Dave27

I read a guy on hear found all the plastic had come off his timing chain gears and clogged up his oil pump on his L79. My L79 has 64,000 origonal miles on it and I started it the other day for the first time in 10-12 years and it ran great. My question is do you guys as a routine maintenance thing change the gears and chain to a double roller just to be safe. I have easy access to mine due to the front clip is off the car,should I do it or as the old saying goes "if its not broke dont fix it"Thankyou....Dave

Mark Riles

After 64K miles I would think it would be a good idea to pull the timing cover and at least inspect the chain for slop. I doubt you have the nylon coated gears. I think they were a short lived replacement part installed during service and not installed when the engine was originally built. I could be wrong about that though. If you find slop in the chain, buy a new timing set and replace both gears with it.

Dave27

Oh so they didnt come stock on the L79.Mine is an untouched L79 so whatever came stock on it is still in it.

Mark Riles

I don't know that for sure. However, no harm in checking. You can check for slop and to inspect the gears.

Marlin

Yea if the front is already off I would pull. I would even put on a basic roller one if it was me.

63mako

I am 99% sure that engine came with a nylon gear set from the factory. The material breaks down and disintigrates over time, heat, oil exposure and wear and the factory chain stretches, more so on high powered engines. I would change it out if it is easy.

Easy Mike

No. Changing a timing set is not routine maintenance. It's usually a "have to" situation.

Just the same, since you have the access with the clip off, probably would not hurt to make the swap.

Jims66

New chain with steel gears or you'll worry everytime you're running down the road. Do it and don't look back...

Jeff_Keryk

Replace that chain and gears.

loup68

Dave27, I'm the guy that you read about. Mark Riles, I beg to differ, but I was always told that they all had nylon teeth for quietness from the factory. Dave27 my chain on my 68 went in 1975 with only about 43,000 miles on it. Change it to a steel double roller,Lou.

Vette5.5

Another vote for changing the timing set out. If you're going through all the trouble pulling the brackets, balancer, and front cover for inspection, may as well have the parts ready for a swap out. Helped a buddy repair his moms Chevy wagon as high school kids, and the cam gear looked like a ring of nylon, with little nubs on it. This was one of GM's brainstorms, called a "Quiet Gear". Wonder which genius came up with this one.

Dave27

Ok you guys talked me into it. I'm going to pull the cover this week.Which leads to another question. I dont plan to pull the pan unless I see all the teeth missing from the gears. I know there is a trick to reinstalling the cover without disturbing the oil pan. Does anyone have exact directions you could give me as to doing that. If I remember right dont you nip the corner at a 45 degree angle on the inner edge of the groove on the timing cover and then squirt alittle extra sealer in there. Everyone i have seen remove the cover and not the pan has leaked so I want to make sure I do this right......Thanks much guys.....Dave

7t9l82

i vote for a pan gasket too it isn't alot more work. and yes the nylon gear was factory installed and as they go bad trouble is around the corner so get it as soon as you can

jyounane

It will fail....just a question of when and where!

I wish someone had warned me about this. You can spend $200 now or $5000+ later. In my case, the cam stopped turning when the timing chain slipped on the broken nylon teeth at 4000rpm. It bent valves etc. on my 69 L36 with 53k miles...full rebuild required.


Joe

john 72-04

Front clip off and easy access do it. Lower the pan and do it right or you stand a good chance of bending the cover lip and it will leak. You don't have to pull the pan out just lower it. Chain and gears timing cover seal kit pan gasket no more then $100.00 at advance auto parts. Easy job.

Dave27

Ok done deal I'll probly start on it tonight after I drop off all the front end parts to the sand blaster then off to the powder coaters they go.Thanks for the advice.....Dave.....Oh the L79 in a 1968 is just a standard timing set correct or is it large journal or small journal specific......Thanks.....Dave

Vette5.5

Since the mention of Advance Auto, maybe order online, as you can usually save 20% that way. Just pick up instore, an hour or so later. If over a $100 purchase, they'll sometimes send you a $50 code towards a later online purchase. I used all their perks, and they work.

Dave27

Picked up all the parts at my local Carquest they even had a true double roller from edelbrock someone had ordered and not picked up.Timing chain set,gasket set and oil pan gaskets came to 70.00 not to bad. I'm going to start taking it apart tonight.As I take it apart my wife is going to clean and repaint the parts so it should go back together fairly quick and look fresh and new at the same time

Professor Fate

A double roller timing chain may require some block clearancing behind the cam gear area. Check for interference closely and if you do need to grind off some humps make sure you protect the open parts of the engine.

Dave27

Ok thankyou I'll check it out. From what I have read though its supposed to fit purfect as well as fit under the stock timing chain cover but I'll check it out.