Finding 428 Blocks but have questions.

[Gaugster]

So I am in the market for a 428 engine/block. I've seen 2bbl A scratches as well as 428 Cobra Jets in various states. I need help interrupting this sonic map. I was informed this block has one (1) sleeve. Based on what I have read the sleeved cylinder should be reporting a thickness like 0.090". I.e. only the sleeve thickness. But I can't see it in the data. Would you normally report the sonic test data before any machining was performed? If so then the post-machining sonic results would be even more thin. On the flip slide this data is suspect if it's after a sleeve plus bore and honing. I haven't asked these questions to the other party as I am not knowledge enough to defend my position. However I am very aware that the price these blocks fetch has certain risks.

Thanks in advance!

[thatdarncat]

You are correct, that sonic test is not showing a sleeve. And yes, the sonic test of a cylinder with a sleeve will just show the sleeve thickness, which of course will depend on the sleeve used and how much it was bored. And the sleeve will show a fairly uniform thickness all the way around and top to bottom. I imagine a seller could supply a before and after sonic map, it would certainly be good info to have before boring or sleeving.

Just curious, did they say why that block needed a sleeve?

[FElony]

I've seen 2bbl A scratches ...

Um, no 2V 428's or 410's. "bbl" is Plymouth.

[Gaugster]

You are correct, that sonic test is not showing a sleeve. And yes, the sonic test of a cylinder with a sleeve will just show the sleeve thickness, which of course will depend on the sleeve used and how much it was bored. And the sleeve will show a fairly uniform thickness all the way around and top to bottom. I imagine a seller could supply a before and after sonic map, it would certainly be good info to have before boring or sleeving.

Just curious, did they say why that block needed a sleeve?

That makes sense. You'd want to sonic check anything before extensive machining. I will inquire more about the block history and documentation. The measurements on the thrust sides don't make an obvious case for adding a sleeve any one cylinder as far as I can tell. However it's entirely possible that I am missing something.

[Gaugster]

I've seen 2bbl A scratches ...

Um, no 2V 428's or 410's. "bbl" is Plymouth.

Great point! I hadn't caught that flub... Looking back at the picture I was provided it's indeed a 4V intake. Someone was telling me a story about some 428 out of a wagon with only a 2V carburetor. Guess I failed that test.

[FElony]

I've seen 2bbl A scratches ...

Um, no 2V 428's or 410's. "bbl" is Plymouth.

Great point! I hadn't caught that flub... Looking back at the picture I was provided it's indeed a 4V intake. Someone was telling me a story about some 428 out of a wagon with only a 2V carburetor. Guess I failed that test.

Nothing personal. Myself and others try to nip stuff like this in the bud before half the planet suddenly remembers that dad had a factory 2V 428 Country Squire and it could spin the tire down the entire block. Back then, I don't doubt that many people switched out their gas guzzler 4V carb for a gas miser 2V using an adapter, so history gets a bit fuzzy.

You should see me when I read the Comments sections of YouTube vids covering Cobra Jets and other FE's. So many stated "facts" that are entirely erroneous that I often have a meltdown. Sometimes I go on a correction rampage. Sometimes I just say "screw it" and let the populace meander hither and, yes, even thither in their fog. Whichever.

[C6AE]

I have a standard bore C scratch 2V 428, never been apart, still has the aluminum 2V 428 tag on the manifold.

(Industrial motor  )

[Gaugster]

I've seen 2bbl A scratches ...

Um, no 2V 428's or 410's. "bbl" is Plymouth.

Great point! I hadn't caught that flub... Looking back at the picture I was provided it's indeed a 4V intake. Someone was telling me a story about some 428 out of a wagon with only a 2V carburetor. Guess I failed that test.

Nothing personal. Myself and others try to nip stuff like this in the bud before half the planet suddenly remembers that dad had a factory 2V 428 Country Squire and it could spin the tire down the entire block. Back then, I don't doubt that many people switched out their gas guzzler 4V carb for a gas miser 2V using an adapter, so history gets a bit fuzzy.

