Broken distributor gear on BBC

[DUECE'SDAD]

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Not bronze gear on a hydraulic cam, has been running great and fine for 2 seasons, then all of a sudden cruzin across the lake at about 30 mph the thing stumbles and dies, great oil pressure, and the oil pump isnt locked, but it just lost fire, and so i pull the dist cap and the rotor isnt turning. pull the distributor hoping that the roll pin broke in the gear. Not the case, The gears on the distributor are chewed off, and from what i can see down in the hole the cam gear is x-tra sharp. The distributor gear looks like it was riding high, on the teeth left the mash pattern is only showing riddin on the bottom half of hte gear. What do i need to do ? ? ? Im sure i should put new cam, new gear bronze, pull pan and clean ??, Machine the distributor or intake to allow to ride further in hte hole ?? Im pulling it from the hydro to put in my 57 chevy and im wondering where to start ! !! !

[GofastRacer]

Let's see a pic of the gear, anytime you build a motor or just change intake manifold you need to check for proper distributer location!..

[MESA BALANCING]

I started a post on another marine site with defective cam cores and worn dist gears after some research I found there were around 8000 defective cores that had come into the states and they are very difficult to detect I found one of the things that gives them away was the new cam gear is over .005 out of round but it's going to be hard to detect that now in your set up. Good luck Laz

[MandDPerformance]

Any time we install a distributor or mag. etc. we always check for proper gear engagement. You should be able to mach up install your dist. in the engine withuot a gasket or sealant and bottom it out and leave a gap on the manifold. Measure the gap and add .050 for clearance. This will insure proper pump engagement as well as gear mesh.
The right way to check gear mesh when the engine is out of boat is to remove rear cam plug with cam out and make sure dist.drive gear is in right location.
Either way you do it, do it.

[victorfb]

did i read that right were you say you had great oil preasure but the distributor isnt turning? if the teeth are gone on the distributor gear and not turning the shaft, whats turning the oil pump? not trying to be defensive, just wondering what you meant. because if the distributor isnt turning and your still seeing oil preasure on the guage, you may have a faulty guage or something. would suck to loose oil preasure and not know it. know what i mean?

[Squirtin Thunder]

The Gen VI or Mark VI BBC are notorious for chewed distributor gears. One is they don't get adequate oil and two they are not set properly from the factory. I know you said that you do not have a bronze gear and that you are going to a bronze gear. Unfortunately you cannot do this unless the cam is a billet cam. Now there is a polymer gear that is out that wil actually outlast a cast gear. I believe it is made by Comp Cams. But what I would do if I were you is call up Mercury Racing. Once you get in the door and start talking to there techs, they will tell you how to set up your distributor and increase the oiling to the gear, to protect it. If nothing else, you get som insight from the Mercury Racing techs.
BTW - NOT Mercruiser techs.

[DUECE'SDAD]

did i read that right were you say you had great oil preasure but the distributor isnt turning? if the teeth are gone on the distributor gear and not turning the shaft, whats turning the oil pump? not trying to be defensive, just wondering what you meant. because if the distributor isnt turning and your still seeing oil preasure on the guage, you may have a faulty guage or something. would suck to loose oil preasure and not know it. know what i mean?
Well the crank is still turning, so the oil pump is too

[lucky]

Well the crank is still turning, so the oil pump is too
???? wow --

[DUECE'SDAD]

Had to do it ! ! ! ! ! I used a primer to make sure the oil pump wasnt locked up, but thanks for your concern of my oil pressure gauge, but that isnt the problem

[Jim W]

Hey Duces Dad,
I had the same thing happen this summer with my 396 BBC. Wiped the dist. gear teeth off but my cam gear looks ok.
My machinist--who is real sharp-- said people put high volume oil pumps into BBC's and they dont need one. The high volume pump is much harder to turn and is bypassing or over pressurizing the system. This puts too much load on the dist. gear and wipes it out. In my case, the gear lasted about 60 hrs of running.
To get me throught the summer he suggested a synthetic oil as thin as I dared. I went with Mobil One--0-30 weight or something like it. He also pointed out that the base of the dist has a groove cut around it. In this groove is engine oil pressure from a oil galley. He said what they used to do is cut a groove with a hack saw from the groove downward to the dist. gear to spray oil onto the dist. gear just as it contacts the cam gear. If you look at all this, you can see how to "time" where to cut the groove to get it to spray correctly. I plan on either selling my boat or redoing the engine this winter and will go with a stock oil pump.
Hope this helps ya.
Be good, Jim

