[65nss4spdGTO]

My dad and I were doing some sonic checking of a few blocks in the shop. We are looking at building a stroker assembly for one of the 59's we have, this will be a street car. We have a few 59 blocks and decided to tear a couple apart. One was set up for a blower, bored 4.190", that's .130" over bore, the other was .030" 4.180" over. We sonic checked the blocks and compared it to a factory 1971 455 H.O. block we are freshening for a customer. The 455 H.O. block was bored +.030, the cylinder walls showed the thinest spot at around .120" wall thickness. The thinest spot on the .130" over bore 59 block was still .145" thick. We compared the thickness of one of the other 59 blocks and the castings wall were consistent to the large bore block.

It's a shame the factory thinned out the blocks as the years went on. Just image how many stroker sleeper GTO's could have been out racing if the factory would have standardized 3" mains and maintained all of the block casting that could be effectively bored out to 4.210" with a 4.000" crank.

Calvin Hill
Hill Performance
708-250-7420

[Don 79 TA]

i guess the say'n they don't make stuff like they used to still applies
i remember something like this when i had a 66 283 i was gonna do for a Vega.
I remember the guy who was looking at the motor said you can really overbore them and there is still plenty of meat.

[rad400]

GM has done alot of dumb things over the years.

[mgarblik]

From a GM bean counter's point of view, look at the millions of pounds of cast iron I saved for GM!! I am a hero. At the 2-300 HP these engines make stock, a .150 cylinder wall is thick enough. Certainly good enough to get through the 12 month 12,000 MI warranty they had at the time. That's all they really care about. I guess that's why there are car guys and bean counters and it is clear who runs GM and the other OE's. I do get your point though Calvin. Look at GM's entire design history. Build a high quality, stout piece. Then slowly take the material and the cost out until it is a piece of crap. Then discontinue it. The 301 is a good example. Their other approach is produce a complete of crap, work on it and improve it just enough to get by, then when it is finally decent, discontinue it. The Fiero is a good example of that.

[Steve Barcak]

Originally Posted by 65nss4spdGTO

My dad and I were doing some sonic checking of a few blocks in the shop. We are looking at building a stroker assembly for one of the 59's we have, this will be a street car. We have a few 59 blocks and decided to tear a couple apart. One was set up for a blower, bored 4.190", that's .130" over bore, the other was .030" 4.180" over. We sonic checked the blocks and compared it to a factory 1971 455 H.O. block we are freshening for a customer. The 455 H.O. block was bored +.030, the cylinder walls showed the thinest spot at around .120" wall thickness. The thinest spot on the .130" over bore 59 block was still .145" thick. We compared the thickness of one of the other 59 blocks and the castings wall were consistent to the large bore block.

It's a shame the factory thinned out the blocks as the years went on. Just image how many stroker sleeper GTO's could have been out racing if the factory would have standardized 3" mains and maintained all of the block casting that could be effectively bored out to 4.210" with a 4.000" crank.

Calvin Hill
Hill Performance
708-250-7420

Calvin,
Yes, I learned this about 20 years back through sonic testing and my own experiments. at the time, none of the performance Pontiac books ( actually, even today they probably still do not ) acknowledged just how stout these early block were. What I found was hard to believe and the shop doing the sonice testing told me it was very unusual to find a block with that much meat on the walls. They ended up asking what exactly is was that I brought them because no other Pontiac block was like this. I then knew I was onto something good.
Based on what I learned in the early/mid 1990's I starting basing most everything on these early blocks and remain so today. I designed my 1st '59 389 with a 1.050" billet stroker crank, custom billet long rods and raised deck with an overbore of .310". This displaced 577". Then went on to build 399 '59 389s blown on nitro for my AA/Fueler. They remain an outstanding foundation for any performance build. Especially something blown and around 7 litres.

For years and years, no one would listen to me when to talked about the virtues of these early blocks.................

