I just finished building a brand new 460 from Ford for my motorhome, added a mild Comp Cam w/ lifts, rocks, etc. This is 1989/90 TBI. I took it for a 50 mile test drive and shear'd 4 teeth on the distributor gear... had to get a tow. What the heck?

I bought a new aftermarket rebuilt distributor and plan to stick it in. Comp Cam claims the stock distributor gears should work just fine with this cam.

I don't want to shear another or get another tow.

Any ideas why this happened? What next?

 

If it is a flat tappet cam it should work with stock dist gears, it's only on roller cams that you need a different dist gear. Usually when you have a problem with something binding you shear the pin for the gear so this sounds like either a misalignment problem, or the gear on the cam is cut wrong or possibly someting got into the engine and between the 2 gears. If it was me, and I know this is a pain in the tail but I would pull the front cover when I reinstalled the new dist and check the alignment of the cam, and dist gears. You might also want to check the cam gear visually by pulling the cam part way out at least make sure it's not damaged in anyway, and compare it to the original cam to make sure the teeth are the same just incase comp screwed up and cut the wrong gear into the cam.

 

Take a peek down the distributor hole and check the camshaft gear. Add a little lube to the dist gear and drop it in. Run it a while! Hope for the best! Sometimes stuff happens for no aparent reason?

 

Thanks for the feedback. I coated the dist gear and dropped it in for matting. The gears seem to be matting just fine. I set the timing and drove around the block a couple of times... seems to run fine. I will continue to test for another 50 miles or so and then pull the dist to see how the wear is going. I sure hope the gears are getting oiled.

I will continue to review ideas and feedback.

 

this happened to me also never did find anything wrong got almost 5000 miles on it now and never another incident,by the way the only oil that gets to those gears is from the slinger and possably some drain back

 

The oil slinger doesn't provide any oil to the dist gears basically all it does is keep oil off the front main seal so that it doesn't get to much up there and leak (it's not truly an oil slinger at all) The dist gear gets it's oil from what comes out the front cam bearing and comes down from the lifters and splash off the crankshaft. there is a modification you can do for dist gear oiling you can do, click HERE for directions.

 

Wow... I wished I knew this when I had the front off. I plan to take a test drive on Friday or Saturday... I will pull the dizzy to inspect following.

thanks

 

Back to the drawing board... my cam chewed up another new dizzy gear. I don't know what to do now. I guess I will get back on the phone with Comp Cam and see if they can ensure they sent me the right cam. I drove it about 75 miles... atleast I didn't require another tow.

I really like the mod on this thread to get more oil on the dizzy gear... however, I really think there is something else wrong.

Also, the motorhome never ran good... horrible performance.... although appears to be in time.

Any other suggestions?

 

I'd put a different cam in it. There are only 2 pieces to this puzzle.

 

I agree with Mark. I would try another distributor first. Maybe a used unit with a used gear. After that its camshaft time. Sorry, wish I could be more positive,

 

I have decided to tear it back down rather than try another dizzy.

I downloaded Comp Cam's installation manual but would like to know if someone has details about the Ford 460 installation. Does anyone know where I can get complete details to installing a 'flat tappet' cam in a Ford 460 TBI motor?

I have two problems I am trying to fix...
1.) dizzy gear chewing
2.) horrible performance... possibly cam timing

I think I know how to do this, but obviously maybe not.

I also plan on drilling the block to get better oiling on the dizzy gear.

 

When you get to the camshaft sprocket pull on it to see if you have a lot of end play. There may be a problem with the camshaft retainer. The reason I suggested another try with a different (used) distributor is that there may be a problem with the location of the distributor gear's placement on the distributor shaft. Drilling an oil gallery for the distributor gear on a street rig is way overkill IMHO! All the oil in the world will not resolve a gear mesh problem. I think it is unlikley that the gear on the camshaft is cut incorrectly. I guess it is possible but more likley an error occured on the distributor gear installation or camshaft installation/retainer. Just my opinion. I sure hope you find out what the problem is, I am really curious.

 

When you get to the camshaft sprocket pull on it to see if you have a lot of end play. There may be a problem with the camshaft retainer. The reason I suggested another try with a different (used) distributor is that there may be a problem with the location of the distributor gear's placement on the distributor shaft. Drilling an oil gallery for the distributor gear on a street rig is way overkill IMHO! All the oil in the world will not resolve a gear mesh problem. I think it is unlikely that the gear on the camshaft is cut incorrectly. I guess it is possible but more likely an error occurred on the distributor gear installation or camshaft installation/retainer. Just my opinion. I sure hope you find out what the problem is, I am really curious.

 

I first used the original dizzy, it only had 39k on it and inspected great. Before I put the new one in... I mic'd all measurements on both dizzy's, they were exactly the same. I also checked the wear pattern on the gears... perfect match with my eyes.

I am considering endplay, but not sure I know how to address the problem if I have too much endplay. I suspect I will see wear on the retainer plates if endplay is a problem. I will probably have to buy some expensive tool to measure it

I also think I may have a cam shaft timing problem to address, so I will need to be very sure how to set this before I go back together with it. Ignition timing appears to be set, it idles great but peforms absolutely horrible.

I have just a few days turnaround before I cancel my week trip with the family in this beast... it really sucks for this damn thing to ruin our last year vacation, spend $1000s and invest 80hrs to learn I need to pull it down again at the last minute.

 

Timing chain sprockets are marked. Installation involves lining up the marks, double checking and reassembly. The crank gear may have three slots in it, use the center one for straight up camshaft timing. When the timing chain cover is off, install the distributor and see how it mates with the camshaft gear. Do this before you install the lifters so you can turn the camshaft by hand using the sprocket. If you have excessive end play (any end play) you will be able to feel that by hand, no expensive tools needed.