Dump the gear and go timing chain?

[HouseofSpeed]

The opinion of chain life in the BUICK V6 by Jim Ruggles. (naturally aspirated applications)
"Engine builders will argue ad nauseum about the relative superiority of chain and gear drives. With regard to a V-6 engine, such arguments are irrelevant. Due to reverse acceleration of the valvetrain, chain drives will have a very short life."

More of his opinion coming up.

Without a tensioner...when the chain goes slack and the valvetrain gains speed on valve closing events there is opportunity to "jerk" the chain, somewhat akin to freewheeling a bicycle sprocket and losing the chain....but when that slack is controlled mechanically or hydraulically that concern has no merit. Truly that reverse acceleration concept has to apply to any OHV application, correct? How would a Buick V6 differ in that regard to a Chevy V6 or a Ford V6?

Nowhere in your quote does he spell out a Buick application...or even a racing application. My question for Jim would be why do we not see gear drives on factory applications? If a chain is such a no-no....how could hundreds of manufacturers through the years have used chains and racked up millions and millions of miles on said engines with chains? They had to pass durability testing to even make it into production.

 

[HouseofSpeed]

I asked about chain technology specifically, but thanks for your suggestions. I also want to say, I do appreciate your responces. Thank you.

I enjoy the discussion Donnie....its hard to find a good automotive debate these days!! Truly, I am on your side...understand where you are coming from.

 

[HouseofSpeed]

I think the belt drive issue is availability and cost as the main issue which is why more people are not using it.

I think there is merit to that Cheese...but as expensive as it is to run a Stage setup....what's another grand or $1500 in the scheme of things?

 

[Alky V6]

Example is that chain tensioner design in that picture I supplied....takes care of a lot of the problems Jim saw with chains back in the day. That is a fabricated cover and mechanical chain tensioner that could be built for a Stage engine as well.

Again, I am giving you examples of engines that see far more abuse than a Buick V6 and in some cases are of a more fragile construction....I know you have tunnel vision on this topic...but there is no inherent frailty to the Stage 2 which would cause me to say that what works on a NASCAR V8 from a design and tech standpoint would not work on a Buick V6.

Again, a quote from Jim Ruggles.

"Whether the cam selected is of the "plain vanilla" or super exotic variety, it must be hooked to the crankshaft in some manner. Some engine builders prefer chain drive, others consider gear drive to be superior. With a V6 engine gear drive is preferred because adequate piston-to-valve clearance is maintained. Due to the reverse acceleration of the valve train, timing chains stretch excessively in a six cylinder race engine. The situation is made worse as valve spring pressures are increased, and due to the valve train componentry and rpm level at which a Grand National engine runs, a good deal of spring pressure is required.
The valvetrain used in a Buick V6 is very similar to that of a big block Chevy and consequently the same liabilities apply. Both engines have long pushrods, virtually identical valve lifters, high ratio, heavy rocker arms and long valve stem valves. (A Buick V6 has a camshaft with a small base circle). Valvetrain mass requires a healthy dose of spring pressure to keep valve action precise. The only negative aspect is timing chain life; with 25% fewer lobes than a V8, the reverse acceleration of the camshaft in a V6 is more severe so timing chain life is short.
While a timing gear drive is considerably more expensive in terms of initial purchase price, over the course of a single racing season, it will actually be more economical than a chain drive because it never needs replacing (barring a catastrophic engine failure). Another advantage is that gears don't stretch like chains so cam timing remains consistent.
On the other side of the coin, there are theories that harmonic vibrations in an engine will be transmitted through the gear drive to the valve train. According to Ruggles, "We're investigating that, I don't discount it, but it hasn't been a problem to date. And I think our 3 liter engine proves that because when you're winding in the area of 9200 rpm and running over 7000 rpm for 24 hours at Daytona, and you don't have any valve spring problems, the gear drive isn't causing any trouble. The liabilities you're picking up are more than outweighed by the advantages. It's a trade off - just like everything else in an engine."

 

[HouseofSpeed]

Again, a quote from Jim Ruggles.

