Engine shake

[Smedley]

************Problem solved. I bought an 87 reman 302 years ago and drove the Bronco, when I started the resto I saw that I had and 87 block, so I bought 50 oz. flywheel and harmonic balancer, as anything past 81 would need that. I never looked at the old stuff I took off. Well I had an 87 block with earlier internals. I just installed a 28oz. flywheel and harmonic balancer and the Bronco runs great.******* See post 26 for possible solution. Working thru an issue. 1987 302. New 50 oz harmonic balancer and fly wheel. Running the FiTech Go Street 400hp, which seems to be running as it should. New spark plugs, wires, and coil. Plugs all looked good, although a little lean. I've it set at about 10 degrees of timing. Motor mounts are brand new and tight.
I have a pretty good engine shake. I can see and feel it at idle. It seems to smooth out a bit at higher rpms. But really kicks in when dropping back down to idle. Could the harmonic balancer have "slipped"? What else could it be? I have only had it running for month or so, but it ran much better when it first started.

This the balancer I have. https://www.tomsbroncoparts.com/product/harmonic-balancer-50oz-late-5.0l-302-3-or-4-bolt-new

Thanks,
Will

 

[Smedley]

Clutch is not engaged. It's in neutral.

 

[Smedley]

Everything is new, except for the long block. Clutch, pressure plate, flywheel, harmonic balancer. Not that a new part couldn't fail, but just FYI.

 

[blubuckaroo]

With the clutch engaged, (pedal released) both the pressure plate and disc are suspect.
With the clutch disengaged, (pedal depressed) just the pressure plate is suspect.
Whether it's in gear or not makes no difference.

It could have loose pressure plate parts.
Also, you should identify the crank, flywheel, and balancer. Check part numbers to make sure there wasn't a boo-boo at the parts warehouse.

 

[DirtDonk]

In my experience with the wrong imbalance, the idle will be decent but as soon as you reach 1000 rpm or more, it shakes worse and worse as the rpm increases.
Different from what you're experiencing, but that was with the wrong flywheel. Not sure if the symptoms would be exactly the same with the incorrect damper or not. I would think so, to a lesser extent perhaps (or perhaps not) but I would think it would act somewhat the same at least.

Paul

 

[DirtDonk]

Have you tried to see if any one cylinder is acting up more than the others? With all this new stuff, it could be as simple as a bad plug or wire or distributor cap.

Or... the incorrect firing order. Any chance you changed the cam?
Are you using the correct firing order for that '87?
Is anything in the engine different now, or did it start after doing some one thing (like adding EFI) or another?

Paul

 

[Smedley]

The engine ran well when parked 7 years ago. With the resto, the engine is about the only thing I have done much to. New 50 0z balancer and fly wheel. Both appropriate for an 87 302. Firing order is 15426378, which is correct. New clutch and pressure plate. When I first got it started about a month ago, it seemed to run better. But I might have just been excited that it was running. However, in the last 2 weeks it is running worse. Nothing has changed since I first got it started a month ago. I replaced the wires, cap, and coil. No change.
The shake seems worse around 1000 rpm. It does not go away at higher rpms, just does not seem as severe.
I am running a FiTech 400hp with FCC2. I have pulled logfiles on that and it seems to be running as it should.

Before I start pulling things off, I figured I ask here to see if I'm missing something.

 

[DirtDonk]

A couple of things.
Having sat for so long, I wonder if one or more cylinder walls got a little rust on them and are creating some mischief until they wear back down (hopefully) to a more smooth finish again.

And second, did you put an old cam in yours? Or is it a Speed Density engine out of a Cougar or something? Were there even any of those left by '87?
Reason I ask is because that's the wrong firing order for an '87 mass-air engine. They should (I think) all have been 13726548 by then.
At least that's my "assumption" based on my skimpy memory about such things. I might have the timeline wrong, but having worked with mostly the Mustang and Explorer engines, the newer "351 and HO" firing order has been the only one I've messed with.

But to my mind, it's absolutely worth checking into. Let's get some expert opinions on what an '87 5.0 should have with regard to a firing order.
But let us know what it came out of originally, if that makes a difference. And what computer you're using to fire it these days.

Paul

 

[Smedley]

A couple of things.
Having sat for so long, I wonder if one or more cylinder walls got a little rust on them and are creating some mischief until they wear back down (hopefully) to a more smooth finish again.

And second, did you put an old cam in yours? Or is it a Speed Density engine out of a Cougar or something? Were there even any of those left by '87?
Reason I ask is because that's the wrong firing order for an '87 mass-air engine. They should (I think) all have been 13726548 by then.
At least that's my "assumption" based on my skimpy memory about such things. I might have the timeline wrong, but having worked with mostly the Mustang and Explorer engines, the newer "351 and HO" firing order has been the only one I've messed with.

