Distributor Gear Wear

[stroker87]

GRUMPY?
well done some tuning to the truck felt really good better then ever! Decided to go out for a nice drive tonight and had no spark so I started hunting this is what I found

Can you tell me what caused this? And being the truck felt so good how much damage go’s along with this? I’m not sure if you can tell from the pictures is wear not broke or chunks missing, the dirt you see is from me wiping it down (not metal)

This is out of my 383 Stroker Roller Engine

READ THESE LINKS
http://www.carcraft.com/techarticles/di ... index.html

viewtopic.php?f=52&t=57&p=70&hilit=cast+cores#p70
check with the manufacturer anytime you have similar questions, on any valve train or ignition component.
but Id bet the stock distributor gear is what will be recommended,on any new engine build with a new cam installed.
this whole web site is designed to make it far FAR easier on guys wanting to build the required knowledge base required to learn the skills youll require to excell in this hobby.


coat any new cam and distributor gears with a good moly paste lube

READ THE RELATED INFO CAREFULLY AND USE A GOOD MOLY LUBE ON THE DISTRIBUTOR AND CAM GEARS

most stock chevy v8 distributors will use this gear. .491 diam.
https://www.summitracing.com/parts/ado-10456413/overview/make/chevrolet

many aftermarket distributors will use this gear .500 diam.
https://www.summitracing.com/parts/msd-8561/overview/make/chevrolet

bronze distributor gears are generally used on billet steel roller cam cores
https://www.summitracing.com/parts/msd-8471/overview/make/chevrolet





http://garage.grumpysperformance.com/index.php?threads/distributor-gear-wear.1701/#post-5252

http://garage.grumpysperformance.com/index.php?threads/distributor-gear-info.1186/#post-4155

http://garage.grumpysperformance.com/index.php?threads/oil-system-mods-that-help.2187/#post-5890

http://garage.grumpysperformance.co...stalling-the-intake-manifold-distributor.464/

http://garage.grumpysperformance.co...ear-articles-you-need-to-read.282/#post-61429

http://garage.grumpysperformance.co...ting-rebuilding-hei-ignitions.2798/#post-7247

http://garage.grumpysperformance.co...y-in-building-a-good-engine.11682/#post-54682
THE CAM MANUFACTURER WILL BE ONLY TOO GLAD TO SELL THE CORRECT MATCHING DISTRIBUTOR GEAR TOO YOU
and like a lifter on a cam lobe it is usually going to last longer if both the cam and distributor gear are new, coated with moly assembly grease and allowed to lap in and mate surfaces , rather than use used worn distributor gears on new cams

viewtopic.php?f=70&t=251&p=299&hilit=shim+distributor#p299

viewtopic.php?f=54&t=2187&p=5890#p5890

keep in mind the distributor base forms one wall of the lifter gallery oil passage

so grooving the lower oil band helps spray extra oil on the distributor/cam gears contact area

any time you change cams youll need to use a matching distributor gear, the cam manufacturer should be able to help tell you what matches, obviously checking clearances helps
and dipping the gear in moly assembly lube before it installed helps
be sure you inspect the distributor gear for excessive wear
especially if you changed from a flat tappet to a roller cam.
if your seeing the timing change a few degrees, back and forth,
slack in a worn, loose timing chain, worn distributor gear or not having the proper shim clearance on the distributor center shaft will provide slop that allows timing to vary several degrees


http://www.summitracing.com/parts/CCA-12200/

http://www.summitracing.com/parts/CCA-12140/

MOST of the chevy and after market cams will work with the standard replacement mellonized distributor gears

http://garage.grumpysperformance.com/index.php?threads/slowing-distributor-gear-wear.57/#post-70

http://garage.grumpysperformance.co...the-intake-manifold-distributor.464/#post-570

http://garage.grumpysperformance.com/index.php?threads/shiming-a-distributor.251/#post-299

http://garage.grumpysperformance.com/index.php?threads/distributor-gear-wear.1701/#post-5252

