Chevrolet Demon 5,7 l marine engine

BucketLister

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Apr 22, 2022
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Does anyone know what a Chevy Demon 5.7l marine engine is ? What are their weaknesses or quirks. What manual should I use for it?
 

Bondo

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Ayuh,.... Welcome Aboard,...... Where are you gettin' the name Demon,..??

The 350 Chevy is probably the most common boat motor in the world,.....
 

BucketLister

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Apr 22, 2022
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Ayuh,.... Welcome Aboard,...... Where are you gettin' the name Demon,..??

The 350 Chevy is probably the most common boat motor in the world,.....
The person I got the boat from called it a demon, but I never heard of a Demon Chevy before so I just wanted to check,after all I haven't heard of everything.
 

Scott Danforth

Grumpy old guy who plays with boats
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So for an engine manual I just use a Chevy 350 for it's year, Right?
No.

while the GM motor is used by most all of the marinizers. you need to have the manual from the marinizer. Volvo Penta, Mercruiser, etc.

Chevrolet doesnt marinize motors and Demon is a variant of a dodge dart, or a variant of a holley carb

you obviously bought the boat from someone that didnt know what they didnt know. what else did they not do maintenance wise, or what else is wrong with the boat?


so, start at the beginning.

what did you buy? boat brand, length, etc.
what motor and drive are in it? post serial numbers
did you test it out thoroughly?
did you sea trial it?
did you inspect it for rot or damage?
 

tpenfield

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Jul 18, 2011
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The person I got the boat from called it a demon . . .

Probably why he was selling the boat :LOL: . . .

There are moments when we all call our boats names of various sorts, although demon is not highly used as opposed to some other choice words/phrases.
 

BucketLister

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Apr 22, 2022
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No.

while the GM motor is used by most all of the marinizers. you need to have the manual from the marinizer. Volvo Penta, Mercruiser, etc.

Chevrolet doesnt marinize motors and Demon is a variant of a dodge dart, or a variant of a holley carb

you obviously bought the boat from someone that didnt know what they didnt know. what else did they not do maintenance wise, or what else is wrong with the boat?


so, start at the beginning.

what did you buy? boat brand, length, etc.
what motor and drive are in it? post serial numbers
did you test it out thoroughly?
did you sea trial it?
did you inspect it for rot or damage?
Sunrunner ultra 292 with a Chevy 5.7l engine coupled with a Volvo Penta 290 outdrive with twin props. It had no damage but needed cosmetic work and upgrading of it's electronics and isinglass.the interior was also remodeled. It runs fine but is not a speed demon, just a big cruiser for a family.
 

Scott Danforth

Grumpy old guy who plays with boats
Joined
Jul 23, 2011
Messages
39,680
Sunrunner ultra 292 with a Chevy 5.7l engine coupled with a Volvo Penta 290 outdrive with twin props. It had no damage but needed cosmetic work and upgrading of it's electronics and isinglass.the interior was also remodeled. It runs fine but is not a speed demon, just a big cruiser for a family.
without a year, cant help with the model.

however I am speculating...... if its an AQ271, or an AQ290 or AQ311, it would have a holley 715 CFM 4150 carburetor that the prior owner could either have swapped out the bowls for Demon Carburetor bowls. hence the confusion. Again, I am speculating.

a Sunrunner ultra 292 comes up as 1989. so that would most likely be an AQ271C or AQ271D

your boat is a bit on the big side for a small block. that thing has to be propped down to B2's or B3's to get a boat that big up on plane.
 

BucketLister

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Joined
Apr 22, 2022
Messages
13
without a year, cant help with the model.

however I am speculating...... if its an AQ271, or an AQ290 or AQ311, it would have a holley 715 CFM 4150 carburetor that the prior owner could either have swapped out the bowls for Demon Carburetor bowls. hence the confusion. Again, I am speculating.

a Sunrunner ultra 292 comes up as 1989. so that would most likely be an AQ271C or AQ271D

your boat is a bit on the big side for a small block. that thing has to be propped down to B2's or B3's to get a boat that big up on plane.
It has a dual prop setup. It gets up on plane around half throttle.
 
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