I have a 86 f150 with a 351w 4V HO. I recently rebuilt the engine, being very careful. After rebuilding the engine ran well for awhile, but the first time I drove it, the cam shaft ate the cast iron distributor gear! When I rebuilt the engine I replaced the stock cam with a mild cam from PAW and replaced the cam thrust plate. When it ate the first drive gear I bought a new distributor and tried again with the same result. Next I disassembled the front of the engine and and inspected my work. There I discovered that the tab on the fuel pump eccentric had been bent by the cam shaft dowl pin and the the tab had actually scored the dowel pin end! I got PAW to replace the cam and lifters. It turned out that the cam was supposed to come with a long and short pin. My first cam only came with one pin. The replacement cam came with 2 pins, one long and one short. I bought a new fuel pump eccentric and reassembled the whole front of the engine carefully. It ran well, but today while doing some last minute adjustments before getting a smog inspection the engine just quit! I pulled the distributor again and the distribtor drive gear is gone again and this time the distributor is locked up! ( I think it bent the shaft this time!) Does anyone have any advice on what I am doing wrong!!!!
Dave

 

[updated:LAST EDITED ON 29-Dec-01 AT 06:45 AM (EST)]6;30 a.m. sat 12-29-01
Just a thought,last couple week's somebody had a simular problem, and the theroy of hi volum oil pump combined w,close bearing tloerance was causing extra load on gear,tang twistoff failures etc.
Of course this would not account for pin lgth not correct. I have done a few rebuild's but never had these problems. Interesting.
caddy chuck:-X12

 

I tried to reply yesterday but was unable to. The high volume oil pump thing was my first thought too. Did you install a high volume pump? Do you know how much oil pressure your engine is producing?
DannyP

 

I am currently rebuilding my 351W and was told time and time again that a high volume pump just isn't worth the hassle. This was also my first thought. When you started talking about the pin, I thought that maybe a cam bearing might have been installed incorectly. Just a couple of thoughts.

Hope this helps!!

 

[updated:LAST EDITED ON 05-Jan-02 AT 10:56 PM (EST)]OK here goes. Roller cam's and non roller cam's use a different distibutor gear. Find out what type of cam you have and buy the correct distibutor gear. Otherwise you will keep eating the gear off of your dustibutor. I found out the hard way too.

 

I had the same "first thought" as airharley. If you are running a roller cam, you need to use a bronze distributer gear.

"Don't Laugh At This Truck Mister, Your Daughter Might Be In Here!!"
'78 F250 4x4/302/NP435/NP205
lifted/"35 mudders
'78 F100 2wd/360/C-6/"9 inch
4bbl int+carb

 

The need for a bronze distributor gear is if your cam
is cast or steel. If it is cast you use a steel gear and
if it is a steel cam it requires a bronze gear.
I have a 302 which has a Comp cam part # 35-518-8 grind # xe274hr-12
installed with an MSD distributor and steel gear and no problems. This is a 351W cam.
The use of a hi volume oil pump should be planed for when you
set bearing clearance and you should use a light oil at start up
to lower the stress on cam and distributor gears. Roller cams
need no lobe beak-in, but do need gear break-in.
I have a hi volume oil pump which gives me 35psi at idel (800rpm) and
70psi above 2500rpm. I Think you might need to see what material
your cam is and if you need a bronze gear for it. Also if you have
a bent distributor shaft check to see if it was bent because of the
cam and distributor gear miss match or if the cam moved. I don't
think your cam moved forward to bend the shaft.
Just my take on it.
Ken