 

[grumpyvette]

read this

http://www.carcraft.com/techarticles/di ... index.html

viewtopic.php?f=54&t=123&p=326#p326

http://www.jegs.com/InstallationInstruc ... 1-8560.pdf

obviously youll want to verify the correct distributor gear material to use with the cam manufacturer, before using it and providing extra oil flow, to the gears should help reduce wear
http://www.summitracing.com/parts/LUN-89027LUN/

theres several likely reasons and the most likely is a combo of less than ideal lubrication flow and a material in-compatibility between the cam and distributor gears,its always a good idea to call the cam manufacturer and ask what is the correct matching cam gear and distributor gear set,and how its correctly installed. add the extra drag the oil pump is likely to produce after ingesting metallic crap from the gear wear..well...Id sure take a strong light and look down the distributor hole at the cam gear and hopefully its NOT similarly worn.
some roller cams came with steel gears that require a bronze alloy distributor gear, if your experiencing that wear Id suggest inspecting the oil pump also as theres a good chance its damaged, due to the crud its ingested.


when you get rapid wear on a distributor gear is almost always the result of mis-matched materials in the cam and distributor gears or lack of adequate lubrication
if you have a gear go bad in under 1000-1500 miles its probably both.
Id sure call the cam manufacturer and verify the correct cam gear material is being used on the distributor gear too match the cam your using,a distributor or cam gear that's correctly lubricated and made of the correct material should easily last 60-80kk or more, like a stock gear normally will on a stock cam, and don,t fall for the crap about it being the result if a high volume oil pumps extra load on the gears, that's not the cause if it wore out that fast, you've got other issues.
obviously step one will be to change oil and filter at a minimum, (personally Id disassemble and clean out the engine, oil passages and replace the bearings but hey that's just me)you may get by with an oil and filter change, but the fact that you'll probable see crud indicating rapid cam gear /distributor gear wear on the dipstick would indicate to me that fine metallic craps getting pumped to the bearings,rings, lifters,rockers etc.
some of the better distributors with o-ring grooves have a small oil hole drilled between the o-rings that allows a steady stream of pressurized oil to enter the lower distributor shaft, the upper bearing is sealed so oil can,t exit into the upper distributor, but oil is routed to lube the lower bearing in the distributor, the oil exits to spray over the cam gear/distributor gear contact area, look closely at yours
a tool like this should have let you now months ago something was wrong

get the cam gear material match to distributor gear material match,wrong or oil flow match incorrect and rapid wear can result

make sure the oil groove lines up with where the gears mesh when the distributors installed and timed correctly.

on Chevrolet engines, Crane recommends that a .030-inch-wide and .030-inch-deep groove be machined or filed into the bottom band on the distributor shaft as shown (arrow) to provide lubricant to the distributor gears. Place the groove on the distributor so that when timed properly, the groove will face the camshaft. With the distributor in this position, oil will spray both the distributor and the cam gear to significantly reduce gear wear. This trick can improve gear life for any type of camshaft. Ford engines have an oil passage plug that points directly at the distributor gear. A .025-inch hole can be drilled into the plug to lubricate these gears.
viewtopic.php?f=54&t=938

cutting a groove in your lower distributor oil band in-line with the beginning contact point between the gears meshing will provide extra oil flow to the gears but having compatible materials and clearances will be critical, your cam manufacturer will know the correct distributor gear material to use.

