I have a 85 260 mercruiser I know I can change the heads over to the vortec head an a different intake. My question is can I run the stock cam? With the vortec heads an intake without any issues?? I was wondering with it having flat top pistons if my compression would also get bumped up with out a cam change?

You can swap the heads and intake and run the original cam, you will just be leaving power on the table because the cam is a small flat tappet.

Your compression will increase from the smaller combustion chambers of the vortecs but this has nothing to do with the cam.

With the smaller 64cc vortec heads how high would the compression increase?

about 9.4:1

Thanks for you help

If changed my cam to comp cam xtreme energy.xm256h
Would I have to change the springs in the vortec head? I tried to find out before an I keep getting different answers.

I don't know the spring specs of the stock vortec head (80#s or so at 1.7 install height?) but I imagine they are mild as the lift was only around .42 inch, but was hydraulic roller. The stock head is good for about .48 lift. You can probably run them.

That cam doesn't look that much different than what is already in the motor and I can tell you there wouldn't be much diffence in power if you changed it out with the stock heads as I have done it. With the vortecs you may see more. My opinion, if you are going to get into cam swap you should spend the extra money and go to a hyraulic roller.

Not sure of your money issues, so two options to think about. Just get rid of the factory bumpstick it is almost as bad for your motor as the 76cc heads!

1- run the vortecs with the comp 262 flat tappet marine cam, and a decent intake. You should certainly see a substatial gain in power and speed.

2- run the vortecs, good intake and spend a little extra and go with a retro roller cam set up. You can get fairly aggressive(for a boat) with the cam and stock exhaust manifolds because a roller cam is a whole different animal compared to flat tappet.

Either way I would suggest talking to a cam mfg about the springs. My guess is stock springs and flat tappet will be close, the only concern is going to be the open spring pressure as flat tappets like around 270-310lbs open. Seat pressure you will be fine as flat tappet and mild roller are the pretty close in seat pressure.

Now if you go retro roller with a healthy profile you will need to change out springs as 140lbs average seat and 360lbs open is about minimum.

I can help you out best I can, I just built two pretty sick sbcs for my boat with full roller conversions. Good luck

Ya I was just going to stick with a flat tappet cam upgrade with the vortec heads an intake. Don't really want to spend the money for a roller cam. Thanks for all your information.