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Original Message
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| RE: 428cj vs 390 |
| By Mike McQuesten - 12/28/2001 6:16:25 PM; IP 63.50.124.163 |
There are a couple of things to be careful of here. First and foremost in my mind is the flexplate/flywheel you'll use? Your tired 390 is internally balanced and if you use its old flexplate/flywheel(you don't mention stick or automatic?) you'll have a balance problem that will mean a engine vibration problem. This will be no problem if you get the 428 flexplate with that short block 428SCJ. But if not, I'd recommend you find a 428 flexplate/flywheel for your application and use it. Again, do NOT just bolt on the old 390 flywheel/flexplate.
Second, what heads are on your 390? You've mentioned that the 428SCJ is a short block and to me a short block has always meant headless, right? So if you bolt on the 390 heads you have.....? I would check the cc volume of the heads you plan to run and compare that figure to the 428 CJ heads, C8OE-N. You probably don't want to have a compression ratio beyond 10.5:1 and that's marginal on our standard "High Octane" 92 unleaded fuel.
Third, does your 428SCJ have the harmonic balancer? This dampner is extremely important like the correct flywheel/flexplate is to correct engine balance. Again, you can't just bolt on your 390 dampner and not have vibration problems.
Those are just a few things that pop into my mind. All of them can be easily cared for. I would recommend that you do get your hands on that good 428 SCJ short block.
BTW, how do you know it's a Super Cobra Jet 428? Is that pan off? Can you see the rods? Please, don't just take the word of someone telling you that it's a 428 Super Cobra Jet.......a 428 Ford is a good start most times, but there are a lot of folks who like to use the terms Cobra, Cobra Jet and Super Cobra Jet rather loosely. |
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