[grandam1979]

No matter what it’s out of the block and caps will always be worth 1000-1500 as a good core. Any person restoring a 71 that doesn’t have the original would love to have that block.

[shaker455]

I went thru my Pete McCarthy book again and on Pg. 3 it has the same info as OP posted.

Pg. 50 creates definition:

Only two block codes for all 71 455's that year : 438677 & 485428, both are called HO, 2nd one called late HO
So then it boils down to the stamped letter codes on the blocks as to how they were outfitted:

All 71' 455 "YC" stamped blocks used # 66 D-port heads, 067 cam, 325HP

All 71' 455 "WL" "WC" "YE" stamped blocks are (LS-5) 455H.O. package : 197 Round Port heads, 068 cam, aluminum intake 335 HP

The ad is misleading in the sense when you see "455HO block" it is assumed it was part of the LS-5 455H.O. package.

I have a bare 71' "YC" block myself and I would not advertise it as a 455HO block.
Buyer beware.

[Tellyshavilli]

Originally Posted by shaker455

I went thru my Pete McCarthy book again and on pg. 3 it has the same info as OP posted.

Pg. 50 creates definition:

Only two block codes for all 71 455's that year : 438677 & 485428, both are called HO, 2nd one called late HO
So then it boils down to the stamped letter codes on the blocks to how they were outfitted:

All 71' 455 "YC" stamped blocks used # 66 D-port heads, 067 cam, 325HP

All 71' 455 "WL" "WC" "YE" stamped blocks are (LS-5) 455H.O. package : 197 Round Port heads, 068 cam, aluminum intake 335 HP

Good info from Pete but he missed the 483677 block , it on rare occasions has been used in very early 1971 455 HO applications (WC ,YE )

[4dblnkldude]

Good info from Pete but he missed the 483677 block , it on rare occasions has been used in very early 1971 455 HO applications (WC ,YE )[/QUOTE]

I just checked my block in my 71 TA, 483677. I've been following this thread. I remember in the early days of ebay people would advertise these all the time as HO's. Then laughing... I cannot spot a recoated phosphate bolt six states away but there is a ton of misinformation out there and gap in info from the "old heads" to the new blood in the hobby young or old.

['ol Pinion head]

Originally Posted by shaker455

I went thru my Pete McCarthy book again and on Pg. 3 it has the same info as OP posted.

Pg. 50 creates definition:

Only two block codes for all 71 455's that year : 438677 & 485428, both are called HO, 2nd one called late HO
So then it boils down to the stamped letter codes on the blocks as to how they were outfitted:

All 71' 455 "YC" stamped blocks used # 66 D-port heads, 067 cam, 325HP

All 71' 455 "WL" "WC" "YE" stamped blocks are (LS-5) 455H.O. package : 197 Round Port heads, 068 cam, aluminum intake 335 HP

The ad is misleading in the sense when you see "455HO block" it is assumed it was part of the LS-5 455H.O. package.

I have a bare 71' "YC" block myself and I would not advertise it as a 455HO block.
Buyer beware.

Pete McCarthy's reference in his book to these two casting numbers is what is wrong. The "late 455 HO" connotation has been repeated time & time again by website compilers that have very little hands on factual sense concerning actual usage.

['ol Pinion head]

In many posts I have noted much of the following original '71 model 455 HO engine information. Many times these were in '70-72 A-body Tech forum as well as the '70-73 Firebird Tech forum.

The earliest '71 455 HO engine blocks were actually E & F of '70 dated 9799140 factory 4 bolt main blocks. These were the extremely early '71 455 HO blocks. Pete M did not know this & it was not printed 30 years ago in his book! A bunch of near worthless compilers did not take the time to compile known factual info, but instead threw what they had and which was often copied from Pete's book up on their own sites. Dont question the webmasters, they are often near clueless. I once sent an email to the GTO Heaven webmaster & kindly mentioned that no '71 Pontiac A-body's were built out of the Arlington Texas or Baltimore MD plants. He wasn't interested in those FACTs, his poorly compiled info was flawed but he was sticking to it!

There are at least sixty documented low VIN number '71 455 HO engine builds that used the E & F dated 9799140 blocks. This usage has been known by quite a few of us that have owned these cars & parts since well uhhh, before PY forums & before Al Gore invented the Internet (humor). 3 of us including myself that have already posted on this topic know this first hand as we've owned such early 71 455 HO cars. Know of two others that regularly post also have owned dozens of '71 455 HO cars, & know this exact same thing.

483677 blocks were first actually cast in early July of '70. I've personally had nine 483677 cast 455 & 455 HO coded blocks/engines, & have pertinent dates and info on many many more in a database of '70-73 Pontiac engines/trans & original matching car builds. That data stream with less errors is much larger than what John Wallace has posted on his site.

