Heads & Cam for 454 MKIV

[Ramjetfish]

I recently got some oval port heads, free of charge, and going to install those heads onto my motor which currently has peanut port heads. While in there, I plan on adding a roller cam to it as well. Any recommendations on a comp cam that I should use?! Boat is a 21' howard running a 22P Mirage 4 Blade. Boat runs well as it is. Just giving it a top end refresh. Thanks for the intel and the insight.

 

[PlumLoco]

I'm going down this road currently and I asked the same question and didn't get a lot of help. I'm adding 049 heads where there were previously the peanut plug heads. My builder is very happy with this grind and has built several using it several marine engines.

 

[Nanu/Nanu]

Dang! I dont know much about cams, but when you look at oem engine specs going from a flat tappet to a roller cam and rocker arms the engine specs would gain like 50 hp. Not 100% sure its related to valvetrain efficiency but i would suspect it is.

I think the biggest thing would be talking with howard cams and making sure the cam will meet your needs for your style of boating. Seems like some of these cams are similar but slightly different to appease folks who want top end or more bottom end or better mid.

Obnoxious Barry would probably be a good resource. In the past i have talked to him and he was very helpful and honest.

Keep us posted i have a 454 mkiv as well. Would like to know if this is a good investment as i currently have a hyd. Flat tappet cam.

 

[obnoxious001]

In general, a roller will keep the valve open longer for similar advertised duration as the ramps are steeper, allowing the events to happen more quickly

With a marine engine it's critical to be aware of where the water enters the exhaust, and keep the duration short enough to not be sucking water back in through the exhaust valves.

As to valve train efficiency, I have seen dyno testing showing that roller rocker arms give zero gain if they are the same ratio as the stock stamped steel. Easy enough to look that up, think it was on Engine Masters at Westech Dyno.

 

[obnoxious001]

I recently got some oval port heads, free of charge, and going to install those heads onto my motor which currently has peanut port heads. While in there, I plan on adding a roller cam to it as well. Any recommendations on a comp cam that I should use?! Boat is a 21' howard running a 22P Mirage 4 Blade. Boat runs well as it is. Just giving it a top end refresh. Thanks for the intel and the insight.

Need to know which oval port heads, combustion chamber sizes vary, valve sizes vary, and port sizes vary.

 

[Ramjetfish]

Need to know which oval port heads, combustion chamber sizes vary, valve sizes vary, and port sizes vary.

Thanks for the comment Barry .... I'll need to do some additional research on this as I was told the boat had a MKIV engine in it but after looking at it yesterday while I was doing some cleaning I found the casting number, 10114182, to be a GenV. I was sure this was a MKIV as there is no electrical fuel pump and come to find out the mechanical fuel pump is attached to the top of the impeller. Now I'm trying to figure out if its a Mag or MPI. Can't tell and didn't have time to pull the valve covers to check the P/N of the heads. That will be for another weekend.