report the post and it will get some attention from the board gods.

I've been on OSO from the start and really enjoy picking up info from guys like you. This is a valuable resource to a lot of folks, and we need all the help we can get!

Bulldog AKA Ronnie
NASA Center Operations Directorate
Stennis Space Center

jpclear

This would be the perfect time to contact "RMBuilder", an OSO member who often posts here. He can spec. out a program for you that will easily exceed 600 hp on readily available pump gas. --- Jer

mrhorsepower1

Thanks for the welcome BullDog! If I can be of any help what so ever please contact me. We have been around along long time and can help! Thanks again!

Dean