What's better A timing chain setup or a gear drive setup

[1980RS]

I know a belt drive is the best, but I had a buddy over today asking me why I was selling my cam gear drive setup for a BBC. I asked "why? is there something wrong with a chain setup?" Me personally, I had always thought there were to many harmonics with a gear drive even though the noisy ones sound cool. So which is better and why?

[Tom68]

Roush tested the various cam drives, there's an SAE Paper on it.
Didn't test belts, rejected for low tensile strength.
HyVo type chain sucked up the least power from memory.
Paper would be mid to late 90's.

[ChopperScott]

I don't have an answer to your question, but I personally chose a billet double roller after contemplating a gear or belt drive.

[rebelrouser]

I always use a roller chain unless I have close piston the valve clearance. A chain will always stretch a little, and retard the cam timing at high rpms which is beneficial for power production. If I have really close piston to valve clearances and don't want to machine the pistons for more relief a gear drive set up holds the cam timing much tighter.

[ClassAct]

Roush tested the various cam drives, there's an SAE Paper on it.
Didn't test belts, rejected for low tensile strength.
HyVo type chain sucked up the least power from memory.
Paper would be mid to late 90's.

Do you have a link to that paper? The one I found tha I think was by Roush only tested a dual idler gear drive.

[ClassAct]

I know a belt drive is the best, but I had a buddy over today asking me why I was selling my cam gear drive setup for a BBC. I asked "why? is there something wrong with a chain setup?" Me personally, I had always thought there were to many harmonics with a gear drive even though the noisy ones sound cool. So which is better and why?

If you are not going to buy a fixed idler 3 gear drive don’t bother. Dual idler gear drives are junk. I’ve been running gear drives since 1986, never had a failure and not a single sign of an unhappy valve train. I won’t use anything else.

[Tom68]

Do you have a link to that paper? The one I found tha I think was by Roush only tested a dual idler gear drive.

I have the paper somewhere, don't know if it's online.

[rebelyell]

FWIW and in general --- SAE isn't a "free lending library" --- SAE sells its papers to both members and non-members.
Yes, we may find the occasional SAE paper which someone has scanned and posted outside SAE.

[lefty o]

ive owned and used a number of different gear drives over the years, and personally for me, ill take a good double roller 99 times out of 100.

[ClassAct]

Do you have a link to that paper? The one I found tha I think was by Roush only tested a dual idler gear drive.

I have the paper somewhere, don't know if it's online.

Would you mind (if you can find the paper) taking a look at it and letting me know what gear drive(s) we’re tested?

TIA

[Walter R. Malik]

Just curious, Why did Chevrolet make single roller timing sets with huge motorcycle type drive chains for a while but, not anymore...?
I used them a lot until I couldn't easily get them anymore.

I did use a Milodon three gear drive set-up years ago on S.B. Chevy Trans-Am 310 engines and had no issues.

[rebelyell]

Just curious, Why did Chevrolet make single roller timing sets with huge motorcycle type drive chains for a while but, not anymore...?
I used them a lot until I couldn't easily get them anymore.

I did use a Milodon three gear drive set-up years ago on S.B. Chevy Trans-Am 310 engines and had no issues.

dunno if GM made those or if supplied by likes of Cloyes, Melling, SA etc?

BIG 1/2" pitch HD SINGLE Roller chain for SBC
cloyes numbers follow --- perhaps can xref to melling etc.
chain alone 9-4149
several sets early v. late, 1 or 3 keyway etc

replacement grade
C-3055
C-3092
performance grade
9-1157
9-3157x1
9-3157

[Tom68]

Do you have a link to that paper? The one I found tha I think was by Roush only tested a dual idler gear drive.

I have the paper somewhere, don't know if it's online.

Would you mind (if you can find the paper) taking a look at it and letting me know what gear drive(s) we’re tested?

TIA

Will do, when I get to that location next, hopefully over the weekend.

[jsgarage]

FWIW, in my opinion a 4-steel-gear drive is more durable and precise than a chain on a street car, as the engine in question is a 351-Cleveland with a cam that redlines that big heavy valvetrain at 6500 rpm. Especially since that area of any V-8 pushrod engine is lubed by random splash, which is probably less effective the faster you spin it. But since the car is also a daily driver and I have normal hearing (and wish to keep it), I use the best double-row true-roller chain I can find. Cam chains are a consumable item like wiper blades & tail light bulbs for this engine. I get about 25K miles per chain set before static ignition retard tells me that wear is affecting that area. YMMV-

[quickd100]

I use a Milodon geardrive on my 605 Hemi. Things are a bit close inside the block. I've got .060 cam lobe to connecting rod clearance on 4 lobes.