350 Chris craft motor build

[Bwilliams]

Hi,

I am currently rebuilding 2 chris craft 350 motors. I am buying new 350 blocks, new complete balanced rotating assembly etc. I am trying to make it as reliable as possible after some complications last season!! I am unsure of what New Heads to purchase, as The old heads were a mixture of different casting numbers 882, 624 ....... I do not want to have remanufactured heads, but some nice solid reliable bare heads, I am going to have them built to my spec after rather than buying them complete. I have available some new 72cc bare heads, And will be using a Fel pro gasket ( 0.039 ) The guys who are building the rotating assemblies want to know what compression ratio I am going for, but I am unsure what I should be trying to get for a marine engine like this???? I am looking for some reliability not power. I have made a calculation that with a new block, 72cc heads and 0.039 gasket I will get 8.95 compression ratio. any advice on this would be much appreciated.

 

[RicardoMarine]

Sounds like you are enthusiastic about this, and want to do it correctly.

It often isn't as simple as just ordering parts. Everything must work together.
For examples:
Have you considered Marine Load Detonation? If so, steer clear of these:

Is a Quench Effect combustion chamber on the table for you?
With your new rotating assemblies..... just which piston profile is included?


Will your new piston profile work with the 72cc chamber heads giving you the correct static C/R?
Have you calculated this via one of the on-line C/R calculators?

Are you wanting to use Vortec cylinder heads.

Does your camshaft profile work in harmony with this C/R?

Does your compressed head gasket thickness of .039" work with your piston deck height dimension?
(using rough figures: .039" + .016" to .024" deck clearance = .055" to . 063" )
If you plan to include a quench effect, .055" to . 063" is on the high side for a Marine SBC!

After all the sugar, flour, honey, milk and butter are added, if you have not created a quench effect, you'll be leaving hp and torque on the table.
It all boils down to giving your engine a good LPCP!
No Quench Effect.......... NO good LPCP.


You may want to read this thread beginning at page #7.


And, NO.... this is not a Hot Rod or HP Auto build.
This is will offer you a more true SBC Marine build.



.

 

[bondo]

Sounds like you are enthusiastic about this, and want to do it correctly.

It often isn't as simple as just ordering parts. Everything must work together.
For examples:
Have you considered Marine Load Detonation? If so, steer clear of these:

Is a Quench Effect combustion chamber on the table for you?
With your new rotating assemblies..... just which piston profile is included?


Will your new piston profile work with the 72cc chamber heads giving you the correct static C/R?
Have you calculated this via one of the on-line C/R calculators?

Are you wanting to use Vortec cylinder heads.

Does your camshaft profile work in harmony with this C/R?

Does your compressed head gasket thickness of .039" work with your piston deck height dimension?
(using rough figures: .039" + .016" to .024" deck clearance = .055" to . 063" )
If you plan to include a quench effect, .055" to . 063" is on the high side for a Marine SBC!

After all the sugar, flour, honey, milk and butter are added, if you have not created a quench effect, you'll be leaving hp and torque on the table.
It all boils down to giving your engine a good LPCP!
No Quench Effect.......... NO good LPCP.


You may want to read this thread beginning at page #7.


And, NO.... this is not a Hot Rod or HP Auto build.
This is will offer you a more true SBC Marine build.



.

Ayuh,.... Agreed,... Vortec heads, deck the block to achieve .040" to .045" quench, 'n d-dish or inverted dome pistons to get 'bout 9.5:1 compression ratio,...

You'll have a strong, solid reliable Runner,...

 

[RicardoMarine]

Bill is a very smart man!

BTW, I've updated that thread and added some more info........... sump'n I've been wanting to do for a while.

Also, I'd strongly encourage anyone doing this, to be very careful when gathering information from the SBC Automotive enthusiast types.
They know their stuff.... don't get me wrong......., but they may not be aware of the subtle little differences that set the Automotive SBC far apart from the True SBC Marine build.


And while we're here... I want to get something off my chest.
(yes, I'm a wanna-be cartoonist!)