From Sallee Chevrolet. http://www.sallee-chevrolet.com/PriceLi ... 3.726.html


Melonite QPQâ„¢ is a thermochemical process (ferritic nitrocarburizing) used for the case hardening of iron-based metals. In a molten bath of special salts, nitrogen, carbon, and small amounts of oxygen are diffused into the surface of the steel, creating a super-hard surface, called the "compound layer." Additionally, small amounts of carbon are pulled from within the substrate, toward the surface, creating a "diffusion zone," which exhibits a gradient of concentration of carbon and nitrogen, decreasing toward the core. Thus, the process provides both a hardening of the surface, and a gradient alloying of the substrate, which improves the ductility and overall strength of the material.


http://www.hotrod.com/techarticles/engi ... index.html

01103952 - Distributor, Late model HEI F/I, small cap. This complete distributor is used on late model V8 engines with fuel injection and computer controls. = 168.92 ( Does not say hardened gear or for roller cams )

01104060 - SBC Distributor Assembly, for Ram Jet 350. This complete distributor is used on the Ram Jet 350 port fuel injection engine. - 176.09 (RJ350 has a roller cam, but does not say this has hardened gear. so what is the diff. in this one and the one above? )

01104067 - HEI HO Distributor. This distributor has the melonized cam drive gear P/N 10456413 for steel roller camshafts. This distributor is required on all crate engines and roller camshafts that are made of steel. If engines are assembled not using this gear, it may affect your engine warranty. Use connector wire P/N 8917052 to ignition. Used with all small and big-block V8 High Output engine assemblies. Technical Notes: Components in these groups are interchangeable with small-block Chevrolet V8s. GM Performance Parts distributors cannot be used with "tall deck" Bow Tie block P/N 14044808. - 227.41 ( only one that says it's for roller cams, but this is a large cap HEI ).


10456413 - Distributor HEI Gear, large cap. You must use this gear with the new roller cams. This is a hardened gear. This distributor gear is used on all Chevrolet small and big-block engines, including steel roller camshaft engines. - 22.88

10469459 - Distributor HEI Gear, small cap. You must use this gear with the new roller cams. This is a hardened gear. Also fits some Mallory distributors. - 23.74
The bottom of a Chevrolet distributor housing can be and SHOULD BE! modified to spray pressurized oil onto the distributor drive gear. The extra lubrication will reduce distributor gear and camshaft gear wear. This is especially important when the gear is used to drive non-standard accessories, such as a high volume oil pump, or a magneto that puts additional loads on it and the cam. <P>When the distributor is installed, the bands at the bottom of the housing are designed to complete the internal right side lifter galley on all small and big block Chevrolet V-8’s and 90° V-6 engines. If you hand file a small vertical groove .005" wide x .010 deep, that's the diam. that crane recommends Ive always used the larger .050 wide, and about .005 deep groove with no problems, deep on the bottom band (above the gear), pressurized oil running between the two bands will be directed downward onto both the gear and the cam This procedure is recommended for all Chevrolet engines no matter what material gear (cast or bronze) or what type of camshaft (cast or steel) you are using keep in mind the groove MUST be lined up with the cam gear when the distributor. is installed

IF the cam gear looks worn you'll need to replace the cam, or( if the gears a separate component get that replaced)( IT is on some billet cams btw)
BEFORE you go installing a new distributor gear or that will also wear at an accelerated rate
YOU must both match the correct gear materials and provide the correct lubrication, Id suggest two new gear surfaces, a good coat o MOLY assembly lube and cutting the lower distributor oil band for increased oil flow, ID also replace the oil pump.
BTW if you have a mijnor oil leak around the distributor base youll want to verify that
you have the GASKET between the intake and distributor housing, and a decent clamp?

http://www.summitracing.com/parts/MRG-1009/?image=large

 

[stroker87]

Grumpy, Thanks for the info

I'm just going to get a new cam I wanted to change it any way along with a new oil pump and dirstributor gear, I'll be asking A LOT of questions dont feel like going thought this again!

