External or Internal
- Thread starter Johnny
- Start date
Keeper
Active Member
The 454 and larger big blocks are also external. A big block and a small block flywheel will interchange but they don't balance the same. So a 427 flywheel would work fine on a 283. But the 400 and 454 flywheels are external balance and have a weight welded on, but they don't interchange.
Also on the small block if you build a 383 stroker with a 400 crank then you need a 400 flywheel.
Harmonic balancers are the same way.
Screaming Metal
Active Member
Rons right....I've seen many a fat motors bearings pounded to death or worse...all because some folks don't know a 454 is externally balanced....
When you have a motor built and its balanced....include everything...the flexplate, the bolts, harmonic balancer....and when you get it back, label everything as to where it goes and in which location....
When you have a motor built and its balanced....include everything...the flexplate, the bolts, harmonic balancer....and when you get it back, label everything as to where it goes and in which location....
Mike
Well-Known Member
One thing to bear in mind is that 1986 and later small blocks with the one piece rear main seal are also all externally balanced. Obviously, these components are different, but it's worth bearing in mind. And these late model motors do not share the same external weights as the 400.
If you are having issues finding a proper flywheel, check with your local machine shop to see if they can do and internal/external conversion for you. We had an old S-W balancer that would throw a counter-weighted flywheel across the shop at you, but we did countless conversions on our Hines balancer. Another of our popular jobs was balancing Harley-Davidsons. The mirrors on a bike would be steady as rocks after balancing the wheels.
If you are having issues finding a proper flywheel, check with your local machine shop to see if they can do and internal/external conversion for you. We had an old S-W balancer that would throw a counter-weighted flywheel across the shop at you, but we did countless conversions on our Hines balancer. Another of our popular jobs was balancing Harley-Davidsons. The mirrors on a bike would be steady as rocks after balancing the wheels.
Screaming Metal
Active Member
Yes n deed...the balancing...as Mike said, if you have to run a diff. flywheel combo, get it balanced. IF, you don't have anyone close to where you are that can get you straightened out, you can call these guys, they have a weight that bolts to your existing flywheel to get your motor back to stock balancing specs.
http://www.goodson.com/
If you don't feel comfortable going this route, get your rotating assembly done by a competent pro, your motor needs that balancing done.
http://www.goodson.com/
If you don't feel comfortable going this route, get your rotating assembly done by a competent pro, your motor needs that balancing done.
I got a question. How can you correctly balance an external flex plate, for lets say a 400, if you don't have the bob weight numbers. Also the little bolt on weights that go on a internal flex plate to convert it? When I worked in a machine shop and did the balancing, we always balanced the flex plate and balancer on the crank it was to be used with, especially if it was an external balance.
Screaming Metal
Active Member
Ron Theres a chart the tells what the stock weights are for balancing certain cranks....but most cranks when yourspin balancing whatever, it gives you a certain weight it calculates, it strobes the part, then slows the thing down shoots a beam to where you gotta add the weight and tells you how much.
I tried copying a picture of the bolt on weights that bolts to the rear ofthe crank for our folks....this thing has still got me baffled...well....I'll keep trying....
Please excuse it if I send it a couple of times.....
Screaming Metal
Active Member
Well...heres another try...lets see what blows up now.....
Screaming Metal
Active Member
Well, heres another....
ruggs
Member
Somehow this doesn't sound like something out of the "You Can Do" series....More like "Don't Try This At Home"????
Screaming Metal
Active Member
Well...Here goes...
Let me try again. You have, say a 383 stroker. with super lite pistons and rods in it. So now you have lite bob weights on the crank and being it is a 383 with 3 3/4" stroke, you have an external balance flywheel. So you put it all together and it runs great and you take it to the track and break the flex plate. Now just to be the devils advocate here, you have no idea about the bob weight and can't even find the guy that built the motor or balanced the engine. How do you now balance a new flex plate to that engine without taking it apart and spinning the crank again. I understand about the strobe and the light and meter on the machine. I balanced 100s of engines back in the day. And back in the day we could not do what I just ask. I was wondering if there is a way to do it now?
Just one more reason to love the 377 SBC combo. 
Russ
Russ
Here is the little ad on balance weight we are talking about.
Then here is the article about it.
balance weight
Screamin send me a contact # please. tbucket@comcast.net
Then here is the article about it.
balance weight
Screamin send me a contact # please. tbucket@comcast.net
Screaming Metal
Active Member
OK, Engine balancing....more or less....in laypersons terms is angle of the v, the # of cylinders, the intended rpm to run, the weight of the pistons and the rods, and with a little math....(The study back in high school that you said you wouldn't use)....well, it comes in handy here. As long as you have the weight of your components, can figure out your power impluses, the angles....yada,yada,yada...not much to it. I like doing it longhand...I've gotten the past few years where I depend on the machines too much.
For Engine Balancing 101....here ya are.....for all that are curious.....
http://www.enginebuildermag.com/Article/48121/understanding_crankshaft_balancing.aspx
As you can see....its not really that hard, for those of you that really truely want-to-know....
For Engine Balancing 101....here ya are.....for all that are curious.....
http://www.enginebuildermag.com/Article/48121/understanding_crankshaft_balancing.aspx
As you can see....its not really that hard, for those of you that really truely want-to-know....
ruggs
Member
Okay, dumb question of the day, but I figure if I don't ask, I might not ever know. I was looking at flex plates and it listed for external balanced and internal balanced. How do you know if your engine in externally or internally balanced???
Thanks, Fellas
SBC 400 - external
SBC everything else - internal
Thank you for quick reply. I'd just found that out about 2 minutes ago. Amazing the things you can find out on google.
I'm probably wrong for involving myself but, Have you noticed that Johnny got his answer and hasn't been back on this thread. He got his answer and now it has turned to a PeePee match. It's Ok cause I am not forced to read all of this but I have enough experience to know what is right and what is wrong...Aye Curumba muchachos....
Thanks, Fellas
SBC 400 - external
SBC everything else - internal
Thank you for quick reply. I'd just found that out about 2 minutes ago. Amazing the things you can find out on google.
I'm probably wrong for involving myself but, Have you noticed that Johnny got his answer and hasn't been back on this thread. He got his answer and now it has turned to a PeePee match. It's Ok cause I am not forced to read all of this but I have enough experience to know what is right and what is wrong...Aye Curumba muchachos....
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