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I wanted forged pistons to be able to run a blower without worrying about the pistons coming apart. Since I have to buy them new I decided to get the size that would be the least expensive to get rings for. Other reasons are that the upgraded piston designs now being employed are far superior to old school and stock stuff. Thinner ring designs with different tensions and minimum groove/ring clearances, exact compression with a given combustion chamber volume, lighter weight, pin oiling, spiral locks, thin wall pins, great oil control with stronger ring lands and bored oil return holes instead of slots, cheaper h-beam rods and rod bearings by using Pontiacs so the pin size can be corrected ; the list goes on. This was actually Ross Pistons' idea. A friend in San Antonio, Fred Byrod, bought a set for a 331 with a 283 Chevrolet bore configuration of 3.875 because Ross suggested it. The actual size is a .065 overbore, which should be safe for about any early hemi even if the sonic test is not done. You are only giving up about .060 more bore. And smaller bores on any rebuild equates to better ring seal every time. The idea sounded good to me so I am just passing it along. Why would you want to save a little money with all these bonus features? I even got a set of plasma moly rings on eBay a while back for a .005 over file-to-fit 283 std. bore. I think they were only about $25.00 which is dirt cheap for such a quality ring set. Kinda planning for the future so to speak. Since the ring gaps will be a little wider because of the blower I still have a small margin of safety with the gap widths . Buddy

I have one of these same blocks bored to 4.00. I have one small area low in the bore between 7 and 8 o'clock (non thrust) in cylinder # 5 which sonics at .085.

Just an update...

The reason I've been asking about this is because I've had the fear since day one that this block might be bored over entirely too much. My fears are a reality. The block was bored to 4.040" from a stock 331 bore (3.8125, I think that is). I don't know why someone would do this, but after finding water in the oil, and exhausting all other possibilities of where the leak could be coming from, I tore it down and found all 8 cylinders to be in the water jackets. Just wasn't clear until after running it. What a shame. The engine ran just fine because the cracks were not in the compression area of the cylinders, but obviously, it got hot and was dumping into the pan. What a shame. I put the block in the corner to deal with later in life. Maybe it can be sleaved, who knows. Not going to happen right now though.

Pics for you. These are the two worst cylinders. The others were were not quite as obvious.





So, I guess that's that... Maybe it will live on another day. On to one of my other blocks in the mean time...

Ross Pistons has a couple of early hemi forgings, one under 4", and one over. The over 4" forging is far lighter and by far my choice. Also, the ring choices for under 4" bores are severely limited. Ask for Pat O'Neil at Ross. Squared away, knows his stuff.

Danny

My '56 331 truck block is a "W" casting too and the casting number clearly shows it as a 331 hemi truck engine, not a poly. I plan to punch mine to 354 STD as well.

Rob wrote:My '56 331 truck block is a "W" casting too and the casting number clearly shows it as a 331 hemi truck engine, not a poly. I plan to punch mine to 354 STD as well.

That's considered max on a 331 for street driving.

George wrote:

Rob wrote:My '56 331 truck block is a "W" casting too and the casting number clearly shows it as a 331 hemi truck engine, not a poly. I plan to punch mine to 354 STD as well.

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That's considered max on a 331 for street driving.

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Unless the bores are badly rusted and corroded on the water jacket side or there's an unusual amount of core shift, a '56 331 heavy-truck block should be perfectly safe taken out to the 354 3.94 bore size. Most standard passenger car 331 blocks would be pretty thin and about maxed out, bored to 3.94 - but most (or all?) '56 and later 331 heavy-truck blocks were actually cast using the 354 molds and cores and were simply machined to the smaller 331 3.81 inch bore size.

mart
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Well I will certainly find out when I have mine sonic checked. With all that I have read, it varies from block to block and there is no hard and fast rule. Take the engine above. It was into the water jacket, yet was a running engine. Obviously, it had cylinder support. At 4.040, he is .022750 OVER a STD 331 bore, yet it appears to have JUST gone through. That 4.040 is .125 over from the STD 354 bore size. That's .0625 on either side. Something tells me just from those numbers, there's a LOT of material in that block. Enough to support a STD 354 bore easily. I've read where people have gone .030 and .040 over 354 with a 331 block. It all depends on how thick the block is and how much core shift there was. I am not doing this without careful thought and if mine does not check out well, I will pass these on to someone who can use them. They are NOS chrysler pieces that have been on the shelf somewhere for a LONG time. I have been blessed with good luck with this project at every turn so far. I have no reason to believe I will strike out this time.

mart wrote:Unless the bores are badly rusted and corroded on the water jacket side or there's an unusual amount of core shift, a '56 331 heavy-truck block should be perfectly safe taken out to the 354 3.94 bore size. Most standard passenger car 331 blocks would be pretty thin and about maxed out, bored to 3.94 - but most (or all?) '56 and later 331 heavy-truck blocks were actually cast using the 354 molds and cores and were simply machined to the smaller 331 3.81 inch bore size.

mart
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Yes, this is my perception from all I have read. But, I will have a sonic check because the last thing I want to do is ruin a good Hemi block.

