Engine deck height 5.7 block

[Limited-Time]

I have a Mercruiser 5.7 that blew a head gasket between (#s 3&5), also burned the head, (now junk) and block. The damage to the block appears minimal, small depression about ¼ of the way across the area between the cylinders. Looks to be .005 to .010 deep, at the deepest point, (nearest the #5 cylinder). I assume this needs to be corrected before I reassemble the engine.<br /><br />Opinions or options please. <br /><br />If it requires machining is there a "safe" or maximum amount that a block (5.7) can be decked and still be reassembled using stock components?

 

[Buttanic]

Re: Engine deck height 5.7 block

You need to take a measurement with the piston at top dead center(TDC)to see what the difference is between the top of the piston and the deck. You may be able to cut as much as .005 from the deck without having the piston top above it at TDC. Also the head gasket thickness needs to be taken into consideration as it will allow for the piston top to be one or two thousanths above the deck and still have sufficent piston to head clearence. Any automotive machine shop should be able to advise you if the block can be saved.

 

[Bondo]

Re: Engine deck height 5.7 block

You also have to take into account the Valve Train Geometry,... You might need different length pushrods......<br />

Any automotive machine shop should be able to advise you if the block can be saved. <br />

A Hot Rod/ Local Racecar engine builder/ MachineShop is Even Better............

 

[Buttanic]

Re: Engine deck height 5.7 block

I don't think piston to valve clearence would be an issue with a stock lift marine cam.

 

[Limited-Time]

Re: Engine deck height 5.7 block

Thanks for the responses. I know cutting the deck height down to re-establish the correct flatness and block geometry is a pretty standard thing. And I figured as popular as the 5.7 SBC block is (80+ zillion produced since the late 60"s) there may be a standard allowable amount of material that could be removed.

 

[rodbolt]

Re: Engine deck height 5.7 block

I have taken as much .01 off many decks. but if you do one side do the other. keeps things level. same as shaving heads. some got shaved so much it caused issures with the distributer and intake mounting but .005 to .01 should be ok. I would disscuss this with the machinist doing the work myself.

 

[Limited-Time]

Re: Engine deck height 5.7 block

Thanks rodbolt,<br />Will the removal of that amount of material effect the fit of the intake manifold? I know if the block/head heights are modified to extensively the intake manifold needs to be modified as well.

 

[rodbolt]

Re: Engine deck height 5.7 block

.01 should have no effect on the manifold or distributer height. wont affect rocker geomety enough to worry with either. like I said though its something to disscuss with the machinist thats going to deck it.