suppose to be 305 but on the back of block says gm5.7lc

[boatermarquis]

This guy got motor cheap, but says it's a 305, but has gm5.7lc stamped into block.on top has all the 5.0 vs alpha one stuff.could it be 350?

 

[boatermarquis]

Re: suppose to be 305 but on the back of block says gm5.7lc

Serial 14893638

 

[boatermarquis]

Re: suppose to be 305 but on the back of block says gm5.7lc

I'm thinking they took car motor and rebuilt it to marine specs.it had block drain plugs.but no mercruiser tag on side.doesnt even look like tag was ever there.and date code i017 sept, first 1987.did mercruiser drill holes for tag?

 

[scoflaw]

Re: suppose to be 305 but on the back of block says gm5.7lc

As it would sit in a car, the 5.7L would be cast not stamped on the drivers side by the bell housing and if that's the case 5.7 means 5.7

 

[alldodge]

Re: suppose to be 305 but on the back of block says gm5.7lc

Serial 14893638

I cannot find the casting number for any GM block. It probably is a 350 and your number could be a foundry number. Look at this link for casting number locations

Chevy V8 Engine Block and Head Casting Number Locations

 

[Bondo]

Re: suppose to be 305 but on the back of block says gm5.7lc

This guy got motor cheap, but says it's a 305, but has gm5.7lc stamped into block.on top has all the 5.0 vs alpha one stuff.could it be 350?

Ayuh,.... Dead 305s are replaced with 350 Long Blocks All the time,....

I'm guessin' the Merc dressin's no doubt were on a 305 one day,...

If it says 5.7l on the aft flange, That's what it is,... unless somebody stroked it to a 383,....

 

[boatermarquis]

Re: suppose to be 305 but on the back of block says gm5.7lc

14093638 that's the serial.i was just worried about it not having marine internals.im thinking they put all the 305 stuff back on it heads ect.i know I could use it some day in a boat.500 bucks isn't bad if internals marine.

 

[Walt T]

Re: suppose to be 305 but on the back of block says gm5.7lc

Head casting numbers are under the valve covers. As for marine internals, it's all the same. Head gaskets should be marine, cam may be a 'marine' grind which is subjective but I've found them to be somewhat of an 'RV' cam, but not always. A lot of folks are under the impression marine motors are beefier or cast thicker, or always have 4 bolt mains. Not true. Otherwise there would be a demand for marine motors in racing applications. Its the externals you should be worried about. 5.7 is a 5.7

 

[boatermarquis]

Re: suppose to be 305 but on the back of block says gm5.7lc

The motor was rebuilt with only 400 hours on it.if 305 heads raise the compression, can I do a test to see if it's got 305 heads?

 

[Walt T]

Re: suppose to be 305 but on the back of block says gm5.7lc

A lot of heads were used on both. You can look at the markings on the end of the head and narrow it down a bit but casting numbers are best. Compression is usually the same on both.

Chevy cylinder head Identification - Small block casting numbers

http://www.crankshaftcoalition.com/wiki/SBC_cylinder_head_identification

 

[Bondo]

Re: suppose to be 305 but on the back of block says gm5.7lc

The motor was rebuilt with only 400 hours on it.if 305 heads raise the compression, can I do a test to see if it's got 305 heads?

Ayuh,.... More than likely, a Long Block was swapped, 'n the 305 heads went away with their block,...

Check the head's castin' numbers to be sure,...