[Jeff Walker]

[quote=screamingchief]The 455 block is the same deal,drilled and tapped for 4 bolts,the other 400 block was'nt,I guess because it was a 2 bbl motor.quote]

I don't know about that. The pic of the block that I posted is drilled and tapped for 4 bolts. I pulled it out of a 69 catalina. The code on the block is YB which is the 265 HP 2 BBL package. So who knows what Pontaic's rhyme or reason was?

Oh, I when I put it back together, this time I'm gonna make sure to make use of the outer bolt holes this time, but that's another topic.

[screamingchief]

I think as pontiac moved further and further away from selling cars with 4 bolt mains they became less and less likely to drill and tap those outer holes.

Seeing as how that particular 400 block I have is a '74,maybe they just omitted the extra machining procedure to save time and money vs. the earlier blocks.

In addition to being slated for 2bbl. use.

I would reason they did drill and tap some in case they were to be used as service replacement blocks or such possibly,and maybe from time to time they pulled some blocks from that "pool" of blocks to install into production line cars.

Shortages happen quite a bit in auto production,when I was a tech at the ford dealership it was'nt uncommon to have a damn hard time getting a new trans or something for a car under warranty as often they were all going to the line,and service units were secondary priority units.

And god forbid they have a bunch slip off the line with something that was defective or something,then hell would freeze over before you'd get one for a vehicle needing warranty service,they would take all the service units for refitting the factory refit/delivery units.

Those RA IV block pics sure were interesting,had to save those to the HD,appears to be a '70 block or a SR block as it has all the mount bosses.

[cooke]

Ignorance is bliss.........I guess. This topic is making me sick. So basically what you guys are saying here is that; as far as 455's go, the '70 - '74 are the strongest and '75 - '76 are okay for mild applications. And just do a visual inspection on "webbing" in the early years; especially when considering a 4-bolt conversion. I currently have one right now (455) that is not drilled for 4-bolt caps; but I believe it is older than a '75. I haven't checked the date code yet. Wouldn't the splayed caps be a wiser choice assuming there is adaquate material? At this time I just can't swing an aftermarket block.
What's crazy is; a few years ago we built a '75 455 out of a low mileage wagon. It had factory 2-bolt mains, Eagle rods, stock crank,flat-tappet cam, #62's, 1050 dominator, etc. All motor. It was in a '71 Firebird that had a race weight of 3680 lbs . It went a best of 10.73 @ 126 mph and a typically went low 10.80's most of the time. Never did come apart. The car was subjected to some fairly long "jaunts" on the street. The motor sold and went to Marty Parker (East Texas) and as far as I know; is still going fine. I was never aware of all of the weak "short-comings" that the late model blocks had.

[joegio]

I suppose that the block casting number not the block code dictate the structure of the block.

I seem to remember that the dowels in the 557 casting are through while the earlier (pre 557) blocks are blind thus thicker in that area.

How tight are those studs with oil now ?

[69birdboy]

Originally Posted by cooke

I was never aware of all of the weak "short-comings" that the late model blocks had.

The weak block they are referring to is the late 400, cast number 500557. I'm pretty sure the 455 stayed with the thick casting to the end.

[75TA]

Screamingchief:

You are right it is a 1970 block. It is the real deal and not a SR block. It came out of an identical car as the GTO in the November HPP magazine. Same color, same top different interior.

[cooke]

Originally Posted by 69birdboy

The weak block they are referring to is the late 400, cast number 500557. I'm pretty sure the 455 stayed with the thick casting to the end.

Thanks for the reply.

[PONTIAC DUDE]

Originally Posted by trim

It appears that the 500557 blocks want to break from the dowls. Could one stress releave the block (like you do when you side polish a rod) by champering the sharp edge on the main?

Why bother ? It has limited application and use it accordingly. It's not a total loss. It will work, just gotta watch what application you are applying.

