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Recommended Performance Motor Swap
#1
Hey all,

This might be heretical to suggest, but my shop mentioned that my 429 in the 71 seemed to be a little weak and I've been giving some thought in replacing it with a new performance motor of some kind. Probably would replace just about everything at once, motor, drive train, suspension etc. Looking mostly at the motor in this thread, do you guys have any suggestions for high HP/torque motors that will fit? Probably looking in the $5k-$10k range.

Thanks in advance and looking forward to your suggestions!
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#2
460 stroker would be awesome!!!



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#3
A picture is worth a thousand words. More than $10K, but.......

https://jonkaaseracingengines.com/shop/b...boss-nine/

Steve
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#4
Is it a original 429 car with a numbers-matching or at least date-correct block? if so, it's of course up to you but you should probably rebuild that one and keep it in the car from a historical perspective. Do you agree with your shop that it's weak? What are compression and other readings? Depending on the state of the block and any past rebuilds, maybe you just need a hotter cam and some other standard performance mods along with some really focused tuning. If you're not concerned about numbers-matching and the 429 is truly shot, then sure a built 460 seems like a good avenue to take. Your suspension and other items are already likely set up to handle the big block.
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#5
I agree with donkost, I can see a fresh up rebuild with hydraulic roller cam system, and roller rockers. I do know that the 1970 Cyclone 429's had 375 hp. from the factory. Maybe you can look at the compression and other specs to mimic that 429.

Thanks,
mustang7173 Thankyouyellow

"Courage is being scared to death but saddling up anyway" -- John Wayne
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#6
Theres alot you can do with a "385" series 429 now. You can get some John Kaase Racing goodness for it that will launch you to the moon. All it takes it Money, lots of money.

https://jonkaaseracingengines.com/

https://jonkaaseracingengines.com/shop/e...1-engines/#

"I drank what?" - Socrates
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#7
(10-21-2019, 10:20 PM)DarthRevan39 Wrote: my shop mentioned that my 429 in the 71 seemed to be a little weak

... and what evidence did they provide to support that claim? "Weak" is a rather subjective opinion. If they did a leakdown or compression test and the numbers came back bad, or you're using an excessive amount of oil, then okay. However, to start considering dropping $10K on the suggestion from a shop (that I'm sure would love to get paid to do the work) "thinking" your engine is weak?

IMO, do a compression and leakdown test. If the numbers how you have a problem, then go from there.


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#8
(10-21-2019, 10:20 PM)DarthRevan39 Wrote: Hey all,

This might be heretical to suggest, but my shop mentioned that my 429 in the 71 seemed to be a little weak and I've been giving some thought in replacing it with a new performance motor of some kind. Probably would replace just about everything at once, motor, drive train, suspension etc. Looking mostly at the motor in this thread, do you guys have any suggestions for high HP/torque motors that will fit? Probably looking in the $5k-$10k range.

Thanks in advance and looking forward to your suggestions!
 Only heretical if you're considering a "Chevy" motor!!
Just wondering if your "shop" guy is wanting to screw you out of the 429. Weak or not, make sure you don't get "talked into letting it go for "scrap" if you get my meaning.
If the block is still good, rebuild it would be what I'd do.
Geoff.

Geoff.
 I learn something new every day!
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#9
(10-23-2019, 07:47 AM)Hemikiller Wrote:
(10-21-2019, 10:20 PM)DarthRevan39 Wrote: my shop mentioned that my 429 in the 71 seemed to be a little weak

... and what evidence did they provide to support that claim? "Weak" is a rather subjective opinion. If they did a leakdown or compression test and the numbers came back bad, or you're using an excessive amount of oil, then okay. However, to start considering dropping $10K on the suggestion from a shop (that I'm sure would love to get paid to do the work) "thinking" your engine is weak?

IMO, do a compression and leakdown test. If the numbers how you have a problem, then go from there.
I would agree with them that it doesn't seem to be strong especially during idle. I do need to do a leakdown test for sure. Probably should check the spark plugs and distributor first too. I think "tired" was the actual terminology they used.

I don't think this shop offers engine swaps so they aren't really trying to screw me. This is also something I'm just thinking of doing in the future. It isn't the original block either because the original was a 351 according to the VIN. It's one of those instances where I got the vehicle from a person who did a partial restore and they didn't exactly do the best job and I'm not even sure what all they did or where this block came from. The engine probably needs a whole teardown, inspection, and cleaning TBH. I do like the idea of doing a 460 Stroker if I'm going to go through the trouble of a teardown.

Really just looking for different opinions and to see what people have done to get ideas for the future.
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#10
(10-22-2019, 12:27 AM)rvrtrash Wrote: A picture is worth a thousand words. More than $10K, but.......

https://jonkaaseracingengines.com/shop/b...boss-nine/

Steve
Man that would be awesome to put in! Worth more than the car itself though. Honestly might consider it in a few years lol
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