['ol Pinion head]

Originally Posted by tanksteve

The casting number says it is an early 1971 455 HO block as the seller claims. The YC code makes one suspect it is a dealer stamped service replacement block even though we cant see the sr on the EUN number. Or somehow the factory ran out of 2 bolt main 455 blocks on that day. Rocky Rotella is probably the best expert on early 455 blocks..

Wrong. Not an early '71 HO block. Same casting number was used on all '71 Pontiac 455 blocks cast between early Gxx0 & 1100. Have mentioned before, I've owned an early Gxx0 dated YG 455 that was mistakenly factory machined/assembled with 4 bolt caps. Some '70 model 455 YH code blocks were also misbuilt with factory 4 bolt caps. Having the outer bolt holes in the block drilled & tapped then assembled with 2 bolt main caps does not make the block a factory 4 bolt block.

71 455 casting numbers.... Pete's book 33 years ago listing the 485428 casting number as "late" '71 455 HO is the source of that.

[caddor38]

So folks, I know its Christmas but I am bored and decided to list all the sites that document my 455 block casting number 483677 as an HO block. For all of you folks saying this is a non- HO block please send an email to the sites listed below.


Wallace racing list the 1971 casting 483677 as an HO motor

Wowmusclecars.com list the 1970 YC motor as a GTO HO motor.

Transamflorida.com or trans am specialties list the 1970 455YC motor as an automatic HO motor

Butler performance specifically calls out a 1971 455 with a casting number of 483677 as an HO

pattersoncoachworks just says the 1970 YC motor is a GT0 motor

wildaboutcarsonline says the 1971 casting 483677 is an HO motor

pontiaction.com state casting number 483677 is an HO block

[wovenweb]

Originally Posted by caddor38

So folks, I know its Christmas but I am bored and decided to list all the sites that document my 455 block casting number 483677 as an HO block. For all of you folks saying this is a non- HO block please send an email to the sites listed below.

Wallace racing list the 1971 casting 483677 as an HO motor

It is a nice block and probably worth your price; but the evidence points to it not being an HO block.

You seem to focus on 483677 as an HO when convenient and YC as HO with other sites. You have to use the two numbers together to identify what you have.

The Wallace racing site clearly shows that a YC coded engine with a 483677 block code is not an HO block.



Between these forums and the Wallace Racing site, you can get as close to a definitive 99.9% answer as is possible. I wouldn't rely on any of those other sites for Pontiac code information. In fact, I've never heard of most of them. I have bought lots of parts from the Butler's and will continue to do so, but their parts code info is incomplete to incorrect.

[tom s]

BUT does not the pontiac service manual say its a 325 HP 455 with heads with pressed in studs and lower CR?I would believe the Pontiac printed info more than most any other.You know its a 455 YC,you know its a 455 and you know its a 4 bolt block so what does it matter if its a HO?If you had the complete engine with ALL the original parts like heads,cam,dist carb etc which would give further proof of what you have.Threads like this pop up on here from time to time try to to prove what a engine was or is with just a block.The 64 heads are for sure 1970 455 HO which was the last year for hi CR pontiac engines,71s got hit with lower CR.Tom

[caddor38]

Urghh, yes this is discouraging. I suppose the question would be can you replace a failed original numbers matching “HO” designated block with this block and be considered a correct year matching block instead of number matching.

I suppose all of this info make me poop out of luck selling this motor. Urgghh, well lets see what other avenue i have is.

[caddor38]

Originally Posted by wovenweb

It is a nice block and probably worth your price; but the evidence points to it not being an HO block.

You seem to focus on 483677 as an HO when convenient and YC as HO with other sites. You have to use the two numbers together to identify what you have.

The Wallace racing site clearly shows that a YC coded engine with a 483677 block code is not an HO block.

Attachment 580620

Between these forums and the Wallace Racing site, you can get as close to a definitive 99.9% answer as is possible. I wouldn't rely on any of those other sites for Pontiac code information. In fact, I've never heard of most of them. I have bought lots of parts from the Butler's and will continue to do so, but their parts code info is incomplete to incorrect.

I actually found another page on Wallace racing showings its an HO, give me time and i will find it.

[caddor38]

Originally Posted by wovenweb

It is a nice block and probably worth your price; but the evidence points to it not being an HO block.

You seem to focus on 483677 as an HO when convenient and YC as HO with other sites. You have to use the two numbers together to identify what you have.

The Wallace racing site clearly shows that a YC coded engine with a 483677 block code is not an HO block.

Attachment 580620

Between these forums and the Wallace Racing site, you can get as close to a definitive 99.9% answer as is possible. I wouldn't rely on any of those other sites for Pontiac code information. In fact, I've never heard of most of them. I have bought lots of parts from the Butler's and will continue to do so, but their parts code info is incomplete to incorrect.