[GTOGEORGE]

Why would anyone buy an IA2 block for their 1,600+HP engine when you can get a 1950 something block with GOD knows how many miles or what kind of abuse it had. Sounds like a plan to me.


GTO George

[GTOGEORGE]

Why would anyone buy an IA2 block for their 1,600+HP engine when you can get a 1950 something block with GOD knows how many miles or what kind of abuse it had. Sounds like a plan to me.


GTO George

[taff2]

I listened Steve! My '59 block sonic checked at virtually .240"/ .250" at 9 places on each bore, if I remember right the deck was 5/8" in most places!
I can think of a couple of reasons to use a ,59 block versus aftermarket,especially if you only want around 1000hp.
COST- $300 instead of $3000.Even with a $1000 machine costs you're way ahead.
LOTS OF MILES = seasoned block instead of a 'green' block.
WEIGHT- I bet a '59 block weighs less than an aftermarket block.
KUDOS-there's something cool about making old stuff run hard versus just getting out your chequebook.
I'm not against aftermarket blocks,they have their place in really high HP builds.

[i82much]

Originally Posted by taff2

I listened Steve! My '59 block sonic checked at virtually .240"/ .250" at 9 places on each bore, if I remember right the deck was 5/8" in most places!
I can think of a couple of reasons to use a ,59 block versus aftermarket,especially if you only want around 1000hp.
COST- $300 instead of $3000.Even with a $1000 machine costs you're way ahead.
LOTS OF MILES = seasoned block instead of a 'green' block.
WEIGHT- I bet a '59 block weighs less than an aftermarket block.
KUDOS-there's something cool about making old stuff run hard versus just getting out your chequebook.
I'm not against aftermarket blocks,they have their place in really high HP builds.

I had pretty mixed feeling about getting an IA2 for a street car. Thought about finding a nice vintage block and using a tripower or dual quad setup, would look so "right" in my 65. Instead I stuck a big fat holley 850 on a torker II and stuck that on a 505 IA2 with a mild cam. I can see the plus sides either way. Who knows, maybe one day I'll pull it and sell it to a racer and go the vintage route. There are a lot of cool fun ways to build a car.

[Brian Baker]

Originally Posted by GTOGEORGE

Why would anyone buy an IA2 block for their 1,600+HP engine when you can get a 1950 something block with GOD knows how many miles or what kind of abuse it had. Sounds like a plan to me.


GTO George

We heard you the first time.

Perhaps it's because at a 4.181" bore, my IA-2 block sonic checks at .394" on the thinnest wall, with all the others sonic checking at over .400" (with the thickest being .422"). Not to mention it has more meat in any part of the block than any factory block.

Now if you have a slew of '59 blocks in your back yard like Steve does, and machining them isn't an expensive endeavor, knowing that your going to blow some up on nitro' as you learn the tune-up, working with them is a smart move over a $3000+ iron block.

Did that 577" monster ever run Steve?

[65nss4spdGTO]

A few other considerations with the 59 blocks. The core shift is minimal, I've seen some major core shift on the later 455's and many 400's. The casting quality is superior to most other factory blocks and much better than the IA-II. Now if they would have braced it in the open lifter bores like the SD-455's.

As a side note, we have a few of the standard blocks and two "A" blocks (345HP), we don't see much difference between the two.

Correction to my first post. We have a few 59 blocks and decided to tear a couple apart. One was set up for a blower, bored 4.190", that's .130" over bore, the other was .030" over 4.090".

Calvin Hill
Hill Performance
708-250-7420

[70 bird]

The blocks were only as good as the cast rods Pontiac put in them.

[BruceWilkie]

Originally Posted by 70 bird

The blocks were only as good as the cast rods Pontiac put in them.

Actually... the 59 had forged rods but they were less trustworthy than cast...

My 1st 59 block was .150" over at 4.21 bore...(early forged rod hurt that one) GM hadnt started on the thinwall casting technique...that came around 1961...

