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Discussion Starter #1 (Edited)
This car had basically been abandoned by the owner, out in the woods for the last year with hols n the top and LH window broken out... Took some persuasion (and $$$$) but he finally let it go. Spent more than I wanted to, but it's was still a fair deal. Sad thing is, it's a 2nd owner car with only 41k on it, and was really nice just 10 years ago....

So trying to figure out what this engine is, found a stamped number SR 8 48 30, in front on RH side of engine (LH side if you're looking at it from the front). Assuming it's a service replacement block, would that # be the consect. # from another car?
See another #, raised, 6M-5, may have a D below it. Another raised # looks like L168. Can anyone make sense of these? Can't access any #'s on the distrib pad, and no raised casting #'s on front.

What a mess in the engine compartment.....:frown3: See next post for engine # pics.

Appreciate any observations/info!
Darcie
 

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Agree that the "SR" most likely is Service Replacement. The heads appear to be 1968 #16 heads dated L=December, 16 = day of month, 8 = year, 1968. So the heads are late production 1968 heads. New model year, 1969, would begin in September 1968 so it is not uncommon to have 1968 castings going into an early production car - which yours may be.

The codes at the distributor will provide more info on the block. Casting number for 1968 & 1969 is 9790071 (Ram Air is 9792506). Just under the casting number near the edge of the block is the date code.

You also want to get the PHS documents for your car which will tell you when it was built and its options. If it is an early production 1969 GTO, then I would say the heads are original to the car and you need to confirm the date on the block, which may give you an idea when the block was replaced.
 

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Discussion Starter #4
...

The codes at the distributor will provide more info on the block. Casting number for 1968 & 1969 is 9790071 (Ram Air is 9792506). Just under the casting number near the edge of the block is the date code.
Thx Jim, is it possible to access these numbers with the engine installed? I can't figure out how you could...maybe the config he's got going on with the coil so close to the distrib isn't factory? I need to get a good pic of how the engine should look (I've been more of a Ford girl and this is completely different), so I can get it back to original- I know he removed the PS and then moved the alt...was in the process of moving the battery to the trunk. Yikes.

Darcie
 

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Picture shows a L168 dated,#48 casting head, not a '68 model #16 . Big valve #16 's being factory installed on '69 model V8's is disinformation that made it into the most common copied code book, that happened nearly 30 years ago. Have owned several early '69 model WT's, all had original date matching #48 's. Same experience with hundreds of other long time Pontiac collectors. '69 YS coded 400 blocks eceived #62 casting heads.

On this convert, body tag shows an 11C body tag build. Not sure if Baltimore plant had a body bank. Even if Baltimore had a body bank, looking at a time window of a painted body having to set in the body bank 6 weeks, minimum, so it could be united with an original engine with L168 dated heads. With no UAW strike, to throw things off, would surmise the 4 week later cast #48 heads are not original, but were picked up & installed at a later date on the SR fitted short block.

The block casting number is cast on the block flange area coming up from the oil filter hsg mtg pad. A fully ground off & stamped "071' 400 block casting have never ran across. Have had in my hands, many original "2506"s both original use, and SR's. Once the #48 1988 casting 400 blocks began being cast in June of 1970, SR 4 bolt 400 blocks had all 6 digits ground off & was replaced by the applicable 400 4 bolt casting number. Similar deal with 428's. On the block in the above '69 convert, it would be of interest to know the alphanumeric casting date by the distribution hole.

Congrats on the save! Being in MN, you are in a hotbed of GTO restorer/enthusiasts! Need select condition hard to find original parts, GTO JOHN used to post on this board. He as well as a good friend further west, both are deep stocked on '69 parts & '69 projects. Need their numbers, can fwd them.
 

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Discussion Starter #6
Congrats on the save! Being in MN, you are in a hotbed of GTO restorer/enthusiasts! Need select condition hard to find original parts, GTO JOHN used to post on this board. He as well as a good friend further west, both are deep stocked on '69 parts & '69 projects. Need their numbers, can fwd them.
While I try to figure out what all that means lol, I would love some contact info for parts- got a lot of orig stuff missing in the engine compartment for sure. Feel free to message me here, or email me at [email protected]

Thx for the info!!
Darcie
 

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PH is 100% correct on the heads, my bad. A quick look and I saw #16 on the center port. So that indeed changes things a bit. The 2-digit casting number on the exhaust center port is what we are referring to in ID'ing the heads. Here is a link that gives you a little more info on those heads. Here is what to look for in ID'ing: http://www.wallaceracing.com/5chead.jpg First letter in month goes "A"=January, "B"=February, "C"=March, etc., then 2-digit is day of the month, last digit is the year.

OK, using the book Pontiac Musclecar Performance 1955-1979 by Pete McCarthy, the #48 heads were used on the HO (High Output) 350CI/330HP, 400CI/350HP, 400CI/366HP Ram Air III engines. Definitely a good head to have/use on any Pontiac performance engine, but with stock pistons, the compression will be too high to enjoy pump gas and you will need a good high octane racing gas to run it without detonation.

