[grandville455]

Originally Posted by JD311

I checked my program splayed caps and they are drilled for 1/2 in as well. Looks like it would still work for the 59 block I have though. I have had these for awhile and just noticed it. Wonder if I should try to send them back or use them?

Thats exactly what my guy did, just drilled and tapped it for 7/16"...

[LMSRACER]

Originally Posted by Tom Vaught

Thank You Larry, for your efforts.

Tom V.

Thanks for the Acknowledgement Tom.

I would say that ALL of this information (Not Just what I Posted) is applicable to the Majority of Racers or Fast Street Car Owners. I'd say any Build in the 600ish to 750ish Horsepower Range for sure.

I appreciate the others that have taken their time to post and am just "Paying it Forward".

Larry S.

[chuckies76ta]

Thank you Larry for all the info and pics you just posted. Even more reason to sticky.

Charles

[LMSRACER]

Originally Posted by chuckies76ta

Thank you Larry for all the info and pics you just posted. Even more reason to sticky.

Charles

Your Welcome Charles...

I didn't plan to spend My ENTIRE Saturday doing that, but what the Heck...

I'll tell you Guys what I'm going to use for My Next (Personal) "Stock Block" Performance Build.

A Late 1971 to Late 1974 #481988 400 2-Bolt, 2-Bbl. (No Cylinder Bore Chamfers), with Splayed Caps on the Center Three and 7/16" Fasteners on the Outer Bolt Position.

This Block is Very Similar to the (1972) Cast #485428 455 Block that I Illustrated.
(Now I've got to find one with sufficient Cylinder Wall Thickness.)

"Screaming Chief" shows what this Block looks like in His Posts #171 and #172.
(Thanks for Showing that 1977/78 Block with the 1974 Casting. I was Totally Unaware of that. Once again showing that there are No "Set Rules" Pertaining to Casting Numbers and Date Codes.)

Have a Good One,
Larry S.

[taff2]

IMO, you can't beat the early 389 blocks . '58 to '60 are the best but are probably a bit limited on bore size . If you want a smaller cube engine the 2 bolt block can be fitted with splayed 4 bolt caps and they are very thick in almost all dimensions going by the one I sonic'd. I also have a '61 389 block to use in my next n/a build,although this doesn't have the lengthways stiffening rib that the '58 to '60 blocks do, it is also very thick dimensionally and has the 1/4" taller main caps too. Although these blocks need an adapter to fit them to a TH400 pattern gearbox, this isn't too difficult to make. Now if someone could start manufacturing these adapters cheaply in 1/4" steel........ (The ali Wilcap adapters are a bit thick for my liking and quite pricey too)
Thanks go to Steve Barcak for bringing the virtues of these early blocks to the attention of the Pontiac world.

[LMSRACER]

Originally Posted by taff2

IMO, you can't beat the early 389 blocks . '58 to '60 are the best but are probably a bit limited on bore size . If you want a smaller cube engine the 2 bolt block can be fitted with splayed 4 bolt caps and they are very thick in almost all dimensions going by the one I sonic'd. I also have a '61 389 block to use in my next n/a build,although this doesn't have the lengthways stiffening rib that the '58 to '60 blocks do, it is also very thick dimensionally and has the 1/4" taller main caps too. Although these blocks need an adapter to fit them to a TH400 pattern gearbox, this isn't too difficult to make. Now if someone could start manufacturing these adapters cheaply in 1/4" steel........ (The ali Wilcap adapters are a bit thick for my liking and quite pricey too)
Thanks go to Steve Barcak for bringing the virtues of these early blocks to the attention of the Pontiac world.

taff2,
I agree with All of that. As you have mentioned, the Bore Size is the limiting factor. IMO, for a Racing Application, I don't want a Bore Size any Smaller than 4.185". I prefer 4.210" or Larger.
Therefore I believe that the trouble associated with the Early 389 Blocks just isn't worth it. That's My ...
On the other hand, the CV-1 Cylinder Head with the Correct Ports could change all of that. The Bore Size would be less of a factor, for sure........ The Jury is Still Out on that one.

