Getting ready to replace engine, need opinions please.

[Jorge6.5]

So my tbi flywheel and starter will work on the vortec?

The way I understand it, the roller cam requires a melonized gear on the distributor

Thanks

 

[TylerZ281500]

whats melonized mean though? you can run a stock tbi dizzy with any roller cam, and yes just about any small block starter will work on a sbc and as long as both motors were 1 piece rms theyll swap

 

[Jorge6.5]

No clue why it's called that but from my research so far, it's what's required for the cam gear in a roller cam block so the tbi distributor works in the vortec.

 

[michael hurd]

You should be using a melonized gear on the roller cam yes, or Comp Cams and others have brass gears and now a new polymer that is compatible with a steel billet roller. Brass is recommended for race applications and would require frequent replacement ( yearly or so ) in a street application. The composite is compatible with all camshafts.

A flat tappet is made out of cast iron, using a gear that was designed for compatibility with the OE flat tappet on the steel roller is not recommended at all.

OE GM roller cams are made out of 5150 steel from what I have read, the melonized gear was developed specifically for use with that material. Most aftermarket roller cams are made out of 8620 steel.

There are different shaft diameters for distributors: most aftermarket like MSD uses .500" diameter, older HEI is .491, and TBI 'should' be .428". ( haven't measured one )

You can have a machine shop ream out a .491 to .500 if needed, but don't install a .500 aftermarket gear on a smaller shaft. Make sure you get the correct one.

The GM pn for the gear is .491" is 10456413
The GM pn for the .428" gear is 19052845

 

[Jorge6.5]

Thanks for shinning some light on that area. I plan on using my current tbi distributor with new melonized gear.

 

[TylerZ281500]

im still lost, ive never heard this before =(

 

[90W7]

Pardon the copy + paste, just a little more info..

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

First off, no steel distributor gear is compatible with both flattappet and hydraulic roller cams. This is because hydraulic rollers canbe made from two possible materials and either of those materialsrequires a different gear than the flat tappet cam. Regardless, a steelgear is not compatible with a cast iron flat tappet cam.

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 aftermarketdistributor manufacturers use these as the default gears for theirdistributors)

4.Bronze(conforms well to the matingcamshaft gear and will not damage the camshaft gear, but it is a selfsacrificing gear intended to be used in race applications only andshould 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

COMPCams recommends the composite gear because it is compatible with allcamshaft gears – flat tappet, austempered cast iron cores, and billetcores. If the steel gear is not hardened, it is not compatible witheither of the roller cam types.

Note:If you have anaustempered core hydraulic roller cam and a .500? shaft distributorwith a steel gear, verify with the manufacturer of the distributor thatthe steel gear they use is a melonized or hardened steel material andit will work fine.

 

[Jorge6.5]

That's awesome to know. Thank you for posting.

Well I guess the only other questionable part left is the crank pulley. Can i use the stock tbi crank pulley to match the rest of the front accessories?

 

[Faithful94]

What can not using melonized gear actually do can it destroy cam gear?
Can it ruin gear on distributor making it hard to time

 

[Supercharged111]

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