What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

HEI drive gear worn ?

phreddei166

phreddei166

1/2 ton status
Joined
Jun 21, 2007
Posts
374
Reaction score
6
Location
Mass-hole !
My 350 sbc with less than 3000 miles was making a rattling ball bearing sound. Traced it to distributor. Pulled it out and drive gear was 1/3 worn away. See pics. Any ideas on problem ? Engine ran great, just loud distributor. Some specs, .060 over , comp cam 4x4 extreme cam, Melling oil pump and drive shaft 10% higher pressure, Petronix HEI, Edelbrock performer intake. My questions are : Is distributor gear softer than cam gear ? Is my cam trash ? How do I fix this problem ? Shim dist. up ? I want to hear 4x4 HIGH 's opinion.
 
Last edited:
What is the part number of your cam? Some cams out there are steel and you have to use a steel drive gear with them or stuff like that happens. Only way to know for sure about your cam is to pull it and inspect it. I would want to pull the oil pan as well and take a look at the inlet screen on the pump and to see where all the metal from that drive gear ended up.
 
you are right its bronze gear with a steal cam. and then you use iron for iron. Here I go confusing the guy!
 
Hydraulic flat tappet Comp cams # 12-231-2 . I have Filter Mag on my oil filter. Maybe that helped to capture metal frags.
 
a filter should get it or the pickup screen did. That is an iron cam and looks like a stock iron drive gear from the photos. My concern then would be the high pressure oil pump. I have heard that those eat up dizzy gears. I would want to look at my cam shaft considering the wear on the gear.
 
i have a hydro roller cam and they said i need a hardened dizzy gear or "extreme engine damage will occur" but they had some fancy name for hardened, i forgot what it was.
 
Melonized? Or am I thinking of something (well, two things) in the Pigpen again? :haha:

-- A
 
Checked my part # on Melling oil pump. # 10552 , 10% increase on VOLUMN not pressure. Using reccomended melling pickup and shaft. Oil used was Shell Rotella T 15w-40 . 20 psi hot idle. 50-60psi anything over 1500 rpm.
 
i just remembered,that weird word for hardened is "melonized"
Click to expand...

melonized sounds more like gallagher smashing the cam with his hammer.

041301_gallagher.gif
 
There are a couple things that will cause the gear to wear very quickly. The first is using the wrong distributor gear with a steel billet cam (not the case here, supposedly). Second would be the use of a high volume or high pressure pump, third is if the thrust face of the block is bad that could cause this. Also not all of comps cams use a standard iron gear. I would definately pull the cam and check for wear and then call comp cams and ask for their input. There is one last thing that could cause this failure and that's if there isn't suffiecent clearance between the oil pump drive shaft and the end of the distributor shaft itself.
 
A couple of additional things to check:
Distributor bottoming in pump before contacting manifold - bad. Typically this occurs when the heads are milled. Worthy of checking without the dist gasket. If it bottoms than shims are needed under the distributor housing.

Distributor gear axial clearance. Should be around 0.010. Most distributors are very sloppy http://members.shaw.ca/crussel/hei/HEIrebuild.html
 
rcamacho said:
A couple of additional things to check:
Distributor bottoming in pump before contacting manifold - bad. Typically this occurs when the heads are milled. Worthy of checking without the dist gasket. If it bottoms than shims are needed under the distributor housing.

Distributor gear axial clearance. Should be around 0.010. Most distributors are very sloppy http://members.shaw.ca/crussel/hei/HEIrebuild.html
Click to expand...

I've already mentioned that.
There is one last thing that could cause this failure and that's if there isn't suffiecent clearance between the oil pump drive shaft and the end of the distributor shaft itself.
Click to expand...
 
Replacethe dist gear with a hardened gear. Pull the oil pan and check the screen for shavings. Reinstall pan and run 1000 miles and pull dist and check. If gear looks good and no noise OK. If worn or noise returns, replace oil pump with NEW ( not rebuilt ) OEM pump.
Remember the oil pump is a hydraulic pump. It takes a lot of HP to run it. The melling pump is higher volume (and pressure) and thus requires more HP to operate.
 
DO NOT run a hardened gear unless you're sure it is required (should not be with a ductile iron cam). Using a hardened gear with a ductile iron cam will ruin the cam in a few minutes of running.
 
You must log in or register to reply here.

Latest Posts

Top Bottom