Early 90's, I pulled an early G of 70 dated YG casting 455 block out of a local pick-n-pull. That 280 horse small valve headed YG coded 483677 casting block was mistakenly built with factory 4 bolt main caps, simply a factory screwup, over the years I've seen it quite a few times. More times with '70 usage YH 455's out of Bonnevilles & Executives. Once a well respected PY member put info on a misbuilt 73 455 Dport application block with factory installed 4 bolt mains. Def another factory misbuild.

483677 blocks were cast on certain days. Other than the above early July built YG screwup that I pulled as a specialty core, the July of 70 cast 483677's Ive ran across nearly all were machined & assembled with 2 bolt main caps. Typically stamped & assembled as YC coded 455 engines. Pontiac needed a MASSIVE amt of YC 455 engines for all their higher line big cars, & GP's (when so ordered). A few '71 Pontiac A-body's & F-body's also were ordered with the YC code 325 horse Dport 455. I've owned two & parted on two other 71 455 Dport GTO hardtops. Espen posted on this site near ten years ago about his factory 455 YC engines 71 LeMans Sport convert . Espen posted a long and very detailed buildthread of he frame off restoration of that extremely early '71 455 Dport YC engined car. FWIW, all 71 Pont A body converts were assembled in Pontiac. The original YC engine in his car was an extremely early cast July of '70 483677.

As August of '70 Pontiac engine production rolled on, if one pays attention, one will finally see 483677 blocks that were actually machined & assembled with factory 4 bolt main caps for the '71 455 HO applications. 483677 blocks continued to be cast and machined & assembled up until Sept 10 of 1970 with both 2 bolt main caps (YG, YC), & 4 bolt main caps (WL, YE, WC 455 HO applications). From this topic, one can surmise at least one Dport application 455 YC block was mistakenly built with 4 bolt main caps, OR someone has taken the trouble to add those 3 center caps. Not an easy task to properly fit 4 bolt caps off another engine.

More factual history... Mid Sept of 1970, a '67 day UAW strike crippled all of General Motors Auto & Truck mfg. This stopped all casting at Pontiac Central Foundry, as well as the mfg of nearly all component parts. This effects date spans of installed dated parts! The strike lasted till aprox Nov 20th 1970. Several Pontiac assembly plants including Pontiac MI, Fremont, & VanNuys then slowly reopened. A few plants like Norwood, Lakewoood GA, & Oshawa did not resume production until mid to late January of 1971.

When Pontiac's Central Foundry did fire back up in Nov, the first items I've ever spotted that were actually cast were externally dated SR 614 casting RA4 heads. These incorporated the revised rocker boss casting. Have examined two pair & owned another nos pair of 614's.

Later in the month of Nov, the first 485428 casting 455 blocks began to be cast. All of the very late Nov & early Dec cast 485428 blocks that I've personally owned or examined were two bolt main cap YC coded 455's, not 455 HO blocks. Why is that one might ask? One has to understand that there was a considerable supply of 71 model usage YE & WC 455 HO engines in stock at most of the different A & F -body assembly plants when production resumed (most likely a low supply at Oshawa). As each plant received orders to build certain 455 HO cars, those 455 HO engines were pulled from engine banks & then used up. As at least 3 assembly plants did not open back up til at least mid January of 70, this created even wider date spans in those plants between actual engine casting, machine, assembly, til the fully assembled engine actually being installed in a 455HO A-body or F-body (ESP Norwood builds). This is fully evident in the listings in my database. Have posted here on PY numerous times about this over the last 20 years.

The very rarely ordered WL coded 455 HO engine was assembled & eventually was used up as HD 3 speed 455 HO cars were ordered. The '71 WL's I have info on were installed in performance A-bodys, & quite a few had very wide date spans from engine block & component casting dates til actual use.

Having pulled becoux of Pontiac engine cores since the mid 80's, having worked way too many national club conventions, swap meets, & having owned multiple dozen '71 455's both as core engines, and as engines in original 455 HO project cars as well as several 455 YC engined '71 GTO's & GrandPrixs, my earlier post is 100% accurate as to what the above I020 dated YC engine is. Simply put for what it dates & VINs out as, it is a Pontiac plant BIG CAR usage block that was most likely misbuilt with 4 bolt main caps. I'm sorry the very weak compiled websites don't offer more insight into casting numbers & codes. Near twenty years ago Rocky & I compiled a list of numerous "missing" from Pete's book 2 letter engines codes that were used in '72 model Pontiacs & 76 model Pontiacs.

By far the vast majority of '71 455 engine cores I've had over the last 4 decades came out of B series Pontiac yardcars. Pontiac 455's that were originally built out of the X, D, P, C vin assembly plants. As A-body & B-body Pontiacs were built out of the same home Pontiac assembly plant, Pontiac had to differentiate the confidential block stamping for theft regs what car line these engines went in. That is why Pontiac began the last 6 digits of the partial VIN with a 1 for A-body's, followed up by a 2, later in the production year. For the Pontiac Catalina's, Bonnevilles, & Grandvilles produced out of the Pontiac plant, that first number of the last 6 numbers began as a 3 for '71 models.

