SBC INTAKE MANIFOLDS

[Larryowen]

To replace my abused and tired SBC 350, I have ordered a 350/5.7L long block from Summit -- Vortec heads, 1-piece main seal, roller rockers -- 373 HP / 400# torque. $2,599.

Concerning the intake manifold for the (Vortec) heads: does it have to be marine designated? Could I choose an Edelbrock standard performance spread bore manifold and use brass or stainless fasteners ... and even paint it to curb corrosion?

Also, what are your thoughts about aluminum vs cast iron. thanks!

[fitz73222]

The standard intake manifolds on marine engines were cast iron just like in their automotive applications. You can use whatever material you like. Holman Moody Ford engines used in some Donzi's had beautiful aluminum intakes back in the day. Maybe give it a shot of high temp clear coat to keep it from getting powdery if you go with aluminum. You will need to have brass freeze plugs, a sealed starter, distributor  and alternator for marine use to keep sparks away from fumes. 

[GoneFission]

Summit sells marine long blocks:  https://www.summitracing.com/search/part-type/crate-engines/brand/first-mate-marine/oil-pan-included/yes/rear-main-seal-style/1-piece/cam-style/hydraulic-roller-tappet?N=4294869887%2B4294447174%2B402160%2B4294869607%2B4294924890%2B4294891641&SortBy=DisplayPrice&SortOrder=Ascending&keyword=marine%20engine 

Or you could consider a replacement full marine engine: 
https://www.michiganmotorz.com/turn-carbureted-engines-c-49_78.html 

https://marineenginedepot.com/20024/0/Mercruiser-882575-New-5.7L-GM-Marine-Partial-Engine-Package 

You should not use an automotive engine for a marine application, as they are not suitable for enclosed locations (sparks cause explosions!) and do not have the corrosion resistant internal parts.  You can refit a auto engine with marine parts (starter, carb, water pump, intake, freeze plugs, distributor, etc.), but it is often more expensive a difficult than getting an engine built as a marine model. 

Hope this helps - good luck! 

[wingtime]

The big question is do you have raw water cooling or do you have a heat exchanger with a closed water cooling system.  Also some of the marine intakes had the carb mount on an angle so the carb sat level.  This is used since many marine inboards are installed on an angle.  If yours is level then you don't need it.  As mentioned brass freeze plugs.  Also some marine heads have have differnt valves and seats.  Keep in mind automotive engines are not run at a constant HIGH RPM like boat motors are and the valves can take a beating an fail.  I learned this from replacing a marine long block in the past with a crate motor... 

[GoneFission]

Don't forget the starter location - marine engines have the starter on top of the engine - most automotive engines have the starter toward the bottom - in the water if you have a wet bilge.