A question for all folks with MARINE intake on board, please comment!!!

**Aksl** · 11-09-2016

Hi guys,I wonder, my chevy k1500 5.7l 1990, with vortec head swap and CSFI manifold (spider injector), is not very stable working, and i would like to change to MPFI, but i wonder:With the marine intake there is a well done instraction "pacificp" forum, so for now no questions about it. But the main question is, why did you choose marine mercruser manifold, why not to use the manifold from pontiac firebird, impala, and other models with L31 engine and exterior fuel rails, would it not be easier? Thank you all in advance.

**mihela** · 11-09-2016

The F-body cars do not use vortec heads. They are LT1 engines that use a different bolt pattern and have no provisions for a rear mounted distributor.

**1project2many** · 11-09-2016

why not to use the manifold from pontiac firebird, impala, and other models with L31 engine and exterior fuel rails

There are none that I'm aware of. L31 is truck engine with only one configuration. Marine engines use same heads as L31 so intakes will fit L31. Adapting LT1 engine is challenging and at time of first marine swaps, was equal or greater money with much additional work. Now you can get a specially made base to use the tuned port intakes but those bases weren't around several years ago.

**Aksl** · 11-10-2016

Thank you very much for explanation, I run in a Pontiac Firebird 1982 thru 1992 Heynes repair manual book, and in it, all looks the same as on my engine. Since I have changed the heads to vortec, and the entire top end (manifold, CSFI, throttle body and so on), I wanted to try on the manifold from an impala my friend is fixing... So I guess it will not be necessary, since you confirmed that bolt pattern is different, and it will be extremely difficult to adapt (if possible at all). I have another question, I contacted some boat service, and they seem to have the manifold with all of the attached equipment on, from mercruser 5.7 MPFI marine engine, but they have two different versions, the difference is in injector fitment, the degree is different, one is 45º and the other one is 90º fitment. So which one do I need, for marine intake transformation?Thank you once again for your help!

**1project2many** · 11-10-2016

you confirmed that bolt pattern is different, and it will be extremely difficult to adapt (if possible at all).

There are aftermarket parts that will adapt your manifold.
http://sdparts.com/i-23896057-sdpc-s...baseplate.html

Marine intakes come in several versions. I have never seen them listed as 90 deg or 45 degree injector fitment but it looks like the commonly swapped manifold might be 45 degree. Can they send pictures or part numbers?