[PONTIAC DUDE]

Originally Posted by cooke

Ignorance is bliss.........I guess. This topic is making me sick. So basically what you guys are saying here is that; as far as 455's go, the '70 - '74 are the strongest and '75 - '76 are okay for mild applications. And just do a visual inspection on "webbing" in the early years; especially when considering a 4-bolt conversion. I currently have one right now (455) that is not drilled for 4-bolt caps; but I believe it is older than a '75. I haven't checked the date code yet. Wouldn't the splayed caps be a wiser choice assuming there is adaquate material? At this time I just can't swing an aftermarket block.
What's crazy is; a few years ago we built a '75 455 out of a low mileage wagon. It had factory 2-bolt mains, Eagle rods, stock crank,flat-tappet cam, #62's, 1050 dominator, etc. All motor. It was in a '71 Firebird that had a race weight of 3680 lbs . It went a best of 10.73 @ 126 mph and a typically went low 10.80's most of the time. Never did come apart. The car was subjected to some fairly long "jaunts" on the street. The motor sold and went to Marty Parker (East Texas) and as far as I know; is still going fine. I was never aware of all of the weak "short-comings" that the late model blocks had.

Not true. Nothing wrong with any of the 455's. Some are just cast better then others. I have seen all of then split up the center. Doug Hite with his Orange GTO split many a good prepped 455 block running nitrous.
I built a 455 2 bolt block (non drilled) that went 10 flats with iron heads in a stock chassis 69 Trans Am. Cecil Canterbury. Many down here know that car. And went mid 9's on spray back in 96.

[Half-Inch Stud]

P-dude said """"""Personally I don't know why the shop 4 bolted that block? Makes it even weaker in that area.""""""

Matches my sentiments.
=============================================
Overall, Thusfar, I have not seen a so-called "stronger PMD block" in this thread. My examples: 425A, early SD, 73SD, Ram V.

I dare to summarize that the "stronger STOCK blocks" of folklore are not better-enough in the Main Web to be siginficant. My non-methodical pathetic homework was to compare MAINs by visual inspection on the 68-350, 67/68/69-400, 67/68/68-428s, and the 70/71/72/73/75-455s. The 60s-68 showed more meat behind #1 than the 69s'-75s' thin front wall. We're not crackin the front wall are we.

My only valuable opinion on this is the 67-400 showed a bit more in #2 #3 #4, while even my YK 428 4-bolt blocks (Nov 1966, Dec 68) did not show a real value in #2 #3 #4. My 67 428 block had a casting-breach (a gaping hole) in a #3 Main Cap inner bolt-boss. That held together with a 455 N-crank and Stock Caps to 12's over 200+ runs just fine. That as-cast "gaping hole" would fail everyone's visual inspection if it got photo'd and posted.

We can be glad the MRs and IAs are out there...

[Tom Vaught]

Quote:

"I dare to summarize that the "stronger STOCK blocks" of folklore are not better-enough in the Main Web to be siginficant."

"My only valuable opinion on this is the 67-400 showed a bit more in #2 #3 #4, while even my YK 428 4-bolt blocks (Nov 1966, Dec 68) did not show a real value in #2 #3 #4."

Last time I looked Mains 2,3,4 were the ones that the factory put 4-bolt mains on AND if you had a non drilled 67 block with the extra "bit more" the block lends itself very well to splayed caps on the 2,3,4 mains.

If you run a front and rear motor plate, the sides of the block only see the stress from the splayed caps. 3 years of high hp over 1500 can't be all wrong.

Tom V.

ps I will tell you another secret. Marty paid to have a company stress relieve the block with one of the special tables for that deal. I firmly believe that helped.

[Half-Inch Stud]

""""""you had a non drilled 67 block with the extra "bit more" the block lends itself very well to splayed caps on the 2,3,4 mains""""""

Yea I agree, the block code YD comes to my mind. Thought it was obvious that blocks DRILLED for 4-bolt caps were, uhm , WEAKER in the webs.

Front&rear motor plates, yea....you be singing in my choir. We could get a Barbershop quartet going.

[screamingchief]

Here are the YS block pics:

Casting = #9799914
Date = ?/??/?
(I forgot to check exact date code when I took pics,had checked it when I got it,I do know it's a '70 motor...)
code = YS
Application = 350 HP/A-body (330 HP/F-body),A/T,4bbl.

[7T2]

maybe i can put in 3 cents worth here- casting v feature...

for hd block id the first 2 inspections are visual:

1. ensure good casting integrity- ie no holes or gaps in web areas
2. id good main web castings by disquallifying bad ones- if the web in question wont accomodate 4 bolt caps with an inch of outside bolt penetration, its a dud- send it back.
3. with a dial caliper, measure the web thickness at the dowel pin location. look for uniformity from all 5 mains with a thickness of over .900"
hope this helps,
jim

[Half-Inch Stud]

Jim, that is helpful.