Again, the Pontiac Historical Services (PHS) will have the build sheet for your car and worth getting in helping you ID exactly what engine/trans/rear your car originally came with from the factory. Maybe it came from the factory with a Ram Air III engine which would add a big value to the car.

Check out the Wallace website as it has a lot of good info and all kinds of "Automotive Calculators" which can be very helpful when building an engine. Wallace Racing-Drag Racing Pontiac powered Firebirds,Trans Ams and Dragsters

Do you know that the engine is a 400CI and not a 350CI? Here is a good site which shows you where to look: How to identify your Pontiac engine

:thumbsup:
 

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Discussion Starter #8
Do you know that the engine is a 400CI and not a 350CI? Here is a good site which shows you where to look: How to identify your Pontiac engine

:thumbsup:
I do not. I spoke to the guy I bought it from, and he said he rebuilt the engine it came with, he assumed it was orignal. His dad bought it in 1988 and they could tell it had not been touched in many years at that time, so guessing the swap would had to have been done a long time ago. He is looking for the PHS docs that his dad ordered many years ago, I'll give that a few more days and then I'll reorder it.

What's interesting to me is, the '69 GTO 400/4 spd convert I owned in the early 80's (I actually posted here looking for it a couple years ago), also had a service block, orig owner told me it blew up right before the factory warranty expired and he got a brand new one. Kinds odd that so many seem to have had this happen.

Wish I could access the back of the block. Thx for the info, it's much appreciated!

Darcie
 

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Discussion Starter #9
OK my son and I were determined to get these #'s, so he crawled into the engine compartment- here's what we got:

9790071
Correct casting # for a 68/69 400 engine?

D140
Apr 14 1970?

70
1970?

GM-5 D N
?

And again the engine code is SR 8 48 30.
Service block, and who knows what that # is for...

So to me, it looks like Pontiac replaced the engine in 1970, with the correct one. Am I right?
Still working on getting the PHS docs to see if the 400 was a HO.

Thanks for all the help!
Darcie
 

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OK, its a 400CI, easily ID'd by the "400" casting which indicates the cubic inch, so not a 350CI.

The D/N refers to what shift the block was cast, D=Day, N=Night and the arrow points to the "D".

You are correct on your dates of the block and you will also see "70" above that which further indicates a "1970" block.

The casting number for the 1970 block is different from the 1969 block. The 1970 block is cast 9799914, but you can see that the last four digits have been ground off and 0071 stamped in their place. This would reflect the engine casting for 1969 to which your original engine would have come with. So, being no expert, the original engine went bad under warranty and a Service Replacement engine (either block or short block assembly) was installed with the casting code restamped (possibly by the dealer who did the warranty work) to reflect the casting numbers of the original engine block. So I don't think there is any "trickery" going on here, just simply a warranty replacement block was put in the car.

As for the heads, Pontiac did things that are not always textbook correct and the internet/books are not always 100% either. Most say the #48 heads are the RA III heads, some say they were used on the GTO engine due to which factory they were assembled at. What does seem to be in agreement is that the #48 heads were used on the manual transmissions GTO's which yours is. So I would be inclined to believe that the heads are original to the car and were re-used on top of the Service Replacement block - which would make sense.

Once you get the PHS documents, you will be able to verify the original engine code and know what HP engine your car would have been built with. So you still have a unique piece of history in that you have a car with a Service Replacement block original to the car under warranty work done at the Pontiac dealership. How many GTO's can claim that? :thumbsup:
 

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Discussion Starter #11
Awesome, next best thing to a matching # engine, so along with the #'s matching trans, I'm pretty pleased!
I will be ordering the PHS docs probably tomorrow, and will post the info when I get it.

Thx!!
Darcie
 

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OK my son and I were determined to get these #'s, so he crawled into the engine compartment- here's what we got:

9790071
Correct casting # for a 68/69 400 engine?

D140
Apr 14 1970?

70
1970?

GM-5 D N
?

And again the engine code is SR 8 48 30.
Service block, and who knows what that # is for...

So to me, it looks like Pontiac replaced the engine in 1970, with the correct one. Am I right?
Still working on getting the PHS docs to see if the 400 was a HO.

Thanks for all the help!
Darcie
All the SR blocks that I have seen are stamped SR8 followed by 4 addition numbers. I believe the first 8 is for 8 cylinder engine....the other 4 numbers are a mystery to me. I think your engine is an authentic service replacement fitted short block that came from the Pontiac engine assembly factory sometime around late April-May of 1970. From time to time the engine assembly plant would receive instructions to build Service Replacement units so they would start with whatever casting was in production at that time. In this case, the 9799914 casting was the current casting for 1970 so the "9914" was likely ground and re stamped "0071" at the engine assembly plant, machined and fitted with pistons and cam bearings etc. It then was stamped SR8xxxx and shipped out to dealer parts departments all over the country for use as a correct short lock replacement for cars that originally came with a 9790071 engine casting. It's anyone's guess when the SR engine was installed but it's likely to have been sometime in 1970 like you suspect. If it would have happened in 1971 or later then it's likely that your block cast date would be later as well.

