# 455 question?



## tyler t (Aug 15, 2010)

so i read up on the history of the 455 and i come to find out the block vin decoder i found online lied to me. i was told i had an HO but HO didnt start till 71. i have a 1970 455 ram air IV with 4 bolt mains . whats the real difference in the 71 455 HO and my 70 455 with 4 bolt main? do all 455s have A 4 bolt main?  i cant say i have an HO any more


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## JustAl (Mar 20, 2010)

Gotta agree with you about all the sites/people/books that claim to know the 2 bolt 4 bolt applications. While all blocks were machined and tapped for 4 bolts many were not equipped with the 4 bolt caps. The 455 block I have according to most authorities should have 4 bolt caps but doesn't. That said I really don't know about your particulair engine, but 4 bolt mains really aren't a requirement unless you are making serious power. A well prepped 2 bolt block will support well over 500 HP if done correctly. No one will ever know how many bolts screw done the mains but you.


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## BearGFR (Aug 25, 2008)

tyler t said:


> so i read up on the history of the 455 and i come to find out the block vin decoder i found online lied to me. i was told i had an HO but HO didnt start till 71. i have a 1970 455 ram air IV with 4 bolt mains . whats the real difference in the 71 455 HO and my 70 455 with 4 bolt main? do all 455s have A 4 bolt main?  i cant say i have an HO any more


Hey Tyler, welcome to the "inter-tubes". Not everything you read on-line will be correct 

To properly identify your engine, you need two pieces of information: the date code on the top near the distributor hole for when it was cast, and the two-character engine code from the front of the block. The block casting number, on top of the block and just behind the passenger side head can also be helpful. All three pieces of information matter, because the same engine codes and casting numbers were used across multiple model years, and not always for similar configurations and power levels. For example, the same 400 block casting number was used in different years, one for Ram Air III GTO's, the other for "low performance" 2-bbl Grand Prix's.

What was already said about 4-bolt mains is true. They aren't really "needed" until you're making more than 600-650 HP. Also, 455 blocks are generally not as strong as 400 blocks - 400's have more "meat" and therefore strength in the main webs due to the smaller main bearing diameter.

Bear


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## tyler t (Aug 15, 2010)

do you have a good link to a block vin decoding sight?


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## tyler t (Aug 15, 2010)

if the 400 is stronger why didnt they keep the same size main journals? is the 455 crank stronger because it is enlarged?


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## BearGFR (Aug 25, 2008)

tyler t said:


> if the 400 is stronger why didnt they keep the same size main journals? is the 455 crank stronger because it is enlarged?


Hey Tyler,

There were links to decode information buried in my original post for you.


Both 400 and 455 factory iron cranks are very strong - much stronger 
than ::cough:: Chevys. Their strength comes from the fact that they are much shorter and because of that, more rigid. The roots of the 455 go back to the 428 (introduced in 1967) and the 421 (introduced in 1961) - all 3 have 3.25" mains. The 400 comes from the same family as all other Pontiacs that have 3.00" mains. The reason I've heard for the larger main journals had to do with engineers thinking that the resulting decrease in bearing "surface speed" would help the main bearings better withstand the stresses due to the longer stroke. It turned out not to be necessary. In fact, the weaker block due to the "smaller" main webs turned out to be more of a liability to longevity than the faster "bearing speed" of the smaller journals would have been.

I'm in the process of getting my 69 GTO going, and for power I built the numbers-matching 400 block into a stroker 461, using a 3.00" main 4.25" stroke cast steel crank (the 400 factory crank was 3.75" stroke). So far, I'm very happy with the result  Here's the dyno sheet, and a link to a video of it running 




So far, I likes it 

Bear


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## tyler t (Aug 15, 2010)

so my engine is out of a automatic 1970 pontiac grand prix. some times it feels better to live in denial. i guess it has a more atractive body now hahahaha

nice video i have the same cutouts now. i dont have a video of it now that i put the exhaust on it. im sure youve seen my video in my signature.i have the factory 400 in the shed in my back yard... oh and your dyno sheet link didnt work


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## BearGFR (Aug 25, 2008)

tyler t said:


> so my engine is out of a automatic 1970 pontiac grand prix. some times it feels better to live in denial. i guess it has a more atractive body now hahahaha
> 
> nice video i have the same cutouts now. i dont have a video of it now that i put the exhaust on it. im sure youve seen my video in my signature.i have the factory 400 in the shed in my back yard... oh and your dyno sheet link didnt work


Oops --- I typo'ed the link. I edited my post and fixed it, so it should work now.


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## Mr. P-Body (Jan 20, 2011)

Interesting...

