Rebuilding motor: Timing gear or chain?

[Scooterwrench]

With the old non-roller chains it was more the chains wearing into the gears as it was the chain stretching. I once had a car come in where the chain was so loose it had worn through the timing cover. It's a little hard to judge chain stretch by watching the rotor button because of gear lash between the dist. and cam gear.

 

[L31MaxExpress]

Try it yourself. Remove the cap and watch the rotor while you turn the crank back and forth with a ratchet. You will see the slack. No delay with a gear drive

All of my single roller chains move instantly. The one I put back in the budget L31 has over 100K on it too. The stock distributor has much more slack in it than the chain and that can be shimmed up.

 

[skylark]

Holy cow! Revival of a necro-thread! I didn't realize until I saw fast orange post and I was going to ask how he has been because I haven't seen him in forever.

 

[Sean Buick 76]

I really only suggest a gear drive for the sound on a carbed application. I like the sound! Using one on my new turbo sbc

 

[Schurkey]

Three kinds of "gear drives".

1. Bottom-feeder junk: Pete Jackson dual-idler style, the Asian knock-offs of the dual-idler style, and the Communist Crap knockoffs and counterfeits of decent/expensive single-idler drives.

2. Expensive single-idler drives that no-one buys any more because they won't spend the money to get a quality product.

3. OEM and OEM-style no-idler gear drives which spin the cam shaft backwards compared to a chain-drive system. When converting from a timing chain, they need a special distributor gear to go along with the special camshaft. Used as original equipment on some BBC truck engines, International SV-series engines, some six-poppers, the horrible Iron Dukes, and so forth.

IF (big IF) a person is working on an engine family that has an OEM gear-drive cam, I'm good with it. If a person is racing in a class where an aftermarket gear drive makes sense, I suppose I'd be OK with it simply because that's way out of my experience and I'd have no basis for complaint.

But poking an aftermarket gear drive onto a street-driven engine that was designed to use a timing chain system, is just setting fire to money in order to annoy people within shouting distance.

 

[L31MaxExpress]

Three kinds of "gear drives".

1. Bottom-feeder junk: Pete Jackson dual-idler style, the Asian knock-offs of the dual-idler style, and the Communist Crap knockoffs and counterfeits of decent/expensive single-idler drives.

2. Expensive single-idler drives that no-one buys any more because they won't spend the money to get a quality product.

3. OEM and OEM-style no-idler gear drives which spin the cam shaft backwards compared to a chain-drive system. When converting from a timing chain, they need a special distributor gear to go along with the special camshaft. Used as original equipment on some BBC truck engines, International SV-series engines, some six-poppers, the horrible Iron Dukes, and so forth.

IF (big IF) a person is working on an engine family that has an OEM gear-drive cam, I'm good with it. If a person is racing in a class where an aftermarket gear drive makes sense, I suppose I'd be OK with it simply because that's way out of my experience and I'd have no basis for complaint.

But poking an aftermarket gear drive onto a street-driven engine that was designed to use a timing chain system, is just setting fire to money in order to annoy people within shouting distance.

My 4L85E in my 97 is already whines enough to annoy me and the TH400 in the 87 is not lagging far behind.

 

[Schurkey]

My 4L85E in my 97 is already whines enough to annoy me and the TH400 in the 87 is not lagging far behind.

That can't be good.

Any idea if it's pump noise, or geartrain noise? Pump noise used to be common on the 400s due to air pulling past the single O-ring where the filter tube plugs into the pump housing. I always install double O-rings there. Low fluid level can do it, too--as well as old fluid where the anti-foam additive has worn-out.

Geartrain noise is pretty-much always expensive. Chipped teeth, broken roller bearings including roller thrust washers.

 

[L31MaxExpress]

That can't be good.

Any idea if it's pump noise, or geartrain noise? Pump noise used to be common on the 400s due to air pulling past the single O-ring where the filter tube plugs into the pump housing. I always install double O-rings there. Low fluid level can do it, too--as well as old fluid where the anti-foam additive has worn-out.

Geartrain noise is pretty-much always expensive. Chipped teeth, broken roller bearings including roller thrust washers.

Geartrain as it dissapears entitely in 3rd gear. I have never heard one that is quiet though.