Thread: 1968 327

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I have a 1968 Mark Twain Boat that has a 327 in it well today i learned that the block is cracked my Question would be is on the front of the motor there is a Plate that mounts the motor to the boat are all small blocks have the same bolt pattern in the front and rear?

All Chevy Small Blocks, 265 cu. in. thru 400 cu. in. from 1955 thru 1996, "first and second generation", have two bolt bosses on each side of the timing cover just above the pan rail; they are oriented one above the other, and may or may not be threaded. These are the points where the front mounts bolted on in '55 thru '57 cars, and thru '59 pickups. Depending on your mount plate, itmay bolt in just these holes, or it may be larger and also bolt at the water pump mounts between the water pump and the block; however, it should fit small blocks '55 thru '96.

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Ok Looks to me it's bolted at the water pump and 2 other bolts on each side of timing cover The Casting number on the block is 3858180 looks to me a 64-67 can't tell if it's a 2 bolt main or 4

3858180 - 250-375hp, 2 bolt main, Tonawanda plant. These motors went into 64-67 passenger cars, Chevelles, Camaros and trucks. A few (very few) possibly went into '65 Vettes.

A picture of the front of the engine would help immensely; there are quite a few styles of front and rear mount plates for Chevy engines in marine applications. Look it over really well, see if you can find any numbers or markings on the mount plate; the casting number indicates the block is a '64 to '67 327 with 2 bolt main caps, and a universal application - in other words, it was used in many different applications; a generic engine block if you want to call it that. So, as I said before, any first gen or second gen small block Chevy will fit in it's place, you just need to be careful not to overpower your hull.

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Here's a Pic (hope it works) I JB welded the Block on the out side Ran water no leaks Must be crack on the inside too after running engine for 20 mins the oil is Milky Toast, but the good news my brother has a 350 small block 4 bolt main in his Storage unit i will pick that up in the next week and rebuild it

It might be a Mercury inboard/outboard unit. They used a lot of GM units for power. They typically painted everything black. The last one I worked on was listed as 100 horsepower, it used a 6 cylinder chevy and was mounted in a 24 foot "Slickcraft".

I have a crazy question i was looking up parts like the camshaft and it comes up right hand camshaft or left hand camshaft I do know that for some reason i have a left hand Prop, Looking straight at the motor what way should this be turning?

That whole front assembly should just swap right over to another first gen or second gen small block; just keep good notes and take a lot of pictures for reference as you dis-assemble it. The right hand cam-left hand cam thing: it seems to me that in multi engine applications, one engine turns one direction and the other goes opposite, something about balancing the thrust from the props so your boat doesn't try to run in circles all the time. There are a couple of guys here who are former marine mechanics, maybe they will chime in here. The only thing I ever had to do with boat engines was getting them out of the hull so we could get to the rebuild part, and then dropping them back in right where they came from, and they were always single engine boats. I have reached the limit of my experience here.

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Originally Posted by Superbee68104

I have a crazy question i was looking up parts like the camshaft and it comes up right hand camshaft or left hand camshaft I do know that for some reason i have a left hand Prop, Looking straight at the motor what way should this be turning?

Looking straight on at the front of the motor, the crank would be turning clockwise on an automotive application Chevy.

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Some marine applications used a special crank. What was special about it is the front and rear seal area, the crank has "lines" formed in the crank which is used to "pull" the oil back into the crankcase. If you use the wrong crank it will actually push the oil out, ask me how I know this!?!?! Yep, btdt!

And if it is 2 engines side by side, then one of them will turn in a reverse rotation to counteract the thrust.

Behind the boat look at the prop--if it needs to turn clockwise from that position, then the engine will need to turn in a counter clockwise rotation from the front of engine view--------and that's reverse rotation

If the prop needs to turn counter clockwise from the rear view----the engine will be clockwise(standard automotive ) from the front--------

Then there is V drives?????????

and of course besides the crank grooves for the rear rope seal era of engines-----there is issue of waterpump if they use automotive pump------

Generators might be issue IIRC but alternators will work either direction

And of course-oil pump and distributor

this might be an anti -clockwise motor as the fins on the alternator pulley are setup for reverse rotation.
pull the coil lead off an crank the starter while watching the pullies an you will soon know.

So, it turns out there is a lot more to this than meets the eye. I'm going to keep an eye on this, maybe learn something new.

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Well I will get a battery in there and fined out if it runs clockwise or counter clockwise i never paid attention to that will let you know