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Old 05-19-2003, 01:31 AM
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I currently have A EFI 302 mustang, I going to do a 351 swap. The 351 is going to be stroked to just under 400ci. I know I can keep it EFI, but would it be easier to go carb? What are the power differences? Also what is the difference between a roller block and non-roller? I found a 94 351 roller shortblock for $400.00 or should I just get a older/cheaper block sence its going to be stroked? I really want to get this swap done but I really need all the advice I can get this will be my first engine swap. And I plan on doing it myself so any help would be great. THANKS

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Old 05-19-2003, 01:58 AM
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not much of a ford guy here, but to keep the EFI, you`ll need to step it up to the new displacements requirements, which may require a computer change or chip change, bigger injectors, different knock sensor or the like. I`d go with the roller cam, there far superior to any flat tappet cam. there are some real good ford guys on here that can tell you more than i can on the fuel injection issue. just giving my 2 cents.
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Old 05-19-2003, 03:28 AM
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I will second that on keeping the EFI. From what I have seen the Ford EFI systems work very well even on highly modfied engines. Like state earlier, you will need to match the injectors to the application and probably do a chip upgrade. There are are also new ECU's available that allow you to completely customze the fuel and ignition curves. I would also recommend ether a intake port job or an aftermaket intake. They are a bit price, but pretty important to get the most of your combo.

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Old 05-19-2003, 04:35 AM

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Stay with the EFI. My Bud built a 347 and droped it into his Mark VII, replacing the 5.0. He used all the wiring harness, computer(chip mod) and some Holly bolt on items and has a 400 Hp, 400 ft lbs monster that looks like Grannie's Grocery Cart. And he gets 24 mpg crusing the interstate at 70 with ac blasting!!

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Old 05-19-2003, 04:35 AM
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Going to a carb is cheaper and easier, at least on the most common skill level. On a high performance engine that's properly dyno tuned, there is no real difference between EFI and a carb, that's been proven. But in the real world, EFI adds 5-15 hp. Why? The driving environment changes constantly, and the EFI computer tunes the engine to match conditions. A dyno tuned carb is great -- for the conditions it was tuned under. You have to change tune 2-3 times during the day, most drag racers will tell you that. The computer changes tune every few minutes! So driveability is the main reason for keeping EFI.
If you have the type with a MAP sensor it's easy to change. The same chip can be used for the 302 and 351, just size the injectors correctly. If it uses a MAF (mass airflow sensor) you'll have to replace that with a bigger one as well as change the injectors. Use a modest cam and the stock computer will be fine -- something about like an RV or econo-power grind. Get wild with the cam and the computer won't work right, you'll have to have a custom chip made.
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Old 05-19-2003, 04:39 AM
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If your going through the trouble of rebuilding port and polish the intake and the heads. Go roller and have your ECU reprogramed.

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