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Hey guys, I need some help before the rest of my hair turns gray.
I recently bought a vehicle with a 403 (numbers matching). When I bought it, I got it for pretty cheap because I noticed immediately that there was some kind of balance issue, as it was vibrating quite a bit around 2000 RPM's (steering wheel would start shaking, you can feel it in the drivers seat). I was hoping that it was just a matter of an incorrect balancer or flexplate, and bought the car.
After buying the car, I went through some paperwork and found a phone number from a previous owner in 2015. I called him up, and he told me that he bought the car from the original owner who bought it new in '79, modified it for a few years, and then it sat for almost 30 years. Along with the receipts are some machine shop receipts, performance parts (cam, head work, springs, intake, carb) etc. The point I am making is that the original owner was trying to hop the car up. The second owner brought it home, got it running again, and also noticed the vibration. He changed the flexplate, it still had a vibration, and then he sold it. A few years later, the car is in my possession.
Okay, so here is what I am dealing with..
As you can see from the block numbers, it is certainly a 403:
Here is what I am seeing up front for the balancer and pulley - an OLD Kenne Bell pulley (have receipt for it) and what looks like some aftermarket SFI balancer, which appears to have that chunk of metal on it like the 403 balancers should:
I also saw a strange looking flex plate that didn't look right, so I took it out planning to replace it with an ATP-Z120 direct replacement. Here is the flex plate I took out, which has dual bolt patterns and a weight that can be removed/moved:
I went to install the new flex plate, and it didn't fit. I must've rotated the thing 10 times before calling it quits - the holes would not line up with the crank. Then, I started thinking... is it possible that it was using the early style bolt pattern on the old flex plate, and if so, why?!
Well, correct me if I'm wrong.. but is this a 330 crank? Did the original owner put one in because those cranks were forged?
I'm a Chevy guy, so this is all new to me. I know these parts aren't easy to find, but what can I do? If the block has a 330 forged crank in it, then I would assume that I need the correct 330 flex plate and balancer/damper as well. Can anyone point me in the right direction before I just LS swap this thing? How do I balance this engine?
NOTE: I've already tried running the engine with the converter disconnected, and it still vibrates. I've also tried moving the position of the flex plate weight to the other position, as well as removing it entirely. That just made it worse.
Thank you very much.
Last edited by Evilws666; August 31st, 2022 at 08:15 PM.
Does it vibrate in park and neutral? It is possible that a 330 crank was put in. It could be the wrong flexplate, where did you get it? It could be the motor wax rebuilt, hopefully it was properly balanced. My 330 crank has the same notch as your crank.
Last edited by olds 307 and 403; August 31st, 2022 at 08:34 PM.
Does it vibrate in park and neutral? It is possible that a 330 crank was put in. It could be the wrong flexplate, where did you get it? It could be the motor wax rebuilt, hopefully it was properly balanced. My 330 crank has the same notch as your crank.
It vibrates in park, and definitely when in gear and driving.. not sure about neutral. I disconnected the torque converter from the flex plate and started it, still vibrated.
the second owner said he bought it from the original owner in a “non drivable” state, and rebuilt the engine, including putting on that flex plate. He also stated that he may have replaced the balancer, but couldn’t remember for sure. Judging by everything else in the car, he either replaced the balancer, or that’s the same balancer that’s been on there since the 80’s.. and I’m not sure if it looks that old or not.
Originally Posted by Sugar Bear
I'm reluctant to ask but here goes...has the firing order been confirmed to be correct?
No worries, fair question! Yes I did check the firing order. As well as timing, plugs, wires, and carb.
There’s no doubt that the crank installed in my 403 is *not* a 403 crank. Question is.. how do I get it back to being properly balanced? The machine shop receipt shows that the block was balanced back in (I think) 82. So I have to wonder what was on it when it got balanced. If they put in a 330 crank way back then, im guessing they balanced it with a 330 flex plate as well. I was able to find someone with a 330 flex plate from a 64 that they are willing to give me, but that still leaves the balancer - is my current 403 balancer with the big chunk of extra metal on the back of it correct for a 330 crank, or do I need a different one? And where would I find one? I don’t know how 330’s were set up and I can’t find parts.