Other things that are notable on the 59 ...the reinforcing rib along the pan rail, ... thick meaty bulkheads... big main caps...all same height as 455 caps(bolt shoulders and cap center are @ 1/4" taller than std 400 caps...

Need an adapter to use modern bell and have a place to hang a starter... I made mine from 5/16 steel plate but 1/4" is minimum you need...(I had 5/16 on hand plus most good flexplates are .030" or more thicker than stock and its easier to shim for excess convertor pull-out than have insuficient pull-out)

The 61-64 full size starter pattern fits best...I tried a 58 Delco but last full mock up with a pair of headers thrown on and trans bolted up I realized bolt pattern would be a pain for easy starter service once motor was in car!!! Now I know why they went offset in 61 when they went to"modern" bell.

IMI has a mini for the offset pattern 61-64 big car and it appears the RobbMc "nailhead' starter has the same bolt pattern/pilot.

Wilcap and Bendstein have transmission adapters but they are thick and clunky ... expensive too.. The 55-60 block has the bell face recessed@ 1/4" relative to crank flange compared to newer blocks... rather convenient... the nuts for t400 pattern are welded to back of plate...two needed a slight shave on edge(mostly was weld bead) to clear block but could grind clearance on block... I took the easier of the two. Four of the 59 pattern bolts are under the t400 bell. I used 7/16 thread countersunk flathead allens... Regular bolts left no wiggle room... Upper t400 holes need to be enlarged to accept 7/16 bolts used on 59 block.
Mine also will serve as a mid-plate.

I've been trimming weight out of my adapter... I'll try to get a pic posted tomorrow... most of the ugly will be hid by the trans lol . If time I'll post dimensions and some instructions too.

[Nicks67GTO]

-When did they start thinning out the blocks?? Was it progressive or a given year? I have heard that 67' is the best/strongest year for a 400 block. Is there truth to that?

-Why did they bother with the 3.25" main if they were worried about cost savings and overkill?? 3" Mains are already a pretty stout main size capable of handling anything the factory could have thrown at it. 3.25" seems like complete overkill??

[GTOGEORGE]

Taff2,
So let me try to understand your reasoning, you will be saving money (3,000-300=2,700) by buying a block that is about 55 years old that has a TON of miles on it (you call it seasoned) that may or may not have been Gernaded at one time AND may or MAY NOT hold up to the 1,000+ HP you're going to pump through it. So when this 1959 block breaks and you lose the crank, rods, pistons, heads how much money are you saving now? I'm just saying, an aftermarket block has been tested to take well over 2,000hp the 59 block (a very good piece for its time) can take more HP then a newer factory block but let's face it they weren't even thinking of it taking the HP levels we are at now when they casted it. So I guess it's like this........ "Pay me NOW or Pay me Later". Just my opinion.


GTO George

[RUDOLFSSON]

He would have to pay a lot more than 3 grand for an aftermarket block....

[thadeal4real]

-Why did they bother with the 3.25" main if they were worried about cost savings and overkill?? 3" Mains are already a pretty stout main size capable of handling anything the factory could have thrown at it. 3.25" seems like complete overkill??[/QUOTE]

I believe it has something to do with Journal overlap

[Region Warrior]

Late 60's/early 70's blocks havent been lay'n round here(unless you know the few guys that cleaned out the yards 20 yrs ago) let alone 59 and earlier.
Back in the 70's all the 50's cars where already crushed.

[BruceWilkie]

Originally Posted by GTOGEORGE

Taff2,
So let me try to understand your reasoning, you will be saving money (3,000-300=2,700) by buying a block that is about 55 years old that has a TON of miles on it (you call it seasoned) that may or may not have been Gernaded at one time AND may or MAY NOT hold up to the 1,000+ HP you're going to pump through it. So when this 1959 block breaks and you lose the crank, rods, pistons, heads how much money are you saving now? I'm just saying, an aftermarket block has been tested to take well over 2,000hp the 59 block (a very good piece for its time) can take more HP then a newer factory block but let's face it they weren't even thinking of it taking the HP levels we are at now when they casted it. So I guess it's like this........ "Pay me NOW or Pay me Later". Just my opinion.


