427 marine block

[Hipopinto]

Hey all

I’m potentially working out a deal on a 427 marine block

I would like it to be for a large Cubic inch Monster

What should I look for on these?

Obviously BBM is a better block but are these worth using?

What are these going for now a days? I just want to make a fair offer should it shake out!

Any feedback would be great

Dave

[thatdarncat]

Hey all

I’m potentially working out a deal on a 427 marine block

I would like it to be for a large Cubic inch Monster

What should I look for on these?

Obviously BBM is a better block but are these worth using?

What are these going for now a days? I just want to make a fair offer should it shake out!

Any feedback would be great

Dave

There’s a wide combination of 427 marine blocks, some are center oilers, a few are side oilers, and many were made with 427 blocks that used side oiler molds in the casting, but machined as Center Oilers, with a portion of the side oiler “hump” on the side machined away. Like any FE it should really be sonic tested, preferably before you spend your money, but certainly before you build it. The issue with a 427 is you’re paying a big premium for a “427”, and then to find out it has thin cylinder walls can be depressing. And like any block, you should find out if it has already been bored and how much, that will effect value too. With marine 427’s you want to find out if it had a closed loop cooling system, or cooled with fresh water or salt water. That can effect how much corrosion is in the water jacket. With the sonic test you’ll have a better idea how thick the cylinder walls are, and how much core shift there is, and where the core shift is, and that will guide if you’re even able to bore it, and how much. Along with all that the usual things apply to checking a block - testing for cracks, stripped bolt holes, previous repairs, cracks in the mains or oil passages, etc. Another thing to consider is best practice now days is to leave the cylinder walls as thick as possible for best ring seal, and 427 blocks sometimes have relatively thin cylinder walls to start with, it’s really luck of the draw.

If you really want to build a “Large cubic inch” FE you’ll be miles ahead going with the BBM to start, but we all understand the allure of 427 fever.

[Hipopinto]

Ok

This is the type of info I’m looking for!

I just don’t want an expensive piece of junk

Dave

[Katz427]

Well, my story, looking for a decent 427 block. Over 1 year looking, buying one, just to find out, I should have passed on it. Ended up buying a BBM. All the blocks, marine, center or side oiler, all needed machine work, and a sleeve or two. Yes and the least expensive one was asking $2500. I bought it but it was in need of a couple more sleeves. So on the advice of the machinist, I sold it, (got $575 for it). I did find a nice standard bore marine block for $ 3300. It would have cleaned up at .010 over, but then I was basically at the price of a new BBM. The gentleman did eventually sell the block. Looking back ,I am glad to have the BBM block. ( I looked at probably 12 blocks, so good luck to you )

[Hipopinto]

You guys are helping make my mind up quickly!

I think I will hold out and just get a BBM

if I can be in at 2000 I still have to machine it and after all the costs will be close to a BBM cost and not be as strong or as well made

Thanks guys
Dave

[70tp]

Still be careful of closed loop cooling     The one I have was closed loop and apparently at one time it leaked or somehow still got salt water into it.    Looked ok from the outside but I think it may be junk.  Lots of corrosion at the deck surface around the end water slots   I’m not sure it would hold a head gasket and then there is the problem of how thick are the cyls. 

[HR427]

I had mine bored to 4.249..... the thinnest spot was .125

It was bored some more and finished at 4.280. Its been filled up to the water pump holes.

[fairlaniac]

Mine is a C6AE-B  '66 Marine 427 casted as a sided oiler but not drilled. It has good wall thickness (I cannot located my sonic sheet at the moment) and the bore was 4.263. I made a 484 stroker of it and finished the build back in April. It runs great and runs around 190 degree on average using a non OEM radiator and twin Spal electric fans.

[HarleyJack17]

Doesn't the BBM block require finishing machine work? Just so the OP understands fully, it is not get a BBM and put it together.

[blykins]

Doesn't the BBM block require finishing machine work? Just so the OP understands fully, it is not get a BBM and put it together.

Yep.  Doesn't matter what brand/type block it is, they all require the same stuff.  Shelby, BBM, Dart, World, you name it.  None of them are ready to run out of the box.

[gt350hr]

   Buying a new block will save you in the long run. As mentioned above , you can end up spending a TON in saving the old stuff and it's still OLD.

[TomP]

I suppose it depends what you have to pay for it, if it's more than half the cost of an aftermarket block then i'd save up the extra. If it's a bunch less then it's worth building but check for it having salt water damage. One locally needs sleeves because the bores are eaten through from the water jacket side. I looked at another where the deck water passages were enlarged past the gasket sealing rings.

I run a marine block, no issues with that at all.