 

[grumpyvette]

ideally you will dissasemble and carefully inspect the whole engine simply because theres been a good deal of metalic crap floating around due too the gear wear and most likely other stuff effected by the resulting metalic debris.
now of course you can just slap a new cam and distrib gear into the engine and theres a decent chance youll get away with that at least for awhile, but since you really don,t know the extent of the damage to other components (if any) the smart routes to pull it down and closely inspect the engines components and flush out the oil passages and replace all the rings and bearings, and any other component found to be damaged

Properly Matching Your Camshaft and Distributor Gear



Matching camshaft and distributor gears is one of the most critical, yet often overlooked step in engine assembly. The proper distributor gear for your camshaft differs by both the material and the kind of lifter for which your camshaft was designed. Using the wrong material can lead to premature gear wear, possible camshaft wear and ultimately engine failure.

First off, no steel distributor gear is compatible with both flat tappet and hydraulic roller cams. This is because hydraulic rollers can be made from two possible materials and either of those materials requires a different gear than the flat tappet cam. Regardless, a steel gear is not compatible with a cast iron flat tappet cam.
while your worrying about your new billet steel roller cam tearing up your old soft distributor gear, you might want to think about swapping to a bronze tip fuel pump push-rod to prevent excessive wear on that expensive billet steel cam core on the front end ,

Distributor Gear Materials:

1. Cast Iron

2. Composite (offers great life, conforms well to the mating cam gear, and is compatible with ANY camshaft gear material)

3. Melonized or hardened steel (material that OEMs use with factory roller cams; many aftermarket distributor manufacturers use these as the default gears for their distributors)

4. Bronze (conforms well to the mating camshaft gear and will not damage the camshaft gear, but it is a self sacrificing gear intended to be used in race applications only and should be replaced about once a year)

If you have a cast iron hydraulic or solid flat tappet cam, your distributor gear options are:

1. Cast iron distributor gear

2. Composite distributor gear

If you have an austempered ductile iron hydraulic or solid roller cam, your two options are:

1. Melonized or hardened steel distributor gear

2. Composite distributor gear

If you have a billet steel hydraulic or solid roller cam, your two options are:

1. Bronze distributor gear

2. Composite distributor gear

COMP Cams recommends the composite gear because it is compatible with all camshaft gears – flat tappet, austempered cast iron cores, and billet cores. If the steel gear is not hardened, it is not compatible with either of the roller cam types.

Note: If you have an austempered core hydraulic roller cam and a .500˝ shaft distributor with a steel gear, verify with the manufacturer of the distributor that the steel gear they use is a melonized or hardened steel material and it will work fine.

Tech Tip courtesy of Comp Cams

 

[stroker87]

When its dissasembled "if" it all looks ok every thing need to be reinstalled in the same location? lifters, bearings, caps & ect.....

 

[grumpyvette]

since your looking at a new roller cam the lifter location can be random, the rings could be reused but most guys will replace them, All bearings should be replaced

Distributor Gear Compatibility
If you've experienced excessive wear of a camshaft distributor drive gear, and maybe had to replace either the cam or the distributor drive gear itself, here's some good information you'll want to retain. Crane Cams roller tappet camshafts are ground on 8620 billet steel cam cores that are heat treat hardened to resist wear.

This 8620 steel billet material is wonderfully tough stuff, but it can also be very hard on distributor gears! To remedy this, Crane 8620 steel billet cams MUST use a high silicon copper alloy distributor gear, to prevent rapid wear of the camshaft's distributor drive gear. These are usually referred to as "bronze" gears.

Cast iron hydraulic or mechanical tappet cams are also susceptible to premature wear of the camshaft distributor drive gear or the distributor gear itself. This problem, when it occurs, is usually accompanied by the use of a high volume oil pump in a stock or mildly modified engine.

Cam gear or distributor gear wear is usually NOT caused by the high volume pump itself, but by insufficient internal engine running clearances.

Chevy V-8's, small block, big block, and 90? V-6 engines, all use splash lubrication to oil the distributor gear. Although higher RPM operation provides sufficient lubrication to prevent wear, low speed use can be a problem. The situation can become critical if a high volume oil pump is used. The high volume oil pump was developed for engines where bearing clearances were increased over stock. These work fine in racing engine applications, where extra clearance is provided in the short-block.