There was a "455HO" option for the '70 GTO and Grand Prix. It was rated at 370 HP. It DID have 4-bolt mains (at least every one I've disassembled). It had "d-port" heads (casting no. 64), though, not "round port" like the later HOs. It was the ONLY factory "high compression" 455 (10.25:1) produced. The 360 HP version from the "big cars" was also 10:1, but not the "good" heads (15s). Unfortunately, most of the 64s have been "gobbled up" by the 400 crowds from the '80s, as the 84 CC chamber is perfect for a 9:1 400...

The larger mains were developed out of ignorance in the late '50s/early '60s about the strength of a nodular iron crankshaft versus the block. It was "convention" then to make the crank as strong as possible. They never gave a second thought to the size of the "hole" down the middle of the block. Smokey Yunik discovered the negative issues with the "bearing speed" (higher with a larger diameter) when testing the 4" stroke 421s in late '61 for the '62 NASCAR season. He ground the mains down to fit in a 389 block and welded the thrust, effectively "introducing" the first Pontiac "strokers". He found that reducing the main journal by 1/4", the bearings would "live" at 6,500 RPM for 500 miles (Daytona 500, to be specific) and the block was less apt to "split" in the bulkheads. 

What we have learned since then, is the crankshaft in the Pontiac is actually the STRONG point rather than the weak link. The block is the weaker of the two when power levels climb past 700 HP. Unlike Chevys and Fords of the day, with their little mains, the Pontiac cranks were WAY past the others. Consider that the BBC and Chrysler "Hemi" have 2 3/4" main journals, and are about 5" LONGER than the Pontiac. Thus the requirement for those engines to have a good forging , even at more modest power levels. Chevy boys would KILL for a crank that can "hold" 700 HP for under $300. Most of the import "stroker" cranks for the Pontiac are more than capable of that.

That being said, for a serious performance application, the ONLY reason for using a 421, 428 or 455 block is "bragging rights". The 400 blocks are stronger, and are just as capable of the power using today's aftermarket stuff. IMO, 4-bolt caps aren't needed until power reaches at least 650, maybe a bit more. Wer have several examples of 600-plus "pump gas" engines living long lives with 2-bolt caps and ORIGINAL bolts. All that "studding" and align-honing, etc. is Chevy "mythology" (Chevys need it, Pontiacs don't). Once your power levels exceed that of the factory casting to "support", IA-II is called for.

FWIW

Jim


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## tyler t (Aug 15, 2010)

i dont know what to beleave any more. ill just say i have a 1970 455ho. im tired of wrong information from the internet.


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## BearGFR (Aug 25, 2008)

tyler t said:


> i dont know what to beleave any more. ill just say i have a 1970 455ho. im tired of wrong information from the internet.


It's the nature of the beast, Tyler. People are people, and not everyone "out there" really knows what they're talking about, or is necessarily "honest".

I'll tell you this though, if Jim (Mr. P-Body) says something's a certain way, you can take it to the bank.

Bear


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## geeteeohguy (Feb 2, 2008)

Tyler, if it's a '70 casting, and came with 4 bolt mains, there's a good chance it IS an HO. Most 428's and 455's came with two bolt caps. I second what Bear said, Mr. P Body
gives objective information that is based on fact and experience, not opinion. That's about as good and as accurate as it gets....


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## Instg8ter (Sep 28, 2010)

:agree sounds like 70 455 HO... i would take it from Mr. Pbody a man who has taken apart more of them than any of us will probably see...


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## tyler t (Aug 15, 2010)

ill take his word for it. some sight i googled had a history and said ho didnt start till 71. im gonna trust mr. p body till i find a real good decodidng site


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## 68gtohawk8369 (Oct 26, 2009)

*Pontiac engine technical answers*

Tyler' you can beleive Mr. P body he runs an excellant Pontiac engine shop . He know his stuff and has been around a long long time .


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## BearGFR (Aug 25, 2008)

tyler t said:


> ill take his word for it. some sight i googled had a history and said ho didnt start till 71. im gonna trust mr. p body till i find a real good decodidng site


Hey Tyler, try this one

How to identify your Pontiac engine

And while you're at it why don't you post the date code (4 characters next to the distributor) casting number (6 or 7 digits on top passenger side rear, "behind" the head), and the engine code (2 characters, front of block, passenger side, just below the head) for us to take a crack at? Some of us are weird enough to enjoy that sort of thing.

Bear


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## Indecision (Oct 24, 2010)

BearGFR said:


> It's the nature of the beast, Tyler. People are people, and not everyone "out there" really knows what they're talking about, or is necessarily "honest".
> 
> I'll tell you this though, if Jim (Mr. P-Body) says something's a certain way, you can take it to the bank.
> 
> Bear


So just to clarify... we shouldn't trust everything you say? :lol:


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## geeteeohguy (Feb 2, 2008)

Don't trust Bear for a New York Minute. When he gets that beast of his on the street, he's going to tell the Chevy guys "it's just a Pontiac 400..."  And Tyler, I personally helped a friend part out a nice, clean, 4-speed '70 HO455 GTO. This was early '80's. The car was all original, down to its red paint and white vinyl top, and hadn't been played with. It was a used, ten-year-old "gas hog" that we got for $175 (points wire was fried and it didn't run..fixed the wire and drove it the 40 miles home) and immediately pulled the drivetrain out of to ressurect a '66 GTO. Who were we to know we were parting out a solid, one of about 108 made, 4-speed original '70 HO??? Boy, that '66 sure screamed, though!!!


