1966 XS GTO
 

So a little back story about my car. The original owner went to Royal Oak, MI and got the car from Royal Pontiac. My dad bought the car from the original owner and then sold it in 78 or 79. The same guy kept it all these years, he passed a few years back and I was able to buy the car from his wife. It was ordered as a drag car and I have the original window sticker and it is an XS car. The problem is the 389 is long gone and has a 400. It still has a tripower on it. So needless to say I'm looking for a needle in a haystack. If there are any leads on an xs engine please let me know. The 400 runs very well so if I can't find an xs block I'd rather not get rid of the 400.

That’s a rare and valuable car you have there. If you scroll down and post this in the 66-67 GTO tech section you might get some additional eyes on it. And pictures would be cool too.

I'll post a couple pictures there

190 XS GTO's were produced in 1966, out of 96,000 + GTO's total.

Being that rare, I suspect that you are the gentleman on the GTO forum who's looking for the guy who last posted in 2005 about his '66 XS engine with no car.
If so or if not, you should check out the GTO forum and PM the moderators and try to track down the long gone guy who has the XS engine.
If not, you'll just have to be happy with the rare car you have as it is. It is cool no matter what.

Yup that's me. Haha I'm very happy with the car as is would just really really be the icing on the cake if I could find a true xs block.

The XS block is the same as the other 389 blocks produced that year with the exception of the bolt-on stuff that made it special. It has no internal differences than a garden-variety GTO 389 or passenger car block.

You have the equivalent of a Hemi Mopar with a replacement engine. Do you have any of the ram air stuff from the original 389 besides the intake? Like the steel ram air pan, etc? Heads from the 389? Does it still have the 4.33 rear gear and M-21 trans?

A XS 389 block may be a very difficult find. The few folks that collect blocks for builds these days are likely only paying attention to 400 and 455 blocks. They likely wouldn't even buy a 389 block.

Tell us more about your car, and pictures!!!

Will, do you have the 400 valve covers on the engine? Reason I ask is that I have a 400 in my 66 and wanted to make it look as tho a 389 was in it. I bought the 5/16th cork gaskets. I now have the 66 389 valve covers installed. No one around here really knows what's going on with it until tell them. That said, it looks better with them on instead of the 400 covers. ;)

If you want to cheat do it the right way. ;) LOL

There is hope. My RA II GTO is 1 of 199 with a 4 speed. I found several WY blocks for it.

I do not have anything from the original engine. The original owner of the car did not like the performance of the 389. He then put a 421 in it that he had from his previous drag car. Life has been hectic lately so I haven't been in here in quite some time but I'll put a picture of my car on here.

Best of luck with the search!!

Great that you were able to purchase your Dad's old car.

Good luck on the search for a correct 389 and associated bolt on parts.

Rotated the picture.

https://forums.maxperformanceinc.com...2&d=1690128902

If you don't tell it's a 400 in it, then no one will know the difference. As I said a while back... get the 5/16 cork valve cove gaskets and 389 valve covers and put them on it. No one will really know the difference with them on it.... unless it's a very observant Pontiac guy. All the others won't have a clue. :rolleyes: I've been asked if mine is a 389 or 400. They go with whatever I feel like saying it is and don't know the difference. ;)

And some will ask if it's a Big Block. You know the answer to that.

Exactly.

Out of curiosity, is there a designation somewhere that calls this car a 'X' ?VIN or such?

Rear?
 

Does it still have the Nodular 4.33 rear that it should have?

1972-newer Pontiacs had the engine code in the VIN. 1971-earlier did not.

I think there was a 'XS' code 400 in late 70s. Much more common and likely cheaper when found. IIRC i saw one in a junkyard TA.

There is a couple up here in the Brainerd MN area that has a red 66 xs GTO.

Simple Simple
 

“No one will know the difference”. Some of the post made here are hilarious ��.

389 has 2 freeze plugs on each side of the block.
400 has 3 freeze plugs on each side.

All you have to do is look.

Give the guy a break, obvious newby.
Tom V.

I have seen several instances of 400's and other late engines having the cup area of the center core plug filled in with JB weld or similar and then textured and painted. The actual placement of the 2 plugs vs the 3 plugs blocks is different but it takes a "real" Pontiac person to detect this. Hell, I have seen many, many SBC engines painted Pontiac blue and stuffed in Pontiac bodies and very few , if anyone notices the difference at local type car shows. LS engines with goofy grafted on valve covers and the like in old GTO's and Firebirds presented as stock go mostly unnoticed. Lets face it, there are probably less than 10,000 people still living that could tell the difference between a 389 and a 400 installed in a car. Reality sucks. 95% of the College level students in my classes couldn't tell you the difference between a Pontiac and a Plymouth and which one was part of GM at one time in the ancient past. But they could tell you about all the running changes in the latest Kia Turbo engine.

They built around 180 Ram Air GTOs in 66. Compare that to the 67 (751) or the 69 TransAm (697). This car deserves better than some 400 wearing early valvecovers.

TV says cut someone saying something dumb some slack, and then proceeds to roast the guy (Join Date: Aug 2007) by calling him an obvious newby.

yea after all they are both "big blocks" ;^)

I stand by what I posted. Newby means you did not own the car in 1964 or 1966.
Say you joined PY in 2007. Bought it/ post about it in 2007, 2007 IS NOT 1966.
1976 (10 years), 1986 (20 years) 1996 ( 30 years), 2006 (40 years).

PY says I joined in 2001. ( I bought my 64 GTO in April 1965).

So my NEWBY comment applies, despite what the member (he joined in 2004) who posted in Post #23 thinks.

Tom V.

Nobody was posting about their GTOs, on the internet, back in 1965. And drop the I-have-seniority nonsense, you're going to chase the OP (Join Date: Dec 2022) off of the forum with that. He's looking for a needle in a haystack, and I for one hope (fingers crossed) he eventually finds it.

Good for you.

Tom V.