Rollmaster timing chain problem?

[Nick Micale]

Over the past few months, I have heard about a few high HP Buick engines that have broken their Rollmaster timing chain?

If anyone has had this happen, please contact me direct, especially if you have the broken chain and gears, thanks.

 

[gnxtc2]

Nick

I have seen the 2 cars that had broken chains.

I believe due to the irregular lobe seperations coupled with high spring pressure from the solid roller, the chains are taking a beating. One needs to come out with a belt drive system that is much less complicated than a Danny Bee.

Also I seen a broken Comp chain in a street driven TR that broke at idle.

Billy T.
gnxtc2@aol.com

 

[summit]

I had one split on the lower gear in my street driven Stage II car.
We thought it was defective. We then replaced it with a different brand and after a few months the key sheared on the crank and bent all the exhaust valves again. Based on that we figured the key sheared the first time as well, then the gear broke when the valves started hitting. Custom made valves at $120 each being replaced a second time was not good. I then just machined the slot in the crank the full length and used straight keystock instead of the half moon factory ones. I guess they did not like 7500 rpm and 800 pounds over the nose.

On a related story the upper gear was marked exactly one tooth off. We degreed the motor about 20 times before realizing it was off exactly one tooth. Remarked it for future reference and went about our business.

Greg Kring
Arlington, Texas

 

[Alky V6]

I had one split on the lower gear in my street driven Stage II car.
We thought it was defective. We then replaced it with a different brand and after a few months the key sheared on the crank and bent all the exhaust valves again. Based on that we figured the key sheared the first time as well, then the gear broke when the valves started hitting. Custom made valves at $120 each being replaced a second time was not good. I then just machined the slot in the crank the full length and used straight keystock instead of the half moon factory ones. I guess they did not like 7500 rpm and 800 pounds over the nose.

On a related story the upper gear was marked exactly one tooth off. We degreed the motor about 20 times before realizing it was off exactly one tooth. Remarked it for future reference and went about our business.

Greg Kring
Arlington, Texas

Greg. The keys that you broke. Were those hardened or just the standard keys?

 

[odell4o8]

I must be lucky. i have used the same chain and sprockets for three years rollmaster from TA valve springs are 300lb seat and 750lb open, and it has seen 8000 rpm few times, my other stage engine has champion heads and 225 seat and 600 lb open, same rollmaster after 50 or so runs i took it apart and the chain was little loose but not enought to worry about, so i have no rollmaster problems,

 

[summit]

Well, it wasn't a daily driver by any means but it did see more street cruising duty than the average 9 flat 150 mph car. Aftert he first break/shear I tried to find a better woodruff key but it seemed they were pretty much standard with no such thing as heavy duty or extra hard. Now the replacement square stock I got through ATI and it was a hardened tool steel key stock and not your typical hardware store square key. Next time you put a chain on a buick motor notice how little of the keyway is actually engaging the lower sprocket. Most of it is in the balancer.

Greg

 

[lazaris]

Keep an eye on the bolt that holds the gear to crank. Make sure you lock tight it. They can come loose and put more strain on the key than they were designed to carry.

 

[Alky V6]

I thought TA had hardened keys for the Buick V6.

 

[laz]

Hey are all the failed chains on stage 2 heads only ? I thought the ones i know failed where on ta alumiunum block with stage 2 heads at over 1200 hp . I was thinking the alumiunum block needs more slack if it grows more and the reason i bring it up is i run an Ls1 and the stock chain are very loose and i know for a fact that the ls1 block deck grows as much as .012 when hot or under a load we set up our cold pistn to head as close as .034 and have yet to see them hit .

 

[Alky V6]

Wow. Glad I'm using a gear drive.

 

[John Wilde]

Over the past few months, I have heard about a few high HP Buick engines that have broken their Rollmaster timing chain?

If anyone has had this happen, please contact me direct, especially if you have the broken chain and gears, thanks.

Gee who told you about that???:wink:

 

[EightSecV6]

I have had 1 Rollmaster chain break and 1 top gear break on 2 seperate solid roller engines in 10 years(both belonged to Avon) and each one had well over 200 passes on it, so I would think that is to be considered reliable?

 

[oldtimer]

Wow. Glad I'm using a gear drive.

Don,

What gear drive are you using ? I've heard that gear drives don't work well in our cars ... I can't see why not .... any tuth here, in your opinion?

George

 

[Alky V6]

Don,

What gear drive are you using ? I've heard that gear drives don't work well in our cars ... any tuth here, in your opinion?

George

I'm using the Milodon competition set. I did do some modification to provide pressure fed lube oil to the idler gear bearing. It's a very quiet setup. That said, I have not come across any reason to abandon the gear drive setup. After installing a few roller chain drives on street application cars, and having to go back in for various reasons, I'm surprised by the amount of stretch that has occurred in such a short period of time. With a chain, from day one, your cam timing begins to change. A geardrive in a street application may require a check of the idler gear and bearing for wear from time to time, but at least the timing will have remained predictable for that time period, not leaving you wondering how much the timing has changed.

 

[odell4o8]

indy cars with buick engines run gear drives or the three that i bought and took apart had gear drives, kent rebeck used to run gear drives in his 7 second car,

 

[John Wilde]

indy cars with buick engines run gear drives or the three that i bought and took apart had gear drives, kent rebeck used to run gear drives in his 7 second car,

Thanks OC!

 

[GARY HARVEY]

This maybe overkill but for years, I've had the RollMaster and gears cryo'd (and coated) with regularly checking for excessive clearance. Moly/Teflon coating was used on the gear(s) and Plain Black DuPont Ind. grade Teflon on the chain without anything but a good chemical cleaning, phospate wash and a single pass of black teflon for the chain (then cook). Dropping the chain in a vessel with lube @ 100 psi on the vessel overnight to relube the chain is also a positive.
Never had key problems because of using harden tool steel stock (with a full length, not the half moon Key) staking the key and replacing the balancer bolt and measure to insure the balancer seats cleanly to the shaft for a proper fit.
Do not assume that parts all fit together cleanly, take a little time fitting things together (it) will help you sleep easier at night.
Gary

 

[Jeff Strube]

I'm using the Milodon competition set. I did do some modification to provide pressure fed lube oil to the idler gear bearing. It's a very quiet setup. That said, I have not come across any reason to abandon the gear drive setup. After installing a few roller chain drives on street application cars, and having to go back in for various reasons, I'm surprised by the amount of stretch that has occurred in such a short period of time. With a chain, from day one, your cam timing begins to change. A geardrive in a street application may require a check of the idler gear and bearing for wear from time to time, but at least the timing will have remained predictable for that time period, not leaving you wondering how much the timing has changed.

Witch Milodon are you using They List 2 Part # 13800 and 13805 ?

Will these work with Stock timing Covers with the Stock Dist?.

You said these are Quiet?.

 

[STGMAN]

rolemaster timing

I've used a milodon gear drive in my stage 2 engine since 1999, 7 second ride with no failures, did break a crankshaft but did not damage the gear drive. Did not modify it in any way. Would not work on stock block with stock cover. I tried it.
bob

 

[Alky V6]

Witch Milodon are you using They List 2 Part # 13800 and 13805 ?

Will these work with Stock timing Covers with the Stock Dist?.

You said these are Quiet?.

One gearset is the competition gearset (caged ball bearing in the idler gear)which is the only one available last time I checked. The other gearset has been discontinued.

It will work with the stock timing cover with modification. I have used the gearset on a stage II oncenter block and currently on a TA block. It was a little work to adapt it to the TA block, but it came out t?ts. Don't know about using it on a production block. Never checked it out.