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## ppurfield001 (Jan 21, 2008)

tyler t said:


> so i read up on the history of the 455 and i come to find out the block vin decoder i found online lied to me. i was told i had an HO but HO didnt start till 71. i have a 1970 455 ram air IV with 4 bolt mains . whats the real difference in the 71 455 HO and my 70 455 with 4 bolt main? do all 455s have A 4 bolt main?  i cant say i have an HO any more



Not to add to the confusion, but I have a question. Did 455s come with Ram Air IV equipment? I thought that Ram IVs were only 400s.


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## geeteeohguy (Feb 2, 2008)

I've never heard of a Ram Air spec 455...either 3 or 4. In the 1971 movie "Two Lane Blacktop", actor Warren Oates brags of his '70 Judge's "455 with the Mark IV Ram Air" to anyone who'll listen. I think it was Hollywood there, not fact. IMO, all the Ram Air IV engines were 400's.


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## Instg8ter (Sep 28, 2010)

just some more Intertube info as Bear would say...lol, helps confirm the 70 HO

455 HO

The 455 HO designation made its debut in 1970 as appeared on vehicle invoice, rated at 500 ft/lbs of torque and 360 or 370 horsepower depending on the body style. 455 HO's were seen in the 1971 model year with HD blocks, The Round port Heads came as #197 for 1971 year and #7F6 for 1972 year. Both having Round Port Exhaust. Special large valve heads with screw in rocker arm studs, Special aluminum intake with removable exhaust crossover, Special streamlined Ram Air Exhaust manifolds, Higher lift and larger duration camshaft and 800 CFM Quadrajet carburetor with specific jetting.

The 455 HO's were similar to the yet to come SD455 in 1973/74. The 455 HO was available in the Firebird (base, Formula and Trans Am), and the LeMans, GTO, T37 and GT37 models. The SD455 took the HO 455 to the next level in durability, power and performance.

Last seen in 1976, ending the era of the 455 HO in lackluster fashion, delivering only a paltry 200 hp (150 kW). It shared nothing with its 1971 brethren except the displacement. Standard in Catalina/ Bonneville Wagons. Option in LeMans, Grand LeMans, Firebird Trans Am, Catalina, Bonneville and Grand Prix.


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## Thumpin455 (Feb 17, 2010)

Dont worry about if its an HO or not, if it has 4 bolt mains or not, you have a 455 and that engine can make silly power easy. Dont listen to ANYTHING the chevy guys say about going fast or making power, they know nothing about how to make your engine haul the mail. They always looked at me funny when I told them I had 350 rods in my 455 and that it came stock with 2.11 intake valves. The cranks really mess with them since the Pontiac 350 and 400 have the same stroke. 

Mr PBody knows what he is talking about, he is one of the gurus and even though he may not always agree with other gurus, he knows what works and what is out there. This is one of the places you will get good info, if someone has something that isnt quite correct those in the know will point it out (nicely) and provide correct info.

455, 428, or 400, it doesnt matter as long as you go with the right cam, intake, and have a decent set of heads on it. Most of the factory stuff will make great power with just a cam swap and headers, we dont even really need an aftermarket intake if we have a 4 barrel one already. You have a great engine that will live a long time as long as you dont ask it to do things it was never meant to do, like spin over 6000 rpm. Some guys have never even seen a 455...

and I tell all the chevy guys I run a 301 in all my hot cars.


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## tyler t (Aug 15, 2010)

well i have 2 sites that tell me it is a 455 4bolt main that came out of a 1970 automatic pontiac grand prix with 370hp. i cant find the first site that told me the wrong info any more. 
what do the set of numbers above my 2 digit block code mean? its a 7 digit number.


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## Mr. P-Body (Jan 20, 2011)

Tyler,

If I "qualify" a statement as an "opinion", it's subject to dicussion. If I tell you something as a "tech", you can "take it to the bank". The previous post is NOT an opinion.

Jim


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## BearGFR (Aug 25, 2008)

Indecision said:


> So just to clarify... we shouldn't trust everything you say? :lol:


You're catching on! :rofl:


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## tyler t (Aug 15, 2010)

thank you mr p body. but i take everything from the internet as an opinion now. the heads also have the number 64 on them and they are d ports.


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## BearGFR (Aug 25, 2008)

ppurfield001 said:


> Not to add to the confusion, but I have a question. Did 455s come with Ram Air IV equipment? I thought that Ram IVs were only 400s.


