Mercruiser 5.7 Vortec Intake Manifold gasket mismatch?

[Ragazzoni]

Hi Masters and Gurus!
I have had water in oil issues with my Mercruiser 350 and machined the heads and changed to new risers/ exmanifolds— now found the problem. When taking the intake manifold off its clear that the gasket did not seal the water passage at the rear... This has not been a problem earlier years, so I guess we used a different gasket that dont allow the shape of the intake.

The heads look like Vortecs, bolt on like vortecs, got combustion chambers like vortecs, but are something unknown- even after extensive search on #13120906
The intake is also unknown- though was fitted with 4barr Holley. (atm 2b Holley)

Question: Anyone know of a gasket with small water passages that could seal the gap in the pictures?
The current gasket is ”Felpro 90131 (R1)”





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Kind Regards
/Björn, Gothenburg, Sweden

Donzi Ragazza R25

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[Scott Danforth]

are you sure on the casting number? it is not coming up http://www.mortec.com/castnum.htm

the vortec marine intake set is Felpro 17303

 

[Ragazzoni]

Yes - Those are the only numbers I can find. Another guy had the same dilemma. It seems all gaskets fits on the heads.. The manifold that dont seem to have proper wallthickness. Will look at the set you suggested. Thanks a lot!

 

[alldodge]

This has come up before but no answer

https://forums.iboats.com/forum/eng...d-engines-outdrives/10334191-vortec-906-heads

This goes into detail about the two versions 906 and 062

http://nastyz28.com/threads/vortec-cylinder-heads-the-definitive-guide.56505/

 

[Scott Danforth]

my guess is these are the 906 heads, however a batch may have been made with incorrect casting number

google comes back with limited hits, two are the iboats threads

the GM casting number for the 906 heads is
10239906...96-up...350.........."Vortec 5700", "L31", 64cc chamber, 170cc intake port, 1.94"/1.5" valves

 

[Scott06]

Are the heads a problem for sealing or just the intake ? It looked to me that only the intake was missing a little material ? If so and the intake is aluminum have a machine shop weld material that is missing and mill it you can use the same gaskets if this is the case

 

[AShipShow]

Either do what scott said or could be a good time for a edelbrock manifold and 4bbl upgrade to make use of those vortec heads.

 

[Scott Danforth]

Either do what scott said or could be a good time for a edelbrock manifold and 4bbl upgrade to make use of those vortec heads.

it already is an edelbrock intake. note the lack of the bronze in the water passages. BTW, no power advantage on the edelbrock intake over stock cast iron at RPM's a boat motor turns.

 

[Bondo]

Ayuh,... I donno which one, considerin' Rag's location, but I'd No doubt, find another intake,... probably a carb too,....

I love the AFB carbs,....

 

[Ragazzoni]

Are the heads a problem for sealing or just the intake ? It looked to me that only the intake was missing a little material ? If so and the intake is aluminum have a machine shop weld material that is missing and mill it you can use the same gaskets if this is the case

This is probably the way to go. Its only ... a cut off toenail (20 square millimeters in inches? to weld.. Will do it and maybe grind it down manually.. or ask previous boss if I can come borrow the old milling machine..

Would be easiest with gasket, but with my luck its a bastard intake for a Italianmade Acadian Submarine made to run on Saltwater..

Thanks for your replies!! Very greatful. If use of a boat in Gothenburg archipelago, come by.. (bring toolbox)

/Björn

 

[Ragazzoni]

Either do what scott said or could be a good time for a edelbrock manifold and 4bbl upgrade to make use of those vortec heads.

I got a 4bbl Holley that was put aside due to some unexplained flooding. I will check it over to see if its worth fixing.

Any input of what size carb I should have? Some ppl say a little extra is good, some say higher airspeed with smaller is better for ”mileage” .. If I dont consider it possible to run economical anyhow, what size shoul I go with? ..and is the sizes corresponding between e.g. Holley and RockOrchestra?

/björn

 

[achris]

...Any input of what size carb I should have? ...

A marine 5.7 litre engine can't use any more than a 650 cfm.... These are not high revving engines that require huge venturis to 'breathe'... If you put a 'big' carb on (more than 650cfm), idle quality will suffer. BTW, Merc stopped using Holley because fires in boats are bad news. Best carb for those engines is the AFB. Made originally by Carter, then copied by Weber (as the 9600 series) and Edelbrock (the 1409).... I also don't have a problem with Q-jets, although they can be finicky to set up.

Chris.........
(Currently off Norway. )

 

[Scott Danforth]

yet Ilmore, Volvo and OMC used Holleys. I personally like holley carbs.

a small block will 5000 RPM top end and 85% volumetric efficiency only need 500 CFM. 600 CFM is more than enough as that would be over 115% volumetric efficiency

no mater what the carb is (holley, webber, rochester, edelbrock ) 600-650 cfm max

flooding on a holly is improper float height or a failed float or a failed needle/seat. running rich in low to mid RPM is usually a broken power valve