7.4mpi rebuild to 454MAG
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7.4mpi rebuild to 454MAG
Can a 7.4mpi be rebuilt to a 454mag? O r would it be more cost effective to sel a good running 7.4mpi and buy a rebuilt 454mag? Would the fuel system from a 7.4 be compatible with a 454mag? Thanks fo any info. Ball park what is a usede 7.4mpi worth it had a great leakdown test and runs great 400hrs now.
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Re: 7.4mpi rebuild to 454MAG
If you are only looking to get the output of a 454 Mag out of your 7.4 MPI, and it is running good, leave it alone. I don't know what kind of boat it's in, but 30-35 HP is not worth the hassle. Just my .02.
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Re: 7.4mpi rebuild to 454MAG
Originally Posted by Whiteknuckle
If you are only looking to get the output of a 454 Mag out of your 7.4 MPI, and it is running good, leave it alone. I don't know what kind of boat it's in, but 30-35 HP is not worth the hassle. Just my .02.
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Re: 7.4mpi rebuild to 454MAG
I would look for another engine, and keep yours for a spare or sell it...
I had a 7.4mpi with 165 hours in my 22ZX Donzi. I found and bought a used HP500 with 180 hours on it for $7500. I then reworked it and added some things and ended up with about 10k in it.
I then sold my 7.4mpi for 3k.
So, I have about 7k in an HP500!!!
You should be able to find a complete mag of some description for not a huge amount of money.
Take care,
Kent
I had a 7.4mpi with 165 hours in my 22ZX Donzi. I found and bought a used HP500 with 180 hours on it for $7500. I then reworked it and added some things and ended up with about 10k in it.
I then sold my 7.4mpi for 3k.
So, I have about 7k in an HP500!!!
You should be able to find a complete mag of some description for not a huge amount of money.
Take care,
Kent
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Re: 7.4mpi rebuild to 454MAG
I tried to hop up my 7.4 MPI last year with a bigger cam and good exhaust. The re-calibration of the fuel injection became a big hassle to say the least.
I have also been told that the GM MPI intake will not flow enough to make power above 4600rpm so this limits the potential output to about 375HP.
The base L-29 engine is an OK base to build up if you are willing to ditch the fuel injection for a carb. It is a roller cam engine with 9:1 compression and vortec heads.
With the right cam, intake, and carb, 420 HP at 5000rpm is not all that far fetched...
I have also been told that the GM MPI intake will not flow enough to make power above 4600rpm so this limits the potential output to about 375HP.
The base L-29 engine is an OK base to build up if you are willing to ditch the fuel injection for a carb. It is a roller cam engine with 9:1 compression and vortec heads.
With the right cam, intake, and carb, 420 HP at 5000rpm is not all that far fetched...
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Patrick
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Re: 7.4mpi rebuild to 454MAG
Been there done that too!! And Pat hit it on the head. I stuck with the MPI and should have gone carb.
Another member bought my heads and cam and had bobl do his for him. Only difference was his is/was a Volvo and he did go carb. He's somewhere in the 425-450 HP and for the money (saved a lot buying my heads and cam) got decent performance. To do it all, it's probably not worth the money. You could probably buy a good 454 MAG for the money.
I ended up with a new 540.
Another member bought my heads and cam and had bobl do his for him. Only difference was his is/was a Volvo and he did go carb. He's somewhere in the 425-450 HP and for the money (saved a lot buying my heads and cam) got decent performance. To do it all, it's probably not worth the money. You could probably buy a good 454 MAG for the money.
I ended up with a new 540.
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Re: 7.4mpi rebuild to 454MAG
SRJim, hows your stationwagon runnin these days? Blown away any Fountains, lately???
Yup, I saw your bad boy at FTM!!!!
Did you get your props ironed out?
Kent
Yup, I saw your bad boy at FTM!!!!
Did you get your props ironed out?
Kent