1. Would a 389 engine out of a 1964 Pontiac Bonneville fit into my IROC?

#2. If yes to question #1. Would it fit easily?

#3. What basic things should i replace while performing an engine replacement?

I wanted to know if the 389 will fit because my brother and i have a 1964 Pontiac Bonneville 4-door sitting down at a storage yard.

 

Im not sure if 389 isin the same family as BOP400 and 324(early catalina) but if it is, I might have an answer.A while back, my buddy and i had a 400BB out of his 80 trans am (gen 2) we measured it up to my thirdgen, and the exhaust would just about rub the frame rails. pontiac motors dump at an almost parallel to the ground, and are bulkyto boot. IMHO, youd be better off trying tosqueeze a chevy 427 or 454 in there
just my thoughts, experience
mike

 

Any engine other than a small and big block chev will fit in a third gen but your need to do alot of planning and fabrication to get it to work. Nobody makes any swap kits for any other engines other than BBC. The tranny will have to be changed. B-O-P and Caddy engines all use a different bellhousing bolt pattern than chev.

The first thing about doing a swap is figuring out where the engine mounts will have to go. There's a good chance they won't be anywhere near the factory locations. If the engine sits too high then hood clearance could be a problem.

Exhaust would be next. If factory manifolds won't work then a custom set of headers would have to be fabricated.

Rad hoses would have to be changed since they won't line up with the new engine.

All the electrical wiring would need to be re-routed or changed.

Once you find a tranny that will work, a different tranny crossmember would have to be made as well as a proper length driveshaft.

It's a lot of work to put some other model engine into a car. It's not impossible to do but planning needs to be done.

I've seen many Dodge and Ford cars at the race track with chev engines in them and a chev with a ford engine in it.

Opening your hood at a car show and showing some unusual powerplant in it will get a lot of attention but dropping a better SBC or even a BBC under the hood is far easier to do.

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Stephen's racing page

87 IROC-Z Pro ET Bracket Race Car and knocking on the SuperPro ET class
383 stroker (carbed) with double hump cast iron heads and pump gas
454 Big Block buildup now in progress for the 2001 racing season

Best results before the 383 blew up
Best ET on a time slip: 11.857
Best corrected ET: 11.163
Best MPH on a time slip: 117.87
Best corrected MPH: 126.10
Best 60 foot: 1.662

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

87 IROC bracket car
91 454SS daily driver
95 Homebuilt Harley

 

It will fit, there have been people that have done it. I wouldnt call it easy though. As far as Pontiac engines go, I'd go with a 455 for all the effort its going to take to put it in. Rather than sticking the 389 you have in there, I'd just put a modded 350 Chevy in there instead. Theres not much less cubes, and its a hell of alot lighter than a 389.