Larry S.

[grandville455]

Larry
Thanks for Putting the time into this! These pictures are awesome!
Im using a 70 400 2 bolt block, that is using the program splayed blocks.

[LMSRACER]

Originally Posted by grandville455

Larry
Thanks for Putting the time into this! These pictures are awesome!
Im using a 70 400 2 bolt block, that is using the program splayed blocks.

Question....
Did your Program Splayed Caps come Drilled for 7/16" Outer Fasteners or 1/2" Outer Fasteners?

I ask because I just received a "Splayed 400" set that were Drilled for 1/2". I've always gotten Caps from Program Engineering that were Drilled for 7/16" when the Caps were Splayed. I haven't called them yet because I just noticed it yesterday.

NOTE:
Of course the Factory Style (Straight not Splayed) Program Caps are Drilled 1/2" for the Outer Fasteners. That matches the factory Drilled Holes in the Block.

Thanks,
Larry S.

[grandville455]

Originally Posted by LMSRACER

Question....
Did your Program Splayed Caps come Drilled for 7/16" Outer Fasteners or 1/2" Outer Fasteners?

I ask because I just received a "Splayed 400" set that were Drilled for 1/2". I've always gotten Caps from Program Engineering that were Drilled for 7/16" when the Caps were Splayed. I haven't called them yet because I just noticed it yesterday.

NOTE:
Of course the Factory Style (Straight not Splayed) Program Caps are Drilled 1/2" for the Outer Fasteners. That matches the factory Drilled Holes in the Block.

Thanks,
Larry S.

They came with 7/16x 2 3/4 Grade 8 Bolts, so Im guessing their drilled for those? Block is at machine shop yet. I bought the caps from Butler.

[LMSRACER]

Originally Posted by LMSRACER

Question....
Did your Program Splayed Caps come Drilled for 7/16" Outer Fasteners or 1/2" Outer Fasteners?

I ask because I just received a "Splayed 400" set that were Drilled for 1/2". I've always gotten Caps from Program Engineering that were Drilled for 7/16" when the Caps were Splayed. I haven't called them yet because I just noticed it yesterday.

NOTE:
Of course the Factory Style (Straight not Splayed) Program Caps are Drilled 1/2" for the Outer Fasteners. That matches the factory Drilled Holes in the Block.

Thanks,
Larry S.

Contacted Pro Gram Engineering.. Their Answer was Woops.....
I sent them Back Already. They'll be sending out a New Set as soon as they receive them.

Check Everything, Every Time....

Larry S.

[GRX]

Great job Larry. The pontiac community is all the greater because of your efforts.

If I may ask ... have you noticed if the casting variances you mentioned relate in any way to the foundry numbers? (GME, GM5, GM10, etc ...) Would make identification of desirable blocks in fully assembled engines much easier if true.

[LMSRACER]

Originally Posted by GRX

Great job Larry. The pontiac community is all the greater because of your efforts.

If I may ask ... have you noticed if the casting variances you mentioned relate in any way to the foundry numbers? (GME, GM5, GM10, etc ...) Would make identification of desirable blocks in fully assembled engines much easier if true.

Well , I can tell you that the 5 Blocks that are here in the Shop have 5 Different Block Codes. GMC, GM1, GM3, GM7 & GM8.

I've concentrated on Block Dates, Casting Numbers and Applications. (Such as, 2Bbl. or 4Bbl., Low Performance or High Performance, Etc.)

I believe that in order to be able to determine a correlation between Block Castings and "Pontiac Foundry Casting Line Coding", that it would take a Large Number of Blocks with the same Block Casting Number and Different Build Dates. Then you could analyze the Foundry Codes to see if there's a trend.

I've never had enough Blocks with the same Casting Number to do that accurately.

If you get it wrong, then you may end up passing on a Good Block.

It is a Good Idea and It could be done with a combined effort on the part of the PY Forum Members.

Larry S.