"Whether the cam selected is of the "plain vanilla" or super exotic variety, it must be hooked to the crankshaft in some manner. Some engine builders prefer chain drive, others consider gear drive to be superior. With a V6 engine gear drive is preferred because adequate piston-to-valve clearance is maintained. Due to the reverse acceleration of the valve train, timing chains stretch excessively in a six cylinder race engine. The situation is made worse as valve spring pressures are increased, and due to the valve train componentry and rpm level at which a Grand National engine runs, a good deal of spring pressure is required.
The valvetrain used in a Buick V6 is very similar to that of a big block Chevy and consequently the same liabilities apply. Both engines have long pushrods, virtually identical valve lifters, high ratio, heavy rocker arms and long valve stem valves. (A Buick V6 has a camshaft with a small base circle). Valvetrain mass requires a healthy dose of spring pressure to keep valve action precise. The only negative aspect is timing chain life; with 25% fewer lobes that a V8, the reverse acceleration of the camshaft in a V6 is more severe so timing chain life is short.
While a timing gear drive is considerably more expensive in terms of initial purchase price, over the course of a single racing season, it will actually be more economical than a chain drive because it never needs replacing (barring a catastrophic engine failure). Another advantage is that gears don't stretch like chains so cam timing remains consistent.
On the other side of the coin, there are theories that harmonic vibrations in an engine will be transmitted through the gear drive to the valve train. According to Ruggles, "We're investigating that, I don't discount it, but it hasn't been a problem to date. And I think our 3 liter engine proves that because when you're winding in the area of 9200 rpm and running over 7000 rpm for 24 hours at Daytona, and you don't have any valve spring problems, the gear drive isn't causing any trouble. The liabilities you're picking up are more than outweighed by the advantages. It's a trade off - just like everything else in an engine."

I understand Jim's point of view as well....and I have a final example that is similar to what we are driving at here....involves solid roller applications that will live in driven street cars. Obviously greater spring pressures and valve train stress in this example as compared to a hydraulic flat tappet...and up til about 10-12 years ago a durable solid roller for the street was all but unheard of....no engine builder would recommend it. Comp saw where the failures were (typically in the lifter) and designed their Endurex series lifter specifically for driven solid roller engines....increased reliability, decreased valvetrain maintenance and failure were all a product of this new design. A lifter doesn't know what engine it goes in...it just knows what diameter it is and what lifter bore it fits.....there are tons of Chevy race engines that use ..... GASP ..... a Ford (.875 dia) or a Mopar (.904 dia) lifter in some applications to increase the contact surface between lifter and lobe. So, just because it is labeled as pertaining to this specific engine...doesn't mean that a better design is not out there and can be fitted to the application....killing long held beliefs about what will or won't work in the world of the race engine.

 

[Alky V6]

I understand Jim's point of view as well....and I have a final example that is similar to what we are driving at here....involves solid roller applications that will live in driven street cars. Obviously greater spring pressures and valve train stress in this example as compared to a hydraulic flat tappet...and up til about 10-12 years ago a durable solid roller for the street was all but unheard of....no engine builder would recommend it. Comp saw where the failures were (typically in the lifter) and designed their Endurex series lifter specifically for driven solid roller engines....increased reliability, decreased valvetrain maintenance and failure were all a product of this new design. A lifter doesn't know what engine it goes in...it just knows what diameter it is and what lifter bore it fits.....there are tons of Chevy race engines that use ..... GASP ..... a Ford (.875 dia) or a Mopar (.904 dia) lifter in some applications to increase the contact surface between lifter and lobe. So, just because it is labeled as pertaining to this specific engine...doesn't mean that a better design is not out there and can be fitted to the application....killing long held beliefs about what will or won't work in the world of the race engine.

I get your point, but there are some that are still searching for a timing chain that will last in a hard hitting Buick V6.

I mentioned something about my front camshaft bushing wear and how the bushing being used with a gear drive has shown virtually zero wear compared to a chain drive. I would suspect a belt drive would wear the front cam bushing the same as the chain drive does considering how the both designs pull downward on the cam driven gear to cause rotation.

 

[HouseofSpeed]

Again, a quote from Jim Ruggles.

