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351C Engine Vibration > 2500 RPM


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Thanks Gents, I will pull the fuel pump and see if I can feel the slack in the timing chain.

 

For now I want to get the distributor back in and running before I work on the timing chain. I was able to pull out distributor and use an impact driver to break loose the screw that held in the plate. I have cleaned all the components and am ready to put it back together. The shaft seems to be relatively close fit with the bushing with a .002" diametral clearance. The gear has some wear but seems to feel tight when meshing with with the mating gear. See photo and let me know if it looks wrong.

 

Not sure if I should lubricate anything in the distributor and with what as I assemble.

Thanks

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Check out the link below, it covers how the mechanical advance works. The tabs affect the rate of advance, not how much. Bending them out just increases the spring tension which will delay the mechanical to a higher rpm

 

http://www.reincarnation-automotive.com/Duraspark_distributor_recurve_instructions_page-2.html

 

Before you stick your distributor back in, see how much play is in the upper bushing, as was mentioned in another post, if it is loose, you will have problems.

 

Also make sure that the mechanical advance plate is moving freely as they can stick. I'm not sure what to recommend for lube, but it should be something that stays slick at high temps...

 

Also, as was mentioned, if your timing chain is sloppy, having all of the above issues corrected won't matter, the car will still have issues...

Matt

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Maybe it is an optical illusion in the picture but to me the distributor gear looks crooked on the shaft.

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Also, as was mentioned, if your timing chain is sloppy, having all of the above issues corrected won't matter, the car will still have issues...

 

 

Completely agree here, with 14* of slop, I would get a good quality roller timing chain on hand and installed. The stock cam gear had nylon teeth that tend to break and end up in the oil pan. Sometimes they end up in your oil pump, which on a 351C will usually shear the distributor gear roll pin and stop the engine. Worst case is it snaps the oil pump driveshaft and the engine continues to run without oil pressure. If you see any missing teeth from the gear when you remove it, drain your oil and clean out the pan, either through the front of the block or by removing it from the engine.

 

My main thought on your vibration is a worn or broken valve spring. I had one on a truck that would run fine one minute, then be barking and backfiring through the carb the next....

 

 

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Maybe it is an optical illusion in the picture but to me the distributor gear looks crooked on the shaft.

 

I'm with you Mike, if it's an optical illusion it's a good one, it sure looks like it's crooked on the shaft.

Jim

 

M code 71 Mach 1, 351 4V Cleveland, Ram Air (not factory), C6 Trans, 3.5 rear

 

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I have checked the bushing/shaft fits and TIR a little closer. The photo is an illusion. The bushing is .002" larger than the shaft-not much lateral movement. The shaft runout between Vs is less than .0002" -on centers it is .004". The gear has a close fit (.0003" clearance) with the shaft. TIR of the gear - over pins and major diameter measured less than .001". The cam high points were within .002" TIR

 

My guess is this is not the cause of my vibration. I do still to need to work on the mechanical advance though.

 

Next put the distributor back in and run it. Then work on the timing chain.... maybe the valve spring.....Thanks Eric

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  • 2 weeks later...

I have been watching this thread. Similar situation here.

 

I have been getting my car back on the road after sitting for years. After getting it running and tuning it, I noticed the vibration. I noticed it about 2500 rpm and higher. Seemed to smooth out over 4000.

 

Here's what I did...

New harmonic balancer - no fix

New plugs/wires - no fix

New distributor - no fix

All new vacuum lines - no fix

 

Since I had already put in a new flywheel and torque converter after some transmission pump work, I didn't think it was either of those. On a last ditch effort (which I wish was my first), I unbolted the torque converter and pushed it back the 3/8" space that I had.

 

Started the car up and was smooth as butter. Apparently the new converter is out of balance. Now I have to pull the transmission out again :-/

Dave from PA

1972 Mach 1

 

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  • 4 months later...

I purchased a new timing chain set from my local Ford parts store to replace when I get the car out of storage this Spring. I try to use Ford nos when available however the cam sprocket is plastic/nylon covered. Does this look like the right sprocket D0AZ6256A?

image.thumb.jpg.fd46bf61882971bb8096c98460acd664.jpg

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It looks right, but I would not use it. The nylon gets brittle and breaks off and ends up first in the pan, then in the oil pump, then your engine needs a rebuild. A good aftermarket double roller timing chain requires no alteration to the motor and is far more durable. With the engine buttuned up you'll never know the difference and you'll have a better part (at a cheaper price I imagine)

http://www.7173mustangs.com/gallery/1_01_07_15_8_53_18.png

 

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!

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+1, do not use the OEM gear, you never know when it will fail, you just know it will...

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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I have to agree with the other guys here, I would not use those parts. I would use a quality full, two-row roller chain with all steel or iron gears. Summit Racing has many to choose from in the $70 to $100 range...

Matt

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  • 9 months later...

i finally got to work on the timing chain. I think timing was critical on this one (pun intended) . The chain had considerable slack as shown in the photo. It is a a picture of the crank timing gear. No pieces were broken, just worn out. I suggest to all, if you do not know what condition your chain is please check. Thanks for the advice. image.thumb.jpg.03cb1644de5bc51c9dcc5df12642688e.jpg

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