305 SBC new/old style

Haven't found an answer after searchin for awhile so figured i'd just ask..

Friend of mine has a marine 305 chevy that using a gear to gear timing set. (cranks spins counterclockwise) The motor spun a main bearing and hurt a few rod bearings. In searching for another block we can only come across the new style blocks with the one piece rear main. His block is the old style with 2 piece seal. My question is can a new block be used in this situation or do we have to find an old style block? The end of the crank where the flexplate/flywheel bolt on are 2 different sizes. The newer style block's crank end is bigger around then his style and we have to use his flywheel because it has a spring setup on it resembling a clutch disc setup. We have to keep this setup for the paragon gearbox thats in the boat.
Also does anyone know if the bolt pattern on both blocks are the same to wear they mount to a bellhousing? Thanks for any info.


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Marine blocks and automotive blocks are interchangable. You don't need a marine block. There are literally millions of 2-piece blocks out there. You can't walk down the street without tripping on them. They're kinda like bird poop.

Old 2-piece cranks can be used in new blocks with an adapter. Its not cheap, but it works fine. The rest of the crank is the same, just the rear seal is different to account for the different crank.

But like I said, any of the hundred million 2-piece small block chevys out there will work fine.

If you're looking for a good rebuilt marine engine, allow me to suggest Rapid-O marine in Florida. Talk to Raul. Great stuff, cheap price, hundreds of reman engines ready to ship.



Yes they are the same. I just put a 1-piece 350 in my boat when I took out the 2-piece block that was in it.

This is the adapter Curtis is talking about for putting a 2-piece rear seal crank into a 1-piece rear seal block. But like he stated, 2-piece rear seal blocks are everywhere.
http://www.competitionproducts.com/...ts.asp?dept=367

I would like to stick with the old style block. I'm not really wanting to spend money just to adapt the crank for the new block when I can find a old one.

I have no idea where to look for an old block considering the junk yards probably got rid of a lot of their stuff when the steel prices sored last summer... Any idea where I can find one around the Ohio area??

www.craigslist.org.

Seriously dude, they're everywhere. Here is an example of a search in columbus:
http://columbus.craigslist.org/pts/1006929658.html
http://columbus.craigslist.org/pts/987541722.html

And Cleveland
http://cleveland.craigslist.org/pts/997471588.html

Any junkyard will sell you a 305 core for $150. They are seriously EVERYWHERE. In fact, keep looking and you can often find them for free.

While you're at it, upgrade to a 350. Everything external is identical, but inside its 45 more cubes

Or here http://www.rapidomarine.com/default...es/default.aspx

Complete remanufactured 305 marine engines for $1100
Or 350s for $1250

Add heads for another $150 and shipping to your door for $150, and you have a complete remanufactured engine delivered to your door for $1700. Swap over your intake, carb, ignition, and accessories and you're good to go. Raul is also very keen on negotiation. I negotiated a 350 vortec longblock with flywheel and a bellhousing for $1400 delivered. That was 2 years ago, but give him a shot and see what he can do for you.

Another good resource is Jamie at Lakeside Marine in North East PA.

Another fair resource is ebasicpower.com. Terrible customer service, but a huge selection of tough-to find parts for cheap.

It seems we might have found a good 305 block.. After thinking more into it I thought about another thing... The timing set in the boat is a gear to gear setup and with the way the starter bolts on it spins the crank backwards which in turn spins the cam like normal. My question here is does anyone know if the marine block would have the locating grooves for the bearings on the same side as the automotive one? I would think it wouldn't matter since the caps have the grooves in them that you match to the same side as block obviously. I ask that because the block spun 2 main bearings and it never ran low on oil and didn't have much time on the rebuild. I didn't rebuild the motor the last time it was done so I have no clue if it was assembled like it should have been..