Best Timing Chain Set

[Trenton]

My 1998 truck has the 5.7L L31 Vortec engine with 255k on it, and I want to replace the timing chain. I know it has slack, and the timing cover leaks so why not change it while I'm replacing the cover? I'm not sure at all which timing set to get. I would get Rollmaster, but I don't need something of that quality. I want something of OE quality. There's also the problem of inverted tooth vs single roller chains. Do engines require a certain type or can I choose which one I want? This would be a great help please and thank you!

PS I can't find timing sets for ACDelco but I can find just the chain. I'd like to replace the sprockets, too.

 

[df2x4]

I'm interested to hear some opinions on this as well. My '97 K1500 Suburban is also leaking from the timing cover front seal and I've been thinking about having the timing set replaced whenever I have that taken care of.

It looks like the ACDelco part numbers for the timing gears in the Vortec 350s are 10128346 for the crankshaft gear and 12552128 for the camshaft gear. The chain is 14087014.

https://www.gmpartsdirect.com/auto-...rim/5-7l-v8-gas-engine/engine-cat/engine-scat

Side note... I made a similar thread recently about Vortec 350 timing covers and another member turned me on to these Holley aluminum ones. They have a natural finish (21-152) and black (21-153). I bought the natural one and will be using that instead of the OEM plastic style.

https://www.summitracing.com/parts/hly-21-152

https://www.summitracing.com/parts/hly-21-153

EDIT - Here's a link to that thread I made about timing covers. It's a good read. @Schurkey brought up some good points, like the fact that the harmonic balancer may have a groove worn into it from the timing cover front seal.

https://www.gmt400.com/threads/96-vortec-5-7l-timing-cover-valve-cover-gasket-recommendations.43771/

 

[Schurkey]

What you have for a timing cover may affect the choice of chain/sprockets you can use.

You have a 5.7L Vortec engine, you're not going to be installing a double-row timing set.

Remember also that the OEM step-nose roller cams have a smaller bolt-circle on the front of the cam, so a timing set that fits a flat-tappet cam isn't going to fit the step-nose OEM roller cam.

I rebuilt a 5.7L Vortec last December. No idea how many miles were on the short-block, which was taken out of service because of a "rod knock" that turned out to be a broken flexplate. I re-used the timing set. When I degreed the camshaft, I was within one degree even with the used chain 'n' gears. It's hard for me to complain about OEM parts when I can re-use them.

I ordered--and returned--one of these. The package I received had a single keyway on the crank gear. If you receive the multi-keyway unit as advertised, it's probably a good deal.

https://www.summitracing.com/parts/clo-9-1157

 

[GMTNZ]

I’d be interested to know what y’all think is best for a TBI 350 too. Looking to replace the cam in my 94 with the comp 12-249-4, thought I’m best do the timing set as well and front seal with 185k on the clock, probably do the distributor too. Sorry to hijack the Vortec thread.

 

[c1500deathtrap]

Single roller. Would also fit under the holley aluminum cover posted earlier. I hate Hyvo chains. https://www.summitracing.com/parts/nal-12371043

 

[arrg]

Single roller. Would also fit under the holley aluminum cover posted earlier. I hate Hyvo chains. https://www.summitracing.com/parts/nal-12371043

This is the timing set my L31-R crate engine had on it from the factory. I guess GM didn't like the original design either. The oil gallery plugs behind the cam gear were drilled to provide better lubrication to the timing set also. It was cool to see that on stock replacement engine.

 

[upper_tanker]

Comp Cams lead me to buy a double roller set for my L31. Obviously, it didn't fit. I did some research and ended up going with Cloyes. I have probably 10k on the build and still have no issues (which isn't saying much, I know...).

 

[Supercharged111]

I used an adjustable Cloyes single roller back in 2015 on my 1500. Straight up it was within .5 degree of spec, but at least I had the peace of mind of adjustability and a beefy single roller, not like the bike chains used on the 4.3 and LT4.

 

[Schurkey]

I’d be interested to know what y’all think is best for a TBI 350 too. Looking to replace the cam in my 94 with the comp 12-249-4, thought I’m best do the timing set as well and front seal with 185k on the clock, probably do the distributor too. Sorry to hijack the Vortec thread.

https://www.summitracing.com/parts/cca-12-249-4
You're nuts to install a hydraulic flat-tappet cam in an age of OEM roller cams, unless your engine block casting won't accept OEM roller lifters.

First Guess: OEM roller lifters will drop right in. All the parts to make it happen are thick on the ground at any Treasure Yard, or as close as Summit, Jegs, or a GM dealer.

Again, the flat-tappet cams use a different timing set than the OEM step-nose roller cams. Get the right timing set to match the front of the camshaft.

The oil gallery plugs behind the cam gear were drilled to provide better lubrication to the timing set also..

The oil gallery plugs are vented, but NOT "to provide better lubrication to the timing set". They're drilled to bleed air out of the system at engine start-up. Otherwise, the air in the gallery had to escape by going through the lifters, making them noisy until it bleeds out the rocker arm spurt-hole.

If the timing set gets additional lube from the vented plugs, that's a coincidence more than an intended result.

 

[PlayingWithTBI]

IIRC - some 94s and 95s either don't have bosses for the spiders or, they're not drilled and tapped (think in late 94 was when GM changed it). 88 - 93 were. I priced a roller vs a flat tappet @ Summit Racing, after everything was said and done ~$500 more for the roller cam...