[PurelyGTO68]

Back in the 80s we used to build Pontiac engines and race them at our local drag strip. Sometimes we would search around for factory items that looked like performance parts and threw them together and see how they ran. Some of our friends did the same thing but with whatever brand they preferred (Ford, Chevy etc).

Those guys were always hell bent on starting with a 4 bolt block of whatever manufacturer they were running. We didn't really care that much. For most every power level we encountered....a well prepped 2 bolt block seemed to be plenty strong for our needs. We only raced 400 ci engines though. We tried some 350 and 455 engines but we couldn't get them to run as well as a 400. Other guys were pretty good at those other displacements but we pretty much stuck to a 400 ci engine and had a lot of fun with the hobby.

Every once in a while we would come across a 4 bolt block and we would set it aside for some 'monster' build that never happened. Other guys would usually offer us some ridiculous amount for the blocks, usually twice what we paid so we let them go. We came across them on a regular basis so it wasn't that big of a deal to wait for the next one to come along.

We didn't pay that much attention to casting codes and almost ignored the 2 digit block codes entirely. We mostly looked for blocks with 3 freeze plugs per side and 5 motor mount pads so we could have more options (we didn't always put our engines in Pontiac vehicles....). At any rate, I know I have one 4 bolt 400 block stored away and I think my uncle has 1 or 2 as well. My guess is that no one has touched these blocks for 25 years so when I go back home to visit for the holidays, I am going to try and dig them out and see if I can identify them.

So, now we are getting to my question....
I searched all my reference books and material and I don't have anything definitive that shows what cars came with 4 bolt 400 ci engines. I did find this listing online that appears to be fairly comprehensive...
http://www.pontiacpower.net/numbers/engine-codes/

So, I copied the data and put it in a spreadsheet so I can sort and filter.
I found about 376 different 400 ci block codes (2 digit codes) that is spread out over 9 different castings. I didn't see casting number 488986 (1975?) on this list so it could possibly be 10 or more different casting codes.

Of those 376 block codes....only 22 show to have 4 bolt main engines.
According to the data from the source listed above....all 4 bolt 400 ci blocks are ram air engines from 68 thru 70. However, I did read a recent post that a fair number of 1970 WT code engines were built as 4 bolt blocks as well. I presume those engines would have cast number 9799914 (??). If you group the 68-70 RA engines with these 'secret' WT 4 bolt engines...then we end up with 3 possible casting numbers.
9792506, 9799914, 9799915 (either 'as cast' or 'as stamped')

Does this sound correct? If so, then I suppose it's possible the 4 bolt blocks we have in storage are RAII, III or IV blocks? I don't remember for certain but I think these blocks have "400" cast in the side somewhere. I think this means they are likely 1970 RA III or IV or later SR blocks.

I say 'or later' because I suppose it's also possible (or maybe even likely) that some or all of these blocks could be service replacement engines. I am just beginning my research on these items. From what I have gathered so far...4 bolt SR engines could have date castings as late as 1973 (or even later?) but would likely have been ground and stamped with one of the 3 codes listed above. Is that correct?

Does anyone know of any 4 bolt casting numbers for 400 ci engines other than the 3 that I listed above?

Did Pontiac make 2 bolt and 4 bolt SR assemblies for 68-70 applications or were they all 4 bolt? Seems like it would be less complicated to make them all 4 bolt units so they could cover every possible application but that could then mean there were more SR 4 bolt blocks produced than original RA engines. Am I on the right track or am I missing something obvious.

[The Boss]

1967 had the late production 9792510 block - it was cast on 1 day only D247 and will have an EUN of 646616 or higher. I had this block back in 2007 and the caps were sequentially numbered. It's now in a car in Massachusetts.

[PurelyGTO68]

Okay thanks. 9792510 doesn't even show up on that data list or on any of my old Pontiac books. Pretty cool that you have documented such a rare piece.

The comment about sequentially numbered caps sounds noteworthy. Is that important for validation of the block? I presume you are talking about part numbers cast on the caps and not the 1,2,3,4 numbers. Correct?

[69goatboy]

The 70' YD block that I used for my goat was drilled for 4-bolt caps, but had 2 bolt caps installed.
I suspect that this was/is a common occurrence?

[johnta1]

9792510 doesn't even show up on that data list or on any of my old Pontiac books.

Try my website:

Engine Code Search

[johnta1]

The 70' YD block that I used for my goat was drilled for 4-bolt caps, but had 2 bolt caps installed.
I suspect that this was/is a common occurrence?

Yes.

[rexs73gto]

Yes in a lot of 400's & 455's , they were drilled for 4 bolt caps but only had 2 blot caps on them. This is very common with the Pontiac engine. But you have to line bore the blocks if you install the 4 bolt caps on them before you try to use them.

