I have a 350/330 HO crate motor running Edelbrock RPM Airgap & 625 Carb with a 2400 stall conv. but I want to increase the HP to the mid 400 range and am wondering what you guys think is the best way to get there. Do you think porting and polishing the vortec heads and adding a bigger cam and carb would get me there? What do you think would get me there if not. I have a budget of about $1500. Thnx[/align]

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first let me say, you have one sweet car, it sounds like you are off to a good start, i would deffinetly recommend porting and polishing the heads, for a cam, i would recommend lunati cams, they are outstanding and i have not had anythin but great feedback on them, people say you feel a huge difference once you install them, and i would have to agree with them 110%, if your looking to get into the mid 400 range, i would also recommend throwing another carb on there with the existing one, for the intake and carb setup with all of the linkages, jegs sells a great package with some holley carbs and a high rise dual carb intake for a little under 900 bucks, i'm sure if yo purchased that you will not regret it, but all of that should get you up to well over your goal, i'll say you'll be pretty close to about 475 give our take a little, the part number for the kit is 350-7110K, good luck wih it man, keep me updated.

 

I guess to start with we need a bit more information is the engine a roller cam engine, are the Vortec heads a stock gm vortec head have they been updated for higher lift, what cam is in it now. Are the pistons stock cast pistons what is the compression ratio. Do not start buying parts at a whim the tunnel ram suggested most likly will not bolt up to the vortec head they are a different angle. The vortec head also proforms very well at rpm levels at 6000 and below look at the published flow info. Also as far as porting the vortec if you are doing it yourself(ie $1500 limit) I wouldnt even touch the intake side it flows real well. I went through the set I have now and I have to say I am impressed with them. I have a stock 350 short block we ran a comp 270 cam the car ran 8:20s in the 1/8th (with a 600 carb)it had the potential to be in the 7s(750 carb)but I had asp lifter go south so we put in a summit cam .420/.440 it runs 8:45 with it idles smooth. You will need more cam than either of these to be in the 450 range with a stock short block.

 

Thanks guys...here are the specs on the crate engine. It was bought from GMPP and is rated at 330 HP @ 5000 RPM with a stock manifold and 600 carb.It came with the following;
4 bolt main block
Cast iron vortec heads w/ 64 cc chambers, 1.94 intake and 1.50 exhaust valves
Hyd. dual pattern cam Int. lift 435 Exh 460 duration Int 212 Exh 222 @ .050
9.1:1 comp. Dished, cast alum.pistons
Has Edelbrock RPM Airgap manifold and 625 CFM carb
Running a 2400 B&M stall in a TH350

I'd like to work with as much of what I alrady have as I can on the way to getting to my goal of about 450 HP. I've looked at some top end kits buth they all come with a new manifold so I'm thinking I can work withthe Airgap intake I have, move up to a 650 or 750 carb, add a larger cam do some work to the heads or buy new heads...$300-$400 for a new manifold isnt that big a deal if I am replacing the heads and they arent Vortec. I know that reworking the heads I have will be chaper than buying new ones with a new manifold too.

So if you had the same lower end what would you add to it/change on the top end to get to 450ishHP?

 

if you ar going to stay with the same bottom end, add little bolt ons, bigger carb, bigger cam, timing chain, and you can probably do a roller rocker setup, and then porting and polishing the heads should get you there.

 

The way I see it if the $1500 is the budget a better set of heads is out of the question and I feel while the 450 is achievable the components you have may not be up to the task in a bolt on environment. 1) stock rods with stock bolts are rated to 400 hp 2) the compression you have with the dished piston takes you away from the longer duration camshafts 3) the main problem is the heads while the vortec head is the arguably the best factory production head gm made for the 1st gen small block in stock form it has some issues. The first being it is lift limited the retainer will be in danger of hitting the valve seal at lifts of greater than .460 which you need to exceed to increase the duration to be anywhere close to meeting your goal. You will need to have the guides cut down and new seals installed the valvesprings will also need changed manly makes a stockcar spring for about $80 that will work. The stock rockers should be ok the upgrade for these are rollers which would be great but they are expensive because they need to be self aligning. You will be limited on a radical lift also because of the press in studs and factory rockers but for your goal I dont think you will need to exceed a .500 lift. As far as the porting goes I would just do the exhaust side there is enough flow on the intake side.
To increase your compression ratio a little try the rubber coated steel shim head gasket from felpro it is .015" thick Ive had good luck with them use new head bolts though. it should raise your compression to 9.5:1. A 270 comp cam will give you a little over 400 hp a 280 might get you to the 420s if I get the chace Ill run a few others but they will be more radical. The carb I should suggest would be a 650 holley type vacuum secondary I run a 750 double pumper which I increased the squirter size to eliminate bog and run a higher stall convertor. The 650 would be better for the street. The 450 hp nut is not the easiest thing to crack with stock components that will last in a street engine and to be honest you might be happier with a 400 hp engine that has a broder torque curve. Ive run alot of engine combos through dd dyno dragstrip similator and peak hp absolutly does not tell the entire story.