My boat has a pair of 350 cu in, 270 HP engines. I'm looking to get the horse power up to 320-325. Budget is tight and everything done is double, so I have limits. Have a couple of questions.

1. Will the stock cast crank, pistons, and stock rods be ok for the upgrade. Replacing any of these components isn't an option.

2. Thinking about changing heads to Vortec, changing cams to whatever is needed (non roller).

3. Replacing stock iron exhaust with aftermarket to increase breathing and reduce weight.

4. I realize ignition changes and carburation mods will be in order.

Any input and reasonable ideas will be appreciated.

Thanks

These will easily get you there. Call Crane or Comp cams (or your cam company of choice) and they will help you with your combo.

I would put Edelbrock performer RPM or equivalents on it to save weight and get a little more power

You may have to retune those Qjets.

If you need cams i have 2 BN in box Comp cam kits..k12-236-3 for a SBC.
Jim

I build 20-30 400HP 350ci's per month. We are using vortec heads with larger valves, dual plane air gap intake, and a custom grind camshaft. With stock exhaust you would be in the range you are talking about. With a set of Revolution Marine ($925 per set) you would be perfect. I think you should be fine with the mods you are talking about. If you need a set of assembled vortec heads let me know. I keep them with larger valves and upgraded springs in stock.
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have a 89 350mag/270hp that I put 9.5:1 pistons,vortec heads,comp xm270 cam,regular performer(so i could run my bb quadrajet),stock ignition.idles real nice(nice lope too) with awsum midrange for about 1200.00(bought alot of it used off ebay) well worth it for the money

change it up to mag spec and you will be there

what are the mag specs?

If you go with the Vortec heads, be careful of what lift cam you install. The Vortec heads have a limited amount of clearance between the retainer and the valve guide. The heads will need to be modified if going with a cam with more than .460 (or something like that) lift. The valve guides need to be machined for clearance.

I have a bunch of small block stuff to get rid of since I just got a pair of merc. crate engines from Pro Tec Marine. I will post an ad in the classifieds later today or tomorrow. Eg. mag engines(dissassembled), exhaust, MSD, Y-pipes, drives, and some other stuff.

I'd go with the vortec head and a small hydraulic about 222-225 degrees at .050 low lift in the .425-.440 lift with 112 lsa and you'll make all the power you're looking for dependable. Good luck Laz