Cam too small?

[Tahoe540]

I am doing a refresh on my 555 with new rings and bearings and also changing out the camshaft.

The motor is going into my Hallett open bow jet boat with a JG and stainless A. One caveat is I have to run logs because I have a doghouse so it has to be ground for wet exhaust. Yes it has to stay the kids love the 2 seats in the back. I am running the Gale Banks/Harman style logs and they have been opened up as big as possible on the exhaust outlets.

The motor has approx. 10.25:1 compression with Brodix BB2Xtra CNC heads with Jesel shaft rockers. The current springs will go up to a .680 lift. I know these are giant heads for under 6-6500 rpm and restrictive exhaust but they are what I have. I would really prefer a 320CC version. I attached the cam card of the hydraulic roller cam I am taking out.

I have a Comp 525 efi cam on the shelf that I was going to use in a 496 build but ended up selling the short block. I don't have experience with this particular cam but people seem to like it on the forums for offshore boats. I would really like to be able to turn at least 6k rpm, I like to have fun LOL.
https://www.summitracing.com/parts/cca-01-446-11

I am really tempted to just get a bigger custom grind, but not sure how much more I could get out with the limiting exhaust. Anyone have experience with the 525 efi grind with a larger cubic inch?

 

[obnoxious001]

The Comp cam is perhaps pushing the limit of what you can do with wet exhaust and will probably work well. The Bullet would probably be too much and cause reversion issues.

But what do I know about this stuff, call Comp and/or Bullet and see what they say. I spent some time with the tech at Bullet not too long ago, friendly, knowledgeable, and we spoke the same language about the cam I have from them.

 

[Tahoe540]

Thanks for your reply.

The bullet is a custom grind and I told them it was for these wet exhaust logs. There was some reversion when I pulled the motor apart. The cam also had to be installed 6 degrees advanced to get to the 109 centerline. I have degreed a fair share of cams (not as many as you) but never had one that far off.

Will give the Comp a try. I am sure it will be a big improvement over the 468 that is currently installed.

 

[obnoxious001]

Thanks for your reply.

The bullet is a custom grind and I told them it was for these wet exhaust logs. There was some reversion when I pulled the motor apart. The cam also had to be installed 6 degrees advanced to get to the 109 centerline. I have degreed a fair share of cams (not as many as you) but never had one that far off.

Will give the Comp a try. I am sure it will be a big improvement over the 468 that is currently installed.

Based on my quick read of the cam card the Bullet was ground on 113 LSA, and they asked for it to be degreed at 109 which would have been 4 degrees advance, so only 2 degrees off which is not unusual for a combination of aftermarket parts. My guess is that Bullet is not as well versed on marine engines, since that 264/270 @/050 is a bunch.

 

[Teague_JR]

I think Ideally you would want to be in between that bullet cam and the 525 Cam. The bullet would be good for the inches and heads but with a 1050 dominator and better exhaust.

The 525 cam is only 236/242 duration (if Im a couple digits off forgive me) REALLY small for a 555 with a big ass single plane intake. Unlikely to make the good top end power 5000-6000

 

[ShawnsPerformance]

If you advanced the cam timing 4 degrees, (ICL at say 105) it'd make more bottom end, and reduce the reversion in the exhaust because youre closing the exhaust valve sooner. Since it isnt going to rev to well through the logs, use what you've got and pull the power down in the range. Low speed cylinder pressure will come up.