What is the minumum safe cylinder wall thickness for a 350? .040 over? Another thing that I noticed is some rust in my Water Jackets. It's only light surface but it is bothering me and I am starting to wonder about the strength of the block. It's a 4 bolt.

Also anyone know of good sources for good deals on blocks. I would be intrested in a new production pre 86 350 with all 5 mains to be 4 bolt "unless price is just too much for my blood" and 20 degree splayed. Everything else as standard as a production block. Anyone have any ideas on this? I would love to keep my current block but at the same time I want to do everything as perfect as possible. So I am really intested in my first question if anyone has any answers.

 

Hard to say, some blocks take a whole lot more than others. It depends on the casting thickness & core shift.

Get yourself some bow calipers and measure the wall thickness through the water holes, at least you'll have an idea of how thick things are.

Minimum thickness is 0.15"or so but some say less.

 

I have done that, I could only go around an inch down, I swear I had around .150 but I want to double check that. Anyways. I am really worried about this, and don't know what to do. I am spending every penny I don't even own yet trying to get the strongest parts already, Now if I throw it all in and go to run and blow a cylinder wall right out, well that would suck wouldn't it.

I am trying to find good prices on some blocks. I found so far the World Products block to be the cheapest at, 1,400 or something. Even cheaper than what I could find from GM so far.

 

.030 is probably the best/most popular. .040 is the next best with .060 over the least althought thousands of engines have been built that way...

Rust in the coolant jackets...that is perfectly normal. It IS cast iron and will rust if not coated. Have you had the block hot tanked? It will remove any foreign material...

4 bolt mains on all 5 mains....never heard of that. Notice the oil pump is mounted to the rear main...if you are making that much hp...a big block is in your future...

Good luck!

 

The worl products for 1400? where I've only seen the motown for 1700 and around 1900 for splayed caps.

Why don't you have a shop sonic test the wall thickness??

Marck


[Modified by Twin_Turbo, 7:17 AM 12/13/2002]

 

I don't have the Engine numbers in front of me, but Gm performance makes a Main setup that uses a 4 bolt cap on all the mains. It was the first time I saw anything like that too. and it's no more expensive than the WP motown block.
I know that price for the Motown block was from HP here in washington. I thought it was rather odd that they quoted a lower price than Summit. Perhaps they goofed.

I am thinking of getting billit end caps on my block and then placing block filler in there to help. Anyone know any details about Block Filler? Heat issues?

 

block filler, no heat issues. The majority of the heat is produced in the head and upper part of the bore. The only thing to keep in mind is you want to pour no further than the freeze plug bottoms, deck must be level and the filler must be spred out equally.

If you're doing it, do the filler first, then the splayed mains (if you're doing that) and have the cylinders honed & the mains line bored. The cylinders will distort a little from the block rock.

Marck

 

I like doing the filler and end caps as my first option, I just want to be assured that it would make the engine be capiable of holding 1k of hp and around 700 LB to torque. Personally with doing those modifications, I don't see the difference between that and a motown. Except for perhaps it does not have priority main oiling.

Also what exactly is the difference between Siemiesed "can't spell it's late";) and regular bores? Do all standard heads and manifolds bolt on the same way?

 

In a conventional block, the cylinder OD (inside the block) attaches only at the top and bottom. The cylinder is "free standing" and water flows 360* around the cylinder. In a siamesed block, the cylinders are joined (like the twins) together. No water can flow inbetween adjacent cylinders. Chevrolet first did this to make the cylinder walls thick enough for the 4.125" bore for the 400 engine.

RACE ON!!!

 

So I hear that if you fill the Block up to the freeze plug level, that the strength is increased by around 70% and you have around a 10 or 15% increase in heat. Does anyone agree or disagree with this?

 

It'll support the cylinder bores, it won't do anything for main webbing strength.

The 10-15% heat increase seems a little much too.

 

Hmmm.. Sounds good then .. I just want to be certain about the HP potential before I go and start reinforcing this motor.

 

1k of hp ???? wow, I'd get a motown, a little m or a bowtie.

 

yeah.. thats what I was worried about too.. I am jsut curious about the design differences really, If I were to fill the jackets, and place CNC caps on it would there be much of a strength differences. Also.... what is involved in filling the jackets? besides "properly pouring it in." what is about placing a torque plate on right after filling it.

 

The torque plate is not for filling the block, it's used when honing the cylinders. The plate mimicks a head bolted to the block. When you torque the head bolts to spec the block actually warps. When you use the torque plate when honing (preferrable fastened with the fasteners you're intending to use!! there's a difference between studs and bolts in the way they clamp & warp the block) you mimick this warping and create bores that are perfectly round when the head is bolted on. You'll get better sealing cylinders.

Going to billet steel splayed mains increases the cap strength and the caps grab into an area with more meat, making it stronger. However the bowtie, motown & little M blocks themselves are much stronger than the stock production blocks. They have thicker bores, stronger (thicker) webbing and other features like priority main oiling.

Do the math, if you're going to have to spend a small fortune to soup up your original block it might be smarter to go with one of those performance blocks and enjoy the improvements over the stock block.

Splayed mains are 200$ a set (moroso), they have to be machined down to sit properly in the registers, the block has to be align bored, you have to fill the block, have it honed afterwards, then maybe some decking to 9.000 some small stuff here, some small stuff there... see what I mean?

Marck


[Modified by Twin_Turbo, 6:57 AM 12/16/2002]

 

Yeah thats what I thought the Torque plate was for, It just made me question cause they basically were stating it like it was a definite part of the process. in my case amazingly I have great walls still with maybe at the most 1,500 miles on it. I guess I am just a sucker for power. who knows what I will accomplish when I hit my prime years.

I have come to the conclusion today that I might as well suck it up and invest in a REAL block. It just really hurts that I have yet another 3k or so to spend on a block and rotating assembily, But I guess it is worth it cause I don't think it would be fun to fnish this and then push the throttle and *SNAP* *BAM* Piston goes flying through the hood windshield and inches from my head. So Now it's time to start searching for a performance block.

Cough Cough Anyone got any hookups to get a good deal on a good performance block?????? ANYONE??