It gets confusing a little, but the honest correct answer to your quesiton is no - there was never any such thing as a "Ram Air IV" 455. 

Now let me 'splain. The specific designation "Ram Air IV' was only applied to 400's, and only for two years" model year 1969, and 1970. Discounting for a minute all of the external 'Ram Air" hood and air cleaner pieces that made up the actual "Ram Air" system, what made a Ram Air IV a real Ram Air IV was a combination of the following parts added to the 400:

4-bolt main block (9792506 in 69, 9799915 in 70)
Casting number 722 (1969) or 614 (1970) cylinder heads
9790041 cam shaft (308/320 "advertised" duration)
1.65:1 ratio rocker arms
Aluminum intake manifold with separate cast iron exhaust crossover
Rochester QJet calibrated and code-stamped specific for the engine

The unique thing about the cylinder heads were the round exhaust ports, as opposed to the D-shaped center exhaust ports that "most" other Pontiac heads have. That feature is what makes those heads very hard to find and very expensive when you do.

Here's the thing though. There are other Pontiac cylinder heads that also have the round center exhaust ports: The 1968 Ram Air II (head casting number 96), 1971 455 HO (197) and 1972 455 HO (7F6), and the 1973-1974 455-SD (16, both years) also were "round port" heads. Some of these engines had other components that were similar to the Ram Air IV, but none of them were called Ram Air IV by Pontiac. That moniker was only applied to the 69 and 70 400's using those specific parts.

That's another example of why it's always important to start with the date code whenever you're trying to ID something Pontiac. In 1968/69, "16" was a large valve, screw-in stud D-port head that was used on lots of "plain" GTO's and other vehicles with the "HO" 400. In 1970 though, "16" was a low-performance, pressed-in stud, small valve head used on 2 bbl and 4 bbl 400's. , In 1973/74 "16" was the head used on the mighty 455-SD. You see similar things happen with the 2-character engine code in different years.

Just the other day I went to look at a 400 a guy had for sale that he thought was a Ram Air III. He said it was a 4-bolt block, but only had 2-bolt caps on it. When I went to look at it and ran "all the numbers" it turned out to be a 2-bbl 400 out of a Grand Prix. In the process though, I found out that the very same block casting was used by Pontiac for both engines  - so it really could have been a Ram Air III --- if it had had 4-bolt caps, the right heads, and was the right year... etc. etc.

Fun stuff. 

Bear


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## BearGFR (Aug 25, 2008)

tyler t said:


> thank you mr p body. but i take everything from the internet as an opinion now. the heads also have the number 64 on them and they are d ports.


Hey Tyler,
If the last character of your engine date code (4 characters on the top rear near the distributor) is a "0", or maybe a "9" wtih a first character later in the alphabet than about "H" or "I", and a block casting number (top, behind the passenger side head, next to the transmission) of 9799140, then you indeed have a 1970 455-HO. The 2-character code on the front of the block, near the passenger side head will tell you more:
WA - Tempest/GTO - Manual trans
YC - Tempest/GTO - Auto trans
YH - 'Full size' - Auto trans
WG - GP - Manual trans
XF - GP - Auto trans​
They all used the same block, so it's a pretty good bet that you've got a 4-bolt block there. What I can't say for sure yet is whether or not they all used 4-bolt main caps. Pontiac is sort of "notorious" for doing that. If the motor came out of a Tempest/GTO or GP, it probably has 4-bolt caps. If it came out of a full size Pontiac --- maybe not.

What might have "confused" those other sites is the fact that in 1970 there was only 1 455 available and they were all called "HO" and had D-port #64 heads. Model year 1970 was the year the 455 was introduced.

In 1971 and 1972, the 455 HO had round port heads.

I used to spend lots of time in wrecking yards looking for Pontiac stuff, and I always carried a copy of H.O. Racing's "Heavy Duty Parts and Specs" books with me.

Fun stuff, 

Bear


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## Thumpin455 (Feb 17, 2010)

tyler t said:


> thank you mr p body. but i take everything from the internet as an opinion now. the heads also have the number 64 on them and they are d ports.


So you have a 1970 455 with 64 heads? Sounds like its the first year HO to me. What is the code on the front of the block? I can look it up in my MOTOR manual for you. That book can give you every specification you need to know about your engine. MOTOR has been in print since the 30s, they are a book for technicians, not for the layman like Chiltons is.


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## tyler t (Aug 15, 2010)

0357604 xf


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## Thumpin455 (Feb 17, 2010)

Automatic 4 barrel and since its at the end of the list with the only other options being manual trans and 4 speed, its a 370hp 455. Like most manuals it doesnt call it an HO because they use that to signify the round port engines of 71-72. Pontiac called it HO though, and you have an engine that would make anyone happy, provided you feed it enough octane to keep it happy. Im going to bet it has 4 bolt mains. You could alway spull the pan and find out. 

