455 Sonic Check Results
 

I finally got an update from the machine shop that’s working on my 455. The sonic check came back, and the verdict is.. so so. Most of the thrusts appear marginal, but there’s concern on the forward sides of 3 cylinders. This block has been subjected to some butchery. It had a sleeve, and then popped a crown off a KB hypereutectic and cracked the sleeve :/ so it needs a sleeve to replace the sleeve. It currently has a 4.18 bore, machinist says the remaining bores have some issues, recommends an overbore to 4.21. On cyl 3(marked on the sheet as 4) that will only leave ~0.060” on the bottom, and and cyl 5(marked 6) will have ~0.080” on the mid and bottom. What do you guys think? Is my block junk?

https://i.imgur.com/lJ8w2zk.jpg?1

No expert here but if it was me, I’d be looking for a different block. Unless that block has some significance to you or the car.

Good luck
Murf

I hate to be the one to say it, but I definitely wouldn’t use it, I mean I guess there are alternatives sleeve the whole thing, but that’s a pretty pricey proposition. Thank god you were smart enough to have it Sonic checked. Can you imagine someone putting twin turbos on that block and never had it Sonic checked.

Hard block it and run it imo.

X2 with the above and once the new sleeve is in it will be fine!

For future reference, you can’t sleeve a whole block because there would be near nothing left to hold the deck on the block, at least in terms of a Pontiac block!

You would be solving one issue and making another just as bad!

Also if the block is a 4 bolt have the shop take a real close look at the outer bolt holes in the main web.
I have seen cracks running down the length of the bolt holes right out of the gate from the factory’s taping process.

for a few hundred bucks....move on. Even if you have ot dig a little deep...better to invest in a solid base than starting with ??????? and building from there.

This is an Internet rumor that most likely came from a Q&A in the back of a magazine that just isn't true.

We have sleeved all eight cylinders in a handful of Pontiac blocks and never had an issue. H-O Racing sleeved all eight cylinders in the 1974 Super StockTrans Am engine and set many records with that engine. They felt it was one of the "secrets" that gave the TA a competitive edge.

My "guess" it that answer from the magazine may have been intended to prevent folks from thinking you can sleeve all eight cylinders and go much larger piston like a 4.25.... That would not be a good idea.

Paul,
Back before all of the after market block that we have today. We had a 426 Chrysler Hemi block that had larger bore sleeves installed and furnace brazed. While not common this was done back then.

Stan

Paul, I agree with one caveat: it depends on the skills of the machinist performing the work. Most “production” shops don’t have the necessary tooling or experience to successfully install eight sleeves.

It's amazes me what work was performed to "get the job done" back in the day. Today a lot of cool projects are killed due to the price of "out of the ordinary" labor costs... It's sad.

Absolutely true! That thought went through my head as I was typing it. Everyone has a different set of skill levels. Highly skilled guys today can easily get a back log that will never end. The World is running out of multifaceted skilled workers.

There are better alternatives out there in the 455 world. I recently bought 2 early 70's 455's for $500.00 for the pair. They are still out there. Both standard bore. 2 bolt main. To properly install and surface 8 sleeves, then torque plate hone the block, you are looking at close to $2200.00 around here. That aftermarket block starts looking pretty darn good at that point. When your done, you still have a lower grade iron block with a compromised deck. Unless a numbers matching trailer queen, I would start fresh with a better block. JMO. On the flip side, I had a customer with an early street hemi in a numbers matching factory lightweight Plymouth. We welded up 6-8 external cracks in the block, put 8 sleeves in it, welded a repair in the block to hold 2 center caps and band aided it back together per the owner's request. He had well over 5K in the block repairs. It survived the dyno. No idea how it did after that. No warranty of any kind on repairs like this .

And saving the numbers matching engine increased the value of the car considerably more that the cost of repairing the block.

Good job Mike!

I remember years ago Jim Butler had made the above claim regarding 8 sleeves. . Likely stuck from there. I had great luck with .100 (non sleeved) 455 blocks. In fact my old 482 short block that I retired in 2010 is going back into service in a friends bracket car until I can get the parts to repair his 467 (The broken main cap I told you about).

Hmm, I spose I should provide some more details. The block has no significance to me/my car. I picked it up as a disassembled short block for $300. It had mismatched heads(66 and 62, massive diff in CCs), so I left those. I was hoping to make it a “budget” build, but that is quickly fading away. The plan was to just replace the sleeve, and keep the rest of the bores at 4.18, to keep cost low. I have a 400 in work at another machine shop that will be my main engine, completely going thru that one. This is more of a side project I thought could be resurrected fairly easily.

Just up to the freeze plugs? Or higher?

Agreed, it seems like the market has swung toward buying new parts from overseas vs paying an American to rework your existing pieces. It amazes me what the guys like Mickey Thompson and Smokey Yunick were able to do 50 years ago, basically on their own. I know parts like Eagle rods are good, but I have some serious hang ups about sending that much coin to China

I definitely don’t want to spring for 8 sleeves, I don’t plan on pushing this engine hard. Solid point about the comparative cost of the aftermarket block.

Wow. Lotta work, but it makes sense for such a rare engine/car combo.

Paul, we would only install eight sleeves in diesel blocks as a last resort (i.e., no other blocks were available). Installing sleeves can be tricky, especially if there is significant erosion and porosity in the cylinder walls. There are probably fewer than ten machinists in the industry I would trust to do it. You are one of those. Paul Carter is another. Here in the Louisville area there is ONE. I've known him for over forty years.

What year is the block? that’s a shame at .030 over it checked like that.