77 Sunbird engine swap or not

[Fred Funbird]

I am regretting my decision to buy a 77 sunbird. It was cheap and I love the body. I knew it was missing the lower thermostat housing assembly, and instead of doing my research I thought the part would be easy to find. I have now been scouring the internet and salvage yards for a week trying to find the part or some other model's part that might fit. Some of this community might know how hard it is to get this part for the 77/78 years of the iron duke (because of the square head bore). Maybe I am giving up too soon, but I also dont want to spend time looking for a part on an engine I don't really want. I have a 327 I would like to swap in, but it is several states away (where I have a buddy with a fab shop to help me) and I want to get this car running. I am thinking of finding a V6 that swaps in with minimal modification. I don't mind dealing with motor mounts, but was hoping to avoid modifing stearing components and steering part alteration. My other thought was to design and 3d print an adapter to modify the iron duke for an easier to find thermostat assembly, then have the part machined if it fit well. Any advice would be helpful, thank you in advance

Funbird Fred

here is a link to a post from '09 trying to find the part I am looking for:
viewtopic.php?f=6&t=32340

[Fred Funbird]

Follow up question: Can I swap the head to one with a round bore for the iron duke?

[gt350fme]

What a pain in the ass, I looked for you and couldn’t find one either, some jeeps had this motor but apparently hard to find also.
Could have one fabed up at great cost.
Don’t know about the head swap, sorry
Don’t know about the v6 swap but seems like a lot of work and trouble but doable, your car really begs for that 327, with parts easy to find.
Depending on what state you live in you may have smog equipment requirements with a 1977 model, it’s 1975 and older that’s exempt in CA just food for thought.
Tow with a car trailer to your friends place and make it happen.

Maybe someone else here has more info that can help.

Good luck

[cosvega76]

Do you know what the difference is between the '77 and the '78 is? I have a GM Parts Manual and have an OE part number for the '78 thermostat housing (GM Parts Catalog Group Number 1.251): 527870. Sometimes the only difference will be an extra bolt or sensor hole. If you have a good GM dealer nearby, some will offer a locating service off of the part number, and see if some dealer across the US may have a dusty one on the shelf. Or check with Jay's H-Shack online (jayshshackllc.com) to see what he may have.

Chuck

[Fred Funbird]

Thanks for both your replies. Sadly the head swap wont work, when they switched from square bore to round bore they also flipped carb and exhaust to the other side, maybe to make this exact situation difficult, jks. I will look at jayshshackllc.com and try a dealer.

Sorry about the delayed reply.

[cammerjeff]

I think you answered your own question about swapping a 79 or later head onto a 77 or 78 Iron duke, its not just the intake and carb being moved over, but the distributor changes also (as does its angle to clear the intake manifold, its almost a total redesign for the 79 model year.

[monzaaddict]

Scott Brown on facebook bought a non crossflow iron duke to rebuild. He might have an extra lower thermostat housing. https://www.facebook.com/scott.brown.7906/

right there is your waterneck https://scontent-lga3-3.xx.fbcdn.net/v/ ... e=69479CB1

On car-part.com you can search 77 pontiac astre engine. 2 show up in search. beg them for thermostat housing.

[monzaaddict]

scroll down to this thread. It suggests chevy 6 cylinder parts may be compatible.



Re: 1977 Astre 2.5l Duke what flywheel flange ???
Postby HI WINDING MONZA » Sun Jul 11, 2021 8:34 am

Mostly 230/250 Chevy Inline Six parts should fit the 77-78 Pontiac 151 motor because its mainly the same design as the 153.

79-83 RWD 151 no...( Pontiac, Jeep, AMC )


Most 80-90's 151 & Tech 4 FWD and RWD no.

Found this listed online for chevy 6 cylinder.
https://www.12bolt.com/store/p157/Therm ... 0_292.html

[monzaaddict]

https://www.ebay.com/itm/286802348040?v ... 53b4a5fd60

https://www.ebay.com/itm/286657343903?i ... Sw1fhf71Hs

[monzaaddict]

https://mrhotrod6.myshopify.com/product ... 1142525385

[monzaaddict]

https://www.ebay.com/itm/127561840505?_ ... R57z-t3kZg

[monzaaddict]

77 iron duke for sale.
looks like he is in ohio

The Real "95J" Jordan Racing
November 21 at 9:39 AM
·Anyone interested in a 1977 iron duke engine all original still runs, lots of 151ci parts and 2.5 parts I'll make a good deal
https://www.facebook.com/permalink.php? ... 3456969965

[Fred Funbird]

wow! Thanks for all the help. I hadn't checked back here in a bit bc I though I had hit a dead end. While I was away I ordered a thermostat of a 70 nova with the 2.5L, it just showed up and looks like it will fit, but I may need to get tricky to add on the vacuum ports. The parts just showed up. I will look at the links you guys sent too. I had pretty much set my mind on finding a rwd firebird or camaro with the 60deg v6 and having the lower end built for a turbo, but if I can get this little 4cyl up and running in the meantime I would be very happy.