GTO George

George,
he's already gone 161 on 18 psi and not sorted traction/launch yet(Hes kind of light so 950 ish hp at 18 psi would be my guess) I dont see his block being a big issue. I hate to jinx him but his forged china crank(4" stroke) might be a concern as he turns up the boost... He does have a good set of aluminum rods though... (iron heads btw)... Keep in mind his costs to have a block shipped across the ocean too.

However... Turbo'd he doesnt have to turn the rpm an NA motor(or even a belt driven blower) does to make that HP! (supercharger belt drives put stresses on end of crank/block that was never part of the design criteria of any production block)

IMO even lesser blocks with less hp... most stock blocks fail due to prep failures, poor harmonic control, detonation, weak recip parts, and rod/crank failures. In other words its rarely the block taking out the motor its usually the opposite! Not that a cracked block hasnt caused issue too. IMO addressing the things that cause the cracks in the first place can resolve or greatly improve on these issues.

RPM/recip weight/stroke puts the bigger stress on crank and block than just HP alone. IA IA2 and MR1 blocks can fail for those above reasons too. Yeah they will certainly hold up much better but that doesnt mean they are not unbreakable. 50-75 lbs of material is bound to be more strength especially tying the valley together.

Stock blocks DO tend to crack up the mains... Several issues can/do cause this... Block twist is primary IMO and the lack of valley support doesnt help. I've written several times my method to only allow chassis twist forces to the block(at bell only) not through it... Plenty of valley fixes that have been shown to help too... YEAH the IA2 MR1 are far beefier and therefore less likely to crack but they are still subject to same forces. I've also found on my 69 400 and 72 455 blocks that there is a very sharp step in the oil passages to the galley and cam bearings... it reduces by@ 1/32 about two thirds the way down the hole!
I dont know if made that way but my 59 doesnt have those sharp edges there. The entry holes at mains are also well radiused.

My 59 block came out of a car parked in 62... the owner got killed in an accident never got to run the motor... (had all fresh parts in it and no evidence of having been run yet, the manifold was off and ports were taped off). Car had 31000 miles showin so...march 59 build dates on everything... vin matched engine vin stamp... guy passed Dec of 62 I'd be comfortable the mileage was original... I have minor surface rust no erosion in the water passages... I almost left the motor behind when I bought the car in 1999... its a very sound block. (2 bolt main holes not drilled for 4... my other 59 was a 4 bolt. Placement of outer bolts on all factory 4 bolts is not a great location in the bulkhead and likely a contributor to block cracks)

The Harvey aluminum blocks were patterned on the 59 castings... Mickey Thompson and Pontiac used the 59 casting for their special pieces... The RAV and SD 455 block both had features borrowed from the 59... while Pontiac did address the lifter bore issue with those later pieces those pieces did NOT get made with the early thick wall casting.
55-59 Pontiac also had reverse cooling... excellent cooling control... in 60 the bean counters won.

Thinwall casting technique started showing up @ 1961.

67 400 was 1st yr of the 400 block... Pontiac tended to make 1st year castings better and start cutting corners from there. Most 66 389's are no where near earlier blocks or the 67 400. When they did the RAV revision it was only for those pieces... no way did they want to spend to keep those features for all the rest of 400's produced... SD455 same thing.

BTW check out the Mondello main cage assembly for Pontiacs. Cody has it mounted on an MR1 block. http://www.cv-1channel.com/forums/sh...ntiac-MR1-CAGE A little extra machine work and it can be fitted to an IA2...

[Mr Anonymous]

I have a 59 block/crank/bellhousing/etc that has about 8 total hrs of run time (was in dads 53 stude and it was a warranty block from the dealer he worked at in 59) that I'd be willing to sell, along with a pair or two of 59 heads... PM me if interested.