Distributor Gear Wearing Out
Thread Starter
Instructor
Joined: Apr 2006
Posts: 194
Likes: 0
From: edmonton alberta
Distributor Gear Wearing Out
JUST WONDERING IF ANYONE HAS HAD THIS SAME PROBLEM ,I BUILT MY NEW ENGINE LAST YEAR AND I USED A GMLT4 HOT CAM WITH A STOCK GM DIST I BOUGHT A G M PERFORMANCE PARTS MELONIZED DIST GEAR AND PRELUBED THE ENGINE BEFORE FIRST START BUT AFTER ABOUT 500 MILES THE CAR STRIPED ALL THE GEARS OFF THE DIST GEAR SO I PUT ON A NEW GEAR A FEW DAYS LATER SAME THING THEN I ENDED UP TAKEING THE TIMING CHAIN OFF TO SEE IF MAYBE I FORGOT THE CAM RETAINER PLATE OFF AND THE CAM WAS WALKING BUT WHEN I REMOVED THE COVER I FOUND I NEVER FORGOT IT BUT THE BACK OF THE TIMING CHAIN WAS `DIGGING INTO THE REATAINER PLATE AND BOTH WHERE WORN OUT BAD .SO I CHANGED IT ALL NEW TIMING CHAIN ,RETAINER ,DIST GEAR AND THOUGHT I SOLVED THE PROBLEM BUT TODAY I PULLED MY INTAKE OFF SO WHEN I GOT THE DIST OUT THE GEAR IS ALLMOST WORN RIGHT OUT .I WAS TOLD THE FIRST TIME IT HAPPENED THAT IT WAS A TIMING CHAIN THAT WAS NOT HEAT TREATED RIGHT SO IT WAS WEARING OUT AND CAUSING THE CAM WALK THAT DESTROYED THE GEAR.NOW I HAD THE BEST TIMING CHAIN I COULD GET AND STILL SAME PROBLEM .ANY IDEAS GUYS
Le Mans Master
Joined: Jan 2002
Posts: 9,036
Likes: 13
From: Edmonton AB
Sounds unusual.
When they said the timing chain was not heat treated correctly, my
vote is that they must have meant the upper gear, instead of the chain.
Do you still have the p/n for the melonized gear? Was this coming
from GM directly?
Was the block one you had in service yourself previously?
What kind of oil pump and what pressure?
Do you happen to run a vacuum pump?
.
When they said the timing chain was not heat treated correctly, my
vote is that they must have meant the upper gear, instead of the chain.
Do you still have the p/n for the melonized gear? Was this coming
from GM directly?
Was the block one you had in service yourself previously?
What kind of oil pump and what pressure?
Do you happen to run a vacuum pump?
.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Ive seen a thread or two on shimming the distributor (Moroso sells them) so it doesnt bind on the cam gear (if thats the problem) but I can t seem to find them. Try pm'ing mseven, I remember he had some good input on setting that.
CFI-EFI has some good info on that too.
CFI-EFI has some good info on that too.
Safety Car
Joined: Sep 2001
Posts: 4,157
Likes: 554
From: Glenbeulah Wi
I have this same problem with the GM gear on my 355 Firebird. After 10,000 miles the melonized GM distributor gear is completly shot. I believe comp cams makes a composite gear that is supposed to take care of this problem but I have not tried it yet.
My thoughts are that the high volume high pressure oil pump I am using is wearing out the distributor gear. My oil pressure at 1500 RPM is always at 60 PSI or higher.
My thoughts are that the high volume high pressure oil pump I am using is wearing out the distributor gear. My oil pressure at 1500 RPM is always at 60 PSI or higher.
Thread Starter
Instructor
Joined: Apr 2006
Posts: 194
Likes: 0
From: edmonton alberta
the block was new ,i never used it before ,and by the heat treating i did mean the top gear,and also when i put in my engine i got a rebuilt dist from napa,and the 3 gears i bought where from g.m.p.p and where melonized .but do you guys think that the dist that is not shimed right can put that much force on the cam where it would wear out the timing chain gear?i am puting on a h.s.r intake now and got a m.s.d dist but i know my timing chain and cam retainer plate are going to need changing again .but i hope all the problems are from this cheap napa rebuilt dist .but if anyone has had or heard of this same problem let me know what it might be ,thanks
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
Pull the dist apart and check the shaft. If it is bent a few thousanths of an inch, it will burn up the gear. If the cam gear on the second timing chan set is suspected of being soft, swap it for a hex adjust. They have a torrington bearing behind them and need almost no oil to work well. I usually drill a small bleed hole in the drivers side oil galley plug to bleed a small spray of oil on the cam gear and chain.
Also, if the cam gear has worn hard, it may have chewed up the gear on the cam. Inspect this closely. If worn, it will burn up any gear you put on it.
Also, if the cam gear has worn hard, it may have chewed up the gear on the cam. Inspect this closely. If worn, it will burn up any gear you put on it.
Safety Car
Joined: Apr 2001
Posts: 3,525
Likes: 2
From: Houston TX
Look up an old posts that I had made "15° retarded" and "setting distributor height". You may also see a post by steel breeze as I walked him through these issues about 2 months ago..
I have a car that I am working on right now with the MRII with yet another "irregular" casting (per TPIS) that makes the distributor set too high. I would suspect that the wear on the timing chain gear is caused by the cam decellerating (walked out then walks back into the block. Get a nice CC thre piece billet cover with a nice cam button if you are no longer using the factory retaining plate (which I have no idea why you would not, unless you were running SR). But the wear on the cam gear is typically due to a misaligned dist gear. And after all of these that I have fixed in the past, I have never seen one eat the cam gear. Distributor gear play should be set between 0.008 - 0.012" when re-shimming (I like to set it tight).
Aaron
I have a car that I am working on right now with the MRII with yet another "irregular" casting (per TPIS) that makes the distributor set too high. I would suspect that the wear on the timing chain gear is caused by the cam decellerating (walked out then walks back into the block. Get a nice CC thre piece billet cover with a nice cam button if you are no longer using the factory retaining plate (which I have no idea why you would not, unless you were running SR). But the wear on the cam gear is typically due to a misaligned dist gear. And after all of these that I have fixed in the past, I have never seen one eat the cam gear. Distributor gear play should be set between 0.008 - 0.012" when re-shimming (I like to set it tight).
Aaron
Thread Starter
Instructor
Joined: Apr 2006
Posts: 194
Likes: 0
From: edmonton alberta
hi,Aaron yes I'm still using the stock cam retainer plate .but something is putting so much force on the cam and timing chain gear that it caused it to dig into the retainer plate and wore out the timing gear bad and so far this is the forth gear that i would have to change.i thought it might be a bad dist .but now you got me thinking about the intake that might have the dist hole out of specs in the machining process.but now i got to change my timing chain and cam plate again.and what the part number for that 3 pcs timing chain cover for the factory 1 pcs seal roller block? thanks
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