Sonic testers are more affordable than they once were.

Paul Carter and I had a conversation about cylinder wall thickness a few years ago. Paul’s contention was that IF you had a cylinder wall thickness of .125 minimum on the non thrust walls you should be OK. Grumpy Jenkins said in his book that .135 minimum on the non thrust walls was OK. Sleeving a block is a crap shoot; a successful sleeving depends on the condition of the block ( core shift and erosion)along with the skills of the machinist performing the work. In my personal view( having machined around 6,000 blocks) I would NOT install more than two sleeves per bank; likewise, I would NOT install two thick walled sleeves side by side. Our rule of thumb was ONE thick wall sleeve per bank. To install a thick wall sleeve you have to remove a buttload of material from the block. 6.9/7.3 IDI diesel blocks have cylinder walls twice as thick as the thickest Pontiac cylinder walls I’ve seen (.220) but we would only install ONE thick wall sleeve (.375 wall) in one of those blocks.

I didnt know that . I always thought you could do all 8. Thanks for telling me that . Im really not happy about the couple of .099's i have but im just going to run it and see how it goes. I say that with a cringe . Part of me wants to see how it holds up . Unfortunately i did this backwards ..

.099 is WAY TOO THIN! I know of two ‘66 389 blocks that came from the factory with cylinder walls of .090 or THINNER. One was the 389 in my Uncle Bud’s ‘66 Tempest with the dealer installed 389 (1 of 1); the second was in my old friend Larry Wilham’s ‘66 GTO drag car. The 389 in Uncle Bud’s failed in service, while the 389 in Larry’s GTO was detected in NDT. There have been companies that sleeved all eight bores(PAW for one), but they used thin wall sleeves that do NOT have the longevity of standard wall sleeves. They also did a half assed job in installing the sleeves. I have seen a couple of PAW blocks where the sleeves did not have a ridge at the bottom of the cylinder to support the sleeves. Proper sleeving is becoming a lost art form because there are so few machinists who know how to perform the operation properly. It’s one of the reasons I wish I could go back to work as an engine machinist, but my wife and my doc would have me committed if I tried.

I would much sooner do a half fill on a block for added support such as that with some questionable areas before putting in even a thin wall sleeve.

The main issue is that in hindsight that block should have been sonic check before the first bore job done to it and then the over bore could have been off set to maximize what was left for wall thickness.

If the jackets are not rusted, then .099 in a zone ought to play well. Hard block is your friend.

My process is clean mag and sonic test before any real work is done. Cut your losses early if there are issues.

How many blocks have you ever seen WITHOUT rust in the water jackets? I’ve seen thousands of gas and diesel blocks. I can count the ones that didn’t have rust in the water jackets on the fingers of one hand. The ONLY way to ensure there’s no rust inside the water jackets is to run the block through a cleaner like Kolene, which burns the rust out. As good as shot blasting cabinets are today, they can’t clean the entire water jacket. .099 before boring is going to be well south of .099 after boring.

Think i have owned a few without rust inside. Whatever scale got cleaned out with hot-tanking.

Had a 455 that was sunk in a pond that had rust-through a couple cylinders. Got sleeved, hardblocked and it ran rather well.

I just bought a sonic tester. They cost as much as getting a shop to do it for you and I do not have to load any blocks in my truck.
If I do not like it send it back to Amazon.

“Hot tanks” that used sodium hydroxide as a descaling cleaner are nearly as illegal as dealing fentanyl anymore. All the machine shop around here have gone to hot water wash cabinets that use strong but EPA legal detergents then bake and blast cabinets. The ONLY legal process that can remove rust is Kolene, but very few companies use that process due to the caustic residue left by the chemical salts that Kolene utilized. If I want a rust free water jacket I use a solution of phosphoric acid ( same ph as white vinegar) to soak the block in. Sleeving is always an option IF you have a competent machine shop locally. Those are getting harder and harder to find. Here in the Greater Louisville area there are roughly a dozen machine shops. I would only let TWO of them anywhere near a block of mine.

Steve, you don’t want thin wall sleeves, period! The thinnest wall sleeves we used were 9/32” wall (just over a quarter of an inch). Thin wall (3/32”to 1/8”) sleeves simply do not hold up. My basic block prep routine starts with a good cleaning, followed by NDT then an ultrasonic check of the cylinder walls. It’s always best to spend $125-150 on an ultrasonic check of the cylinder walls to ensure you have a useable block.

If you are currently using a motor that will come out for a rebuild then I have found that running the DuPont two part cooling system flush thru it is well worth the effort these days since hot tanks can run the chemicals that use to work so well.

I received my sonic tester and poked around my .060 over 67 400 block a bit. Thinnest spot I found was .193 but I did not do the whole block.
Pretty good I thought. Maybe its true that they are thicker than the rest. Much of it was near 1/4". Only did 3 cylinders on one bank.
Whenever I get the time I will take my time and put up a more detailed measurement.
Still on 6 days a week right now.
I have a std 74 455 block and a .030 71 400 block I can check too.
What I will really be interested is when I get a chance to check out the .060 over 70 455 HO block I beat on for 30 years. How much of that bad boy is left.
Can I hard block it and put some .065 or .70 over slugs in her with a tq plate ridged hone ?

That is a good block. Ken ace used to bore 455 blocks .100 over quite often

Yes he did, never sonic tested them either. Had to have been at least a little bit lucky
Last I heard from him he sold all his Pontiac stuff. Got out of it totally and opened a store selling health products.
Said there was more money in it and not enough in Pontiacs.
He did make his mark in the Pontiac world.
His parents came up here on a trip and my wife and I went out to dinner with them. Nice folks.

OK, I sent my first sonic checker back. It did not have a "cast iron" setting and it would not change the numbers as you ran the probe up and down the bore.
I knew that once you got near the top it had to get thicker near the deck but the numbers did not change.
So I did not trust it and sent it back.
I bought this one.

https://www.ebay.com/itm/314314770567

It has 3 different cast iron settings so I gave it a shot.

Just went out and checked #1 cylinder. It would change as you moved it down the cylinder so I felt better about it. This one takes oil on the probe where the other one used water.
The thinnest spot on my .060 over 67 2 bolt 400 block was .157 between the bores. The outside was all over .200 as was the front of the cylinder. The inside was very thick, in the low .300s.
If the other holes are like this I can take this thing .100 over and still have .137 between the bores .
But I would take a minimal amount on the worst bore.

What is considered minimal thickness on a non thrust surface ?
I have always wanted to weld a KRE lifter bore brace into this thing, put some ductile iron Milodon splayed caps with 4" crank. Kinda like the ultimate stock block "440".
I would want to practice ni welding steel to lifter bores on a junk block first. See if its doable.

Hey Troy did you get the prob it comes with or did you get a different one ? I see they say you can get different ones . Looks like your block is pretty thick I think you will be safe . Thanks for posting the numbers

Seems Pontiac was concerned about the 4.21 stroke when it came to the blocks. I guess the 4 inch strokes too. But the 455 blocks went into the lo po years.

They left meat in the bores and didn`t go thin main webs on the 500813 castings. So, those big main 455 blocks might get a little more love now?;)

I have been posting that info, for years, on the board.
Palbykin went into the 6s in 1996, over 25 years ago, with a 67 2 bolt main
(non drilled for 4 bolt mains) block. Why would I lie?

Do not think there is any "Maybe" about it. Your Block is .060 over and is still great for numbers.

Tom V.