Stamped codes on Service Replacement Block

[MalteseFalcon]

I picked this up and got it home this week. Service Replacement block dated October 5, 1973; the 4-bolt mains are are from another engine and I will need to get it line bored. But I had a couple of questions. It looks like it has the code "88 89 6" stamped in about the place where you would normally see the engine code for the application - like "WC" on a 1978 4-speed 400. Does anyone know what it means?

Also, I noticed that the three 4-bolt caps have the numbers 2, 3 and 4 cast into them - that makes sense. But in addition, on the other side of the cap, they have 7100, 7101, and 7102 cast into the caps with 2, 3, and 4, respectively. What is that for?

I think the front main bearing cap has a casting date on it, but I can't make it out. I guess they could be from any 4-bolt from a 421, 428, or 455.

Also, here are pictures of a nice clean 455 4-bolt block for your viewing pleasure.

Thanks!

[firebirdparts]

I always thought the number next to the engine code was for record keeping purposes in the engine assembly area.  They don't link directly to the build sheet though.  At least I don't think they do.

[Rocky Rotella]

The 7100 to 7102 are the last four digits of the individual part numbers of the main caps. What many do not realize is that all five caps were cast as a single unit, rough machined, cut apart, installed on the block and finished machined. They were then specific to that block and will not directly interchange with another block without machining.

Curiously, what makes you think they are from a different block?

While I can't decipher the "88 89 6", the SR8 number lower is Pontiac's internal identifier.

Can you provide some additional images of the casting number and cast date? I'd love to add these images and information into my SR data base.

[MalteseFalcon]

The 7100 to 7102 are the last four digits of the individual part numbers of the main caps. What many do not realize is that all five caps were cast as a single unit, rough machined, cut apart, installed on the block and finished machined. They were then specific to that block and will not directly interchange with another block without machining.

Curiously, what makes you think they are from a different block?

While I can't decipher the "88 89 6", the SR8 number lower is Pontiac's internal identifier.

Can you provide some additional images of the casting number and cast date? I'd love to add these images and information into my SR data base.

Hi Rocky! Thanks very much for your response. I didn't known that all 5 mains were machined from one original casting; I assume that was to ensure consistent properties in the all of the caps on one engine?

Here are pictures of the casting number (485428) and cast date - J053, or October 5, 1973, for the SR block. I had to reduce the size to upload them here; please PM if you would like higher resolution copies of them or any of the others.

Regarding the caps, I was told by the seller that they were from a different block, and I believe that he had put them on this one. I tried to get a better picture of the date code on the front cap, and it's hard to photograph. The first letter could be an "L" or a "C" (or just about anything else); I think the next is 15 or 13; and I'm pretty sure the last digit is a "2". 

I recently got another 455 block and heads which some people have told me is kind of interesting. It's a 483677 casting with a cast date of "H180", which in this case I believe is August 18, 1970. It has 2 bolt mains. There is a "71 "cast into the block, it has "C028808" and "YC" stamped on the front of the block and has #66 heads. I was told it was removed from a 1971 Grand Prix . Using the Wallace Racing database, this decodes  to a 1971 455, 325 HP, 8.2 compression, 067 cam, automatic. Pictures in the next post below. Perhaps the only interesting thing is that the 483677 block appears to be a short production block, used in 1971 between the 9799140 and the 485428 on all 455s, including the '71 455 HO. I think I read that the 483677 block might be a little thicker in the webbing than the 485428.  I think that might be in your Definitive Firebird and Trans Am Guide, 70 1/2 to 1981 .

Speaking of that book, are there plans to do a second printing? I'm still looking for a hard copy, and judging by the prices in the resale market for it, your outstanding book is, not surprisingly, in very high demand. My Firebird library goes back to first editions of Michael Lamb's The Fabulous Firebird and Joe Oldham's Supertuning Your Firebird Trans-Am (I'm not a book collector, that's just when I bought them), and a lot since then, and your careful, thorough, investigative approach to research takes things to the next level.

[MalteseFalcon]

Pictures of 1971 483677 block.  As noted above, it's a 483677 casting with a cast date of "H180", which in this case I believe is August 18, 1970. It has 2 bolt mains. There is a "71 "cast into the block, it has "C028808" and "YC" stamped on the front of the block and has #66 heads. I was told it was removed from a 1971 Grand Prix . Using the Wallace Racing database, this decodes  to a 1971 455, 325 HP, 8.2 compression, 067 cam, automatic.

[Rocky Rotella]

Thanks for the pictures of both blocks and the feedback on the main caps! Let me address each one separately.

Your service-replacement 485428 is interesting in the fact that it was originally a 4-bolt block. For 1971, Pontiac had (2) 455-ci service replacement blocks. 1) 483394 had 2-bolt main caps for 455 d-port applications and 2) 483393 has 4-bolt main caps for 455 HO applications. Beginning in 1972, Pontiac commonized the separate 2-bolt and 4-bolt applications and offered a single service replacement 455 fitted with 4-bolt main caps. Its part number was 487639.
 
The 487639 was the fitted S/R assembly which was comprised of the 485428 block fitted with 4-bolt caps, cast pistons with pins and rings, cam bearings, coolant and oil galley plugs, etc. Expanding upon my “interesting” comment in the preceding paragraph about the 4-bolt main caps, the particular 4-bolt caps found on 487639 carried their own part number. Why? Because in 1973 Pontiac removed the windage tray (which also captured the lower oil dipstick tube) that was bolted to the numbers 2-and 4-main caps. They moved to the baffled oil pan and the lower dip stick tube was bolted to the number-3 main cap. If you see on your block, all three center caps are drilled tap to accommodate the windage tray or bolt-on tube of the original application that S/R block was replacing. These caps were then used into the 1974 model year and possibly beyond on production 455s, but their origin is the 487639 S/R block.

