# 64 GTO 421 engine



## MR2Idaho (Mar 24, 2014)

This has a back story to thread. 
My brother in possible late 63 to mid 64 purchased a brand new GTO. I was fourteen at time. Later in the the 60's the starter went out. He was going to have a new one put in but the starter for a 389 did not fit. The original starter was much bigger and I believe there was a difference in the way it bolted to engine/transmission housing. Anyway he pulled the starter bendix, which had broken at the gear and moved freely. When the auto place pulled a starter bendix for a 389 to compare, there was a big difference in size of two. The actual starter bendix went to a 421, which my brother purchased and went happily along his way. The auto guy did mention at that time that some 421 engines were quietly put into some GTO's of that year.
Fast forward a couple years to around early 70's. My brother had sold car to a another brother who was younger than he with no family. He had a friend who had a later model GTO, either 66 or 67, which had a tri-power setup. My brother wanted to swap the 64 GTO four barrel/manifold for the tri-power setup and they did not match up. After pulling the manifold off the 64 and then the manifold off later GTO, the heads were different in configuration. The 64 heads had very large intakes which were rectangular in shape around 1 1/4 to 3 inches with no water port for water hose coming off head. Compared to later GTO, its manifold intakes were more oval shaped and and about 1 1/4 inch across. And there was a water port for a water hose on the left head.
The engines side by side were definite a differnece in size. But when you are young and want something it was just not noticed at first glance.
The 64 GTO had no motor exchange from point of purchase brand new from dealer to when all of this had occurred. 
Now the questions. 
Does some one have any records of those engines being put into the cars from the factory? 
Does Pontiac have information with regards to these engines? 
Has anyone worked at plant where these were made who may have insight to this?
How would this affect its price with a 421 engine coming from factory.

Unfortunately the car was sold long ago as we grew up but the memory of that car and the engine has made want to know more about it.


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## SCG Pontiac (Feb 23, 2014)

There have been stories about 421 engines installed in GTO's for years. Some guys swear it is true but to my knowledge no one has ever produced any documentation to prove it. With that being said I have no doubt that a dealer would oblige a customer for enough cash to cover the parts and labor to convert one. But you would think that someone would have paperwork on at least one such conversion. It's a bit like Big Foot, plenty say they have seen one but no real proof. The only documented 421 installed into a GTO is the well documented 64 Magazine car ( two cars actually ) that Jim Wangers and Ace Wilson put together to race the Ferrari GTO. If there was a documented proven car I think it would be more valuable from a historic point but at the end of the day it would just be a dealer engine swap so what would it be worth?? I think some premium but I guess what ever a collector was willing to pay.
Most really valuable cars like that need racing history to break the bank.


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## SCG Pontiac (Feb 23, 2014)

Just a follow-up on the last post. Back in the day almost anything at the dealer level was possible . In 1970 my brother had a 1969 Chevy truck that he put a big camper on and wanted more power to pull the weight so he took his truck back to the dealer and they installed a 450 HP LS6 right out of the parts department. 
It didn't really make the truck worth much more but somewhere out there someone is scratching their head wondering how a 1970 LS6 found it's way into a 69 pick-up.

From a collectors point of view there is a big difference in dealer level add on's and a factory off the menu install such as a special order through COPO if it is Chevrolet but Pontiac had it's own version of special orders. The big difference is PHS will have a record of the original shipping invoice to the dealer and if it had any factory installed equipment on it the paperwork will show it. That is one of the really great things about Pontiac's , pretty tough to fake one with Jim over at PHS only a phone call away. It would be great to get your hands on your brothers car though, good luck.


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## geeteeohguy (Feb 2, 2008)

I'll add this: the 389 and 421 used the SAME starter and flywheel. No difference in size or appearance. The same part numbers. The 389 and 421 blocks were identiacal in size. No size difference externally. The only easy way to tell a 421 was the 'pyramid' casting lug on the passenger side of the block by the distributor. 421's used the SAME cylinder head as the GTO in those years. No difference in port sizes or valve sizes at all. None. So a 389 and 421 head were the same part number. No known factory 421 '64 GTO's were built. There were two 'ringer' '64 GTO's built for Jim Wangers by Royal Pontiac for the '64 Car & Driver magazine road tests, but that was it. Also, what you remember about the heater hose water port and intake differences is indeed correct. The '64 and '65 intakes would not interchange. In '65, the heater hose water port went to the rear of the head, and was no longer on the front of the intake. So, a lot of rambling, but I hope it helps some.


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## PontiacJim (Dec 29, 2012)

" The big difference is PHS will have a record of the original shipping invoice to the dealer and if it had any factory installed equipment on it the paperwork will show it."

Looking through my collection on some info, it stated that the 421CI engine installed in the 1964 GTO magazine car shows on the invoice to be a 389CI car. So an invoice would most likely not show a 421CI installation.

