[grivera]

Thanks Jason- it has rubber mounts - engine and trans

So I emailed MDL asking if the FW on the invoice was for an internally balanced engine, as the first page of the invoice states it’s for zero balanced. Rather than just saying “no”, the reply is, “We do offer a Zero balance version for the Pontiac crank, it is not shown on the web site. In stock for $328.00.”

I sent copy of invoice and asked that he confirm which FW was shipped- waiting on reply. Hope this is the issue for the sake of an easy solution but at the same time it would suck if they mailed wrong part.

[grivera]

So Paul from MDL called back and [so far] it looks like the wrong FW (externally balanced) was shipped. He wants to make sure the part number for the externally balanced FW was the same back in 2019 when the order was originally placed. If so, a the correct FW will be shipped. So this assembly has about 1k miles of light driving - no racing or hole shots. What kind of damage if any would there be to the engine from the wrong FW?

Nice call 62posbonny!

[grivera]

So MDL will send a shipping box and label so I remove the FW and send to the manufacturer to turn into a zero-balance FW

[62posbonny]

Good to hear they are making things right. Hope is solves your issue, please make sure you update the thread if it fixes things for you.

[grivera]

Does anyone know what damage if any could be caused by the imbalance in the FW? Anything I should pay attention to once I have the newly zero balanced FW installed?

[Gach]

I’m curious also, sounds odd. The enterally balancing at least my understanding is if for some reason the FW gets wipe out, you can take the new one back to the shop, they have all the balancing info, on file a long with the balancing card they give you, and they can rebalance the new one, which usually entails taking off weight to match the old one. I’m curious how the seller of that FW would know what the weight is supposed to be. Unless they had all the balancing info.
Everyone that I’ve had internal bouncing done, they want The front balancer and Fly wheel included with all the parts for the balance job.

[grivera]

That’s interesting- I was under the impression an internally balanced engine could use any zero balanced FW so long as it was correct for the application

[mgarblik]

Originally Posted by grivera

That’s interesting- I was under the impression an internally balanced engine could use any zero balanced FW so long as it was correct for the application

Your correct in theory. The assumption is the balancer and flexplate, or flywheel are actually zero balanced. Unfortunately, when those components are mostly made in China now, that assumption is a bit of a guess. It all comes down to the quality of those parts. If going for a very precise race balance, the crankshaft will be balanced first to zero. Then balancer and flexplate, or flywheel will be added and checked. In some cases, the clutch may even be added or torque converter. For a street quality balance, we generally stop at the flywheel and balancer. At my school, we have only built a handful of Pontiac engines in the last 10 years. Generally, they have been pretty close, with the zero balancer and flywheel added.
Small Block Fords are terrible. Several different factory balance factors and tons of junk Chinese parts out there. They can easily be off by more than 100 grams if parts are mixed and matched.

[grivera]

Thanks- great information

[grivera]

I just got the FE back from getting it zero balancing - they removed 4.5 oz.

[grivera]

Oops - that should say I got the FW back from getting it zero-balanced. I installed it this afternoon and hope to test it out tomorrow.

[lust4speed]

For what it's worth, the balancing processes I have watched has the crank zero balanced and then the balancer is attached and corrected if needed, and then the flywheel is attached and corrected. As said above, in a perfect world the balancer and flywheel would already be at zero balance, but usually are not.

I think Pontiac external balance is 6.5 oz. and therefore the flywheel was out 2 oz. as originally delivered since only 4.5 was removed to achieve zero balance?

[grivera]

What you describe sounds like the right way to balance an assembly but I assume many who purchase “balanced assemblies” from a place like JBP don’t take the extra step and instead end up buying a neutral/zero balanced flywheel.

Regarding the metal removed on mine, like you alluded to, it already had two holes drilled on one side, and to zero balance it they drilled out two similarly sized holes and a smaller one that’s quite shallow. Either way due to the original holes it took another 4.5 oz removed to true-up

[grivera]

What you describe sounds like the right way to balance an assembly but I assume many who purchase “balanced assemblies” from a place like JBP don’t take the extra stem and instead end up buying a neutral/zero balanced flywheel.

Regarding the metal removed on mine, like you alluded to, it already had two holes drilled on one side, and to zero balance it they drilled out two similarly sized holes and a smaller one that’s quite shallow. Either way due to the original holes it took another 4.5 oz removed to zero it.

[grivera]

I took it for a test ride today with the zero-balanced flywheel installed. It is much improved- I can drive at high RPM and it is smoother. At about 70 mph I notice a vibration coming from the body. When I had the wheels spin balanced they used stick on weights at my request, cause I like the all black wheel. The tech said it isn’t the best way and if I had issues come back and he’d use the conventional weights that go on the edge of the wheel lip- I may try that and the. Paint them to hide the weights.

[62posbonny]

I would guess it is time to pull out the protractor and do some digging into driveline angles. I had serious vibration issues with an engine/trans swapped 71 Cutlass that was lowered 2". After looking at operating angles on my u joints there was no solution but a CV joint driveshaft. Once i ponied up the $ and got it in the car is smooth as glass to 120. I currently have a 63 catalina with bad angles because of the th400 swap that is super sketchy above 70 because of the same problem, but am waiting until i TKX swap it to find a solution.

[grivera]

I have a digital angle finder and adjustable upper trailing arms. If I’m doing all correctly, my angles are within spec. Once I get tires rebalanced I’ll reassess and take to a shop for checking driveline if need be.

[ta man]

I had a pulsing vibration at cruise speed a few years ago and it turned out to be a worn stock harmonic balancer.

[Greg Reid]

I have a minor 'pulsing' vibration myself. Right at 65mph or so. I didn't notice it until I swapped the rear end. I found two stick-on balance weights right where I park my car and noticed a couple more witness marks from missing weights on two wheels. That's going to be the first thing I try. Hoping it's not a differential problem.
Next time I'm going to add a small dab of RTV on each of them