bowtie89

ok it seams as though that a good start for me to get some decent horsepower for my 1989 pre-vortec 350 magnum would be to upgrade to vortec heads and a manifold change!! What gains would I see?? Where can I get these it seems there are so many different ones there are a million on ebay. I do a search and it seems there are so many! Can they be used for marine?? WHere is the best place to get them for cheap?? Do you guys have p/n for either or know a good place to start?

Dangerous Dave

You might want to consider sending your current heads out to a good machine shop/engine builder and get some port work done to them if your on a tight budget. That will probably be cheaper (depending on who you use) than getting a new set of vortec heads. Are you running in salt water or fresh? Don't go with aluminum heads if your in salt. Also, a good top end freshen up along with a new cam, intake, carb, exhaust might give you the horsepower you are looking for.
Dave

bowtie89

I bought the boat last year and it has a 1989 engine in it!! It has excellent oil pressure but hte manifolds were so done I just changed them and the risers!! I am afraid to open the engine up and see how bad it is inside from all the years of saltwater! Liberator 21 said his was pretty bad!! So I may need new heads but yes that is an idea I will look at
thanks

Liberator21

If you're going to go Vortec, remember: In stock trim they don't have 2.02 valves, and they are limited to the amount of cam you can use before you have to start machining spring seats (Bruce Springseat?). The Vortec is an excellent head, but watch out on Ebay, there are one or two casting numbers that are supposed to be junk. You'll have to research that. You'll have to keep an eye out for that when buying used. Go to gmpartsdirect.com. They have the best prices I've seen on all that stuff. They also have the Vortec Hi rise cast iron intake you'll need if you go with those heads. I bought my heads from them.

Paul

bowtie89

12558060_ - Cast Iron Vortec Cylinder Head Assembly
_ _ _




This production Vortec iron cylinder head was first used on the 1996 pickup truck RPO L31 with fuel injection. The intake and exhaust port are very similar to the Corvette 350 LT1 heads. This head includes 1.94" intake valves and 1.50" exhaust valves, with pressed-in 3/8" studs. This head with compatible valves flows more air than bow tie head P/N 10134392, but the casting may not be as durable. The water passages are the same as the original 1955 small block design. The eight-bolt intake bolt pattern is totally different than the early model V8 12-bolt design. Use new manifold P/N 12366573, 12496820, 12496822. _
Technical Notes: The valves seats in these heads can be machined to 2.02" intake and 1.60" exhaust. The rocker arm studs can be pinned or drilled and tapped 3/8". (Casting P/N 10239906 or 12558062.) _


and also using an edelbrock performer vortec intake manifold #2116 is this a good setup ????

bowtie89

I am running in salt water so I have heard that its risky to run the aluminium intake. What intake manifold should I use for the vortec heads that is inexpensive but will create some HP I don't mind changing it every couple years, just not every year!! thanks Does edelbrock make a manifold for salt water use?? also I need spread bore and square becuase I am going to stay with the Q-Jet for this year!! Next year will be a holley 650

Liberator21

There is a cast iron intake available for the vortec head. It's a high rise manifold based on the Z-28 aluminum manifold. The carb mounting flange is dual pattern. Fits both the Holley and the Q-Jet. Go to gmpartsdirect.com
They have the best price on it.

Paul

bowtie89

14096011 Cast Iron High Rise Manifold _ _ _
This manifold is a cast iron version of the aluminum Z-28 intake manifold. It offers the breathing benefits of a high-rise intake manifold in a less expensive package. It is recommended for Chevy enthusiasts on a budget, and for racers competing in classes which require a cast iron intake manifold. It is also suited to marine applications because cast iron is less susceptible to corrosion damage than aluminum. _
Technical Notes: The carburetor mounting pad accepts both standard flange and spread-bore four-barrel carburetors. This manifold is identified by orange paint on the Bow Tie.

Liberator21

Here it is. I thought it was dual pattern though. I'll have to double check the part numbers I have at home.

This dual-plane was designed for 283-400 ci small-block Chevrolet engines using the new vortec cylinder heads P/N 12464298 (bare) or 12558060 (complete). This high rise manifold was designed for maximum horsepower and a broad torque curve to give you great performance. This manifold accepts square bore (Holley design) carburetor and includes externally plumbed hot water crossover passage.
Technical Notes: Vortec heads were released on 1996 RPO L31 truck engines. This manifold only has four bolts attaching it to the cylinder head instead of six like all earlier models. Check for proper to carburetor clearance, especially on Corvettes. Use manifold gasket P/N 12529094 and (8) attachment bolts P/N 12550027.

bowtie89

Where does it say that it is cast iron? I am trying to look now!!

Thank you very much for your help!!!!!


Also if I trailer my boat and flushi it after everyuse will I be able to use aluminium??