Are you sure it is a vibration and not maybe a misfire of some type ? Does it get worse as you increase the rpm above 2000 ?
If you feel sure that the vibration is because of an out of balance condition then the only way you will absolutely make it right is to disassemble the engine and have the entire rotating assembly balanced again.
Do you have the specs or part number of the camshaft ? Some real high performance and race cams can have a pretty terrible rpm range where they just dont run smooth.
This is definitely a forged 330 crank. Unfortunately, without tearing into it, you have no way of knowing if the motor was properly rebalanced when it was assembled, or what other mis-matched parts are in it.
Got to be that it was NOT re balanced and imagine the HUGE difference in weight of a giant diameter 403 heavy piston to a 330 one its balanced to ! Big Guy in a Little Coat syndrome
Got to be that it was NOT re balanced and imagine the HUGE difference in weight of a giant diameter 403 heavy piston to a 330 one its balanced to ! Big Guy in a Little Coat syndrome
It's not just the pistons. The 403 rods are heavier (and beefier) than those in lesser SBOs.
Just a thought for a quick & easy test. Swap the 4 & 7 plug wires and see if it suddenly behaves. It’s a long shot but it could have a 4/7 swap cam in it with wires run as normal firing order.
If only it could be that easy! Not likely, but fingers crossed.
You could find a stock replacement balancer. I wonder if the original was coming apart and they put that balancer on. It is worth a shot, it may fix the issue. A member on here might have a good used one. I do but I am in 🇨🇦.
Are you sure it is a vibration and not maybe a misfire of some type ? Does it get worse as you increase the rpm above 2000 ?
If you feel sure that the vibration is because of an out of balance condition then the only way you will absolutely make it right is to disassemble the engine and have the entire rotating assembly balanced again.
Do you have the specs or part number of the camshaft ? Some real high performance and race cams can have a pretty terrible rpm range where they just dont run smooth.
If I remember correctly, it got worse as the RPM's increased. I'm not entirely sure though.. I currently have the flexplate off so I can't check right now.
I'm going to attach a photo below which is the sheet from the machine shop from the 80's. Says the cam is a "C-113"
Originally Posted by joe_padavano
This is definitely a forged 330 crank. Unfortunately, without tearing into it, you have no way of knowing if the motor was properly rebalanced when it was assembled, or what other mis-matched parts are in it.
I just spoke to the 2nd owner again, and he said he took the engine apart to a bare block and replaced the bearings and such, and reassembled. If a piston were placed in the wrong hole, this would undo the previous balancing, correct? Look at the photo I'm going to attach below, it's a receipt from when the original owner brought it to the machine shop. Apparently it had quite a bit of work done, and was said to have dyno'd at 430HP (don't know if I believe that).
Originally Posted by joe_padavano
It's not just the pistons. The 403 rods are heavier (and beefier) than those in lesser SBOs.
Apparently the receipt shows that rods were resized and crank was ground, along with TRW .030 pistons. It also shows under the "Block" section that "Balance" was performed.
Originally Posted by bccan
Just a thought for a quick & easy test. Swap the 4 & 7 plug wires and see if it suddenly behaves. It’s a long shot but it could have a 4/7 swap cam in it with wires run as normal firing order.
If only it could be that easy! Not likely, but fingers crossed.
…
I'll check when it's back together. Worth a shot.
Originally Posted by olds 307 and 403
You could find a stock replacement balancer. I wonder if the original was coming apart and they put that balancer on. It is worth a shot, it may fix the issue. A member on here might have a good used one. I do but I am in 🇨🇦.
The question is.. what balancer should go on it - a 330 balancer or a 403 balancer?
Originally Posted by v8al
Is that balancer on backwards? I have never seen a balancer numbered upside down like that before...
I don't believe it is. If you look at the other pic of the balancer from underneath, it has the counterweight "chunk" facing the front of the engine, which I believe is correct. Also, I think this is the balancer that's in it, which has the numbers facing the same way:
I think it's really, really difficult to install a balancer backwards.
Yeah, as I said above, I don't think it is. Not to mention 1 of the 4 bolt holes isn't threaded through on the rear side (where the counterweight chunk is).
