Bad Cam and/or lifters ?


Boingo

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SO, I'll give all the details. You decide what is relevant.

My guess is a bad cam lobes and/or lifters.

1986 Ford Ranger 2.9 xlt auto 2wd.

The motor was rebuilt by a very reliable guy we know. It was a family member's truck, then i got it years later. It sat in this truck for 5 years without ever being attempted to run. Lots of circumstances why that happened and not really relevant. It was completely installed and sealed with typical external components.

I had a hard time getting it to fire up. It ran off balance so I thought maybe the wires were 180 off. It took many time turning it over at first to fire.

Now, everything is new, map, injectors, distributor electronics, plugs wires & coil, egr, IAC, have tried two ECMs, grounds are good, fuel regulator, pump/float in tank, new tank...other was rusty, fuel pump on rail, new filters, ....you get the point.

Truck fires right up and runs now. Runs slightly rough like a mis, rev up still slight mis
Vacuum at 17, drops at rev then levels back up and stays solid. Figure no leaks and not a plugged cat
Compression all within a couple numbers around 175
All plugs getting spark
Fuel pressure good and level
Added oil, temp gauge both showing good

Now the rub, In the beginning I found that two push rods had bent on the 4 & 5 intake valves. Had to tap both since the valves were stuck. Not much of a tap. Guess sitting was the issue.
Replaced the push rods.

My best guess is due to the hard starting at the beginning and not getting it revved immediating to 2k+ to break in the cam and get it lubed did damage. Not to mention the bent rods
My guess is the corresponding lifters and lobes were damaged and that is my rough idle
Now i need to replace the cam & lifters and go for the correct break in procedure.

Sorry about the length. I would appreciate any thoughts or confirmation replacing the cam/lifters in most likely the next step.

This is an extra vehicle and why I'm not totally freaking out about all this, annoying as it is...lol
 


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RonD

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If you had a bad lobe or lifter there would be a loud tap

The bent pushrods have interest, so you found those valves were stuck open?
2.9l is a non-interference engine, so hard to bend pushrods

A hydraulic lifter can fail in a way that locks it in a high position, very very rare, and for two to do that, well not going to happen, but could bend a pushrod, but wouldn't explain the stuck open valves

You should pull the valve covers and rotate engine, then you will have more info

"Break in" wouldn't be the start of the issue, I would leave that out of the diagnoses
 

Boingo

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The two intake valves were stuck closed.
I'm thinking the seats stuck to head of the valves from the build and sitting for so long. So when the valves did not move the rods bent.

It might have damaged the lifters since the compressed enough to bend the rods. I was only thinking possible cam damage due to lack of lube you get by revving it high enough to get good oil flow to them on a new set up at start.

Don't get me wrong, i could be completely off. I do appreciate any ideas and other ideas.

It starts and runs fine except the obvious stumble
 

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And no noise?
no tick, tick, tick?

Vacuum is a bit low for 3,000ft elevation and lower, especially if your compression is actually 175psi, 2.9l runs 9.0:1 ratio so expected is 150-160psi, but that could just be gauge error
Vacuum of 18-21 is expected on recent rebuild

Did you set spark timing with SPOUT disconnected
And what did you set it at, 10deg BTDC or 12deg BTDC?
 

Boingo

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Yes, I set the timing at 10deg BTDC with the spout removed.

My elevation is 860, so yes below 3k


It's definitely not 18-21 vacuum, although 17 is just below and maybe the new gauge is off some. I hooked it up at the extra offshoot where the brake booster is plugged into. As far as i can tell the booster is fine, but maybe i should disconnect and plug it to see if there is a change.

There is lifter tap
 

19Walt93

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If it sat long enough for the valves to stick in the guides I'd want to tear it completely down and look things over. I suspect you're going to find rust where you don't want it. Letting a newly built engine sit without running it is a recipe for disaster.
 

Boingo

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I'm finding that out...lol
 

Boingo

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If it sat long enough for the valves to stick in the guides I'd want to tear it completely down and look things over. I suspect you're going to find rust where you don't want it. Letting a newly built engine sit without running it is a recipe for disaster.
Valve covers off and more inspection.

Turn out there is some rust on the original pushrods, not much on the springs, rockers. Thinking maybe the valve head sides had more rust than i can see with the heads still attached. Valve guides and seats could have issues.

I want to do it right and once over being cheap...lol

I doubt this effected the lower end but it seems the heads and possibly the cam are an issue with random rust.

What are the thoughts on having the heads just redone, since there should be no rust at all. Also,while it is apart just throw a cam & lifters in.
 

19Walt93

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I'd be concerned about rust in the block's oil passages which would only be cured by having a machine shop boil the block. The valve stems are more likely to have rusted to the guides than the faces rusting to the seats. If you're thinking of a performance cam do some research first because speed density injection isn't friendly to air flow changes. The tech line at a company like Comp could advise you about what should work. As a rule of thumb when picking a cam, buy the next one smaller than what you think you want. Once you get it back together get it running soon and run it at least 20-30 minutes, shut it off and change the oil and filter. Make sure to use oil with a zinc additive like racing oil or add ZDDP to your oil.
 


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