Remember when I mentioned in my original post that the main caps were cut from a single casting? The main cap casting used for 487639 S/R application carried part number 487099. Each individual main cap was marked with its own part number, which increased/decreased sequentially from the main casting. In your instance they would have been 487100 to 487104. See the 7100, 7101, 7102 that you’re seeing on your caps? Those are the last four digits of the individual part number. That tells me that those *should* be the original main caps for your S/R 455. That doesn’t suggest that the seller wasn’t upfront and correct in that those particular main caps came from a different block entirely, but it remains that those main caps *are* correct for your application and may very well be the original main caps to that block.

[Rocky Rotella]

Concerning the 483677 block, when Pontiac moved to the 455 in 1970, the cast number was 9790140. Pontiac ran out of seven-digit character part numbers that model year and moved to six-digit characters for 1971 and many of the engine parts carried over into 1971 are identical to their 1970 counterpart only with an updated part numbers.

As best I can tell, the 483677 block was identical to the 9790140 in every respect. It was used for a very short time early in the 1971 model year before the 485428 block was introduced in late August 1970. The 485428 casting was revised in that some of the internal bosses were made thinner. And you’re right, I did address this—and so many more details like this—in my book.

[Rocky Rotella]

And speaking of my book—The Definitive Firebird and Trans Am Guide 1970-1981—I wish I could tell you that new copies were available, but I am completely sold out and Cartech elected to not reprint it when the initial run sold out. I urge you-and anyone else interested in buying a copy of that book at a reasonable price-to contact Cartech directly at www.cartechbooks.com. With enough interest, maybe they will consider another printing another run.

[MalteseFalcon]

Wow! That is fascinating information. I just want to make sure I understand something correctly, if you don't mind. So if I do understand correctly, at the time that this SR block was produced (October 5, 1973) ALL 455 Service Replacement blocks were originally fitted with 4 -bolt mains, which Pontiac had started doing in 1972, and continued doing at least through 1974 or later, and those S/R blocks had (and only the S/R blocks had) main caps with the 487099 main part number and the 7001, 7002, 7003 individual main cap part numbers. Do I have that right?

Therefore, if these are not the original main caps from this particular S/R block, they came from another S/R/ block just like it, which is why you would say they are correct for this application (being the S/R block).

My ultimate application for this block is to replace the Chevy 350 that someone along the way installed in a 1972 4-speed Trans Am that I acquired this summer. This SR block would be exactly what would have been ordered and installed by the dealer if the original owner had taken delivery of the car and promptly blown up the bottom end.

Also, I realized that I had sent pictures of all of the main caps except #5, so here is that one, in case you want it for your database. The number is easier to read on a smaller photo somehow; I think it is 485949 or perhaps 485948.

And regarding your book, thanks for that information. I will definitely be contacting them with as persuasive a message as I can write; I think it clearly warrants at least a second printing.

[MalteseFalcon]

After Rocky's comments, I was prompted to call Alain Desjardins, the gentleman I bought the SR block from, to ask him if the caps were on the block when he got it, and if not, where they came from. I got a really helpful detailed story:

He did not know the man he bought the block from. The seller had a few Pontiac blocks for sale. Alain asked a lot of questions without getting any very helpful answers about the block, it's condition, casting numbers etc. but he decided to go and see it anyway. When he arrived he found three Pontiac blocks stored in a small, old, unheated warehouse, along with a lot of junk. When he first got there, none of the blocks had the crank or the main caps installed. 

The three blocks were a 400, the SR 455, and a YY 455 with a casting date of F233 - July 23, 1973. .

After looking through the pile of junk, they located two crankshafts, one with 3.00 journals and one with 3.25 journals - so for a 400 and for a 455. Both of these cranks were rusty, dirty and scratched and were not of much interest. The seller was unable to give Alain any more information. Looking through the junk,  they found a small box with the main caps in it.  Alain thought that of the blocks that were there, they had to be from the SR block, since they couldn't be for the 400 because of the difference in the journal size, and the other 455 block was a '73, and the only 4 bolt main block in 1973 was the 455 SD, and the '73 block was obviously not a Super Duty. So he concluded that the main caps probably went with the SR block, but they weren't on it when he got there, and the seller didn't remember if they were from that block or not or where they came from. At the time, Alain did not know that all SR blocks dated 1972 and later came with 4 bolt mains; presumably, if he had known that, it would have reinforced his conclusion.

When he advertised the SR block for sale, he made no claim that main caps were original to the block, just that they were available to be bought with the block. He even suggested that they were not, and that the block should be line bored.  He told me that since he couldn't prove for sure that the caps came with the block, he didn't want to risk misrepresenting it. Based on these facts, though (combined with Rocky's comments above) I am virtually certain that the main caps ARE original to the block, and I am absolutely certain that Alain Desjardins (of Quebec City, Quebec, if you happen to be dealing with him - he often sells Pontiac parts) is a very honest man.

And of course, Rocky nailed it from the beginning. I am really glad that he asked why I would think that the caps weren't original to the block, and that I got the whole story from Alain!

[Rocky Rotella]

Hey, that's great news! And I'm so glad the seller was able to help. I'd suggest having your machinist check everything to make sure they lineup correctly, but I sincerely doubt you'll find anything out of the norm. 

And sorry for the delay getting back to you. Yes, all 1972-1974 S/R 455 applications came with 4-bolt caps. That assumes the dealer, parts man, etc, ordered 487639 for that application. They could have easily ordered a different application (like 1971 455 2-bolt) since the original applications were guidelines. And you're right on the main cap sequencing.

Where you '72 T/A is concerned, you have the correct SR block for that application. I have to admit, what a lucky find!