OKay here it is drom the Wallace racing website and a screen shot.

http://www.wallaceracing.com/blockcastnum.htm

[tom s]

That block is only good for a car that needs a YC block!What it was called means nothing.Get the actual PHS on the block and know exactly what it was in when it left the factory.Unless someone was doing a car that needs a 455 YC it would be cheaper to get a good early 400 and put for bolt caps on it for a performance engine.Break down,spend a few bucks and get the PHS BUT it will still be a YC 455.Tom

[PunchT37]

Originally Posted by tom s

That block is only good for a car that needs a YC block!What it was called means nothing.Get the actual PHS on the block and know exactly what it was in when it left the factory.Unless someone was doing a car that needs a 455 YC it would be cheaper to get a good early 400 and put for bolt caps on it for a performance engine.Break down,spend a few bucks and get the PHS BUT it will still be a YC 455.Tom

I agree. It`s the YC code that`s killing him for selling that block at that price. Someone needing a real HO block will not use that one.

Still a decent block with either added 4 bolt caps or a freak YC block from the factory. You can`t get HO price with a YC code. No matter the 4 bolt caps and block casting number.

[caddor38]

Out of curiosity, is there a way to tell if the block was actually a 4 bolt block from the factory? I know it is currently drilled for a 4 bolt and has the caps but is there a way to tell after the fact from style/markings of caps or the drilled 4 bolt holes?

It appears the motor may be considered an HO if it was originally a 4bolt main with caps built in 70. Who is to say this wasnt used in a 1970 vehicle? The Vin looks to be pretty high for an early 71 vehicle. and the vin has 7 digits for the number 21P304555. Would this mean it was 304,455th in 1971 car produce from a motor built in sept of 1970, I dont think so? The vin should be lower?

[caddor38]

Originally Posted by tom s

That block is only good for a car that needs a YC block!What it was called means nothing.Get the actual PHS on the block and know exactly what it was in when it left the factory.Unless someone was doing a car that needs a 455 YC it would be cheaper to get a good early 400 and put for bolt caps on it for a performance engine.Break down,spend a few bucks and get the PHS BUT it will still be a YC 455.Tom

Tom, something telling me I get a PHS and it says it was in a Judge i will be ridiculed even if I had the documentation. My gut feeling is that this motor was probably used in a grand pris sj. Could have been special ordered or who knows. I may get the PHS but dont want to come off the money for potetially bad news, or good nes nobody believes

[tom s]

The EUN number might show something.It would be on the PHS I believe.No way to tell if someone put 4 bolt caps on that block.As you have been told many times it’s a YC block,don’t try to make it out to be anything else.Tom

[JSuchma]

FWIW, I have a 455 4bolt block with the same casting number and the exact date code of the subject block being discussed. It is stamped YE. It is definately a 1971 455 H.O. block, as I know of the car it came from. I also know of another 71 455 H.O. 2bolt block stamped WC from a 4speed car. The information about the 2bolt mains on a 455 H.O. block was presented to Jim Mattison and he verified that it did happen occasionally. I'm going to stir the pot even more, I have YS code 400 out of a 70 GTO automatic car and it has 4bolt caps on it. I see no evidence that they were added later on. As for the subject block being discussed, YC was never used as a 455 H.O. code in 1971 no matter what block casting number was used.

[caddor38]

Okay you guys forced me to research this more. Here is evidence of documented HO GTOs with a YC motor, even a mecum action convertible listed for sale now.

https://www.mecum.com/lots/DA0912-13...o-convertible/

https://forums.maxperformanceinc.com.../t-400138.html


This info took me 5 minutes to find.

[John Milner]

Those are both 1970 model cars. As the picture of the vin on your block shows, it is a 1971 model block. A YC for 71 would not be an HO block. For 71, YC is a common block code for a standard 455 with D port heads. Simple way to tell for sure, if you don’t believe everyone on the forum, is to buy the PHS documents to confirm.

[PunchT37]

That 1970 YC has a different casting number than the `71.

[caddor38]

First off my block was made in September of 1970 not 1971, and much like those GTO’s I found received a late production 1970 YC motor. Ther is no evidence the motor made it to a 1971 car and even the Vin indicates a really high number that shows its unlikey to been installed in a 71 vehicle.

Clearly there will be nothing I can do to convince anybody here that the 1970 YC motor has been used as an HO motor even though I have provided proof.

Most everyone has said a YC motor didnt make it to an HO GTO and if anybody thought about buying my motor would be completely pushed away by all the so called experts here.

The real answer here is that many many are speculating at my expense. and if you would have spent 5 minutes like i did searching for HO GTO’s with YC motors you would have come to the same conclusion I did. There is no telling how many YC motors are sitting in 1970 or even 1971 GTO’s.

[caddor38]

Folks I apologize. I am on edge this morning because my grand baby has been here in the hose for whole week and she is crying mor than me about this stupid motor.

[JSuchma]

I hate to go this route, but we are getting no where on this subject. How about this, I will bet my 71 455 H.O. 4bolt YE block against your 455 4bolt YC block. As I stated previously they both have the same casting number and exact date. If you win the bet, I will give you my YE coded 455 H.O. 4bolt block. If I win the bet, I get your 455 4bolt YC coded block. Shipping and the PHS will be paid by the loser of the bet!

[shaker455]

cardor38,
The reason you ad has attracted negative attention is because your engine is not 455HO.
The information you have gathered is incorrect.
I would suggest removal of the ad or have form administrators do so.
Thx