My 56 Merc block needed a shorter timing set due to the align bore issue. I think I used the Rollmaster, I know it came from AU. There were very specific measuring instructions, service and shipping was great. Might be worth an email if the next one doesn’t solve the problem. Last I looked they weren’t listed.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

Tried to get a new Rollmaster and no dice. Unavailable. Thanks for the suggestion. Still hunting. MIKE

Mike, still lovin his 57 t'bird after 53 years!

Unfortunately being made in the U.S.A. is no guarantee on the parts being any better than what can now be made offshore.  My confidence in new ‘shelf’ parts made in the U.S. has been slowly waning but I still have very good results with custom made parts.  While I would prefer to support U.S. manufacturers when I can, parts availability has become marginalized forcing the need to simply use parts that are simply made offshore.  As a general rule, some of the engine parts made in South America are better than most.  Timing chain sets are a good example as gears and chains may be made in different countries and then put together as ‘sets’.

When it comes to timing chain sets, I am not brand particular.  I have had issues with the best of them with many of those issues being around the key slot or dowel pin locations.  If it’s any consolation and when discussing chain sets with excessive slack or free play, timing sets that are too tight are also a problem.  Chain slack comes in second place compared to the timing issues caused by manufacturing variances.  Those gears being machined in ‘stacks’ rather than individually can account for those variances making the gears at the bottom or end of the stacks more prone to manufacturing variances than the ones at the tops of the stacks.  When I have an issue with a particular gear set, I’ll just use another gear set and see if the problem just goes away.

For cam timing, the problem can be in a multitude of places with the gear set just being one of those.   For slack in the chain, it can become more complicated.  Rotating the engine and checking the amount of slack at varying rotational intervals can help to isolate if the problem is at the gear set or potentially with the crankshaft to camshaft centerline measurement or in extreme cases, run out at the crankshaft snout where the lower crankshaft gear is installed.  For a majority of engines, the timing set installation is pretty much straight forward but there are those instances where some extra diligence must be taken to take care of a specific issue.

It’s important to note that the gears themselves may not be truly concentric meaning if the chain has a given amount of slack in one position, simply turning the crankshaft will have that amount of ‘slack’ or looseness becoming better or worse.  I prefer to check the slack amount at 90° crankshaft intervals and with the crankshaft being turned two full revolutions.  Doing it this way will isolate gear out of round issues to being either the crank gear or the timing gear.

Just some early morning rambling so feel free to throw more comments or experiences out there on this subject.

Lorena, Texas (South of Waco)

That come back and explanation was more than adequate.

THANX! for sharing your knowledge/experience ...

Just one thing, when you find a set that won't install correctly and you say you use another set, does your parts jobber allow you to exchange freely or do you keep an inventory?

 

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It is possible to have the gears plated to increase the diameter, my dad was in the platting business for 30 years, when a rocker adjuster was loose in the rocker, A run through the zinc  tank made it as new. this could be done to to timing gears, talk to your platter.

I normally do not return timing sets back to the vendor unless they are for an engine I do not deal with on a regular business.  Both the shipping costs and the 20% stocking fee are a deterrent on the smaller ticket items.  I will try those sets that did not work initially on another engine and some of those do end up working.  Manufacturing variances in the blocks would account for some of this.

For the mainstream engines and typically those that have been align bored/honed, shorter sets are available which simplifies achieving the desired amount of slack in the chain.  For the less popular engines which I tend to deal with on a regular basis, I have gotten away with measuring the gear diameters on the different sets and swapping them around to either tighten up or loosen the amount of slack in a chain set to get to where I need to be.  That's definitely not a recommended practice but I have managed to get away with doing this at times.  As little as a 0.015” difference in gear diameter can make for a significant change in chain slack.  As mentioned earlier, being too tight is also a problem and tends to be a horsepower robber.  Having a chain that's too loose tends to make the ignition timing less stable but the horsepower increase from being looser can be more than enough to offset any ignition timing ‘jitter’ that's present.

Lorena, Texas (South of Waco)

"It is possible to have the gears plated to increase the diameter, my dad was in the platting business for 30 years, when a rocker adjuster was loose in the rocker, I run through the zinc  tank made it as new. this could be done to to timing gears, talk to your platter."

Cliff, I don't think plating  would stand up to a silent or roller chain's constant wear. Sounds good for a mostly static part like a rocker adjuster though!

"FREE SAMPLE"

Yes it stays, cranks are plated all the time, I do this when it's the only thing left. you'll find when a crank or timing gear is nitrated it grows a little, the set in my dragster engine was nitrated, I had to hone the journal so it would fit the cam and the timing chain is tight.  

For the less popular engines which I tend to deal with on a regular basis, I have gotten away with measuring the gear diameters on the different sets and swapping them around to either tighten up or loosen the amount of slack in a chain set to get to where I need to be.  That's definitely not a recommended practice but I have managed to get away with doing this at times. 

It makes perfect sense to me.

THANX for the education.

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You 2 Cliff ...

The sharing of your knowledge is much appreciated ...

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