[PurelyGTO68]

Originally Posted by johnta1

Try my website:

Engine Code Search

Love that site! Been there many times.

Where does it show the list of 4 bolt blocks?

[PurelyGTO68]

Originally Posted by 69goatboy

The 70' YD block that I used for my goat was drilled for 4-bolt caps, but had 2 bolt caps installed.
I suspect that this was/is a common occurrence?

Mine was like that as well. Drilled for 4 but had 2 bolt caps installed. I built it with the 2 bolt caps and never had any issues....probably owned that car for 10 or 11 years. Around 1990 I came across a guy who was parting out his RAIII and his block was 4 bolt with caps so I bought it. Been sitting back home in storage all this time.

At the time I figured 4 bolt blocks were fairly common....well, maybe not common but not super rare either. Now I am a bit surprised to find out that 400 cubic inch 4 bolt blocks only occured in 68-70 RA models. (Except for the few WT and 9792520 blocks. I guess....). I have read in several publications that say the 2506 blocks were the first 400 ci 4 bolt units but apparently the 2510 came first.

[PurelyGTO68]

Originally Posted by The Boss

1967 had the late production 9792510 block - it was cast on 1 day only D247 and will have an EUN of 646616 or higher. I had this block back in 2007 and the caps were sequentially numbered. It's now in a car in Massachusetts.

So what vehicle would the 2510 four bolt block been for? I have read that 68 was the first Ram Air engine but also read that 67 models had that available as a factory option. Was the 2510 a Ram Air block for 67? (If RA existed in 67...)

[johnta1]

In the link I gave, put 9792510 in at the bottom field where it says Misc (Block codes)

Or use the casting # for the others.
(have to use the full code)

Or use the Year field for all the codes for that year.
Or use Year and Engine or combos.
(etc for the other fields)

[johnta1]

So what vehicle would the 2510 four bolt block been for? I have read that 68 was the first Ram Air engine but also read that 67 models had that available as a factory option. Was the 2510 a Ram Air block for 67?

There is a thread here on the RA II's

The RA I was a 67, then the RA II came out, look at the last pic Boss posted, it gives a point where it changed.

The RA I & II's were in Firebird 400 and the GTO.

[The Boss]

The 2510 blocks - (if that is the actual casting number) was introduced late in the 67 model year & it is believed that all of those engines received the deeper seat 997 cast heads. A few of the 2510 blocks were installed in GTO's late in the model year and I believe all of the batch built 67 Ram Air Firebirds which were produced late in the year. Surprisingly it is easier (if that word really applies) to find a bird block than it is a GTO one.

I do have contact with one owner of an early production 68 RA I/Automatic GTO who has a vin stamped 2510 block in his car left over from 67 production.

[69goatboy]

Originally Posted by johnta1

The RA I was a 67, then the RA II came out, look at the last pic Boss posted, it gives a point where it changed.

The RA I & II's were in Firebird 400 and the GTO.

Originally Posted by The Boss

The 2510 blocks - (if that is the actual casting number) was introduced late in the 67 model year & it is believed that all of those engines received the deeper seat 997 cast heads. A few of the 2510 blocks were installed in GTO's late in the model year and I believe all of the batch built 67 Ram Air Firebirds which were produced late in the year. Surprisingly it is easier (if that word really applies) to find a bird block than it is a GTO one.

I do have contact with one owner of an early production 68 RA I/Automatic GTO who has a vin stamped 2510 block in his car left over from 67 production.

How late is late for a RA I in 1967?

The reason I ask is that I have a set of RA I heads in my car, date coded as K077, which would be Nov of 67, correct? If so, that's awfully late in the production year.

I always thought the RA I started in 68?
I'm not trying to contradict anyone, just trying to learn.

[The Boss]

I think John has things confused a little - the combination in 1967 was only referred to as the Ram Air option yet there were early & late engines which had the different heads and the 4 bolt blocks. In 68 the Ram Air option was again available with the D-port #31 heads commonly referred to here as the Ram Air I option. The Ram Air II engines became available in late May and were the first to appear with the round port head configuration. All of the 68 offerings had 4 bolt blocks.

[68gtoMN]

Originally Posted by 69goatboy

How late is late for a RA I in 1967?

The reason I ask is that I have a set of RA I heads in my car, date coded as K077, which would be Nov of 67, correct? If so, that's awfully late in the production year.

I always thought the RA I started in 68?
I'm not trying to contradict anyone, just trying to learn.

Don't focus on the casting date. Remember, even though cast in 1967, it was for a 1968 model year vehicle. For example, I have a GTO with an August 9, 1967 at the Pontiac plant. That was a 1968 GTO. Casting dates do not always correspond with model year. I hope that helps!