Let's compare timing chains versus gear drives

C

clutchdust

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I think both have advantages and disadvantages, I'm just trying to figure out which has the most advantage.
From what I've heard, the biggest problem with gear drives is "spark scatter", while it's main advantage is it never loses timing.
A personal experience I have with chains is that anything less than the top end chains and you run the risk of knocking the teeth clean off. I put in a decent Cloyes chain on my overhaul some years back, then later when that engine bit the dust I pulled it apart to discover the cam gear had eaten nearly half the teeth! If going with a chain, and you're hard on an engine, get a set where both sprockets are heat treated.
So what's everyone else's take on the comparison?
 
In '97, I was told the planned gear drive for this basic ZZ4 engine build was not a good idea, because of interference with the knock sensor, so I went with a Cloyes double roller, a few months ago I mentioned that to a old buddy of mine and he laughs, saying I would be totally shocked to see that chain today, he says it's all stretched and a mess...~100k and pushing 13 years...:smash:

I lazy, wait for the water pump to fail, look at it then....

:clap:
 
Seems like a chain would be more prone to spark scatter (slack in the chain).

Noise is usually an issue for gear drives.
 
Actually no, the gear drive transmits harmonics and is not as steady as you may think it is. In that respect the belt drive would be the best option.
 
BBShark said:
Seems like a chain would be more prone to spark scatter (slack in the chain).

Noise is usually an issue for gear drives.
Click to expand...

That is the one thing that bugs me, my computer is a speed density like a '91 F body, and so at idle the timing jumps all over the joint like the computer can't make up it's mind, this confirmed via the reader and the timing light, now I pull the set timing plug, tan/blk wire loose and it's steady as a rock.....

it's been this way for a LONG time, but it is my RECOLLECTION that my '87 and the first install of thei TPI on the L48 engine did not do this....

chain wear??

:crutches:
 
Twin_Turbo said:
Actually no, the gear drive transmits harmonics and is not as steady as you may think it is. In that respect the belt drive would be the best option.
Click to expand...

I surprised there is that much lash in a gear drive. I've seen a couple of degrees in chains.
 
BBShark said:
Twin_Turbo said:
Actually no, the gear drive transmits harmonics and is not as steady as you may think it is. In that respect the belt drive would be the best option.
Click to expand...

I surprised there is that much lash in a gear drive. I've seen a couple of degrees in chains.
Click to expand...

Kind of curious about how much actual degrees lag/instability there is to the rear cylinders from cam twist with loading...torsion??

wonder how that translated into valve actuation.....:twitch:
 
Kind of curious about how much actual degrees lag/instability there is to the rear cylinders from cam twist with loading...torsion??

wonder how that translated into valve actuation
Click to expand...
Well, I guess the push rod motor has never been the most efficient ( as in mechanically not mpg) engine design. Convenient but not efficient.

As far as cam twist, I guess you would never be able to measure it accurately.
The cam lobes are probably what, ground within .5 degree accuracy, maybe even 1 degree?
Anybody ever degree a cam first on #1 then #8?

Gear drive vs chain?
I thought about a gear drive for my (soon to happen) build but even though the sound wouldn't bother me (i think) I'm not sure I would want to drive around with that "souped-up" sound.
It's generally recognized as the sound of a bad-ass motor and it's going to make me look bad if I get beaten at the light.
 
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BBShark said:
Seems like a chain would be more prone to spark scatter (slack in the chain).

Noise is usually an issue for gear drives.
Click to expand...

Timing changes, yes, spark scatter, no.:confused2: Maybe you just reached for the wrong term.:)
 
That's basically the chain I'm considering. I learned from that last motor that if you like to spend any time at higher RPM, a cast chain gear is a crap shoot. The latest motor I put in the Vette has a chain set like that. The motor I'm building for my Datsun track car, though, I don't really care about what noise it makes and it's going to spend some time at high RPM.
 
A double roller with the split bushings. Been using them for years. Some are ever pre- stretched. Cloyes was the first to make these. Put one in 88-reused it on current motor. Generally you get 2 degrees retarded with a stretched chain. I hope this helps.
 
mrvette said:
In '97, I was told the planned gear drive for this basic ZZ4 engine build was not a good idea, because of interference with the knock sensor, so I went with a Cloyes double roller, a few months ago I mentioned that to a old buddy of mine and he laughs, saying I would be totally shocked to see that chain today, he says it's all stretched and a mess...~100k and pushing 13 years...:smash:

I lazy, wait for the water pump to fail, look at it then....

:clap:
Click to expand...

No need to wait. Last summer, I changed heads, cam, valve train, etc., on my son's 96 LT1 with 115K on the clock.

The chain I removed 9to be replaced with a new GM set) had no more slack than the new one. Probably due to the improved block oiling. I could easily have re-used the stock chain and saved myself that $$$.

Then, months later, I read that LT's aren't hard on chains; DUH!

Jake
 
tfs-41478510_w.jpg

that looks an awful lot like the summit brand billet set

sum-g6610-b_w.jpg

I have used those with good success, they are really nice. They come with a torrington bearing, looks like a quality piece. No report on durability yet though. Haven't pulled one of them yet (not many miles on any of them)
 
Summit does have the billet steel house brand for BBC, that's where I got the pic. The part number is SUM-G6610-B it's a little under $70
 
One more twist, look at this from Jegs. The house blend. Cost more than the TF and looks the same as the TF and Summit. Made in the USA.

555-20420-1.jpg
 
a lot of the summit and jegs stuff is just re-branded stuff. looks like we found who makes them.
 
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