ali

Just rebuilt a 454 mark lV. At the 7 hour mark the dist. gear failed.
Mark IV 454
hv oil pump 65 lbs.
Stock flat tappet lifters
Stock heads
The dist. gear was new and the motor ran Perfect!!! There is no wear on the block face from rear cam thrust and the dist. gear pattern shows that the dist is the right height.
Block is now apart to get new bearings and cam etc. But I sure dont want to put it back together with out solving this problem.
Any ideas or things to check or recheck??????

Vinny P

Unless the oil pump froze or the alignment was off, the only time I have seen this happen is when someone uses a steel billet cam with a stock gear.

ali

My first thought was that my cam had some how gotten a billit core. But the cam people asure me its a cast iron cam and gear. Sooooo
OIl pressure was check with mech. guage 65 lbs

otis311

there is a batch of cams out there that are no good and need to be replaced. I have been thru 3 sets of gears in 20 hours of use. Mesa built the motors and couldnt believe what was happening. He did some investigating and found the problem. I think they are making good on the cam and replacing the problem ones. The metals are mismatched and are chewing up the gears. No way around it, you have to replace the cam.

I tried steel, bronze and composite gears and they all chewed. I brought the boat down to Miami on Monday and Mesa tore down the motors to look for wear do to the gears coming apart and I got extremely lucky ,with no damage what so ever. Call Mesa if you have any problems or questions. He has researched this !!!

ali

Thank you otis311 I will call mesa monday morning. I just cant put this back together with out knowing

Lmarth

Please keep us up to date on these kind of problems. Even if you just wear the distributor gear and not ruin the cam, you still have all that metal to filter out and you will have 'spark scatter'. Sounds like alignment was good, so it must be something else. Long story, but I had wear problems with bronze gears in my BBC road race car in a prior life trying to run straight 50w oil. You're in good hands with Mesa..

MESABALANCING

I have worked closely with a very good cam manufacturer and I can tell you there are many cams in use and on shelf ready for use that are defective there are two core suppliers in the country that are bringing in cores from overseas that are a perfect copy of what we produce here and they are causing trouble all over the country I have had personally engines from three different states with three different cam manufacturers and no one is willing to admit it like always . There are approximately 8500 cores that were brought in on the shipment so you will see alot more failed gears before it's over .

cstraub

. ..and I will add this. Over 40K distributor gears have been shipped in to the USA from China for resale. These gears will fit and will work for about 10K miles in an auto; in a boat...who knows. I would stick with well known mfgs like MSD or Crane for distributor gears.

WETTE VETTE

About 10 years ago I had a MSD gear fail and never really found the reason. The cam was a Crane flat tappet solid lifter cam. The gear on the cam looked fine when it was removed from service and once the failed distributor gear was replaced everything worked great for a couple more seasons. We wrote it off as a bad distributor gear which is better than a bad cam gear!! Sometimes bad parts make it past QC even when made in the USA.

ali

Working with bob aka: rmbuilder, I changed out the oil pump to reduce oil pressure to 55 lbs and put in a new stock iron dist. gear. Ran it on the stand for 10 minutes and same wear was showing up. So then I changed it out to a bronze gear and a oil groove to the lower land on the dist. Ran that for 10 minutes and the wear was still evident but much less. So It,s all apart now and I'm going to add a new cam and gear plus all new bearings. Not sure on the piston rings. Just don't have enough experience with this to know if I can run the same rings or have the cylinders cleaned up and put new rings?