XF was also used in 69 for the auto 4 barrel 428, but it would have 62 heads on it.


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## BearGFR (Aug 25, 2008)

tyler t said:


> 0357604 xf


Cool. So did you check the block casting number and the date code too? In order to be sure we have to "prove" that the block was cast in late 1969 or early 1970 and cross-check with the block casting number. If you can confirm those other two numbers then you know for certain you've got a 70 455 HO out of an automatic trans GP. 

Bear


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## geeteeohguy (Feb 2, 2008)

Not all 1970 455's were HO engines. The plain- vanilla 455's that year had the #15 small valve heads. I know, I'm running a set on my '67 406. The HO engines in 1970 had the #64 heads, which I desperately tried to find due to their highly desirable chamber size (84-87cc). Tyler, you have a 1970 455 HO engine. Now go build it and drive it.


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## Indecision (Oct 24, 2010)

BearGFR said:


> It gets confusing a little, but the honest correct answer to your quesiton is no - there was never any such thing as a "Ram Air IV" 455.
> 
> Now let me 'splain. The specific designation "Ram Air IV' was only applied to 400's, and only for two years" model year 1969, and 1970. Discounting for a minute all of the external 'Ram Air" hood and air cleaner pieces that made up the actual "Ram Air" system, what made a Ram Air IV a real Ram Air IV was a combination of the following parts added to the 400:
> 
> ...





BearGFR said:


> Hey Tyler,
> If the last character of your engine date code (4 characters on the top rear near the distributor) is a "0", or maybe a "9" wtih a first character later in the alphabet than about "H" or "I", and a block casting number (top, behind the passenger side head, next to the transmission) of 9799140, then you indeed have a 1970 455-HO. The 2-character code on the front of the block, near the passenger side head will tell you more:
> WA - Tempest/GTO - Manual trans
> YC - Tempest/GTO - Auto trans
> ...


Bear, if you just pulled all of that out of your head I am WAY more than impressed.


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## geeteeohguy (Feb 2, 2008)

He did. And he only made one mistake, too!!


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## geeteeohguy (Feb 2, 2008)

Sorry, Bear. That was pretty petty of me......!!


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## tyler t (Aug 15, 2010)

it has 4 bolt mains ive seen them my self

yeah i checked them all it was cast in december 16 1969. 

geeteeohguy: it is built and i drove it today  

got alot of looks from people today . i drove my dad to autozone so he could get plugs for his f100 and the guys there were like "you let your son drive that?" (im 18) i interupted and said "no i let my dad drive that" lol
arty:


*i have a 1969 gto with a 1970 455 HO *

thanks guys for helpin out with the confusion :cheers


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## tyler t (Aug 15, 2010)

it has 4 bolt mains ive seen them my self

yeah i checked them all it was cast in december 16 1969. 

geeteeohguy: it is built and i drove it today  

got alot of looks from people today . i drove my dad to autozone so he could get plugs for his f100 and the guys there were like "you let your son drive that?" (im 18) i interupted and said "no i let my dad drive that" lol
arty:


*i have a 1969 gto with a 1970 455 HO *

thanks guys for helpin out with the confusion :cheers


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## Thumpin455 (Feb 17, 2010)

I dont let my dad drive mine. The last time he drove my 67 Cougar he ran into a chunk of concrete and bashed the front end up. That was back in 1986 he did that, hasnt driven one of my cars since.


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## BearGFR (Aug 25, 2008)

Indecision said:


> Bear, if you just pulled all of that out of your head I am WAY more than impressed.


:rofl:
Well thanks.... you gotta understand. I fell in love with GTO's the very first time I drove one when I was about 16 years old (posted the story here somewhere) and have loved them ever since. During the period of about 20 years when I'd "started" the restoration on my beloved 69 but wasn't able to actually work on it  (long story) I read everything I could find (which for a long time was mostly just the "H.O. Racing" stuff and McCarthy's book) memorizing parts and casting numbers "just in case" I happened onto something in a salvage yard. That was a long time before Al Gore even thought of the "inter-tubes", much less being able to get it on your phone. Not all of that stuff I posted was from memory, but a good part of it was - like the Ram Air IV stuff (am I sick or what?)  Mostly because I'm running #722 heads on my motor.

Right now, since I could be only months away from driving my 69 again, I alternate between giddy anticipation of getting it done and fear that "something's going to happen". 

I still go out and start it every so often and just stand there, listening to it run, with this big dumb grin on my face 

I'm really enjoying "hanging out" here. 

Hey, I make mistakes just like everyone else. 

Bear


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## Indecision (Oct 24, 2010)

I am pretty good about knowing general information about cars, and popular mods and whatnot. But that is a lot of very specific information, it's very impressive.


