Looking for advice on timing gear options. Charging the water pump on my 73, 350 L48. Thinking wouldn't be a bad idea to change the 50+ years old timing gears while I'm in there. Thoughts on chain drive vs gear drive? Brands? Tips on installation would be much appreciated! Thanks in advance!

 

Cloyes double-roller street set: ~$40-$50. You don't need anything more for a normal street engine under normal driving conditions.
(https://www.summitracing.com/parts/c...ake/chevrolet)

You'll have to pull the oil pan to do it right since the timing cover's and pan's lips mate. If you attempt to pull the cover without the pan off, you will likely severely bend the timing cover sealing surface.

 

12 years ago I had my 50,000 mile original GM nylon timing gears changed to a Comp Cams Magnum double roller timing set. I've had no issues. To my surprise, the condition of the original set wasn't too bad; Just slightly loose.

 

On a stock motor pretty much any of them will work.

 

Yes you need to drop the oil pan. Which means lowering the drag link, yes you need to pull the Harmonic balancer, which could really, really be on there on a 50 year old engine. Then, the timing cover. So order gaskets and seals as necessary.
Any good replacement timing chain set should be fine. Gear drive is silly overkill.
Yes it is likely really worth all of this if your chain and sprockets are original.

 

May also want to look at a Rollmaster, quality stuff

 

Timing gears give a strong whine like a big blower belt versus a timing chain/ gear set and are twice the cost of a stock engine quality chain. Even the quiet ones will be heard before you show up. While the gears are accurate and give no slop a GOOD chain will last many years. Generally you get what you pay for, dont go cheap, dont buy chinese. Your engines life depends on it.

A stock motor only needs a good quality chain/gear set


Shop Summit for good choices

 

Thanks everyone for the advice. I'm mechanically inclined but not a 'mechanic' so all the input is very much appreciated. I have the 73 assembly manual and regularly view YouTube but the advice here is invaluable. I've learned so much by doing 95% of the work myself. At 63 years old, I've had my share of hot rods back in the day but haven't had one in forever. I'll keep you posted on the progress. Thanks again!

 

Schweeet Corvette!

Any part that comes off will be replaced with a new part while re-assembling the engine.

You can't use age as even I am "older" than you are....Lots of us are... "We Are Wise" in the forces of Corvettes even though we may be old...

Lesson #2. NEVER, ever, give any of your car's parts away as "CORES", pay the core fee and keep the original parts. Buy yourself a copy of the Factory Service Manual for you particular year as well as the AIM you have.

RockAuto sells the factory service manuals and AIM's on DVD's for a relative bargain. They have a good collection last time I looked.

We used a Cloyes Timing Chain the last time and it has been nothing but quiet and working beautifully. My engine builder was picky about the timing Chains and pitched the other brand chains that I already had..

It all depends on what you are going to do to your cool Corvette. I just drive my Corvette with a few hard pulls here and there. If I were going to race every weekend then I might buy "Belt Drive" as they are supposed to absorb the harmonics inside the engine very effectively. The "Gear Drives" offer precision that would be hard to beat but make noise at minimum and a Racket when using the noisy version.

A stock timing chains on a SB Chevy engine should be a good way to restore some last power and do it quietly. A stock chain is fairly easy as long as you don't mess up the relationship of the gears. You don't want them to move while installing a new chain.

 

Just a tip here.

Before removing any timing set: With the timing cover off, jog the IGN key until the crank sprocket and cam sprocket marks are aligned for # 1 cylinder.
Then you will know that the new timing set will be spot on when installing.
No second guessing involved, no alignment issues, no TDC of the wrong cylinder.

And you can look for a locking plate for the cam bolts. Used to be around $6, cheap insurance.
The locking plate tabs keep the cam bolts from ever backing-out which would be catastrophic failure of the valvetrain.

 

Thanks again! Great information and education!

 

I replaced the original nylon timing chain/gear set on my 300hp ‘69 last year. It now has a Cloyes 3023CK that is listed as a heavy duty double roller ($40 ish) The box was labeled Made in USA. My car is stock and not raced so going crazy with an expensive chain set wasn’t needed. There were also cases where certain high performance chain sets required clearancing on the block and that wasn’t for me. Do a ton of searches and reading before taking the job on. Invest in good pullers for the damper and crank gear. It is possible to do the job without pulling the pan which is what I did. But if I had the time the pan would have been dropped. I had not done a timing chain in over 40 years and it all goes smoothly if you read up and ask questions.
Before you take anything apart, take pictures of all the bolts and washers that hold brackets and the water pump. You’ll never remember what goes where even if you bag and label stuff. If I knew about the lockplate for the cam gear there would be one in this picture.

 

As long as we're tipping...

I prefer to place the valvetrain at TDC #6 (crank is at the same spot but the cam is rotated 180° from #1). This places the timing set's alignment dots at 12:00 crank and 6:00 cam -- much easier to get them visually lined up rather than 12-12 for #1. As long as the distributor housing was not moved or removed during the chain replacement, it should fire up without any extra steps. After warm up, check timing for the new chain.

To install the crank gear, put it in a 200° oven for 45-60 minutes. This will enlarge the bore so it's a quick slip fit onto the keyed crank snout. Quickly move from oven to engine. Once it cools, it'll shrink down in a few seconds and be unmovable without a puller.

 

I've used the basic $40 Cloyes sets for years.....in big blocks with valve springs you can hold up a house with...and RPM into the 8000 RPM range....

Never had a problem with wear.

Look at the rollers on the chain. You want one with a roller without a separation line where it's been made. Good ones have a roller with no lines.

No need for a "boutique" over-priced gear set. Many are just reboxed...but do pay attention to who's name is on it. There is some real cheap offshore stuff out there.

Now that said...Rollmaster makes good stuff too...it will definitely go on tight in my experience. I've tried some that actually wouldn't bolt in place!

JIM

 

While you’re there:
1. Timing chain housing seal
2. Repair sleeve for balancer hub to seal surface
3. New balancer
Any combination of those parts can be worn. You’re there, good time to fix it now.

Steve O.