However, when a high volume oil pump is used in an engine with stock internal clearances, the increased volume of oil can't flow through the engine fast enough to relieve the back pressure created. This places an increased load on the distributor gear, and leads to accelerated wear.

Once the gear on either an 8620 steel cam or a cast iron cam is worn excessively, the cam itself must be scrapped! There is no repair for this problem, and the only option is to buy a new cam. To eliminate this annoying and expensive problem, we offer a simple, do-it-yourself way to help oil the distributor gear and reduce this accelerated wear in Chevy V-8 and 90? V-6 engines.

On these engines, the lower portion of the distributor housing drops through the oil gallery that supplies oil to the lifters on the passenger side of the engine. Two rings at the bottom of the distributor housing seal the top and bottom of this galley. Oil flows around the distributor, between the two rings.

 

[stroker87]

If I do replace the bearings do I need to have the crank and rods turned or any thing?

 

[grumpyvette]

Id check clearances carefully, but ID seriously doubt that the other components can,t be reused in their current condition

viewtopic.php?f=59&t=1026

viewtopic.php?f=53&t=88&p=5709&hilit=bearings#p5709

 

[jteu2002]

had the same prob and the cam was dead also in mine
another prob is the use of high volume and to high oilpressure that is generated by the oilpump
they need way more force to get them turning and put additional wear on the cam and gear
high volume pump are normaly for an engine where the parts are assambled very loosely to avoid lost of power
from friction .engines built with normal specs don't need those racepumps

 

[grumpyvette]

good point!
most guys don,t seem to understand that a high volume oil pump is one part of a system, the other components that are MANDATORY to its use are a high capacity baffled oil pan,7-9 qts helps , a windage screen,mounted within 1/8" of the rotating assembly arc, too quickly return oil to the sump, and mods to the engine that require its use like the groove in the distributor lower band, a .030 hole drilled in the front pass side oil passage, plug behind the timing chain,lifter bores with shallow groves on the pass side or a flat spot on their side or a hole drilled in their base (DEPENDS ON APPLICATION) slightly looser bearing clearances,oil drain back holes smoothed and opened, a decent oil cooler won,t hurt either in a race application.
if your engines basically stock the standard Z28 pump is fine in a sbc.
while its true that the high volume oil pump does tend to have a slightly higher resistance to being spun since its pumping 15%-25% more oil per revolution and that does increase the loads slightly on the cam and oil pump gears I doubt that's the source of the problem, Ive been running a high volume oil pump in my 383 for 12 years with the same pump and its had the same distributor gear on well over 17 different cams, IVE tested in that engine and the last crane 119661 crane roller cam has over 9 years of use and neither the cam or distributor gear look worn, but then I cut oil grooves in the block and lower distributor body to supply far more oil and Ive done several mods that USE the extra oil flow, like the oil passage plugs in back of the cam drive are drilled with a .030 hole to supply oil squirting on the cam drive gears, and the lower lifter bores are grooved to supply extra oil flow to the cam lobes., If your using the pump as part of the system and the systems DESIGNED to use the extra oil flow and CONTROL and route the extra oil flow and you've got the high capacity baffled oil pan and windage screen, the high flow rates don,t necessarily result in any real pressure increases on the cam gears driving the oil pump, remember pressure is a way of reading the resistance to flow rates not the amount of oil being moved thru the clearances, and lots of extra clean cool oil flowing over the gears meashing tends to lube far better than the limited flow of the stock configuration

viewtopic.php?f=54&t=615

 

[stroker87]

This is the result of the Distributor gear wearing out (reason still unknown at this point)

Grumpy the only thing the might make sense is a bent oil pump shaft (I might be wrong but every thing else seams straight and centered)

would this cam still be useable or should it be sold as a peace of art?

 

[grumpyvette]

in an IDEAL world you replace cams when they show ANY wear, but like you IM broke 90% of the time and that's really not an option, obviously you need to replace the distributor gear with a gear that's compatible with the cam per the cam manufacturer and coating it with assembly lube is mandatory.
yes your taking a chance re-using the cam but I think its fairly low from the pictures.