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## figmoman (Feb 1, 2011)

*455 Questions*

Hello all. Im new to the gto forum. I have been reading for awhile. I recently purchased a 65 GTO hard top. The seller said it had a 74 455 SD motor in it. I saw the decoding tables that were in this thread. I jotted down the numbers on my block. I could not read the numbers by the distributer. The numbers on the front of the block just below the pass. side head are 328910. Below that number is Y8. According to the table it is a 74 290 horse 455. It does not say anything about it being a SD. Is it? If so, how much value does it bring either in or out of the car? I have read that the SD was never installed in any GTO. As i remember it was in either Firebird or Transam or both. Is this motor pretty rare. It seems to have gobs of power. Mike


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## Instg8ter (Sep 28, 2010)

according tho the 455SD registry there were 1296 455 SD's sold

- SD 455 Registry -

i would say that makes them pretty rare...

block casting should be 490132
head casting should be 16
exhaust castings will be 490802 and 490803 (if they did not switch it to headers)
intake castings are 494405, 494419, 485640 or 495107 

as far as value, "as much as someone is willing to pay you for it"...if you were restoring a 455SD TA or furmula to #'s match it would be very valuable to that person so i would seek him out.......nice score if it is an SD


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## BearGFR (Aug 25, 2008)

figmoman said:


> Hello all. Im new to the gto forum. I have been reading for awhile. I recently purchased a 65 GTO hard top. The seller said it had a 74 455 SD motor in it. I saw the decoding tables that were in this thread. I jotted down the numbers on my block. I could not read the numbers by the distributer. The numbers on the front of the block just below the pass. side head are 328910. Below that number is Y8. According to the table it is a 74 290 horse 455. It does not say anything about it being a SD. Is it? If so, how much value does it bring either in or out of the car? I have read that the SD was never installed in any GTO. As i remember it was in either Firebird or Transam or both. Is this motor pretty rare. It seems to have gobs of power. Mike


Hey Mike, if that is an SD, you've got yourself a very rare and valuable piece --- worth as much as the car it's sitting in 

Here's a link to a web site that's pretty good about decoding Pontiac engines
How to identify your Pontiac engine

Always start with the date code on the top rear of the block, because lots of the other codes were "reused" in different model years and meant different things depending on the year. The SD 455 was only produced in model years 73 and 74.

One of the most distinctive external clues is the cylinders heads. They should look like this:
Pon 0505 Sd 4 Z Photo 4

Notice the round ports on the center two exhaust ports, and the 16 cast into the metal above them. These two features together identify an SD head.

There were other Pontiac heads that used the 16 casting number, but had D-shaped center ports. Like these:
http://www.musclecars.net/parts/par...-ram-air-ho-firebird-400-428_170591703019.jpg
http://www.remanufactured.com/455 Pontiac 1972 with 1971 heads.jpg

See the difference?

Also, at least one of the sources that I checked indicated that a 455 SD should have a 2-character block code (front, passenger side, just below the head) of W8, XD, *Y8*, or ZJ. (Now Bear is starting to get excited).

Other things to check. The top passenger side rear of the block (below the head, next to the transmission) ought to have 490132 cast into it.

Another thing, look at the carburetor. There should be a single vent tube on the front, pretty large, and cut at an angle. Like the one in this picture:
http://www.garrettfamily.us/gto/images/IMG_3190.jpg

Only the 455-SD carbs had that large angle-cut vent tube, and is probably worth north of $2000 _by itself_.

Some of those pieces might have been changed though, so if you've got the round port #16 heads, the right block (490132) with a 73 (or late 72) or 74 date code, along with that Y8 block code..... you sir, in fact have a 455-SD and we are *ALL* extremely jealous! 

(And I want photos!!!!!!)

And "gobs of power" would be an understatement. In fact, if that's the original carburetor and if it's never been touched, Pontiac from the factory set those things up so that they intentionally had the secondaries restricted so they couldn't even open all the way. You could have more power lurking under your right foot than you realize.

"290 HP" was a joke. Those things made that much at idle. 

Bear


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## figmoman (Feb 1, 2011)

*455 questions*

Bear. That was some interesting reading. Unfortunatly the original heads are not on the motor. It has Edelbrock performer heads on it now. I have the car on a lift trying to see the numbers at rear pass. side of block. There is something that looks to be part of the cast but i cant make it out. Between that and the dist. is a what looks like a little clock face with an arrow. I wish i could make out trhe number if it is even a number. Im using small extendable mirror. The previous owner did tell me that this block has the plugs for a dry sump oil system that the article talks about. The pictures of the reinforced lifter valley are cool. If i had to take the valley cover off i could see the reinforcement. Now im not sure what figure to insure the car for. I dont want to under insure or over insure because of too high a premium. Car has a lot of costly extras that i dont know how to realisticly value. Mayby some of you guys/gals have an idea. Mike


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## Instg8ter (Sep 28, 2010)

post some pics Mike, and we can kick around the insurance value, hard to find any SD's sold or for sale...yep the dry sump was only on the SD. Only reference i can find on any sold is a old post on craigslist for block only at 1,500.00. There are reported to be 3 GTO's and 1 Grand Am that were factory equipped with SD's for testing and advertising.


