JMcc

1928 Pontiac rotor doesn't turn

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I have a 1928 Pontiac that I got from a friend. It had been sitting for at least 10 years. Got the fuel tank and carb rebuilt and got about 100 miles for fun on it.  As I was putting it away for the winter it was idling away and just stopped running. After a few minutes of investigation I found the rotor was not turning in the distributor. I have pulled the distributor and was surprised that there wasn't a gear on the shaft, nor was there a place for a gear. The shaft appears to run off of a spade at the end of the shaft.  The manual says the distributor shaft runs off the camshaft via a gear and down to run oil pump. Any help wound be appreciated!

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Pull the pan first,not sure if we still have it ,but will check the length of the dis.Sounds like something locked up,oil pump,broke the shaft.At this point,you committed on pullng the pan

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Most likely causes.

1). Check and see if the distributor has  come out. the pinch bolt that secures it to the base plate holding it to the motor may have worked loose.

2). The most likely cause is a stripped fibre cam gear or broken timing chain. A lot of the old cars had a fibre gear on the camshaft, these were meant to be changed about every 50000 miles. Ask Model A Ford owners, it is quite common for the gear to suddenly lose a few teeth and the motor stops as the cam stops turning.

3). It is possible the oilpump has come loose in the block and dropped down, so it wont drive the distributor.

 My money would be on 2). as your most likely culprit.

Viv.

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He has no gear,correct me if I am wrong,As far as a fiber gear.i doubt that,,Not arguing but I thought the fiber gears started in the 60s

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Thanks for all the Ideas. I think I'll pull the pan and the oil pump. If the timing chain and or gears are bad I'll need to pull the pan anyway to get the broken pieces out. I agree with Old Car Fan that the fiber gears were {as far as I know} were started in the 60s. I'll continue to update the findings.

 

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Fiber gears were around LONG before the 60s. I think you just lost one.

 

The trouble is, a camshaft is constantly rocking back and forth with relation to the crankshaft, with a lot of torque, due to the action of the valvesprings against the cam followers and lobes. It really is a violent motion, and there has to be some backlash so the gears do not tear themselves up. The large gear rocks back and forth against the little one and makes a knocking noise. With minor wear, it gets really loud.

 

FIber is a "dead" sounding material, and is used because it makes less noise. It has been around since at least the 20s and probably longer. Anywhere there is a gear driven cam in a passenger car, you will probably find fiber. They still have to deal with all that banging around, even though they do not "ring" like a metal gear. The life of a fiber gear is rather short, and the failure sudden.

 

Later Pontiac flathead engines use a chain and sprockets. I am guessing yours uses gears. @Tinindian will probably know what is in there.

Edited by Bloo (see edit history)

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we have a 28 Knight that has fiber gears .on the generater,The cam is not rocking back and  forth,it is a shaft in cam bearings,the cam is as strait as an arrow It is not violent ,peace of art

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The distributor drive gear is on the shaft just below the housing.  It is pinned to the shaft.  The "spade" at the end of the shaft is below the gear and it drives an intermediate gear that drives the oil pump.  I hope you removed the retainer before pulling the distributor?  (the bolt and lock nut between cylinders 3 and 4 just under the water jacket on the left side.)

019.JPG

020.JPG

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The Chrysler 4 cyl cars of 1927/8 had fibre cam gears, so did Ford model A in 1927. It would be interesting to know who was first to use a fibre gear.

Viv.

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Why do people keep talking about "Fiber Gears".  Pontiac "split head" engines 1926-1932 and their successor 6 and 8 cylinder engines up to 1954  DID NOT HAVE FIBER GEARS.  They used two steel gears with a roller chain.

Edited by Tinindian (see edit history)

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If this is a Delco distributor, there are some that you change the timing by tightening a screw in the center with the rotor removed.  If this screw is loose, the rotor would just sit there and do nothing. 

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There is nothing like that on these distributors.  If he has pulled the distributor from the block and it doesn't look like the picture I posted he has broken something. Most likely the gear sheared off (thankfully that stops the engine so lack of oil doesn't do any damage)  this allowed him to pull the distributor housing and the shaft leaving the lower housing (which olds the unit in place and provides a bushing for the lower end of the distributor shaft and the upper end of the intermediate shaft.  I believe the pan must come off.  Then you need a tubing wrench to remove the oil tube assembly from the main beatings, the oil pump and the block.  When you undo the oil pump the intermediate shaft will come down with it and if the gear has sheared off it should fall down as well.  You probably will need to pull the lower bushing up and out the top.