THE CAM MANUFACTURER WILL BE ONLY TOO GLAD TO SELL THE CORRECT MATCHING DISTRIBUTOR GEAR TOO YOU
and like a lifter on a cam lobe it is usually going to last longer if both the cam and distributor gear are new, coated with moly assembly grease and allowed to lap in and mate surfaces , rather than use used worn distributor gears on new cams

viewtopic.php?f=70&t=251&p=299&hilit=shim+distributor#p299

viewtopic.php?f=54&t=2187&p=5890#p5890



I just got clearer more detailed pictures....
after looking at them ID SUGGEST REPLACING THE CAM, thats a shame because only the gear really looks worn

obviously youll want to verify the correct distributor gear material to use with the cam manufacturer, before using it and providing extra oil flow, to the gears should help reduce wear
http://www.summitracing.com/parts/LUN-89027LUN/

BTW a thought just occurred to me,
BTW, It should go without saying it but Ill post this bit of info anyway, there's an oil pump drive shaft connection between the oil pump drive and the lower distributor, there's a blade/slot type connector at both ends of the shaft and the shaft length should allow there to be about .030-.050" of vertical play or slack in the shaft when the distributors seated and clamped in place and the oil pumps firmly bolted with a stud to the rear main cap,the stud lower end should NOT touch the rear main bearing shell and ideally you'll use loctite on its course thread section in the main cap.
there's several designs and several lengths on these oil pump drive shafts.

the ARP and MELLING design drive shafts with the reduced diam. mid shaft are far stronger than the stock style, and the reduced diam. aids clearance on the larger diam. 400 style crank engine blocks with their larger diam. main bearings, the steel collar that mates to the oil pump slot drive is far stronger than the nylon sleeve found on some on stock drives

http://store.summitracing.com/partdetai ... toview=sku
http://store.summitracing.com/partdetai ... toview=sku

this style
bellow works ok in MOST OF the 350 base engines, but on a few it binds, and it won,t always clear in the 400 blocks, due to the larger main bearing size and clearance issues

http://store.summitracing.com/partdetai ... toview=sku

many guys don,t realize the oil pump drive shaft design is why the distributor will only fully seat on the intake in the two locations 180 degrees apart and that you need to index the drive before seating the distributor to get the rotor to point where you want it too.
If you use a nylon sleeve/collar, its not unheard of for the slot drive to break off a part and the pump to spin erratically at low rpms or fail to spin at high rpms, so verifying its the correct length, not binding, and in good condition, rather than just assuming its correct is smart, and BTW the steel collar prevents the shaft from being installed from the top of the block, you need to install the pump with the shaft attached from the lower block,if you forget don,t get stupid and cut off the collar and drop it in from the top, it will work temporarily but it almost always fails eventually if you do.
so ID SURE USE THE REDUCED DIAM.ARP OIL PUMP DRIVE SHAFT AND CHECK THE VERTICAL PLAY IS NOT BINDING ON THE NEXT BUILD

 

[stroker87]

the stud lower end should NOT touch the rear main bearing shell and ideally you'll use loctite on its course thread section in the main cap.

By change do you have a picture of what you talking about here?

 

[grumpyvette]

viewtopic.php?f=54&t=1192&hilit=stud

as IM sure you know if youve looked closely the stud or bolt used to secure the oil pump to the rear main cap goes thru that cap and if its long enough it will bear against the back of the bearing shell distorting the bearing and main cap, the arp studs are supposed to have the thread section to short to allow the tip of the stud to touch the bearing but you would not be the first guy to install the wrong length stud or bolt



I just got clearer more detailed pictures....
after looking at them ID SUGGEST REPLACING THE CAM

 

[grumpyvette]

9
Click on a thumbnail to see the full-size image
Properly Matching Your Camshaft and Distributor Gear


obviously youll want to verify the correct distributor gear material with the cam manufacturer, before using it and providing extra oil flow, to the gears should help reduce wear
http://www.summitracing.com/parts/LUN-89027LUN/

Matching camshaft and distributor gears is one of the most critical, yet often overlooked step in engine assembly. The proper distributor gear for your camshaft differs by both the material and the kind of lifter for which your camshaft was designed. Using the wrong material can lead to premature gear wear, possible camshaft wear and ultimately engine failure.