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## figmoman (Feb 1, 2011)

*455 questions*

Im not very computer savvy with pictures. Mayby one of my kids can come over. It is a breeze to them. I can list some of the things it has. Its Fontaine blue. Black int all new. Stock looking. Tremic TKO600 5 speed. 12 bolt 3.90 in moser housing. Four wheel disc PS, PB Quick ratio steering. Three twos with ram air pan . Alkuminum intake Edelbrock performer heads. Dougs headers, look like 1-3/4 tubes. Aluminum radiator with electric fan. Not sure on dist. it has a rev limiter. Not sure whats in motor. He said it was 10 to 1. Gear reduction stater. Boxed and powder coated frame. Has a lot of Hockiss stuff. Bushings tubular a arms. Boxed arms in back. New gas tank. I would call it a driver. Definatly not perfect. Oh yeah, ridgid motor mounts and rally two wheels


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## Mr. P-Body (Jan 20, 2011)

If the heads are gone, the value is significantly decreased. These engines are most valuable as "restoraton" pieces. Though orignally designed as a "race" engine, we've learned enough over the years to make the SD block "obsolete". Considering the value (about $3,500 for a short block in need fo rebuild), using an aftermarket block like IA-II is more logical. The SD crank is "nothing special", a nodular casting. The "mystique" surrounding the SD engines is not necessarily accurate to their actual performance. Yes, a TON of "potential", but not well exploited. It was simply too rare to make a significant impact.

Since you already have better heads (for performance, E-heads are better than SD heads), I would use the block as a "bargaining chip" and get a good 400 block and "stroke" it to make good power and MUCH more durable than any factory configuration. The currently popular aftermarket connecting rods are also superior to the SD rods.

We're re-sleeving a 455SD here now. It had so much rust from weather, it needs 8 sleeves and the "sleeves" in the intake runners, too. But the man has the car the engine is original to, so he feels it worthwhile. BIG money.

Jim


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## BearGFR (Aug 25, 2008)

Mr. P-Body said:


> If the heads are gone, the value is significantly decreased. These engines are most valuable as "restoraton" pieces.


:agree Those E-heads, especially if they've been ported by someone who knew what they were doing, are going to outperform the original SD heads. I bet that thing flys!

That circular mark you wrote about is going to be a D-N stamp with an arrow pointing to either the D or the N, indicating whether the block was cast on the day or night shift.

At this point a lot depends on what you want to do with the car and what you want to spend doing it. There's a ton of mystique surrounding the SD, so if having bragging rights is something you care about then you've got a ton of them --- it'd be more so with the original heads, but still.... That ram air Tripower has a huge cool factor too, but a well set up QJet on a ported factory intake will beat it, performance-wise.

However, if your thing is performance then Jim is dead on the mark (like that's a surprise?) He can build, or help you build, a stroked 400 that will eat even that SD alive.

I've been "working on" restoring my 69 forever. There was a period of time 15 or so years ago when I was scavenging parts anywhere I could. This was long before all the "good stuff" we can get now was available. I found and bought a complete set of brand new and never run SD rods, thinking I'd use them on whatever motor I wound up building. At the time, they were the best you could get short of a set of very high dollar custom forged rods. Well, things eventually changed and about a year ago when I did finally start building the motor, the Eagle H-beams were both stronger and less expensive so that's what I used. I wound up selling the SD's on Ebay for a pretty good price (more than $100 each) to a guy who wanted them to restore his SD. The point is, somewhere "out there" someone probably is sitting on a pair of SD heads, wishing they had the rest of the motor. They'd probably pay a lot to get yours  and that'd go a long way towards building a killer 400 stroker.

On the front of your block, down low on the passenger side, next to the timing cover, should be a stamp that has at least part of the original VIN number from the car the motor came out of. It'd sure be cool to know where it came from...

Or, since you've been asking a lot of "value" type questions... are you looking to sell it?

Bear


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## Instg8ter (Sep 28, 2010)

thought you were only taking donations Bear....:rofl:....Hmmmm 1970' 455 SD Judge.....has a nice ring to it.


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## BearGFR (Aug 25, 2008)

Instg8ter said:


> thought you were only taking donations Bear....:rofl:....Hmmmm 1970' 455 SD Judge.....has a nice ring to it.


I've always been a sucker for rare Pontiac engine stuff.... 


