350 vs 357 magnum

[MBAKER]

What exactly is the difference between a reman 350 and a 357 magnum?

Im shopping to repower my 5.0 and cant seem to get a clear answer on what the difference between the 2 is. One place I called has theem advertised as 5.7 service replacement long blocks, but when i called he said they are actually from GM marine and are 357 magnums, but are all the same part number as the mercurty 807449r60?

Any thoughts?

 

[r.j.dawg]

Re: 350 vs 357 magnum

I think there was a thread here about a year ago compairing the two. If I remember right, the 357 is a remaned 350 that's been overbored.

 

[MBAKER]

Re: 350 vs 357 magnum

Yeah i found some threads but not a clear answer. Ive seen or heard that magnum cranks were forged vs cast, ppistons were forged vs cast, and blocks were 4 bolt vs 2. But never can seem to get an answer nailed down.

Since any reman 350 is likely bored .030 - .040 over I really honestly wonder if the 'magnum' name isnt just an attempt to make it sound more attractive and sell more engines, and in reality they are exactlly the same.

 

[r.j.dawg]

Re: 350 vs 357 magnum

I had a 350 Mag MPI in my last boat and was told by our marina mechanic that the only difference it and the 5.7 EFI (TBI) was the fuel delivery was higher pressure creating a bit more HP. I believe the 5.7 EFI (TBI) was 280 HP and the 350 Mag MPI was 300 HP

 

[John_S]

Re: 350 vs 357 magnum

If you are talking the Mercury product, and not someone elses name for a reman,: http://www.mercurymarine.com/repower/mercruiser/remanufactured-mercruiser-products/
Look at the PDF reman guide.

The crate engines are new, the 357's are bored 0.040 over. I doubt that either has forged crank or pistons.

 

[John_S]

Re: 350 vs 357 magnum

I had a 350 Mag MPI in my last boat and was told by our marina mechanic that the only difference it and the 5.7 EFI (TBI) was the fuel delivery was higher pressure creating a bit more HP. I believe the 5.7 EFI (TBI) was 280 HP and the 350 Mag MPI was 300 HP

It is the difference in Throttle Body Injection and Multi-Port Injection. TBI uses an intake like a carb and can get similiar HP. MPI they have better tuned intake runners. Also, some of the 350MAG MPI's had a different cam.

 

[Bondo]

Re: 350 vs 357 magnum

Yeah i found some threads but not a clear answer. Ive seen or heard that magnum cranks were forged vs cast, ppistons were forged vs cast, and blocks were 4 bolt vs 2. But never can seem to get an answer nailed down.

Since any reman 350 is likely bored .030 - .040 over I really honestly wonder if the 'magnum' name isnt just an attempt to make it sound more attractive and sell more engines, and in reality they are exactlly the same.

Ayuh,... Without seein' a cam card, 'n pictures of forgings, I believe This to be quite True...