-------------
The second owner confirmed that he put the new flexplate and balancer on, it vibrated badly, and then he sold it. Searching the VIN, I found that the car exchanged hands through a few dealers over the years since 2015, and now I have it, vibration still there. I'm thinking no one could/cared to figure it out. Either it was actually getting driven some of that time, or someone beat on it, because now there is some clacking noises coming from it, which makes sense as I would imagine it being out of balance would wear the bearings. So I guess I have to take it apart anyway.
Anyway, here's the machine shop receipt I mentioned. You may notice it says "BORE FOR STICK" under the crank section. Apparently the original owner was going to swap a 4 speed in it, but never did. I would assume that means even more material was removed from the crank? I also have no idea what a C-113 cam is.
Unless you are able to get the balancer and flexplate that was on it when it was “balanced” originally, it’s a crap shoot.
This is one reason why I internally balance everything possible. I can tell you that flexplate looks like it came from either Olds Rocket parts or Procomp/Speedmaster. Either way they’re never the same from one to another. I’ve had the same issues with the Pioneer stuff as well.
If it starts to wipe out the main and/or rod bearings then you know for sure it’s a balance issue. Otherwise you might try swapping 4 and 7 as mentioned. If that doesn’t do it then a tear down is most likely your only course of action.
Hope this helps.
The second owner confirmed that he put the new flexplate and balancer on, it vibrated badly, and then he sold it.
And we have a winner. The receipt says that the assembly was balanced. Done properly, that uses the specific balancer and flexlplate that will be on the motor. Replacing that balancer and flexplate without matching the balance of the prior parts is almost certainly what caused this problem. I'm afraid the only option is to disassemble the motor and balance it correctly, then keep the parts matched.
Well, I guess once I get my SBC back together, I’ll yank the 403 out and get it to a machine shop. Called around and balancing starts around $375. I guess it’ll keep the car original, and cheaper than me doing an LS swap.
id like your opinions - should I go through with picking up that original 330 flex plate I found, or just keep the one that I have for balancing it? What about the balancer?
IF it has a forged 330 crank in it then only the early flexplate pattern will work. The 68 and later ones don't line up.
But he can retain the dual bolt pattern flexplate as well.
My advice would be to totally bite the bullet and get it balanced internally. It’s easier on parts too.
But he can retain the dual bolt pattern flexplate as well.
My advice would be to totally bite the bullet and get it balanced internally. It’s easier on parts too.
id like your opinions - should I go through with picking up that original 330 flex plate I found, or just keep the one that I have for balancing it? What about the balancer?
A proper balance job will include the balancer and flexplate. It doesn't matter which ones you use so long as you keep them with the motor and don't change them later.
Kenny Belle used to offer cams numbered like that.
Yep, in the book of receipts I got along with the car, there are receipts from Kenne Bell for that cam, lifters, retainers, and some other things. There's even a product sheet in there from Kenne Bell dated (I think) '79.. was able to find every part number on there except the cam. Most of the parts on the receipt have a dot next to the listing on the product sheet, and there is also a dot next to hydraulic cheater cams. Guessing that's what the "C" is for in C-113.
Originally Posted by Greg Rogers
I've been following this, I had nothing to contribute but am very interested in how you make out. Let us know- good luck!
Will do. It's going to be a little bit since I'm going to have to tear this block down. I'm reassembling a 355 for my Camaro right now. Once that's in and running, I'll swap cars and then yank out the 403.
Search “Kenne Bell C 113,” no Olds specific but the Buick version is discussed in some threads. Relevant? I have no idea! Might give you some idea on specs if you don’t have a card. Someone probably still has a vintage catalog collecting dust and could look it up.
Search “Kenne Bell C 113,” no Olds specific but the Buick version is discussed in some threads. Relevant? I have no idea! Might give you some idea on specs if you don’t have a card. Someone probably still has a vintage catalog collecting dust and could look it up.
i have the “Racer Discount Price List”, dated 1980. The only thing is, it shows the MK C cam range as C440-C477, and no info other than it being a cheater cam. No 113. It does definitely appear to be the same one coming up on the Buick forum though.
Last edited by Evilws666; September 6th, 2022 at 02:52 AM.
August 31st, 2022, 07:51 PM