I run a DeSoto,but I went with a shivolay bore cuz the rings were less expensive and I don't need max bore.

DHEMI wrote:I run a DeSoto,but I went with a shivolay bore cuz the rings were less expensive and I don't need max bore.

Dang man. Goin with a chebbie bore size is gonna slow it down. LOL

In theory, if it has 354 casting #, and it really is just an underbored 354 w/o any wall thickness adjustments, you should be able to bore to 4.000. 331s that were 55 & earlier shouldn't go past 354 std bore. A 354 typically can go to 4.00

George wrote:In theory, if it has 354 casting #, and it really is just an underbored 354 w/o any wall thickness adjustments, you should be able to bore to 4.000. 331s that were 55 & earlier shouldn't go past 354 std bore. A 354 typically can go to 4.00

Where does the '56 331 truck block fit in that theory?

Rob wrote:

George wrote:In theory, if it has 354 casting #, and it really is just an underbored 354 w/o any wall thickness adjustments, you should be able to bore to 4.000. 331s that were 55 & earlier shouldn't go past 354 std bore. A 354 typically can go to 4.00

Where does the '56 331 truck block fit in that theory?

That is part of the puzzle. Be of value if some had in their stash a 56 car block, 56 331 truck bolck & a 354 truck block that was bored to only 331 & see if they all have the same O.D. on the walls with a sonic check. Witch casting # does yours have?

Casting # 1619629-2 Date code C 14 6 and then W It also has the W cast into the side of the block as well.

Rob wrote:

DHEMI wrote:I run a DeSoto,but I went with a shivolay bore cuz the rings were less expensive and I don't need max bore.

Dang man. Goin with a chebbie bore size is gonna slow it down. LOL

It had a V-6 shivolay lump in it when I bought it,would run 75 m.p.h. all day long.Don't need to go any faster,but the car NEEDED my Hemi,that's why I bought it.

Rob wrote:Casting # 1619629-2 Date code C 14 6 and then W It also has the W cast into the side of the block as well.

Casting # is for both 354 car & truck. Does yours have the small timing cover with bolts @ 11 & 1, or the big cover with a bolt @ 12 O'clock? Sounds like it could be bored to 4.00, but definatly not to 4.040 like someone did to Scooter's block. 354 standard would be like a new no milage on the walls 354. Saw 1 of these on EBay a while back but didn't want to pay the shipping.

I would never think about going to 4". And I will not go to the 354 bore size without a good sonic check. And I mean good enough to go 354 over size. I want to keep this a while. Thanks for that info George. Everything I had found showed 331 truck only. what literature do you have, btw?

George wrote:

Rob wrote:Casting # 1619629-2 Date code C 14 6 and then W It also has the W cast into the side of the block as well.

Casting # is for both 354 car & truck. Does yours have the small timing cover with bolts @ 11 & 1, or the big cover with a bolt @ 12 O'clock? Sounds like it could be bored to 4.00, but definatly not to 4.040 like someone did to Scooter's block. 354 standard would be like a new no milage on the walls 354. Saw 1 of these on EBay a while back but didn't want to pay the shipping.

OK, my O.C.D. is kicking in now....

I'm not seeing 1619629 in the book, but I do see 1619829.

I know, I'm an anal retentive freak. Just ignore me.

Not seein it where dangit? What reference do yall have? lol

DavidBraley wrote:

George wrote:

Rob wrote:Casting # 1619629-2 Date code C 14 6 and then W It also has the W cast into the side of the block as well.

Casting # is for both 354 car & truck. Does yours have the small timing cover with bolts @ 11 & 1, or the big cover with a bolt @ 12 O'clock? Sounds like it could be bored to 4.00, but definatly not to 4.040 like someone did to Scooter's block. 354 standard would be like a new no milage on the walls 354. Saw 1 of these on EBay a while back but didn't want to pay the shipping.

OK, my O.C.D. is kicking in now....

I'm not seeing 1619629 in the book, but I do see 1619829.

I know, I'm an anal retentive freak. Just ignore me.

Crap! that is a 6not an 8. Is 6 right?

Rob wrote:Not seein it where dangit? What reference do yall have? lol

Leo's book

Here is the number as cast on the block. 1619629-2

Holy cow, that does look like a 6. My bad.

So now I'm kunfrooshed. Which block is it? Everything I find on line says 55-56 331. But I only find that number one or two places.