Small Block Chevy upgrades
 

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

Re: Small Block Chevy upgrades
 

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.

Re: Small Block Chevy upgrades
 

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

Re: Small Block Chevy upgrades
 

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.
[email protected]

Re: Small Block Chevy upgrades
 

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

Re: Small Block Chevy upgrades
 

change it up to mag spec and you will be there

Re: Small Block Chevy upgrades
 

what are the mag specs?

Re: Small Block Chevy upgrades
 

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.

Re: Small Block Chevy upgrades
 

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.

Re: Small Block Chevy upgrades
 

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

Re: Small Block Chevy upgrades
 

Can any one suggest some good cast iron SBC intake manifolds for salt water use? I bought a fresh water boat with a Victor Jr. manifold and will be running it in salt water. I'd rather not go closed cooling. Thanks.

Re: Small Block Chevy upgrades
 

I think i may have what you are looking for. I will PM you with my phone number so we can talk.

Re: Small Block Chevy upgrades
 

----------------------------------------------------------------------

Try looking at www.cfm-tech.com. Go to "online store", "chevy specialty" & look up the 400-VM ==> cast iron performance manifold. Little pricy, but works well...

Re: Small Block Chevy upgrades
 

Thanks for the input. Like I said before, I'm on a tight budget and dealing with twin engines doubles the cost. Read in Dennis Moores Small Block Book that he thinks the best heads for my motor are the ones that came on it. Said to put in larger valves and some port clean up should net around 20 HP increase. Doing that and a cam and exhaust change seems like it would put me around 325HP which is my goal. Would be cheaper than converting to Vortecs and I could keep my stock iron hi-rise intake, which again Dennis says is the one to use, especially in salt water.

Any thoughts on this approach?