I would agree your SR engine is a correct replacement unit for all 1969 GTOs except RA IV models. I am not certain but I don't think HO 400ci engines were available in 1969.... I think the 1968 400 HO engine was essentially carried over to 1969, fitted with cold air induction and renamed Ram Air (III).

At any rate, nice find. Glad to see another one is going to be saved.
 

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Discussion Starter #13
All the SR blocks that I have seen are stamped SR8 followed by 4 addition numbers. I believe the first 8 is for 8 cylinder engine....the other 4 numbers are a mystery to me...
I wonder if those last 4 #s correspond to the dealer that ordered it? Or the plant? Has anyone tried to make sense of them? Would be interesting info to collect.

Darcie
 

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I wonder if those last 4 #s correspond to the dealer that ordered it? Or the plant? Has anyone tried to make sense of them? Would be interesting info to collect.

Darcie
Yes, there has been some interesting discussions about the SR digits. All V8 engines start with SR8 so we are assuming the 8 is for the cylinder count but I don't think we know that for certain (but it is a good likelihood that part is correct...).

I believe all Pontiac engines were assembled at the same engine plant and then sent to various car assembly plants across the country. I can't imagine a scenario where the automobile assembly plants would need to have SR engines on hand so I presume all SR units went straight to dealership service departments. They would be used for warranty jobs but could also be used for engine replacement after the warranty period expired. Customers could also purchase fitted short blocks over the counter for their own needs.

I don't think the last four numbers are dealership codes because I haven't seen numbers repeat for a given year (although I have only seen a dozen or so SR engines in person over the years...). I suspect the last four digits are serial numbers for use by the engine assembly plant to keep track of their work.


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For sake of comparison....
My '68 convertible GTO has an SR block cast date of Dec 8th 1969. The 9799914 was ground and stamped 9792506 which is correct for my application. The last four digits are 2057. Your engine was cast 4 months later and the last four digits are 4830 so the serial number theory makes sense still.

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Yes, there has been some interesting discussions about the SR digits. All V8 engines start with SR8 so we are assuming the 8 is for the cylinder count but I don't think we know that for certain (but it is a good likelihood that part is correct...).

I believe all Pontiac engines were assembled at the same engine plant and then sent to various car assembly plants across the country. I can't imagine a scenario where the automobile assembly plants would need to have SR engines on hand so I presume all SR units went straight to dealership service departments. They would be used for warranty jobs but could also be used for engine replacement after the warranty period expired. Customers could also purchase fitted short blocks over the counter for their own needs.

I don't think the last four numbers are dealership codes because I haven't seen numbers repeat for a given year (although I have only seen a dozen or so SR engines in person over the years...). I suspect the last four digits are serial numbers for use by the engine assembly plant to keep track of their work.


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SR fitted blocks were shipped from where it was fitted, Pontiac MI engine plant 9, to GM Parts Distribution Warehouses. When a customer had a warranty concern with his cars engine, the car went to the dealer & the dealer contacted the Zone. A Pontiac Zone rep then approved or disapproved the fitted block (&, if needed, cyl head) replacement. Typically, there will be paperwork, ie, correspondence from Zone on the SR fitted block replacement , if car is well documented.

There are many many high horse cars floating around with SR blocks, that the fitted SR block was bought decades later (by a reseller) or over the parts counter in the 70's through a special request. When I first became active in the late 80's as a vendor, fitted SR 400 Pontiac blocks were a much more common sight @ big swappers, than what we've seen...since the late '90's. @ Arlington, quite a few SR "915"s had a sledge hammer taken to the sides of the block, as well as NOS '64 GTO hoods getting run over by forklifts. All of it ended up in rolloff containers. Have spoken with several longtime Parts Distrib employees, the things GM mgmt made them do is very upsetting.
 

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SR fitted blocks were shipped from where it was fitted, Pontiac MI engine plant 9, to GM Parts Distribution Warehouses. When a customer had a warranty concern with his cars engine, the car went to the dealer & the dealer contacted the Zone. A Pontiac Zone rep then approved or disapproved the fitted block (&, if needed, cyl head) replacement. Typically, there will be paperwork, ie, correspondence from Zone on the SR fitted block replacement , if car is well documented.

There are many many high horse cars floating around with SR blocks, that the fitted SR block was bought decades later (by a reseller) or over the parts counter in the 70's through a special request. When I first became active in the late 80's as a vendor, fitted SR 400 Pontiac blocks were a much more common sight @ big swappers, than what we've seen...since the late '90's. @ Arlington, quite a few SR "915"s had a sledge hammer taken to the sides of the block, as well as NOS '64 GTO hoods getting run over by forklifts. All of it ended up in rolloff containers. Have spoken with several longtime Parts Distrib employees, the things GM mgmt made them do is very upsetting.
Super interesting. Thanks for the info.
I wish I had paperwork on our SR block because that would make for a much more interesting story.

When we bought the car in 1987, it came with some spare parts including the SR short block that the previous owner said was in the car when he bought it. We didn't really give it much thought since it was a 1970 engine. It was decades later that we cleaned off the oil and grime from that engine and discovered the stampings.

Without paperwork though....it is anybody's guess how and where that SR block came to be with our car.

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