First off, no steel distributor gear is compatible with both flat tappet and hydraulic roller cams. This is because hydraulic rollers can be made from two possible materials and either of those materials requires a different gear than the flat tappet cam. Regardless, a steel gear is not compatible with a cast iron flat tappet cam.
check with the manufacturer anytime you have similar questions, on any valve train or ignition component.
but Id bet the stock distributor gear is what will be recommended,on any new engine build with a new cam installed.
this whole web site is designed to make it far FAR easier on guys wanting to build the required knowledge base required to learn the skills youll require to excell in this hobby.

coat any new cam and distributor gears with a good moly paste lube

READ THE RELATED INFO CAREFULLY AND USE A GOOD MOLY LUBE ON THE DISTRIBUTOR AND CAM GEARS

most stock chevy v8 distributors will use this gear. .491 diam.
https://www.summitracing.com/parts/ado-10456413/overview/make/chevrolet

many aftermarket distributors will use this gear .500 diam.
https://www.summitracing.com/parts/msd-8561/overview/make/chevrolet

bronze distributor gears are generally used on billet steel roller cam cores
https://www.summitracing.com/parts/msd-8471/overview/make/chevrolet





http://garage.grumpysperformance.com/index.php?threads/distributor-gear-wear.1701/#post-5252

http://garage.grumpysperformance.com/index.php?threads/distributor-gear-info.1186/#post-4155

http://garage.grumpysperformance.com/index.php?threads/oil-system-mods-that-help.2187/#post-5890

http://garage.grumpysperformance.co...stalling-the-intake-manifold-distributor.464/

http://garage.grumpysperformance.co...ear-articles-you-need-to-read.282/#post-61429

http://garage.grumpysperformance.co...ting-rebuilding-hei-ignitions.2798/#post-7247

http://garage.grumpysperformance.co...y-in-building-a-good-engine.11682/#post-54682

http://www.enginebuildermag.com/2009/07/properly-matching-your-camshaft-and-distributor-gear/

http://garage.grumpysperformance.co...-system-mods-that-help.2187/page-2#post-76326

Distributor Gear Materials:

1. Cast Iron

2. Composite (offers great life, conforms well to the mating cam gear, and is compatible with ANY camshaft gear material)

3. Melonized or hardened steel (material that OEMs use with factory roller cams; many aftermarket distributor manufacturers use these as the default gears for their distributors)

4. Bronze (conforms well to the mating camshaft gear and will not damage the camshaft gear, but it is a self sacrificing gear intended to be used in race applications only and should be replaced about once a year)

If you have a cast iron hydraulic or solid flat tappet cam, your distributor gear options are:

1. Cast iron distributor gear

2. Composite distributor gear

If you have an austempered ductile iron hydraulic or solid roller cam, your two options are:

1. Melonized or hardened steel distributor gear

2. Composite distributor gear

If you have a billet steel hydraulic or solid roller cam, your two options are:

1. Bronze distributor gear

2. Composite distributor gear

COMP Cams recommends the composite gear because it is compatible with all camshaft gears – flat tappet, austempered cast iron cores, and billet cores. If the steel gear is not hardened, it is not compatible with either of the roller cam types.

Note: If you have an austempered core hydraulic roller cam and a .500˝ shaft distributor with a steel gear, verify with the manufacturer of the distributor that the steel gear they use is a melonized or hardened steel material and it will work fine.

–Tech Tip courtesy of Comp Cams