Hopefully this is my last post, really struggle reading quite a few of these posts.

[JSuchma]

Well said OPH. I hope we can put this one to rest!!!

[Tellyshavilli]

Yes Great post OPH !

[caddor38]

OPH, great read.
I suppose this proves there were alot of cars getting numerous engine codes which I think makes the engine a rarity. Like some coins minted incorrectly. You said the 4 bolt mains were created as a screw up. I have also heard the 4 bolt mains were created for a specific application or purpose yet the YC code or any other code was stamped on the block and used to meet a need. I dont think 4 bolt mains were created as a screw up yet merely puposed as needed. It would seem that my block was created on the last day of th 483677’s and could very well be the last 4bolt main ever made for that number. I think this motor has interesting history and would be nice to keep alive as a standard bore. I will get the PHS info on it. I wonder if there is a way to determine any more info about this block.

[caddor38]

Lastly, it appears that Mcarthy called this motor an HO motor and now he is listed as wrong. It seemed as though his book was the pontiac bible and now you guys say he made a mistake. Good grief!

Clearly based on OPH the block was either created as a mistake or repurpoused and was not in a GTO but it was cast asa 4 bolt main and virtually identicle to the block it sat next to that may have been stamped WC.

[tom s]

the diff remains is a YC is not a "HO" block!Tom

[caddor38]

Originally Posted by tom s

the diff remains is a YC is not a "HO" block!Tom

Mcarthy say it is, cant go against the pontiac bible

[johnta1]

McCarthy does NOT say the YC is a 455 HO engine.


From his book:

[FASTASSBIRD]

Roger (OPH) can just drop the mic and walk off stage.

[FASTASSBIRD]

Originally Posted by caddor38

OPH, great read.
I suppose this proves there were alot of cars getting numerous engine codes which I think makes the engine a rarity. Like some coins minted incorrectly. You said the 4 bolt mains were created as a screw up. I have also heard the 4 bolt mains were created for a specific application or purpose yet the YC code or any other code was stamped on the block and used to meet a need. I dont think 4 bolt mains were created as a screw up yet merely puposed as needed. It would seem that my block was created on the last day of th 483677’s and could very well be the last 4bolt main ever made for that number. I think this motor has interesting history and would be nice to keep alive as a standard bore. I will get the PHS info on it. I wonder if there is a way to determine any more info about this block.

No you can’t use this logic. Otherwise EVERY 70 400 block would be considered a ram air III/IV block ESPECIALLY early cast WT blocks that came with 4 bolt mains frequently. It’s YC that’s considered NOT the casting number. As I said earlier and Roger incredibly articulated. Stuff happens. **** we are out of 2 bolt main caps. Quick run get some more. I’ll slap these 4 bolt caps on this block so the line doesn’t stop moving and LITERALLY the entire plant stops all over 2 bucks worth of caps. This happened more then you’d think. Or could be a FNG didn’t know. The possibilities are ENDLESS. what we know as fact is the block is 71 block. It has a 71 vin. It has YC on the front. The vin is for a big body Pontiac. It CAN’T possibly not ever could have been an HO based on dates and facts. Also the Pontiac “bible” listed 13 heads as ram air, another error that we have to constantly try and set straight. No one is “perfect” and no one is upset it happened most of us are extremely thankful Pete took the time. Doesn’t make him errorless. As a matter of fact I believe he actually corrected that himself at some point. Maybe someone here can confirm. Regardless the YC code isn’t HO and couple THAT to the date code and vin and all you have is a lucky 4 bolt block. Congrats on that part as it’s worth more then a 2 bolt YC.

[grandam1979]

This is my go to book from 1974 it shows HO with the cross at bottom.

[PunchT37]

Bottom line is, he`s probably got a real 4 bolt main std. bore 455 block. It`s worth more than a 2 bolt main. It`s probably worth what a std. bore 4 bolt 428 block is. But, you won`t get a Patek Philippe price for it.

[caddor38]

Originally Posted by johnta1

McCarthy does NOT say the YC is a 455 HO engine.


From his book:

okay you guys win its not an HO block because somebody stamped YC instaed of WC on it. laughs

[caddor38]

Originally Posted by grandam1979

This is my go to book from 1974 it shows HO with the cross at bottom.

What book is that?

[pggto]

I have a question? I read through this post rather quickly and maybe I missed it. But did these 4 bolt main caps originally even come with this block? I'm not talking about code identification, but did this block physically come with those caps, or did some one stick them on there when they sold the block years ago? I've purchase a few blocks over the years that had the wrong caps on them or none at all. Sometimes it's very visible if you look at the crank bore alignment.