distributor problem

[1slowboat]

i'm running a mallory unilight distributor and having a problem breaking the roll pin on the gear,... i thought it was my oil pump at first and i changed it to another melling high volume,that didnt work...changed my oil thickness from 50 weight to 30...went out yesterday and broke another pin,.. thank god i had a spare pin with me., i also checked the cam endplay and all is fine there,running pete jackson gear drive in a 460 ford, bore and stroked to a 501.... i only have the problem when i floor the boat, after it is warmed up and running about 40 psi, new mechanical oil gauge.i never had a problem until i cut the impeler to an a/b and now turn 5600 rpm,....
any one else had this problem? any help please this is realy starting to bother me, can't race, or play around with anyone for fear of breaking another roll pin...

[77charger]

I have heard of that before seems to be a common prob now.I had a ford but used a recurved stock distributor.rt jas had the same prob on his old boat also a mallory he did solve the prob i believe before he sold it .try to pm him about it

[HOSS]

Did you have the timing cover machined for the gear drive? Are you using a hardenned distributor gear with a roller cam?

[1slowboat]

Did you have the timing cover machined for the gear drive? Are you using a hardenned distributor gear with a roller cam i had the timing cover machined and i am running a hardend gear on a hydrolic cam,thinking that its my ditributor,.....thinking about going to msd for all my ign.components

[1slowboat]

77charger, which rt are you talking about?.....this problem has got me a little upset.. burningm ,...new motor and all, i didnt have the prob. until i cut the impelar from an a to an a/b.....

[Mr Twister]

Was the dist new...are you using hardware store roll pins...are the bushings in the dist good...why does this seem rpm related...does the dist gear and the cam have proper backlash??? Questions to ask yourself. I think the broken pins may be a symptom rather than a problem, food for thought. BTW I run a similar dist and have not had any problems.

[1slowboat]

posted September 07, 2003 04:57 PM
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Was the dist new...are you using hardware store roll pins...are the bushings in the dist good...why does this seem rpm related...does the dist gear and the cam have proper backlash??? Questions to ask yourself. I think the broken pins may be a symptom rather than a problem, food for thought. BTW I run a similar dist and have not had any problems. the dist. was a used one that i bought for 50 bucks, i broke the old unilight with the other motor that i granaded last year,....i used automotive dist. rollpins, i think that its rpm related because i can run all day long if i keep my foot out of the gas,( anything above 5400 i break a roll pin)... every thing else is good, backlash,cam plate ect..
thats why im scratching my head on this one smile_sp

[SuperWrench0166]

there has been a few with that same problem in the gearhead section i know msd had a problem have you tried one of the double roll pins also check to make sure your endplay on yur distributer is ok and its not binding when you try pushing it up or down

[1slowboat]

it slides up and down just fine and smooth,no catch or hard spots,dont know whats going on here :confused: ....everything else says its right. frown

[ttmott]

I had the same problem with a modified GM HEI unit. Ended up being a couple of things. The dist. shaft was a small diameter (around 3/8" or so) and at high RPM the shear on the pin due to torque needed to drive a high volume oil pump kept shearing the pin. Secondly, any play in the pin holes will make it happen again and again. Once the pin has sheared it destroys the roundness and fit of the pin holes on both the gear and shaft causing the problem to repeat. The only fix is to upgrade to the MSD unit which has a .505 shaft.

[1slowboat]

thats what i wanted to here :D thanks for the info :D

[Mr Twister]

ttmott, excellent reply.

[1slowboat]

anybody else had this prob?, and what your fix was?

[cookieman]

I have a suggestion get a chevy thats why its a Fix Or Repair Daily (FORD).Just harasssssing you Travis. They all break sometimes that's why they are boats, run good on trailers, put in water and they fall apart.

[1slowboat]

i know thats right cookie thats why its spelled b.o.a.t.,( break out another thousand) :p

[Squirtcha?]

It's the pins. Mallory is aware of the problem and has a replacement double rollpin. Someone from the banderlog board went through this about six months ago. I'm running the Mallory unilite on my 460 and haven't had a problem with it yet. I turn 5600 rpm on a regular basis. You can find the double rollpins without having to go to Mallory, but it might take a little research.

[lakecrazy]

I have had the same problems with my 460 with a Mallory Unilite. Broke two roll pins in less than 1 year. Sent the distributor back to Mallory and they replaced the shaft and installed a new gear. I also pulled the motor and replaced the oil pump (hi volume m-84dhv) with a stock volume pump (m-84d). Check the distributor shaft, once you have broken a roll pin, the hole in the shaft becomes "loose" and the pin will not have a press fit to retain the gear

[1slowboat]

I have another question.... can't i put the distributor in a vise and drill another hole just under the old one at a 90 deg? wouldn't this fix my problem? :confused:

[058]

1slowboat:
I have another question.... can't i put the distributor in a vise and drill another hole just under the old one at a 90 deg? wouldn't this fix my problem? :confused: Do NOT drill the shaft for a 2nd pin, this will weaken the shaft. The gear needs to fit tight [press fit] and a hardened pin needs to be installed. Any good bearing supply house should have these roll pins. If you look at the pin Mallory uses they are soft mild steel and just one turn [single wall]. The pins used in Ford distributers usually are mutiple turn pins made from heat treated steel.

[Rexone]

Try McMasterCarr for the good pins. I believe they carry them. :)

[lakecrazy]

Mallory now uses a spirol type pin.

[waterfn]

I had that problem on a 400 ford in a bronco I had built, A speed shop told me ford has a problem with the shaft being to long he gave me a shim to put under the distributer when you put it in. I did not have break a single roll pin after that.

[1slowboat]

didnt that affect the timming and the gear placement in the cam and distr.?
less meat so to speak on the gears?

[quiet riot]

I've got a mallory unilite in my 351w ford and it did the same thing the first time I rev'd her up after breakin the motor in. I put a hardened roll pin in it with red loctite and haven't had a problem with it in 8 years.
I even grenaded a oil pump slamming through rapids because the pump had bad clearances and it twisted the oil pump drive shaft in half, but the dist gear stayed on and I was able to drive out. The synthetic oil was a life saver for the 1/2 mile trip to the closest launch. Hard on the engine maybe, but still better than losing the whole boat in a class 4 rapid if I lost power.
jd