Marine 5.7 Intake Manifold Question

[cc190cc]

Hello,

I have a 2nd gen chevy 5.7 engine going in my boat. This was a long block purchased from Rapido marine. I went to start swapping over parts from the blown up Volvo Penta 5.7 and the intake manifold is shot. I was scraping some scale rust off and a whole appeared in the exhaust crossover.

This engine has a closed loop cooling system so salt water/corrosion should not be an issue. This is a fuel injected motor (TBI) and the intake has an adapter plate on it for the TBI.

What replacement intake manifold should i purchase. I really dont want to spend 600 on a marine intake manifold. There is a comparable looking aluminum one at Summit for like 200 bucks.

Any opinions?? Should I be using a TBI intake or get another carburated one with adapter plate?

Any feedback opinions would be good.

**I noticed some people complaining about Rapido Marine not adjusting the valves on there long blocks. It has always been my understanding that this should be done a couple times. Right before startup and then after breakin.

Chad

 

[zbnutcase]

Re: Marine 5.7 Intake Manifold Question

I would stick to an iron manifold w/ adapter plate like stock. And if hydraulic lifters are adjusted PROPERLY at assembly time, they will never need readjusted. Thats one reason automakers used 'em, set them and forget them...

 

[cc190cc]

Re: Marine 5.7 Intake Manifold Question

Greetings,

Do you think stock was a carb intake with adapter plate. Seems like from factory it would come with the correct intake mani..

I am not spending 500 bucks on new cast marine intake so....any other opinions. Why wouldnt the aluminum one be ok if im not running salt water through it. It looks identical, just made from aluminum.

If this was a salt water cooled motor i would not even think about it.

Chad

 

[mkast]

Re: Marine 5.7 Intake Manifold Question

Take your intake manifold into your local GM dealership.
Match it up.

 

[cc190cc]

Re: Marine 5.7 Intake Manifold Question

Lol no, i can find the identical one online but am not paying 3-600 for marine intake on a freshwater cooled motor.

Take it to GM dealership? Sounds like an expensive proposition. If nobody has a better idea ill just go with the identical aluminum one i found for 200 bucks.

Thanks anyways,

Chad

 

[John_S]

Re: Marine 5.7 Intake Manifold Question

I think the main concern would be over the injector control. ie is there any impact for differences in flow from your current intake to the aluminum aftermarket? Mercs are not reprogrammable (or at least, cost effectively), not sure on volvo.

If the intake you currently have is the GM high-rise cast-iron, it can still be had new for a little over $200. GM numbers on it, or a picture posted would get it identified.

 

[redjmp]

Re: Marine 5.7 Intake Manifold Question

http://cgi.ebay.com/ebaymotors/5-7-...6177768QQptZBoatQ5fPartsQ5fAccessoriesQ5fGear
http://cgi.ebay.com/ebaymotors/Chev...tZVintageQ5fCarQ5fTruckQ5fPartsQ5fAccessories

 

[wire2]

Re: Marine 5.7 Intake Manifold Question

Since your injectors are in the throttle body, I'd go with an aluminum Edelbrock, Holley, or whatever. It saves 50 lbs.

I bought a new boat with a 5.7 in it in '84, put a Holley alum intake on it in '85, still on there working perfectly.

 

[GLENN M]

Re: Marine 5.7 Intake Manifold Question

i would stay away from using adapter plate.acording to holley you lose large airflow,why cant you get a stock alum manifold for tbi from auto wreckers . cheaper yet and would not cost you airflow,and your talking using auto manifold anyway.

 

[zbnutcase]

Re: Marine 5.7 Intake Manifold Question

Take your intake manifold into your local GM dealership.
Match it up.

Good luck with that one! Dealers don't stock manifolds, and auto dealers have NO access to marine/industrial division parts!

 

[cc190cc]

Re: Marine 5.7 Intake Manifold Question

OK...so i thought i found an identical replacement online like new, bought it, wrong one. The numbers on the chevy cast intake manifold that i have and need are 14036242. I cannot find this intake anywhere online, the outer bolt holes need to be angled, the inner need to be more flat. The motor is a one piece rear main 86-94 with center bold valve covers, i dont know why the intake i got doesnt work.

Chad

 

[Bondo]

Re: Marine 5.7 Intake Manifold Question

I cannot find this intake anywhere online, the outer bolt holes need to be angled, the inner need to be more flat.

Ayuh,... You have the manifold for motors Up to 1985....

You need the manifold for the 86 to 95 motors...

96, 'n later is Vortec style...