You should see me when I read the Comments sections of YouTube vids covering Cobra Jets and other FE's. So many stated "facts" that are entirely erroneous that I often have a meltdown. Sometimes I go on a correction rampage. Sometimes I just say "screw it" and let the populace meander hither and, yes, even thither in their fog. Whichever.

It's all good. There's so many "gotcha" type moments when searching for a 428. I realize now this block started life as a FT 361/391 as it has the oil return hole for the air compressor used on medium duty trucks. So it should have the larger diameter distributor pilot hole also. Higher grade alloy is a myth. It's a C scratch DIF with 352. Not a mirror 105 though but webbed nonetheless. Could be a great starting point for a stroker build. But that CJ price tag needs some finessing.

Just curious, did they say why that block needed a sleeve?

I was told the sleeve was due to wrist pin drag on one of the cylinders.

[Gaugster]

How does a person measure core shift? Is core shift purely a factory variability or does it also happen over time and usage of the engine?

So looking more deeply at this pre-machining sonic map I'm attempting a sanity check on the numbers. With an original bore of 4.052 the theoretical maximum material thickness between adjacent cylinders .359" assuming "428" water jackets. A couple add up to .354 and .355 so all seems good.

Noting that for each pair of cylinder the rear sonic data tend to measure less that the front I took the differences and averaged them together. The passenger bank would suggest a shift towards the rear of .037" whereas the driver's side bank is more like .047". I set my micrometer to these values and they seem like a lot. Should I just care about individual wall thickness and not be overly concerned about core shift?

[1968galaxie]

I would be concerned with sonic mapping of all 8 cylinders. That is what is important.
One can sometimes see evidence of core shift by looking at lifter bore positioning relative to casting.

[FElony]

I have a standard bore C scratch 2V 428, never been apart, still has the aluminum 2V 428 tag on the manifold.

(Industrial motor  )

Pictures for the record?

[67xr7cat]

What was the bore size when that sonic map was done?

Basically if the bore is 4.05" and you bore it .080" to standard 428 size you would subtract .040" from the numbers on the sonic map.  In reality boring a block usually takes more off in some spots and less in others, but it is a good rough rule of thumb.  If that is the case there would be some spots getting a bit thin.

How thin is too thin? That is a question that will get you a lot of different answers. Intended use is a factor and of course where it is thin.  For street or street/strip typical build a general rule on the sides atleast .100" usually is ok, when you get down around .080" or less expect trouble.  For major thrust .170" seems good for most, although .150" seems to be ok. 

One thing that can be done is if one side of a cylinder is thin, can off set bore that cylinder (take more off the thick side).  I'd say you really need to find out what the bore size was when that sonic map was done. Then have to determine how much it has to be bored to clean up. I would not bore it more than it takes to clean up. 

I'd also say that sonic map would have a bearing on what I'd pay for that block. If it is thin at std 428 size worth a lot less then one that is thick IMO. Considering it has a date code from the 70's it is not really of any value to the restoration guys.  Is just a 428 C scratch block.

[C6AE]

I have a standard bore C scratch 2V 428, never been apart, still has the aluminum 2V 428 tag on the manifold.

(Industrial motor  )

Pictures for the record?

It's down at work and when we get back to work I'll get them.
The stamped aluminum tag is unusual methinks.

[Gaugster]

What was the bore size when that sonic map was done?

I was told the bore was 4.052 when the sonic was performed. Now it is 4.126 with one cylinder sleeved. So .074 over. Can l assume a little material  was left for a final hone or crosshatch base on ring type? So it will end up at .080. Deck height resurfaced down to 10.156.

Thanks for the insights. It seems to comes down to the post machining sonic results which I'd need to request. Ideally a slight offset so that the cylinder wall thickness is more equal.  My application is almost pure street.