james_fearn

Does the ZZ4 cam require a bronze distributor gear?

I was told that GM roller camshafts have a cast gear for the distributor pressed on, including the ZZ4 cam. Can I just put in my 85 HEI distributor, without changing gears, into my new engine w/ a ZZ4 cam?

James

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1985 Z-28 305 TPI
165 ECM,STB,SFC,GW "wonderbar"

five7kid

iTrader: (14)

GM uses what they call a "melonized" gear P/N 10456413 for their roller cams. It's not bronze, but (as I understand it) has a special surface treatment to allow it to stand up to the harder cam.

Absolutely do not just put in your '85 HEI, though. Early death will result.

Funny, that melonized gear isn't listed in their HO 350 conversion kit. Should be, since they have you reuse your old distributor.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam and intake, World 305 heads, Hooker headers & y-pipe, 3" Catco cat & 3" cat-back).
57 Bel Air, my 1st car. 0.030 over 396, 9.7 CR forged TRWs, Weiand Action+, Edelbrock 1901 Q-Jet, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlock header mufflers, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, LT MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Best 15.1/95.5 @ 5800' Bandimere.

JB22

5.7 would that be the same gear that came stock on a roller LB9 ?

Also, whats your toughts on the slight up and down play that is on some distributors? could that cause the gear to get eaten up?

five7kid

iTrader: (14)

Same used on LB9, L98, LO3.

I haven't heard of excessive play causing gear wear, but I suppose it is one possibility. The angle of the gears should keep the shaft in one place.

JB22

OK, I am going to monitor this gear and see how it goes.

Thanks 5.7, you always are a wealth of knowledge

JB22

5.7, so I put in the stock dist. gear from my LB9 into my 350 with ZZ4 Cam and drove it a little bit, then pulled the dist. to see whats doin.

Sure enough, starting to wear a groove into the teeth again

Im not sure what to do now.... im baffled.

I do have a high volume oil pump, could that be causing it?

Could the cam gear itself have gotten worn and causing this?

Need help badly here !

five7kid

iTrader: (14)

Should probably update my original response, as I've gotten older and wiser since then:

Apparently the factory started using melonized gears before they started using roller lifter cams. How far back, not sure, but someone said late 70's. So, it's probably not an issue with any factory 3rd gen gear.

JB, see my response to your PM.

(I see my sig in that original response is my old one - from back before a vB version change, I suppose. Interesting. . .)

WhiteHawk

High Volume vs. High Pressure.

I can see high pressure adding more load, but with the high volume, with an educated guess, means the oil passages and/or rotors are larger to pump a larger volume, if that equates to more load then so be it. I'm about to assemble a used engine w/ ZZ4 roller cam using a high volume, but that is because my bearing clearances are large. Now i'm scared to use this dang cam

five7kid

iTrader: (14)

I've been running mine for 2 years with no problems. I think JB had another issue that hasn't been publicly disclosed yet.

I do agree, though, that high pressure puts more load on the distributor gear than high volume. The difference between standard and high flow is the gear length. Whatever flow isn't needed for the output pressure is simply dumped back into the oil pan. The flow that is bypassed takes next to no power to produce.

Oh, I'm also running a ZZ4 take-off oil pump. Has around 80 psi when I first start it up, usually runs around 70 psi when warm. More than necessary, but doesn't bother me any.

JB22

Dont be afraid of the cam, its a good one.

My issue is not the cam. I believe I have located the issue though.