I am putting a 1982 ford 302 into a 1973 Mercury comet. I have been told that I need to buy a different Flex plate because of the Imbalance on the newer motors is different. BUT previously we took this same engine out of an Automatic Pick Up and put it into a 1987 Pick up with a 4 Speed. We didn't change anything other than stuffing the motor in and hooking up the fuel injection system. We ran it for 10 years with out any vibrations at any speed. We know that the flexplate, torque converter weigh less that the flywheel and clutch assembly. It ran smoothly for 10 years until we pulled it out to rebuild for the Comet. So since every piece is balanced from the factory, Why do we need to purchase a different weighted flex- plate. When the vibration dampner on the front takes out the vibrations If you have an answer please call my Cell as most cell to cell calls are free or nights or weekends are free. my Cell is 775 397-7182 OR email to IdriveTRKS@msn.com Thanks in advance Phil
The imbalance changed around 80-81 or so. Since you pulled the engine from an 82 and put it in an 87 the imbalance was the same. The 73 has an imbalance of 28oz where the 82 has an imbalance of 50 oz. clint
The 73 engine is 28.2oz. balance and that 82 is 50oz balance,you will have a vibration if you use the 73 flexplate. You need a 50oz flexplate,what tranny are you gonna run? 82 and 87 have the same balance thats why you didnt have any problems.
Ok Maybe I am just not getting this but the fly wheel that was on the 4 speed weighs at least 15- 20# More than the the flex plate. Is there also an internal balance? and IF so Where?
Its not about the weight of the fly wheel.Its about the harmonic frequency that the reciprocating assembly wants to destroy itself at.The harmonic balancer is weighted so as to dampen/eliminate that destructve vibrations frequency.Fly wheels/nut plates are balanced to work with the damper balance to keep the crank from bending like a wet noodle.You need a nut plate balanced to match the damper...in your case:50oz.
it's all about the transmission. run a late model AOD and no re-balanced flex plate is needed. run an older C-4 and you will need the re-balance. my engine is a '86 302 h.o. with a '74 C-4 hooked to it. i had to get a re-balanced plate to calm the vibrations.
Thanks for all the Info... I guess Summit gets another order.. they are starting to know me on a first name basis.. Phil
I beg to differ on this. It is all about the engine. a 302 before 80-81 or whenever they did the change over had a balance of 28 or so oz. After 80-81 they changed to 50 or so oz. The harmonic balance on the front follows the same years. The transmission could care less what weight the balance on the flex plate or flywheel it so long as it is the right tooth count to fit the bell housing. IdriveTRKs if you take a look at the old 4 speed flywheel you will notice that on the back there is a coved out area and then around the other side there is a built in heavy area. This is what makes the flexplate un-balanced. If you put the flywheel on a lawn mower balancer for **** and giggles you will see it fall over towards the built up area of the flywheel. On a flexplate for an automatic trans. the weight is welded on and easy to see. Hope this helps. I am not very good at putting thoughts to words like others are. clint
so basically, what you're saying is my transmission didn't need a balanced flexplate? the trans didn't care either way? i beg to differ. hook a late model trans to a late model engine, no imbalance. hook that same engine to an older trans. and -imbalance. just try to stuff a larger flex plate into an older transmission. the trans config has everything to do with the problem. (or bellhousing-flex plate config to be specific). the older trans bellhousings didn't have the adequate room for the correct tooth count.
Thanks everyone for your input. I decided to go with the four speed save some trouble... Maybe... still need to find a clutch/brake peddle assembly.. Any one have an extra? Phil
You're wrong. There's a counterweight welded on the flexplate, that's what matches the imbalance to the crank. And it only bolts on one way, the holes in the crank look like theyre evenly spaced, but they're not. You also cannot stuff a bigger flexplate into a smaller bellhousing. The starter will not be able to engage the ring gear. There were two basic tooth count flexplates used---157 or 164 tooth. Two balance weights too---28 oz/in or 50 oz/in, The 50 oz never came in a 157 tooth size from Ford. That's an aftermarket only flexplate.
did you read anything past the first sentence in my post? i'm going to go find another wall to beat my head against.
That is pretty much what I am saying. The transmission doesn't care what balance/imbalance the flex plate or flywheel is so long as it is the right diameter and tooth count to fit inside the bell housing. The cranks shaft of the earlier pre-81 engines was balanced using a flywheel/flex plate and harmonic balancer of 28.*oz. After the change over of 81-82 the crank shafts of the 5.0's were balanced with 50.*oz flexplates or flywheels and harmonic balancers. I suck putting thought to words but I do the best I can. The transmission is neutral balanced if you will. So long as the flex plate/flywheel fits the transmission and the ring gear is right for the starter that is all that matters so far as the transmission goes. Like baddad457 and I quote "There were two basic tooth count flexplates used---157 or 164 tooth. Two balance weights too---28 oz/in or 50 oz/in, The 50 oz never came in a 157 tooth size from Ford. That's an aftermarket only flexplate." Put a 1972 302 on an engine stand without a transmission. Put an 85 5.0 flexplate or flywheel on it and crank that engine up. Bring the RPM's up to 2000 RPM's if you can. That engine will beat itself to death in short order. Even if you put 85 harmonic balancer on the front it would not help much if any because the 72 crankshaft was balanced using 28.* oz. Does that make better since? clint
Even with a 4 speed you still have to have the right tooth count and balance on the flywheel. Early 302's pre 82 need 28oz later 302's post 82 need 50.oz. UNLESS the engine was rebuilt and re-balanced using something else. Just did a quick search and Ford Muscle is saying the change was made in 1982. I was never sure if it was 81 or 82. They say in the model year of 82 a 302 might be either 28oz or 50 oz. I know it is not 28 or 50 oz exactly. Another member stated what it was I just cannot remember all of the small detail. Old age sucks and is not for wimps. clint