[Chipped Tooth]

Just my 2¢ but wouldn't it be beneficial to eliminate the dowell pin and step the cap surface block side then take the extra material off the cap?

Oh BTW I'm still working on my girdle setup.

[BruceWilkie]

No... dowels stop movement in all directions stepped only stops movement in 2 directions. Fore/aft control just as important as side to side.

Dowel fitment is important... I'd say critical on high powered high rpm engines.

[Chipped Tooth]

Agreed, hence my girdle plans.

But it also seems a dowel pin is a excellent source for a crack to start..... Obvious in the 557 blocks.

The dowel pin design that surrounds the study seems like a better option than drilling into the main webbing.

[Tom Vaught]

Originally Posted by Chipped Tooth

The dowel pin design that surrounds the study seems like a better option than drilling into the main webbing.

"Study" Probably a fat finger and you meant stud. I do those occasionally or the PY spelling deal does it for you and you do not notice.

But back on your "Timing Cover Ring" around the stud or bolt deal.

To make that work you need to counter bore a precision pocket for the ring to sit in.
Not a big deal with the machining except you now created a "step" in the cap hole in a very high stress area of the cap. Much easier to use a normal longer dowel register and be able to finish hone the hole for a very smooth bore and no stress risers vs the step in the cap deal.

Food for thought. This is not a timing cover.

Tom Vaught

[Tom Vaught]

Big Block Chebbys have a "registered main cap" that Keeps the main cap from moving side to side. Deal is it doesn't really work vs a dowel set-up.

When the main cap sees a high load, the high load causes the center if the main cap to get "taller" vs stock and the edges of the main cap move inward. This means that the main cap "register" now has even more slop to it when using vertical 4 bolt mains or a 2 bolt main block.

A Pontiac block uses dowels but the dowels are typically loose and the cap can still move around under load.

A IA-2 (All Pontiac) Block has the chevy register but uses splayed outer bolt caps that when tightened pull the cap tighter to the block register. They also use dowels that keep the cap from moving front to back under load.

The old 59-60 type blocks used a much thicker cap (top of cap to block surface) so the cap could bow upward less vs the later caps, (as mentioned earlier).

In my mind the hot set-up is select fit and longer dowels along with splayed capson a two bolt main factory block for the low buck deal. Use 7/16" fasteners on the ends of the splayed caps as that means more block meat surrounding the 7/16" bolt vs the larger 1/2" bolt.

Tom V.

[Chipped Tooth]

I understand what your saying on the cap getting taller.

I still think the register design is a better option for a weak webbing block instead of drilling a hole for a pin.

I also believe the extended skirt block design is the best for a performance application.

[Tom Vaught]

1)

Originally Posted by Chipped Tooth

I understand what your saying on the cap getting taller.

2) I still think the register design is a better option for a weak webbing block instead of drilling a hole for a pin.

3) I also believe the extended skirt block design is the best for a performance application.

1) Taller cap, more material at the bridge, more strength and less deflection

2) No factory Pontiac block has the cap register design (same as BB Chebby).
Your "register" is actually just a hollow dowel and has less strength vs a solid dowel.
Very easy to mod a cap and block for a 5/16" (.312) tall solid dowel vs machine for a 'ring" that effectively takes away some of the clamp load surface area on the block and the main cap. So the design is flawed.

3) I agree that an extended skirt is stronger. Even a 3/16" extended skirt (like the one added to the All Pontiac Block). In a perfect world you would have a Hemi deep skirt or Ford Deep Skirt design and a cross bolted 6 or 4 bolt attachment design. but most are in love with the Pontiac/chebby design as it is traditional Pontiac/GM design.

Tom V.

ps I have never seen a 5/16" dowel (.312) as stock on any pontiac block or any print showing that larger diameter dowel pin.

[Chipped Tooth]

Yes I missed the study...... Spell check LOL

I don't agree with your timing cover theory.......

Reason is lots of performance connecting rods have this feature..... I think rods are a higher stressed item than a main cap.

But I'm not saying I'm right.