You shouldnt have ANY issues with those blocks..
they are THICK walls... in my SB stuff I havent ever
seen a production block that thick... just my race blocks
good luck with your build

Sounds like he did a comprehensive test.As far as the short fill,it has little effect on the thermal expansion since you are only filling to the core plugs.Thermal issues come into play in the upper portion of the cylinder where the heat from combustion occurs.We also do not like to fill any blocks but with the inconsistant values of the end cylinders can cause distortion from heat.The shorter the cylinder length the less heat effective area and with the short fill the less chance of an issue.We see pin holes and cracks develope within the lower part of the cylinder where the transition from the water jacket to the solid mass of the block is and that's where we are referring to.You could be lucky enough to not need this.For an all out race engine it might be wise,but that your decision.We just seen many later 400 and 440 blocks that could have been saved.

I don't use block filler for that exact reason The heat zone differences above and below the block filler ends up making the cylinder walls different internal diminsions above and below the filler, basically a small step in them

that must be why he explained about blocks that had a 1/2 fill showed a increased amount of skirt scuffing as opposed to ones that dont, and it all makes sense to me because of the difference in thermal expansion in those two areas.

Sorry, but ain't buyin all that. Based on water displacement, I run a 3/4 fill block. Never seen a "line of demarcation" on the cylinder walls. Never had any piston scuffing issues. With the temps we usually run ( under 200 degrees ) don't think there is a lot of thermal expansion / contraction to worry about. If there is any, it would all be on the expansion side, so don't see it scuffing piston walls. On wall thickness, I have run small block motors all out of E58 coded cars. Supposed to be "hand picked blocks", what ever that means. Had two sonic tested. All at .2 or thicker walls ( before boring ). Don't know if those two items are related, but just eyeballing lifter bore holes and castings in the lifter bore areas, looks like minimal core shift on these blocks.

Cement those blocks up then complain about heavy azz cars. LOL. Concrete's for swim-in pools.

I think I would be questioning the measuring equipment.




Chris.

Id kinda agree with Chris, Ive checked quite a few blocks and haven't been that lucky with wall thickness, on my last engine build I didn't find one with that good of numbers out of 10 blocks checked, makes me wonder if my checker is bad?

As far as questioning the test,it seems to be a very comprehensive test using minimally 12 checks per cylinder.We do 16 checks if we find thin areas.
Diffrent types of material have different inherent sound velosities,ie:steel velosity aprox.5918m/s and aluminium is 6350m/s.If the guage is not set correctly the measurements will be erroneous by a certain percentage.
There are 3 ways to calibrate a sonic meter.
1- Calibrate to a known thicknes/material
2-Calibrate to a known velosity
3- A 2 point calibration.
We generally use 1- calabration to the known thicknes, sincethe advent of added alloys and strengthen materials to the parent metal.ie: added nickel in cast iron.Cast iron having a sound velosity m/s of 4572 and nickel having a sound velosity of m/s 5639.
Depending on the amount of nickel interduced into the cast iron will negate using 2-calibration to a known velosity(chart value).The best way to measure a block is to find an area that can be measuered(known thickness)your probe should read the same value.
Other considerations are choosing the correct transducer probe size and diameter as well as a good copulant for seal.Keep in mind test should be done at nominal room tempertures.

To address heat distortion issues,even though we don't do or recommend a tall fill,a short fill does not have an adverse effect.Run a cylinder that is thin and you will see a lot of shadow areas because of heat.

On my .030 440, the old Mopar Performance Engines book had me paranoid about thin wall blocks since the block I used was a 78. It passed sonic check no problem. I can't recall how thick the walls were, but the machine shop said for mine, that .060 over on that block wouldn't have been an issue. Also the majority of BBM blocks they had tested were thin at .030, no matter what the casting date was. I was prepared to go and buy blocks of all different vintages, guess it doesn't matter.

I try to alwyas calibrate my sonic tester to a known thickness, not the posted velocity for the metal being tested I'll take a dremel tool or small hand held air powered high speed rotary grinder with a carbide bit to smooth out around the oil pan rail on the BB in the back near the bellhousing mounting starter areas or in the front near the timing cover ribs to get a smooth, flat surface I measure it with a set of dial calipers and get the meter reading within .005 or less on the meter

So far for me I am using the ears for the engine
mounts.. I touch them up with a 4" disc on my die
grinder for a flat surface.. this would be my known
thickness point to test... but I'm still playing with
my new tester... havent played much lately being I have
stuff thats not working on my junker... soon I will get
back to testing blocks since I have a few I want to look
at for up coming jobs... but so far I havent ever seen some
of the numbers posted

Mr p just curious as to what year 340 blocks did this.I have 2 340 blocks with 7/70 build dates.

I think they are a 68 and a 70.. I have 3 others
but havent looked at the wall thickness yet

One of the most common errors when sonic testing is the use of incorrect probes.Since we do roll cages as well as blocks we have various size probes.For cast iron we use .500-1MHz,for steel .250-7.5MHz amd for aluminium .250-2.25 MHz.The small diameter probes should be used when testing concaved or convexed surfaces as to not have any chance of gaps between the probe and surface.
We have seen some really thick blocks that have exceeded .500 and .400 in areas but they are certainly rare.Uncle Barry bought a hemi block from us that exceeded these numbers.
As for using hardblock on a short fill,it has more advantages than disavantages.As we mentioned we find casting irregularities at the bottom of the cylinders more than anywhere else.This is why you see many cracks at non thrust sides and below the ring travel area.It certanily doesn't hurt and is a bit of insurance.

Lots of good info from BG Racing. Thanks!

Your welcome

I can't wait, Bill. You're gonna shart yourself lol.