[turbo69bird]

I wondering if anyone has pictures of ram air blocks, RAIV RAII and SR etc . I noticed a difference in. Blocks cast even on the same day. So I was hoping those who have pictures of the pass side pan rail on RA blocks might post those pictures .
Also any other anomalies I these blocks noticed please post.

[turbo69bird]

I have seen differences in this pan rail reinforced area and casting number area even on two blocks cast the same day. C118
The cast in 9792506 and non existent are both c118 blocks .
Notice the 1 inch return on the main web in one block but not on the other . Kind of like where the dipstick tube goes through.
I’ve seen blocks w 3 of those returns (including where dipstick sits) , blocks with 2 of them and blocks w 1 , why the difference?

Also notice what looks like a round bulge In The NOS block first bay, odd

[Half-Inch Stud]

That RH Oil Rail seems to be a PMD design factor for the hipo engines, back to the 425As' solid rail.

Far as i can care, it is the Main Web thickness that most matters, since the Cam area is open, all is relatively moot unless RA V or SD-455

[turbo69bird]

Originally Posted by Half-Inch Stud

That RH Oil Rail seems to be a PMD design factor for the hipo engines, back to the 425As' solid rail.

Far as i can care, it is the Main Web thickness that most matters, since the Cam area is open, all is relatively moot unless RA V or SD-455

Here’s the difference I’m taking about.
This difference even shows up on castings from the same day !

The last pic shows block w cast 2506- WY -cast on c118 w all three , block with only 2 is the block w/o casting number also a WY -cast -c118 both blocks were used in cars and not SR

[turbo69bird]

Much later SR block appears to have 2 while this other is a similar later SR block without.

[grandam1979]

Hard to tell from pictures does one block have 2 mount holes and the other has 5? Also the #4 picture that block looks like it’s been sleeved or O ringed that same picture is kind of grainy but are you sure the numbers have not been ground?

[turbo69bird]

Originally Posted by grandam1979

Hard to tell from pictures does one block have 2 mount holes and the other has 5? Also the #4 picture that block looks like it’s been sleeved or O ringed that same picture is kind of grainy but are you sure the numbers have not been ground?

One of the SR (purple dye) is on eBay right now. It’s a 71 date code and has 5 holes for motor mounts . Full stamped 9792506
The other SR is one of mine 979 cast and stamped 2506 w 2 bolt holes for motor mounts can’t remember the date code on it. But it’s a later 70+ date as I recall.

The block w out the casting number pad had a thread posted about it on here it’s a c118 w a vin that isn’t complete. But It is stamped WY correctly and the EUN falls in line correctly. I don’t believe it had Been sleeved or at least dint think that was noted in the thread about it.

I know others have these blocks around w various date codes would like to see pics of these areas and see if there differences

[grandam1979]

On the WY block is one letter a little bigger than the other? We had one in the shop I thought was a restamp until I saw another one just like it.

[mgarblik]

Originally Posted by Half-Inch Stud

That RH Oil Rail seems to be a PMD design factor for the hipo engines, back to the 425As' solid rail.

Far as i can care, it is the Main Web thickness that most matters, since the Cam area is open, all is relatively moot unless RA V or SD-455

I more or less agree. I have noticed huge differences in the amount of material around the lifter bores in the open lifter area blocks. Although no scientific proof, I would prefer to use a block with lots of meat around the un-supported lifter bores vs the paper thin ones. Some of the thin blocks only have about a .090-.100 wall thickness in spots. Currently working with a 68 400 block. About .250 wall on all the lifter bores.

[Sirrotica]

Since Pontiac made millions of blocks, it's highly unlikely the wooden patterns that the foundry used were identical. The wooden pattern that the sand is tamped around to make the molds would be the difference.

Over the years I have also, same as Mike observed, that there are variances between blocks that were cast for the same type of engines. Having worked in a foundry it can only be attributed to minor differences in the mold patterns, used to make the sand molds.

They may have had special patterns to make special performance blocks, but the everyday passenger car engine had to have way more than one pattern, so there's where you would see variations between blocks. If two pattern makers made the patterns, it's unlikely they would be exactly the same mirror image.

The foundry I worked at cast parts for locomotive diesel engines (GE) and there were numerous patterns for the same part. When they are going to do a pour, there were 2 lines making sand molds at the same time, so they would have 2 separate patterns for each line, doubtful they would be mirror images of each other. The wooden patterns take a beating, so repairs to them are ongoing. It's easy to see why there would be variances between two patterns after being beat up during the mold making process.

[turbo69bird]

Originally Posted by grandam1979

On the WY block is one letter a little bigger than the other? We had one in the shop I thought was a restamp until I saw another one just like it.

68 WY blocks always have a funky Y it’s the one block I know of that is that way. Probably wasn’t a restamp.

I’ve been told the theory is the W was stamped first and then depending which car they went in the Y was stamped after. Don’t know if that’s true but kind of makes sense.

[grandam1979]

This is a WU block with the miss match stamps also. This block came out out of Detroit 20+ years ago.

[Burgess]

Here's a pic of my NOS SR 9790071 cast date H167. It has three of the dipstick tube bosses.

When a block is cast, each of the cavities between the mains has a separate sand core, formed independently of the outer shape of the block, placed into the block pattern. You can see a seam down the middle of each of these main cores where the two halves of a pattern (or mold) were used to form these cores. Since the front side of the center three mains is the same, it seems that sometimes the half of the form with the dipstick boss was used to mold the cores. Sometimes not.

In my stash of 400 blocks, there are two 1970 blocks and one 69 with two of these boss anomalies. Others have only the one that is needed for the dipstick. I don't see any extra humps on 71-up cast date blocks.

[sdbob]

I have a 68 4 bolt block,plus couple 67 2 bolt blocks. I'll have to pull them out and look. Hmm.

[turbo69bird]

Originally Posted by Burgess

Here's a pic of my NOS SR 9790071 cast date H167. It has three of the dipstick tube bosses.

When a block is cast, each of the cavities between the mains has a separate sand core, formed independently of the outer shape of the block, placed into the block pattern. You can see a seam down the middle of each of these main cores where the two halves of a pattern (or mold) were used to form these cores. Since the front side of the center three mains is the same, it seems that sometimes the half of the form with the dipstick boss was used to mold the cores. Sometimes not.

In my stash of 400 blocks, there are two 1970 blocks and one 69 with two of these boss anomalies. Others have only the one that is needed for the dipstick. I don't see any extra humps on 71-up cast date blocks.

Thanks for posting this it’s pretty informative. So it would seem two bolts and 4 bolt blocks have the 3 Vs 2 Vs 1.
I’d think a right angle like that would really help stiffen up a block every little bit helps right. Especially adding a right angle like that.
And this would explain why some blocks on the same day have 3 while others don’t.

[turbo69bird]

Originally Posted by sdbob

I have a 68 4 bolt block,plus couple 67 2 bolt blocks. I'll have to pull them out and look. Hmm.

Yeah post up some pics and dates

[Burgess]

I checked out some big main bearing blocks and found two '69 2-bolt cap 428's with three of these bosses. I didn't find any 71-74 455 blocks with this feature, but I don't have a 70 455 to check.

It seems this casting anomaly is somewhat common in the '68-70 era.

Pic of a '69 YH 428 cast date J108