I just read a post here that indicates that with a 460 it's a good idea to change the timing chain after 50-75,000 miles. I'd appreciate hearing more about this from you good folk; I had heard elsewhere that it was not necessary. Advice?

 

I am no expert but...

Most timing chains are good for well over 100K miles. It doesn't hurt to change them earlier but it may be a waste of money.

Chains do not wear out and fail as catastrophically as belts, which do need to be changed every 60K or so. Maybe that is where you are getting the advice? Some one might think all cars use belts requireing regular replacement?

A chain will start to stretch over many many miles and cause vairations in timing, but suaully this is not noticable until well past 100K.

I could be wrong on a 460, but as durable as these engines appear to be, I would think we would have heard on this webpage about any significant problems by now.

I in my personal experience have never seen a broken chain or heard of one from any of my close associates in over 30 years of tinkering. I am sure they do wear out and some break, but it is rare in my opinion. Belts are another matter, replace at 60 to 80 or your engine dies a horrible death.

Just my opinion,

Jim Henderson

 

Timing chains do stretch and may start doing so in little as 40-50k miles. This will make it harder to maintain your correct timing and may cause it to flucuate depending on engine load. Where most of the problem lies in a stretched timing chain is on the ones that have nylon timing gears, they are much more prone to having the chain strip the teeth on the sprockets or jump time. I'm not positive but I don't think the 385 series ever came with nylon timing gears...at least not on the trucks. I'm sure someone will correct me on this if I'm wrong
Deen

 

I just finished the job of fixing a leaking timing cover and while in there replaced the timing chain and gears (went with the pre-emission set to advance the cam timing). The chain was noticeably stretched and this retards the cam timing. I’m not sure of the mileage on my truck, but I am guessing it is in the 150K range. And Deen, it did have nylon teeth on the cam gear.

Having said all that, I would not go into the engine to replace the timing chain at less than l00K miles. But, if I were in there anyway I would replace it if it showed any stretch and because they are so cheap.

Good luck,

Mark

 

They do stretch, I've seen them on high-mileage engines where they looked ready to fall off. Like others, I wouldn't change one unless performance had a noticeable drop from retarded timing or i was in there for something else.

 

By the way, one test to see if a chain is stretched is to use a timing light. If the timing mark flutters a lot, then you may have a stretched chain.

If you do replace, go with a good Double roller or one of those new silent chains, I think they are called multilink or something. They look like 5 or 6 flat links side by side and use I think a steel gear. I could be wrong on the silent chain since it has been a long time.

The double rollers are good and strong but make a little more noise than stock.

Jim Henderson

 

Wstrombe -- Here's a picture of the timing chain on my 460 -
<< http://www.beedzncomputers.com/truck...ng/timing.html >>maybe it'd help you a little.... in the pictures, I am setting the cam and crank "straight up"....

Hoping this helps ~~~~

 

Many thanks for these great responses. What a great help!

On that Cloyes gear: What is the upside and downside to performing that change? How much does the gear change alone accomplish? Any problem with street-legal in 50 states?

Thanks again to all respondents.

 

I replaced my set with an Edelbrock roller set, set to straight up timing, thus advancing the cam timing 4 degrees from factory. I didn't notice a great deal of performance increase, not near as much as with the carb and headers, but any little bit helps. This is NOT smog legal, and my truck will not pass smog in california with this setup. The retard in the cam timing was for cleaner emmissions at idle. Unfortunately, this makes it burn more at speed, but go figure.

When I removed my original timing set (90,000 miles) it was very tight with VERY little noticable slack, and this truck had been quite abused before I got it.

I would not go through the hassle of changing the gears unless you need to.

 

Did your MPG improve by changing over to the advanced valve timing? I hear conflicting stories on this. Some say much better performance, others say not so much.

 

I noticed a BIG difference with going with the lower 429 crank gear. The distributor needs a performance advance profile also to see gains. Cause the distributor is SMOG also !

The MAIN reason to change the cam gear early is the fact its made out of NYLON !!

My 460 was shot at 75K !!!

 

I am half way done replacing my timing set in a 83 460 motor, and once i got to the timing chain, i could move it one inch side to side, and half the teeth were almost gone, and it was nylon. The motor has around 170k, im not sure though, it came out of something else a guy was selling in the newspaper.

 

Speaking of timing chains,What do you set the timing on a 429.Not sure what it came out of,but it is in a78 bronco now.Casting number is dove and i think a 7 or something.TIA Tim

 

Does my 1989 F250 with 460 come with nylon cam gear?

How hard is it to change the timing chain on that truck?F250 heavy-duty.

 

My 93 had a steel gear. I had 204,000 miles on my truck when I changed it out. I wish I never did because it took me all day. The chain was pretty loose but I wouldnt think it would fall off. This spring I am pulling the motor for a fresh 460 that is in my shed right now.