My point is made then: the subtle differences do not represent enough of a design difference to say this or that block is the capable 700+HP foundation.
Rather we're beyond the paltry 80's & 90's dreadblocks. IA2s, MR1s allow the CHOICE to build upon a stout block. Seems the Billet crank is also a CHOICE.

Looks to me : 700+HP builds WILL require ~$5000 in the Block&crank for some peace of mind.

[screamingchief]

I did'nt think this thread had anything to do with 700+ hp block choices,more like those intermediate choices between what is suitable to use for a stock 250-300 HP build,what is suitable for the intermediate 350-600 HP builds and NOT those said 650-700 and up HP builds.

You know,to help keep folks that are new to (or unfamiliar with) pontiacs from sticking they're nice new stroker crank bottom ends in a weak "late" block and having it nuke itself even though it's only making 450-500 HP...

If those here cant see the obvious weakness in the design of the #500557 block castings,then I dont know what to say,just give up engine building and leave it to those who know what to look for.

If I had a better selection of the "late" 455 blocks,like those Brian and Dude keep refering to I'd be inclined to shine a magnifying glass on that subject too,but my 455 selection amounts to 2 right now,and one of those is in a car already,and it's an earlier block anyhow,so that would'nt help much with this project.

I just felt this would be a good reference for STOCK block comparison,a databank one can tap so they can see what the differences are between various castings.

Not another excuse to start a stock block vs. aftermarket block debate...

[PONTIAC DUDE]

Originally Posted by screamingchief

I did'nt think this thread had anything to do with 700+ hp block choices,more like those intermediate choices between what is suitable to use for a stock 250-300 HP build,what is suitable for the intermediate 350-600 HP builds and NOT those said 650-700 and up HP builds.

You know,to help keep folks that are new to (or unfamiliar with) pontiacs from sticking they're nice new stroker crank bottom ends in a weak "late" block and having it nuke itself even though it's only making 450-500 HP...

If those here cant see the obvious weakness in the design of the #500557 block castings,then I dont know what to say,just give up engine building and leave it to those who know what to look for.

I just felt this would be a good reference for STOCK block comparison,a databank one can tap so they can see what the differences are between various castings.

Ditto.

Would be easy to take this to the anal level. LOL. Basically there is a really weak casted block late 75 and newer, (reminds me of the 403 Olds units, LOL). Then a decent cast blocks between 71/early 75 and then 3 good cast other blocks 67/74 to choose from for higher hp builds.
But most any of the blocks from 71 thru early 75 will handel 80% of the customers builds.

Making 350 or 360hp with the 75 and later units isn't an issue with the right parts and prep.

[PONTIAC DUDE]

Also remember that the pre 69 blocks only have 2 motor mount attachement locations. And can create an issue in the later 70 and newer body styles as far as support with adaptors.

[Brian Baker]

Originally Posted by cooke

Ignorance is bliss.........I guess. This topic is making me sick. So basically what you guys are saying here is that; as far as 455's go, the '70 - '74 are the strongest and '75 - '76 are okay for mild applications. And just do a visual inspection on "webbing" in the early years; especially when considering a 4-bolt conversion. I currently have one right now (455) that is not drilled for 4-bolt caps; but I believe it is older than a '75. I haven't checked the date code yet. Wouldn't the splayed caps be a wiser choice assuming there is adaquate material? At this time I just can't swing an aftermarket block.
What's crazy is; a few years ago we built a '75 455 out of a low mileage wagon. It had factory 2-bolt mains, Eagle rods, stock crank,flat-tappet cam, #62's, 1050 dominator, etc. All motor. It was in a '71 Firebird that had a race weight of 3680 lbs . It went a best of 10.73 @ 126 mph and a typically went low 10.80's most of the time. Never did come apart. The car was subjected to some fairly long "jaunts" on the street. The motor sold and went to Marty Parker (East Texas) and as far as I know; is still going fine. I was never aware of all of the weak "short-comings" that the late model blocks had.

Same as what 'Dude said. My block was a '75. I don't recall the date code, but it had all the right stuff that Ken told me to look for in a thicker cast block. It was a 2-bolt. I added 4-bolt splayed caps. I filled it to halfway across the water pump holes. I stuck a light reciprocating assembly in it. It lived with nitrous up to 800-HP in a 3850 lb. vehicle.

[cooke]

Pontiac Dude and Brian-- thanks for the replies.