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1969 Grand Prix J Model

A

airforrest

New member
Hey all.... I have a 69' Grand Prix that had a Blown 428 engine in it when I got it. I would like to install an Olds 1966 425 ci. Motor in it. Has anyone out there installed any Olds Motors in these Cars before? I think the main issue I may have is the Motor Mounts. Thanks for any input :-)
 


well.... this forum is geared more toward W body style Grand Prixs.
Why not rebuild the 428? Or find a Pontiac 400 to shove in there?
I can't say if the Olds block will mount in the stock Pontiac locations. I'm guessing you;ll have to do some work.
And if you have to go the trouble to fab up mounts why not find a nice LS small block?
 
mguzzo said:
well.... this forum is geared more toward W body style Grand Prixs.
Why not rebuild the 428? Or find a Pontiac 400 to shove in there?
I can't say if the Olds block will mount in the stock Pontiac locations. I'm guessing you;ll have to do some work.
And if you have to go the trouble to fab up mounts why not find a nice LS small block?
Click to expand...


The 428 was badly damaged internally, and not rebuildable. I have a built Olds 425...thats why I thought of going that route. Thanks for your reply !
 
You likely need to hear from idrivejunk aka Matt. He seems to have a good feel for the older stuff since he owns one of the older GP's and he works on custom cars all day long.
 
likely all bolt right up. i did a th400 swap from a 70 firebird to a 77 caddy, went from a Pontiac to a caddy engine with no issue other then swapping the tail section.
 
Mine is a 69 J. Cool car. The OP has the right idea, it should be cake except for mounts. But the 69 GP has an arrangement that should be fairly simple to adapt, probably only requiring a fabricated plate and your Olds mounts. Watch out for height though, so you don't create hood interference. Plumbing and wiring differences should be minor or non-existent. Trans and converter should fit.

Not having tried this swap, all I can say for sure is that in Pontiac-speak it's like putting a 389 in a Judge. A step backwards. But it's always cheapest to use what you have. That engine would probably drive nice in there. If you are not sure about the Olds' compression ratio, you may want to do some inspection and research to determine if it's use is feasible with fuel currently available in your area.
 


idrivejunk said:
Mine is a 69 J. Cool car. The OP has the right idea, it should be cake except for mounts. But the 69 GP has an arrangement that should be fairly simple to adapt, probably only requiring a fabricated plate and your Olds mounts. Watch out for height though, so you don't create hood interference. Plumbing and wiring differences should be minor or non-existent. Trans and converter should fit.

Not having tried this swap, all I can say for sure is that in Pontiac-speak it's like putting a 389 in a Judge. A step backwards. But it's always cheapest to use what you have. That engine would probably drive nice in there. If you are not sure about the Olds' compression ratio, you may want to do some inspection and research to determine if it's use is feasible with fuel currently available in your area.
Click to expand...


Thanks man..................Great information, I apprieciate you input !
 
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