A little more research shows that the 1964 GTO engine to be somewhat unique for that year. It used the block mounted starter while some of the other bodies/blocks mounted to the bell housing. All starters interchange from 1965 on up to include the '64 only GTO 389CI block. The '64 GTO 389CI used the 421HO heads, "716", having bigger valves and larger intake port size. The intake bolt pattern changed in 1965, so the later '65 and on intakes will not fit.

This said, it would seem the engine sounds like the factory 389CI which was fitted with 421HO heads & intake, found specifically in the one year only engine of the '64 GTO. It would be easy enough to believe this engine a 421CI given the facts about the heads and intake if the engine code was not verified.


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## geeteeohguy (Feb 2, 2008)

Jim, that's what I was trying to say. Thanks for stating it clearly.


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## PontiacJim (Dec 29, 2012)

geeteeohguy said:


> Jim, that's what I was trying to say. Thanks for stating it clearly.


No problem. Seemed an interesting possibility, but I figured some research might clarify it. I also learned something new as well and did not know the uniqueness of the 1964 GTO only 389CI engine. Another Pontiac factoid to throw around the "bull" table.


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## kilkm68 (May 5, 2011)

Interesting story. I remember as a kid, my best friends older brother had a triple black '62 Catalina convertible 4 speed car. I'll never forget the rides he would take us on and "get rubber" in all 4 gears. He claimed that when he took the car to a shop to have a new clutch installed they informed him that his motor was not a 389 bot actually a 421. Dont know if that was really true, but we've speculated what the car would be,worth today if it was.


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## BearGFR (Aug 25, 2008)

Anything's possible. A friend of mine worked at Pontiac in Detroit back in the hey-day of these cars, and he saw first-hand instances where, when a car was being built for someone who worked at the plant, "somehow there was a mixup" on the line and it just happened to work out that a 421 that had been sequenced to go into a Bonneville or other 'big car' "just happened" to land in a GTO. Doubtful that the paper-work matched on it so there'd be no way to ever "prove" it was factory but at the time no one would have cared about that. Whoever was buying the car just wanted to HAVE the 421 - he wasn't bothered at all about whether or not he'd be able to "prove" it later, especially when the car was 50 years old. If you want to know if you've got a 421, all it takes is looking up the various engine codes. Google "Pontiac Engine Codes" and you should find several sites that will show you how to ID the motor.

Let us know!


Bear


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## Tom L (Aug 11, 2011)

1964 and older 389's=12 bolt intake manifold....1965 an newer=10 bolt. Plus heater hose connections are in diff locations, right rear of engine block on 65+ and right front on intake manifold on 64 older.


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## geeteeohguy (Feb 2, 2008)

421 engines were actually factory installed in Catalina's in '62--'66. So, a very real possiblility. Also they were a common boneyard find back in the day. I stripped a set of 093 heads off of a '66 421 in the boneyard in '86.....they wanted $200 for the whole engine, which was too much for me at the time.


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## rickm (Feb 8, 2012)

"the engines side by side were definite difference in size" im not sure how that could be. an optical illusion. the starters are basically the same size. even the "high torque" starter looks the same. an early 421 super duty is a different animal. love to put one in a gto.


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## geeteeohguy (Feb 2, 2008)

Funny how a '55 287cid and a '70 455cid are the same size, physically. Heck, the 287 looks bigger due to the way it's mounted/equipped!


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## Richard 17 (Jun 24, 2017)

SCG Pontiac said:


> There have been stories about 421 engines installed in GTO's for years. Some guys swear it is true but to my knowledge no one has ever produced any documentation to prove it. With that being said I have no doubt that a dealer would oblige a customer for enough cash to cover the parts and labor to convert one. But you would think that someone would have paperwork on at least one such conversion. It's a bit like Big Foot, plenty say they have seen one but no real proof. The only documented 421 installed into a GTO is the well documented 64 Magazine car ( two cars actually ) that Jim Wangers and Ace Wilson put together to race the Ferrari GTO. If there was a documented proven car I think it would be more valuable from a historic point but at the end of the day it would just be a dealer engine swap so what would it be worth?? I think some premium but I guess what ever a collector was willing to pay.
> Most really valuable cars like that need racing history to break the bank.


I lived in Denver in 1966 and a friend owned a '66 GTO 389 tri power. He raced it a lot and one Fridaynight we cam up to another '66 GTO. We challenged him and from a rolling start of about 40 both put the hammer down and he walked away like we were in reverse. Tried from 60 mph and same result and at 110 or so he was still pulling away. When asked he said he had special ordered the '66 with a 421. Under the hood there it sat a monster of an engine with 2, 4 barrels. Only one I ever saw but the do exist in very few numbers.
Richard 
San Jose, CA


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