....hmm, maybe I shouldn't admit that in public 


Bear


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## figmoman (Feb 1, 2011)

*455 questions*

Hi bear. Sell the car? I just bought it. I got out of the hospital on Super Bowl Sunday. My ailment does not let me drive for a week. Ive litterally only drove the car five miles when i wasent supposed to. The wife was gone and i could not resist. Besides she got to drive it home from the drop off depot while i was laid up. I have some bugs to get out of the car. RF tire rubs front fender on right turns. I need to get to a front end shop. I need to get car insured. Im in process of getting regestered to me. I also get a drive line vibration in 5th that starts about 60 and is worse at 70. I dint have much room to open car up. Mayby the front end shop can check the angles. It appears to be 2300 rpm at 70. Ill see if i can find the partial vin number by timing cover. Are these numbers cast into the block or stamped on a machined part of block like the Y8 is. Ive got some more items that are in motor.PO says he reset speedo to zero or got a new one. If thats right the motor has 428 miles on it I think the PO said the pistons are JE brand. Other stuff he had listed was a Eagle steel crankwith full floating forged rods. Blueprinted oil pump (im not sure why). Comp roller cam and lifters. I have no info on the cam itself. Trick flow pushrods. Roller rockers 1.6. The performer heads are street ported. Aluminum intake with three twos. Mechanical linkage. Dougs Headers with what appears to be 1-3/4 tubes. Pypes exhaust X style 3 inch all the way. The PO was not a very good record keeper. He says he had it dynoed 2-4 years ago and lost the paperwork. He says CR is ten to one. Which i think is okay with aluminum heads and pump gas. What scares me is i look at the JE piston website and dont see a ten to one application. Either HIGH compression or real low compression. One frustrating thing is when i went over the car he let me find the problems but neglected to tell me about things he new were wrong that i did not find like the driveling vibration and the right front tire rubbing. I had him drive the car for a test drive. Looking back on that test drive. all the turns were to the left. There were lies of omission which in my book are the same as a straight up lie. I probably got a decent deal because he needed money. Why not just be honest. Bad things bring bad karma. Hey, you guys on this site are amazing. All your knowledge is a big help. Im sure i will have more questions. As far as makling a 400 stroker. I think ill drive the SD because it is done and has a coolness factor. Theres probably not to many people that know much about the 74 SD 455. Oh yeah, it is bored 30 over. When i decided i wanted a muscle car i looked at all the GM A bodies and Mopar i settled on the GTO. There were 2 ways to go. All correct out of the factory which is probably a better investment over time or go big cubes and an overdrive to get the best of all kinds of driving. The nice thing about a restomod is most of the time you are paying way less than a guy has in it. It may not appreciate as much but it should not go down in value much if any. If you guys go down this list can you give me some guestimate of horsepower and torque. I would rather underestimate and be conservative then have people think im full of S##t. By the way, about what does it cost to have a car dynoed and what is involved. Okay, im as tired of rambling as you are of reading. Im going to bed. Thank for all your input Mike


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## Instg8ter (Sep 28, 2010)

i'm gonna guess close to 500 on the HP, and around 550+ torque, depends on the cam grind. You have all the good stuff in there to make gobs of power. I would have it appraised for insurance purposes, but i am guessing if the body is good i would have at least 30K of coverage on it.


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## BearGFR (Aug 25, 2008)

With those internals, ported heads, and a good cam (how does it sound at idle?) you've got yourself a bonafide MONSTER there.

Two kinds of dynos: a chassis dyno where you "drive" the car on rollers, and an engine dyno (engine has to come out of the car and get mounted on the dyno). Prices can vary quite a bit, depending on where you are and how much competition there is for customers. I've seen chassis dyno sessions listed around here (Dallas) for $75 for 3 "pulls".
Advantages - obviously, a chassis dyno is a "drive on" deal and is pretty simple. Disadvantages - a chassis dyno can only "approximate" actual at-the-flywheel torque/horsepower because it gets its measurements at the rear wheels. You have to try to "back in" to the flywheel numbers by approximating parasitic loss in the drivetrain.

Sound like whoever built your motor knew what-the-heck he was doing just by the pieces he used. Keeping that in mind, I'm going to estimate 550HP, 575-600 lb.ft.

Oh, and those numbers on the front of the block are all stamped onto machined surfaces. The ones on the rear (date code, block casting number) are cast into the metal.

Bear (and I still want pictures)


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## likethat (Oct 5, 2007)

That is a good find. The 70 455ho is a piece that is worth some bucks. I have been offered 3000 grand for it before. This is my 70 455ho xf #64 engine it is complete carb to pan. It came out of a 66 lemans parts car I had, that I got for free. It is in my 66 GTO.
There is more material on the cylinders at the bottom.
Date:








XF Stamp:








4 Bolt mains:








455 Stamp bad pic:


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## genio (Dec 13, 2017)

*Tork*

Pontiac engines produce massive torque if properly built. This makes them great for the street. I wrenched my share of engines and one was my 1973 455SD Trans Am which could match the Chevy L-88 '69 Vette and beat it on a twenty mph roll


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