Small Block & Big Block Chevy Specific Mouse & Rat Motor Discussion & Conversions

older small block differences

Old Apr 6, 2006 | 01:15 PM
  #1  
Russell1337's Avatar
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Default older small block differences

i have a 305 mercruiser (chevy) in my boat, that has a cracked block

the boat is an 85, the motor is carburated.

the valve covers on this motor have 4 bolts, which are on the edges of the valve cover.

i purchased a 93 chevy 3/4 ton van for $225 with 63K mi on it. its a throttle body injected 350. i also got my money back when i scrapped the van so its a free motor. runs like a dream.

now this motor has the bolts on the center of the valve covers.

my intentions are to swap over all the marine parts, including oil pan (gonna get a new marine pump and pickup) swap the intake/carb/dist. use marine intake gaskets, brass freeze plugs and whatever else came on this boat.

i have a few concerns on what is compatible

exhaust manifolds: will the ones off the boat mate up to these heads?
intake manifold: will it bolt up to the heads?
fuel pump: theres a little plate covering where the fuel pump would go. is the rod that drives the pump still there on the 93 motor?
distributor: any problems swapping this over? both motors turn the same way, the boats is not reversed

also, whats the chances of this motor being 4 bolt main? i havent had the pan off of it yet?

thanks,
Russell
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Old Apr 6, 2006 | 01:54 PM
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From: Liberty SC
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Exhaust will blot right up, 85 intake will need the 4 center bolt holes elongated or get a cheap intake for 86 up heads, The fuel pump rod will not be there however the one from the 85 will slide right in, Distributer will drop right in, Not sure about the 4 bolt, when you swap pans you will know, BTW the 85 is most likely a 2pc rear main seal, and the 93 is a 1pc. seal so the oil pans will not interchange.
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Old Apr 9, 2006 | 09:41 AM
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Make sure that the cam has a lobe for the fuel pump. I swapped a motor once and the block had the hole for the fuel pump rod but the cam had no lobe to run it!!!! Took me awhile to figure out why I had no fuel.
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Old Apr 11, 2006 | 03:19 PM
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If its anything like the older 350's, the casting number should end in 010 meaning its a 4 bolt main, I believe I have some pics of my block from my rebuild...
yep here ya go...
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Old Apr 11, 2006 | 03:20 PM
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Originally Posted by towood
Make sure that the cam has a lobe for the fuel pump. I swapped a motor once and the block had the hole for the fuel pump rod but the cam had no lobe to run it!!!! Took me awhile to figure out why I had no fuel.
don't boats need a cam designed for marine use anyway? I'm thinking he may need to swap that anyway. I don't know much about boats though so dont take my word for it.
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