SBF Distributor Gear Stripped WTF

So ive searched and searched and cant figure out why this happened. Just built my bored over 302 with 289 with a melling 68 oil pump. Driving along last night on I-5 and all of a sudden my car starts back firing and dies. We pulled the distributor after seeing that its not spinning and see that and gear on the distributor is ALL FUCKED UP.

 

Oil pump locked up? Or foreign object dropped down in distributor such as that screw you couldn't find when you were changing the points.

 

shouldn't be locked up completely new motor and certain i didn't drop anything

 

Are you using a roler cam. ? How does your cam gear look?

 

right was it the correct gear for the cam ? some require bronze some require steel , i have a 96 crate motor with roller cam , specifies no bronze gear on distributor ,

 

Don't stop there pull the oil pump rod out and make sure it's not twisted. If it is pull the pan and look at the pump. The bronze gear is the first place to start though as that's a pretty common way to ruin both the cam cut and the dizzy gear. Sorry for your troubles, that's a bummer.

Good luck,

Tim

 

Not a roller cam. Will look at the cam gear tonight

 

Subscribed. I see an inspection of the bottom end at minimum. I would pull the pan with the engine upright as not to let all that metal flaked oil flow back into the cylinders anymore that what has happened already.

 

Does the distributor turn easy? The distributor could possibly start siezing when it gets hot, but I'd still drop the oil pan anyways.

 

did pin shear? looks like gear is to far up shaft, may have walked up and disingaged from cam, sorry about bad luck, flat cam takes factory steel gear, not hardened like roller, good hunting..

 

ALL 90's tahoes/chevys do this because of a soft distributor gear.. i have had 2 do it and hear from it from everyone else.. i know youre case is different and a completely diff make but this is def the place to get it diagnosed!!

 

well the last motor that distributor was in. something seized the oil pump and it snapped the oil pump rod. so we think when that happened with the old motor it may have damaged the distributor drive gear.

 

Do some research on corral.net for high volume oil pumps and sheared bronze distributor gears. Apparently, the oil pump can put an added stress on the gear. Most SBF guys say you don't need a high volume pump unless it's a race motor.

 

I stripped a gear on a big block chevy one time, but it was only like 2-3 teeth. not the hole gear. looks like it wasn't seated right on the cam. I would look in the pan and check the pump too. and hope the cam isn't messed up.

 

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GEAR WEAR ON FORD DISTRIBUTORS!
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</td></tr><tr><td class="upperborderline" colspan="2" align="left">How to avoid wearing out the teeth! </td></tr><tr><td colspan="2" align="left">

[FONT=tahoma,arial,helvetica,sans-serif]Excessive distributor gear wear can be a problem with Ford engines. Most of the time, the problem is a result from the use of a high volume oil pump. High volume oil pumps put a lot of stress on the distributor and cam gears. A high volume oil pump is not necessary on a street driven engine that turns no more than 7000 rpm. Only extreme racing engines require the high volume pump. Should you use this type of oil pump, the following precautions will save your distributor gear from early destruction.

(1) Drill a .030" hole in the lifter/oil galley plug behind the distributor. This will allow additional lubrication on the distributor and cam gears. This will not lower oil pressure enough to hurt the engine.

(2) Ford oil pump mounting brackets have elongated holes. Due to this, the distributor shaft and oil pump shaft should be aligned so that the distributor turns freely before tightening the mounting bracket bolts. Failure to do this will cause a binding situation, thus damaging the gear.

(3) Stock Ford hex oil pump drive shafts are know to vary in length which could cause a bottoming or binding situation.

(4) Brass distributor gears can be used to avoid damaging the cam gear. Brass gears are softer and can wear out quicker than the cast gear, but will not cause damage to the cam gear. If using a brass gear, check it occasionally for wear.

(5) Use a zinc additive oil. Royal Purple, Brad Penn and Rotella have zinc in their additive package. This helps avoid wear on all engine parts. Use it.
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[FONT=tahoma,arial,helvetica,sans-serif]http://www.flowtechinduction.com/technical.htm
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I drill a .030" dia hole in a oil passage as shown in the picture below to lubricate, and help cool the gear.

I don't use a high volume, or high pressure oil pump on race engines either, all they do is rob horsepower, it's not needed on Ford Windsor engines.

 

FWIW I see Crane Cams has a universal steel distributor gear that can be use with both cast-hydraulic and solid-roller cams. So you don't need a bronze gear with a roller cam.

(This info from Car Craft, March 2012, page 12)

 

I had a 351 Cleveland with a MSD Distributor. I took out two distributor gears and one cam until I finally solved the problem, after numerous changes, etc.

MSD did not place a bearing in the bottom of their distributors, as OEM distributors and Mallory distributors have the bearing in the bottom of the housing. Without the bearing, the shaft of the distributor would walk on the cam gear, "sharpening" the softer distributor gear.

 

High volume pumps take more power to turn, especially with cold oil. Ford oil pump screens have a hole in the center that can allow things into the oil pump that shouldn't be in there. It could be a piece of gasket or excess silicone. The pump locks up and if the shaft doesn't twist off, the gear will strip and may ruin the camshaft gear as well.

 

I haven't had a gear go like that, but I have had those symptoms on a 351W - twice. Both times, the roll pin on the gear sheared.

And if the last engine it was in seized the pump, it may have sheared or partially sheared the roll pin already.

 

I'd be looking carefully at that roll pin through the gear, if it had previous trauma

 

i still had 50 lbs of oil pressure

 

its just a plain melling 68 oil pump not the high volume one

 

I have seen where the intake was not at the correct height after the combination of decked block and heads. Check for proper higth with a set of dial calipers. I also check the contact pattern with rear end gear gear compound.
Seeing is believing.

 

Ford pump drive shaft will usually snap, before the gear fails... To go on the side of caution, I'd go for a teardown... Too much $$, if even one speck is missed....

4TTRUK

 

If your distributor goes through the intake on your SBF, you have some serious other issues to contend with first. TR

 

Seriously!!

 

And I've seen the roll pin in the distributor gear fail before anything else too...twice.

 

Not in a small block Ford you haven't!

I think this is the tale of the failure. My bet is the gear was already a little chewed up and you didn't notice it, and in you picture it looks like the roll pin might just be gone.
I have seen this happen before in small block Fords and since when the pin shears the motor quits it doesn't do any damage - slide in a new roll pan, off down the road she goes with no issues

 

After going back and looking at it it does look like the distributor gear wore down to the point that the teeth finally gave out. I'd be taking a serious look at the cam gear to make sure that it isn't worn down or damaged.