[Jim W]

Oh, I forgot.
I have read online at some of the drag race forums that the guys in some classes are running 0 weight oil and running the oil level too low.
As they get to the top end, the engine runs out of oil in the pan. Pressure drops to 0 for a second or two and they go faster. Sounds nuts but with the synthetic oil they get away with it.
Try it and let us know how it works in boats OK????
Jim

[GofastRacer]

My machinist--who is real sharp-- said people put high volume oil pumps into BBC's and they dont need one. The high volume pump is much harder to turn and is bypassing or over pressurizing the system. This puts too much load on the dist. gear and wipes it out.
He is correct!..

[MandDPerformance]

Oh, I forgot.
I have read online at some of the drag race forums that the guys in some classes are running 0 weight oil and running the oil level too low.
As they get to the top end, the engine runs out of oil in the pan. Pressure drops to 0 for a second or two and they go faster. Sounds nuts but with the synthetic oil they get away with it.
Try it and let us know how it works in boats OK????
Jim
This is true!!! We do this at the boat drags with Lookie Lu. Mobil 1 Oil is the only thing we run. 8900 RPM with a 565 Chevy.

[MandDPerformance]

Well the crank is still turning, so the oil pump is too
The oil pump only turns when the distributor turns; unless it's an external pump.

[SmokinLowriderSS]

I'm still running the orriginal oil pump in my 454 after rebuilding her last winter. About 300 hours since 1978, stock pump, 10W-50 Castrol Syntech 100% synthetic. Stock 5qt oil pan & stock windage tray on the main-bolts.
55 PSI at idle cold at the ramp
53PSI hot at 4800 RPM WOT for miles at a time, never wavers
23PSI at 850RPM idle after a 3 or 4 mile WFO blast on a hot day
43 PSI at 1500RPM after the WFO blast.
Summit digital gauge, I like it. Am switching the rest over this winter.
No need for a super-output pump 9 times out of 10 IMO.

[DUECE'SDAD]

I just pulled the tunnel ram and found that the cam is running back in the engine, I guess the water pump (its a v-drive) is pushing the cam back to where the lifters are slightly hanging off of the front of the lobes. This explians why the dist gear failed, the cam was hammering against the gear, and this also shows why the dist. gear looked like it was only half engaged, the cam driving back would have been forcing the dist. up. Everything else looks good and since im pulling this motor to put in a car i will be pullin the oil pan so that will solve the broken pieces, and the oil pump quit turnin when the gear exploded, so no problems there, I should be able to put a new cam in and new gear, and i have a gear drive that i will install and a cam button on the front. Anything esle you guys can suggest ? ? ? Thanks for the help, and can any of the v-drivers tell me how you solve the problem of cam walk or rearward thrust with a cam driven water pump ? ? ? Ist there some type of shim of cam button for the rear of the cam, or some way to index the pump so that its no pushing on the cam like mine was ? ? ? Oh yeah and you want me to do what to get it to have ZERO oil pressure ! ! ! ! ! ! !

[Jim W]

I think you are going to find more damage than you think.
The front water pump should not be putting any thrust forward or rearward on the cam.
What I think is happening--- the dist. and cam gear are designed so that as they turn, the cam is pulled rearward by the dist gear and at the front---the timing gear has a thrust surface which rides against the block. I think the added stress of the H/V oil pump has been really pulling the cam rearward and now the block/timing gear has worn down and allowed the cam to move rearward.
I think you will find the front of the block, behind the cam thrust surface will be worn away.
Pull the timing cover and timing gears off and take a peek.
Good luck, Jim

[DUECE'SDAD]

pulled the timing gear, the surface behind there is lightly scuffed, i mean light, it actually looks like you took a piece of steel wool and polished it, there is no gaulging or damage to the block. I am looking at summit at the needle bearing kit, that goes behind there, i am wanting to run a gear drive, unless that will be more of a problem, and was wondereing what or why it says some machineing may be required ? ? ? Also i still dont see the problem being with h/v oil pump. I have another pump and pickup that goes with the pan that goes in my car, its a new mellings h/v, that way i dont have to break the tack weld on my old pump and i can keep that pump/pickup with the oil pan. So what do you think now ? ? ? ? I am still thinking new cam, lifters, dist gear and it should be good, i think this is just a freak deal.