There is allot of posts on cam suggestions for 454's, but I might need something a little different. I am thinking of doing some little modifications over a period of time. I want to upgrade to hydraulic roller cam's and head changes. current setup are merc 425's with large rectangle Chevy high performance heads bowl ported (088's I think).

I want to save up and add the cam and lifters first thing in the spring, then add a set of heads maybe in the mid summer, and then next winter I would like to stroke to 496's.
I am looking to get the most bang out of the 496's when finished. This might compromise a little power when it is still in the 454 stage I understand, but would it be that drastic, or will the 496 components work better with the 454 components I already have. I don't think It would hurt to go with a roller cam.

I know that the heads that would be suggested for a 454 is different then a 540 and you hear allot of head suggestions for 540's and not to many for 454 or stroked 454 (496's)

Heads suggestions, World products, Dart, Afr, my existing heads, other Chevy oval or rectangle port heads. short runners, single-dual plane intake?

Let the replies come!
Jason

Merc made a 454-450 hp in the mid 90's. It had the same sq. port heads, Dart manifold, 800 holley, and Gil exhaust as the 500 hp. It used a hyd. roller cam, probably from Crane. Unfortuately it had a reputation as being overcammed with poor drivability. The fix was more cubic inches in the 500 hp. I'm afraid that's what's going to happen with your engine. If you put optimum components for a 496 on a 454, you'll end up with a doggy 454.

However, if you want to go ahead with the plan, these are the parts I would use to build a hot 496. Afr 305 rect. port heads, Dart single plane, Holley 800-850, Crane 731 hyd. roller cam or custom cam with a little less exhaust duration. Flat top pistons will give you about 9 to 1 compression if the block is zero decked. A 10 quart oil pan and larger oil cooler and lines are required if you want it to last very long. Good luck.

I see that the 731 is a little hot for my 454, but good for the 496. It seems that the 721 would be good for a 454 but would need to go to the 731 for 496's. my engines are .030" over but I don't think that will make any difference. Would I be better off to keep the heads I have on now with the 731 to keep it somewhat restricted. I know these heads can make good HP but everyone said it is at 7500 rpm.

10 quart oil pan? Do I have insuffecient oiling now? I know this is probably for heat displacement. But I use 7 quarts of oil now per oil change and thats not draining ay hoses.

Gm sq.port and Afr 305's have the same size ports but the Afr's flow about 30% better. I don't think the Afr's will cost you much low end but will be worth an extra 50 hp at top end on the 496. A lot of $$$$ however. Neither is a good choice for a 454 but they will work. An oval port head like an Edelbrock would be better there.

As far as the oiling system, you will be adding at least 150 hp. You will have to make modifications to the oil system to remove a lot more heat. A 10 quart pan is a good common size. A Melling M77HV pump is my favorite. Replace all oil fittings and lines with 1/2npt to -10. A number of places sell a 3 x 18 oil cooler for about 200.00. This may sound overly complicated and expensive but if you don't do it, your engine won't live.

do you think I'll have less performance with the head and cam change to my 454's then just running my 425's. If the performance would be the same or a little better with just the heads and cam I would be fine with that. I am looking down the road at the big picture. I just don't want to get into the bottom end of the engines this year. and 150 hp would be good was optimistically thinking maybe 100. 575/ side would be nice.

It depends on how high you want to wind that 454. I bet it'll make over 500 hp but it will be at about 6000 rpm. And it will be a pain trying to shift and dock. The 496 combination will be a little tempermental also but you wanted a powerfull 496.

Rookie,
Save your money and do the engines complete at one time. You'll save money, your time, and boating time if you do.

cstraub, i agree.
What cam, head, intake, compression, carb combo would you recomend.
I would like to use the existing carbs, my Holley Barry Grants.

First what is your goal?
Next what is the budget?

An engine combination must satisfy the budget and achieve the goal.

i have a 496 just back form michine shop will sell $7000. edebrock alm heads roller cam 14qt pan etc have all parts need to be assamble 314 265 3876 john do not have boat for motor.