Engine balance question

[iamlance]

I installed a 351W in my 65. It has a vibration that is definately from the engine. The motor came out of an 84 Van but was not the original motor. (carburated)I drove the van before pulling the motor and there was no vibration noted. My car is a stick and I used the original 28 OZ flywheel and a new Prof. Products 28 OZ balancer. After it was running and I felt the vibration, I put a new flywheel in and the problem persisted. I was looking for a new balancer (I hate just throwing parts at it, but I'm quite sure the motor did not vibrate when in the van) and saw on Romacs sight that they listed a 50 OZ balancer for a 85 up 302HO and 351W. I thought that all 351W were 28 OZ imbalance??? If there is a 50 OZ 351 that could be my problem. Any thoughts?? Thanks

 

[rbohm]

all 351w's are 28oz imbalance. it is possible that the balancer you bought is the culprit here. if it is a 28oz balancer, it should have a large weight cast in the center of the balancer facing the engine. if it is a 34oz balancer(yes the balancers actually used a 34oz imbalance on the 81 up 5.0's but ford, as well as everyone else, refers to it as a 50oz imbalance to avoid confusion) the outer ring of the balancer will have a cutout in it, backside facing the engine as well, that extends about 3/4 of the way around the outer ring.

 

[iamlance]

Thanks, guess I'll try another balancer.

 

[thehueypilot]

I got my fuel injected, roller cam, 351W out of a 1996 F250 and it had a 50oz harmonic balancer and flywheel on it. Maybe the engine out of your van was replaced some where down the road with a later year engine?

 

[iamlance]

So later 351's were 50 OZ imbalance?? Does anyone know what year this started??
The engine was replaced in the 84 donor van so it could have been another year.

 

[67efivert]

351 with a 50 oz huh????

 

[thehueypilot]

In 1981 Ford switched to 50 Oz, external balance. In 1984 they changed the blocks to accomindate a roller cam. My guess is if you did not have the vibration before switching to the 28oz you need the 50oz flywheel and balancer. Worth a try if you still have the original parts off that engine.

 

[dennis112]

In 1981 Ford switched to 50 Oz, external balance. In 1984 they changed the blocks to accomindate a roller cam. My guess is if you did not have the vibration before switching to the 28oz you need the 50oz flywheel and balancer. Worth a try if you still have the original parts off that engine.

The info above is valid only for the 302.

The 351w retained 28oz balance after 81' AND the 351w block was not redesigned for a roller until around 93'-94'.

Engines can be rebalanced when they are apart. You can go 28oz balance, 50oz balance, or even neutral balance if you want to run high RPM's. You wallet would be the deciding factor.

I would try another balancer 28oz (or the orginal if you still have it.)

 

[iamlance]

I'm So Confused!!!!

 

[thehueypilot]

The info above is valid only for the 302.

The 351w retained 28oz balance after 81' AND the 351w block was not redesigned for a roller until around 93'-94'.

Engines can be rebalanced when they are apart. You can go 28oz balance, 50oz balance, or even neutral balance if you want to run high RPM's. You wallet would be the deciding factor.

I would try another balancer 28oz (or the orginal if you still have it.)

I stand corrected......my reference material is wrong. I called Ford Racing hot line and they confirmed 28oz balance on all production 351W but roller cams installed starting 1994. Sorry for the confusion.

 

[TOM B]

are you positive its a 351w and not a 351m most vans had the 351m. IF YOU HAVE THE OLD BALANCER see what balance it is before you buy something you dont need.
I have a prof. product 28oz balancer and when I got it I had to install the weight, if I remember right I think it also came with the 50 weight and when I had the machine shop balance my engine they cut some off the balancer and the flywheel.

 

[iamlance]

Thanks all for the info. Thehueypilot, thanks much for the verification with Ford racing.
I believe it is a Windsor. The intake and distributor I bought and installed were for a windsor. Are these interchangeable with an M motor?? I think an M barely fits between shock towers also.