advice for best solid roller cam 609
 

I am finishing gathering parts for a new motor and am very grateful for advice from some experts out there that have done a similar package before and what worked best.

It is a 609 ci world products block, brodix 3xcnc heads, billet rods, coated J&E pistons approx 9.3:1 compression.

It is in a single engine 27' formula and I want to spin around 6,000rpm wot.

I want to make 800hp or possibly a little more. From what I have heard, this is only going to be possible with a solid roller.

another question relating to the cam, has anybody had good results using the standard stud mount roller rockers or is a jesel shaft style mandatory. (it would be nice to use rockers and k/e 2pc valve covers that i already have)

Thanks in advance for any help.

Sam

Formulaok,

The combination you are proposing is capable of making 800+ reliable, legitimate HP with either a HR or SR cam, given the HR lifter technology available. Either way it is imperative the collateral system components are correct for the application.

The stud mount will work, however the shaft mount will go a long way toward minimizing deflection and insuring valvetrain stability. The cost difference is not insignificant, however saving money in the valvetrain often proves to be false economy.

Bob

I appreciate your advice. Reliability is an utmost concern, as it is going in a single engine boat, so assuming I do have the jesel rocker system, how much HP do you think I'll leave on the table by going HR vs SR? I don't want to have to adjust the valvetrain more than once every 20 hrs or so.

By the way I forgot to list that this is a dart single dominator and my exhaust is cmi full jacketed tailpipes(water isn't dumped into exhaust until the end of tailpipe outside the transom)

Thanks

In my opinion, and experience, Bob (aka RMBuilder) is the absolute guru when it comes to cams and valvetrains for marine applications. I would follow his advice.

Chris

Formulaok,
Agreed, Bob is the guy for your cam needs. He's working on a pair for me as we speak :ernaehrung004:

Are your CMIs of the big tube variety?
I'm currently building 588s with Sport Tubes and this is effecting my exhasut port configuration that is being worked by Jim Valako. The Sport Tubes as well as the standard E-Tops only have an ID of 1.875 (actually more like 1.800. I certainly see this as a choke point for big natural cubes with great flowing large (2.000) exhaust ports and probably would effect the cam selection as well.
I'm sure Bob can shed some light here:cool:
If you have big tubes then it's probably a moot point.

I'm going with RM_Builder spec'd cams and heavy duty Morel hydraulics but then I'm only looking for 700-725hp with my Sport Tubes :drink:

Dave

I had the very same engine a while back, made a ton of power. We could not keep a drive togeather long enough to run the boat. The cam was a SR, .738 I lift, and .710 E. Duration at .20 was 310. Pulled HARD to 6500 rpm. I have more cam info if you need it. Hope this helps.

Thi is the guy to listen to right here.

:ernaehrung004:

As far a rockers go. Since you are going to pull it so high up, I would go with the shaft mount rockers. If you do go with a SR, then they will definately cut down on your maintenance time. They will pick up some power also no matter which cam you pick.

T&D Shaft Rockers to much invested to cheap out now.

Yea i am definitely going with the t & d rockers now. My headers are the big tube ones. Warren, I am interested in any info on that cam you were speaking of.

Bob,

Please advise of what you would do.

Sam

405-850-0515

Making the power will not be a issue...spinning to 6k at that power you better have drives standing by to change like spark plugs ! I would go with a hyd roller and lower the max RPM and shoot for 5500-5600 max, it will make a big differnce when come to keeping drives together....Rob

The nice thing about using a shaft mount style rocker system is that it will also eliminate the need of a stud girdle or a rev kit and of course pushrod guide plates. I have always been told that the weakest link on a BBChevy is the valve train---especially with a stud mount rocker arm system.

By the way, RMBuilder/Bob Madara also designed the cams for my 565cid N/A engines about 4 years ago. There were some special things I asked Bob to do with my cams concerning idling quality..i.e. shifting, drivability, etc, and I am very pleased with the turnout.

RMBuilder/Bob Madara Marine Kinetics N.Y. 585-654-8583

I remember reading where Bob Teague had said that he had seen some guys running the Bravo drives to around 6000rpm with good luck, but never experienced it for myself. I think he was talking about when the racers ran the pre XR era drives and they were trying to make them last. My thoughts were if it could turn that high, I could keep the torque down and save drives. Am I wrong to believe that a late model xr can handle the RPM?

It will handle it, but for how long, who knows. It might last 30 mins, 30hrs or 230hrs. My bet would be somehwhere in the 100hr range if you are very nice to it.

I have allways read that the Bravo would rather spin to a higher RPM, than be lugged down with a bigger prop.

I have never tested this out, but how did this thread get off track? Did a cam ever get ordered? I would like to see what the specs were on that.

I am going to call bob and talk to him about what he thinks. Teague recommends a HR custom grind that have it is

258 - 266 duration
.647 - .647 gross lift
lobe sep. 114

Operating range to 7000RPM

They did tell me this went into their large cube N.A. motor and that they stay away from the SR only because they have to warranty their motors and have no control of the end user.

I am not yet at all convinced by Teague's guy on the cam recommendation, I am going to talk to Bob Madara before doing anything else

Formula spoke to RM@ Bob on friday and he was walkin out the door and heading to PRI @ Orlando till Dec 15th ,if you cant get ahold of him ... :ernaehrung004:

I'd wait for Bob,you'll be glad you did

Thanks

I've got nothing but time until next spring!!

Bravo vs RPM
 

I have used bravos at 7600 RPM 613 hp with small blocks in our old B class boat. My experience is torque killls them not rpm.
Steve

thanks steve

Just for your information---RMbuilder/Bob Madara knows about drive torque loading issues and knows how to design a cam to either avoid it or decrease/minimize its effect on the drive.

I talked to Bob at Marine Kinetics today and got him started on the cam build. He was very knowlegable and helpful. I know I made the right decision. Thanks guys for the recommendation. It is really helpful to gain the instant knowlege base of hundreds of fellow boaters who have been there done that!