This would be a good time to clean the sediment out of the oil pan (from under the screen). Good time to open the pump anc check for wear. Make sure you use a pinch and mark the oil pump cover so you get it on the right way (otherwise it will not pump).  There is no priming needed when you reassemble as the pump sits submerged in the oil.

You might also consider moving this thread down below under "Pontiac Oakland".  Some Pontiac specialists might not see it under this "Wanted" heading.     http://forums.aaca.org/forum/47-pontiac-oakland/

Edited by Tinindian (see edit history)

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Well i finally got to get back to the Pontiac. I pulled the pan and oil pump  but the pump shaft has stayed attached to the intermediate gear. Not to the distributor as in the picture that Tinindian so nicely attached. So now, how do I get the gear out of the block. The bushing appears to have stayed in the block.  Do I try to force the pump shaft out of the gear. I pulled the center main bearing down but that just gave me a slightly better view of the problem. Will I have to pull the cam shaft to get to the gear. I'll attach pictures this weekend.

 I would like to move this to Pontiac/Oakland forum but I don't know how!!

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Moderator might see your comment and move it. But to be sure click on "Report post" which doesn't appear until you hover your cursor in the post itself, and it's in the top right corner of each post.

Edited by Ozstatman (see edit history)

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Well I got it apart. The intermediate gear is welded to the oil pump shaft. I was able to push the lower bushing from the bottom thru a hole in the casting. I was then able to pull the gear/shaft up thru the distributor hole with a magnet. The patterning on the intermediate gear indicates that it had not been running true in the camshaft and striped the intermediate gear. Looks like I'm going to need a Intermediate gear and camshaft!

Dist 1.JPG

dist 2.JPG

Dist 3.JPG

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Looks like the worst kind of a shade tree farmer fix.

No offence intended to shade tree mechanics or farmers just paraphrasing  two old sayings.:lol:

Good Luck.

Edited by Tinindian (see edit history)
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Because of what could have been changed since your car was new, which of the engines below do you have?  If yours is the one with the oil filler forward I have a camshaft that would fit I think.  The parts book says 26-28 are the same and 29-30 are the same.  I think the only difference is the lift and duration.  I think the cam from any split head will fit any split head.  Mine would need to be reground as it has 500,000 miles on it and the lift on the valves is certainly not like my reground one.  If it would work for you it will cost you shipping from V8P 3Z3.

26-1.jpg

28-1.jpg

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1st of all do not panic most likely either the roll pin broke or the camshaft broke the gear on the shaft these are designed to do this to prevent major damage you will have to remove the oil pan to access the oil pump you will have to remove the camshaft  and lifters to check for gear teeth damage you have to remove the radiator then remove the harmonic balance unbolt the front cover then remove the the bolts that hold the camshaft in the cam should pull right out check for broken gear teeth if fine prepare for putting back in use prelude on journals and lobes look for the gear in the oil pan or whats left make sure you remove everything if it is destroyed no problem just replace the gear and roll pin for dist. make sure when you reinstall the mushroom liter use prelude on them remember these are direct drive for oil pump not changed in over 50 years of engineering still the same then you have to retime the engine since the timing chain and crank are way out sinc no problem there are timing dots on the cam gear and crank gear line up both dots crank on top camshaft on bottom then put chain on reseat the cover then reinstall then install the harmonic balancer after that reinstall the oil pan reinstall the side covers and the breather tube then to retime the distributor remember the engine timing is on the heads below he distributor the really easy way is start at 0 deg then use a timing light and with ignition on turn the distrutor until the light flashes not sure off hand on 28 what it is have to look in my service book to see just try until it runs good remember do not use modern oil for these engine's ar not designed to run on them they used parifine based motor oil and use some lead additive for fuel unless someone has replace the valve seats with hardened ones or just use some octane booster added to fuel remember regular in 1929 was 100 octane unleaded fuel is not good for these engines because low octane

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