But to my mind, it's absolutely worth checking into. Let's get some expert opinions on what an '87 5.0 should have with regard to a firing order.
But let us know what it came out of originally, if that makes a difference. And what computer you're using to fire it these days.

Paul

Paul,

The engine was a freshly reman'd one I got back in ~2004. Nothing was done to it, in regards to upgrades. It had about 15-20k miles on it when I started the rebuild. When I first got it started, it had a blown head gasket on the pside. I fixed that and now getting ~120 psi on a compression test on all cylinders. I intend on swapping out the spark plugs today to take one more possibility of the list.

Thanks for all of the input.

Will

 

[DirtDonk]

While the plugs are out might as well verify the firing order at the same time.
Turn the engine over by hand and after you feel compression on your finger over plug hole #1, run over to #3 (or #5 if you prefer first) and see if it's the next one that comes up in the rotation (90° of the crank) and then you'll know for sure.

Sounds like maybe they rebuilt it with the more common (back then) old 302 cam, instead of the later HO/351 cam.
But if not, now's a good time to find out!

Paul

 

[Jfryjfry]

Sounds like a miss. While it is idling rough, unplug each cylinder’s plug wire and see if it changes anything. I’d use a pair of insulated pliers to do this. Or, if you have headers, feel or use an infrared temp gun to see if one cylinder (or more) is cooler than the others.

It could be an imbalance but I’d say unlikely. Verify that the 0* timing mark still correlates with tdc of your number one piston to see if the balancer slipped.

 

[Smedley]

Sounds like a miss. While it is idling rough, unplug each cylinder’s plug wire and see if it changes anything. I’d use a pair of insulated pliers to do this. Or, if you have headers, feel or use an infrared temp gun to see if one cylinder (or more) is cooler than the others.

It could be an imbalance but I’d say unlikely. Verify that the 0* timing mark still correlates with tdc of your number one piston to see if the balancer slipped.

I just replace the plugs. I wish I had read this prior to pulling a wire with the vehicle running. That woke me up. All wires, plugs, coil and cap all replaced. I also took the belts off of the alternator and power steering, no difference.

I verified TDC on cylinder one and my harmonic balancer, it's on 0 at TDC (or as close as I can measure doing it myself).

I am searching for a vacuum leak now.

 

[Rustytruck]

Are you getting any popping or back fire?

 

[Rustytruck]

Put the engine on top dead center. Remove the cap and mark where the rotor is pointing. Put the cap back on and check that your mark is actually pointing to number 1 plug wire.

 

[Smedley]

Put the engine on top dead center. Remove the cap and mark where the rotor is pointing. Put the cap back on and check that your mark is actually pointing to number 1 plug wire.

Just went out and did this. It is pointing at 1 with the timing mark on 0. and I confirmed 0 to be on TDC earlier.

 

[Smedley]

Are you getting any popping or back fire?

No popping or backfire.

 

[Lunar-tic]

My new engine did something similar, it was a mismatched balancer and fly wheel. Human error during the build. Once corrected it was fine, but unfortunately, the error was the fly wheel so that created some additional work for me.

 

[Jfryjfry]

Use a thermometer gun to tread the temps of each cylinder when you cold start it. Headers are the easiest to isolate and manifolds, because they are connected, are more difficult. But if you start with them cold you can still get an idea if you move fast to see if a hole is dead.

Although if you removed each plug wire one at a time while idling and every one of them caused a stumble until plugged back in then you know each cylinder is firing.

 

[69_Sport]

The engine ran well when parked 7 years ago. With the resto, the engine is about the only thing I have done much to. New 50 0z balancer and fly wheel. Both appropriate for an 87 302. Firing order is 15426378, which is correct. New clutch and pressure plate. When I first got it started about a month ago, it seemed to run better. But I might have just been excited that it was running. However, in the last 2 weeks it is running worse. Nothing has changed since I first got it started a month ago. I replaced the wires, cap, and coil. No change.
The shake seems worse around 1000 rpm. It does not go away at higher rpms, just does not seem as severe.
I am running a FiTech 400hp with FCC2. I have pulled logfiles on that and it seems to be running as it should.

Before I start pulling things off, I figured I ask here to see if I'm missing something.

An '87 302 HO should have a 1-3-7-2-6-5-4-8 firing order.

 

[Smedley]

An '87 302 HO should have a 1-3-7-2-6-5-4-8 firing order.

It's not an HO 302.