400 Vibration Problems
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From: Western Slope, Colorado
400 Vibration Problems
I have a vibration problem that comes in at about 1100 RPM and starts to smooth out at 1400 RPM while in neutral and clutch disengaged. This engine has only 500 miles on the rebuild and the vibration problem has been present since installation. I had the engine bored with torque plate, balanced, installed new harmonic balancer, new motor mounts, Edelbrock Performer EGR Intake, Edelbrock 1400 600 CFM Carb and Ford Motor Sport Roller Rockers. The only parts from prior to the rebuild are the MSD 6AL ignition and the stock distributor. I did not have a vibration problem prior to the rebuild. The shop has checked the ignition on the scope and checked for vacuum leaks, all looks ok. I have swapped out the carburetor with a Edelbrock 750 CFM and the MSD 6AL for MSD 6A from my car, also swapped out the distributor. The vacuum advance does not leak and the brake booster does not leak. Any suggestions will be appreciated as we are about to pull the crank and confirm the balance.
Wes
Wes
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400 Vibration Problems
Hi. I have a 400 also with the same vibration. It had it before the rebuild and after. I had the motor balanced, thinking this would solve the problem. It did not. I have 45,000 on the motor now and it still has the shake. Good luck on finding it.
Also I have an automatic so I don't think it is in the tranny.
Chad
Also I have an automatic so I don't think it is in the tranny.
Chad
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From: Porterfield
400 Vibration Problems
OK so you both had your motors balanced, but did you do it with the flywheel and harmonic balancer installed. The 400 has a 28oz imbalance built in to them, if you had it balanced with out them that could be your problem.
I know with my last engine build, My machinist balanced the whole rotating assembly, flywheel and fluidampr and made adjustments to both of them.
I know with my last engine build, My machinist balanced the whole rotating assembly, flywheel and fluidampr and made adjustments to both of them.
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From: Western Slope, Colorado
400 Vibration Problems
The harmonic balancer and flywheel and crank were sent to the balance shop, all three components have fresh drill marks. My machine shop has been farming out their balancing. He said he ordered a balance machine today as to remove any doubt when he is building an engine.
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From: Porterfield
400 Vibration Problems
< The harmonic balancer and flywheel and crank were sent to the balance shop, all three components have fresh drill marks. >
OK and what about the rods,rings, pistons, pins and rod bolts.
Everything has to be weight and matched .
OK and what about the rods,rings, pistons, pins and rod bolts.
Everything has to be weight and matched .
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From: Western Slope, Colorado
400 Vibration Problems
All good points and well taken. Yes the rods, rod bearings, rings, pistons, pins and rod bolts were weighed and 5 grams added for oil weight and then bob weight was calculated by my machinist, I just got back from talking with him, he is confident that he calculated bob weight correctly. He is not sure that the balance operator inputed the parameters correctly. A variable that he is going to control when he recieves his crank balancer. As you can well imagine I would like it to be almost anything but the balance. I am stumped. It is my understanding is that the usual balance operator was not available and that his brother, an experienced operator did the work. The engine is out and unless the vibration can be diagnosed as something other than the crank it will be removed Saturday and in for a balance check Monday. Thank you for the replies guys!
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From: Western Slope, Colorado
400 Vibration Problems
The results of the balance confirmation are in. The back of the crank was out of balance 250 grams (!) and the front of the crank was out 125 grams, Wow! While I am glad the problem has been tracked down, I sure dislike getting more R&R experiance this way. At least the drive train was clean and the bolts were not difficult to remove.
By the way I have received alot of tips reading this forum as I planed and proceded into this rebuild and would like to say thanks for all of the time you folks put into your research and responses! I should be rolling by next week.
By the way I have received alot of tips reading this forum as I planed and proceded into this rebuild and would like to say thanks for all of the time you folks put into your research and responses! I should be rolling by next week.
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400 Vibration Problems
If the vibration goes away with more rpm, the problem isn't in the dynamic balance of the reciprocating assembly. If there is any imbalance it increases with rpm ( it doesn't just go away ).
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From: Western Slope, Colorado
400 Vibration Problems
The vibration problem came in at about 1100 RPM and starts to smooth out at 1400 RPM, started to smooth out, not totally eliminated. After rebalance and reinstallation of the engine it performs awesome. I went four wheeling over four 12,000 passes is S.W. Colorado last weekend and it did not miss a beat.
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