Hello I have bough a rebuilt long block to rick malaga in florida, on the net, it's a 351w marine from 1992 the engine have to go in my boat, a coorect craft 1992 the problem start when the engine start for the first time, it was chaking a lot, vibrating.. So I call the guy and he told me I must use a internal damper and flywheel, so, I bough on summit a new internal damper, and rebalanced the original flywheel to zero as he told me, vibration was More dramatic! Now he told me it's my fault because I didn't use the original parts...and aftermarket won't work on those engines... there is a 50oz flywheel possibility? is that true, how can I be sure it gonna work? thanks for helping me Peter
All sbf are externally balanced. The harmonic balancer for a 351W is a 50oz 4 bolt model. Check what you have on the front, it should be 6.5" OD and 3.5" wide. The balance on the flywheel or flexplate should be 50oz as well. Not sure on the marine engines but have you checked the firing order? It differs from a 302 but some cams will change the firing order back to 302.
All 351W were 28 inch-ounce external balance. The 302 was also 28, then the 5.0L starting in '82 were 50 inch-ounce.
What Relic Stew said. I think there was another combination used very briefly on 302 motors around '81 or so.
The 351W firing order is the better firing order. Don't change it. As has been said ALL 351W are 28oz-in. external balance as are their flywheels.
I thought the 5.8L changed to the 50oz the same time? Since he said his engine was a 92 I assumed 50oz. I'm so confuzed...
351's never changed. NO 351 is 50oz, ever. 302 firing order differs from 351W and 302HO motors. You'd need a road map to know all the changes Ford made to the small block.
Let me un-confuse you. All 351W's from 1969 until the end of production were 28oz-in balance. No need to be confused on this one. Do you know your block casting number by chance? If it's F4TE (guessing it is not since the engine is said to be from '92) it's a roller cam engine. Other wise it's a flat tappet cam engine.
Some marine engines were reverse rotation, so check which way it is to turn, which could explain the vibration?. Good luck.
Mine is a flat tappet one, I have try with 28oz (original set up) and I had vibration, then the guy told me the engine he rebuild is internal balanced so I need to rebalanced the flywheel and change the damper, what I did... and it went worse.. so now, my question is, do I have to try 50oz?
the Nascar 351 engines are nuetral balanced and i have built a couple race engines and had them nuetral balanced (you either have to buy a nuetral balance crank or use a hell of a lot of tungsten , its cheaper to buy the crank) it does make a much smother upper rpm engine by upper rpm i mean 8000 plus but you have to use 0 balance balancer and flywheel or it wont work
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