"Whether the cam selected is of the "plain vanilla" or super exotic variety, it must be hooked to the crankshaft in some manner. Some engine builders prefer chain drive, others consider gear drive to be superior. With a V6 engine gear drive is preferred because adequate piston-to-valve clearance is maintained. Due to the reverse acceleration of the valve train, timing chains stretch excessively in a six cylinder race engine. The situation is made worse as valve spring pressures are increased, and due to the valve train componentry and rpm level at which a Grand National engine runs, a good deal of spring pressure is required.
The valvetrain used in a Buick V6 is very similar to that of a big block Chevy and consequently the same liabilities apply. Both engines have long pushrods, virtually identical valve lifters, high ratio, heavy rocker arms and long valve stem valves. (A Buick V6 has a camshaft with a small base circle). Valvetrain mass requires a healthy dose of spring pressure to keep valve action precise. The only negative aspect is timing chain life; with 25% fewer lobes than a V8, the reverse acceleration of the camshaft in a V6 is more severe so timing chain life is short.
While a timing gear drive is considerably more expensive in terms of initial purchase price, over the course of a single racing season, it will actually be more economical than a chain drive because it never needs replacing (barring a catastrophic engine failure). Another advantage is that gears don't stretch like chains so cam timing remains consistent.
On the other side of the coin, there are theories that harmonic vibrations in an engine will be transmitted through the gear drive to the valve train. According to Ruggles, "We're investigating that, I don't discount it, but it hasn't been a problem to date. And I think our 3 liter engine proves that because when you're winding in the area of 9200 rpm and running over 7000 rpm for 24 hours at Daytona, and you don't have any valve spring problems, the gear drive isn't causing any trouble. The liabilities you're picking up are more than outweighed by the advantages. It's a trade off - just like everything else in an engine."

That 25% reduction would also assume the same operational RPM range...but if I don't turn that V6 but 5500 RPM and the V8 10K RPM....which do you think has the greater reverse acceleration? Because RPM affects EVERYTHING....so how does a belt or a chain live in a 8-9K RPM V8....and since we are on this discussion...what about V10s and v12s? A V8 would be more prone to chain failure than a V10? Never heard that argument,

I know that I am looking past the Buick V6....but this is a point about engines...period. The Buick V6 is not given sovereign immunity in the world of physics or mechanical design....the gravity switch is always on for us Earthlings. LOL

 

[HouseofSpeed]

I get your point, but there are some that are still searching for a timing chain that will last in a hard hitting Buick V6.

I mentioned something about my front camshaft bushing wear and how the bushing being used with a gear drive has shown virtually zero wear compared to a chain drive. I would suspect a belt drive would wear the front cam bushing the same as the chain drive does considering how the both designs pull downward on the cam driven gear to cause rotation.

You are correct...there is correlation between wear on the front bearing in a chain/belt and the absence of said with a gear drive.

I wish I had a chain answer for the big gun Buick guys.....maybe I will dig up an old front cover and see if I can fab up a tensioner setup like that Ford application.

 

[Alky V6]

That 25% reduction would also assume the same operational RPM range...but if I don't turn that V6 but 5500 RPM and the V8 10K RPM....which do you think has the greater reverse acceleration? Because RPM affects EVERYTHING....so how does a belt or a chain live in a 8-9K RPM V8....and since we are on this discussion...what about V10s and v12s? A V8 would be more prone to chain failure than a V10? Never heard that argument,

I know that I am looking past the Buick V6....but this is a point about engines...period. The Buick V6 is not given sovereign immunity in the world of physics or mechanical design....the gravity switch is always on for us Earthlings. LOL

Yeah, but it's much simpler if we just stick to the V6 here, since this is the engine that many reading this thread are trying to come up with answers for. I think many on this site have experienced rather quick timing chain wear and would like to find some answers to their specific problem.

 

[Mike E]

We have the new timing chain technology for the v6's.

Here is a picture of TA performance's newest timing chain setup for the V6 and 350v8. The tensioner isn't shown in this pic, but it's supposed to use one on the V6.

Here is a picture of a timing chain in an ex nascar motor. Probably not the latest and greatest, but it's relatively new. This was posted on Yellow Bullet and as best as I understand this is a a ford Motorsport SVO part.

 

[Alky V6]

We have the new timing chain technology for the v6's.

Here is a picture of TA performance's newest timing chain setup for the V6 and 350v8. The tensioner isn't shown in this pic, but it's supposed to use one on the V6.

Here is a picture of a timing chain in an ex nascar motor. Probably not the latest and greatest, but it's relatively new. This was posted on Yellow Bullet and as best as I understand this is a a ford Motorsport SVO part.

I suspect front cam bushing wear and chain stretch associated with the use of the chain can still be expected?
I like the idea of using some sort of device to control slap if you have to use a timing chain.

The chain shown in the Ford example looks very much like the design that is used in some transaxles. Particularly, GM models. I believe the advantage of that chain design in a transaxle application is low noise level related. Not sure what the durability advantage is with that design. Some of those applications using chain guides similar to what is shown in your picture. Those designs are still not immune to chain stretch.
I'll see if I can find more information on that particular chain design. I know in a transaxle application, noise level is always an important, if not the most important consideration with chains and their designs. Two important factors controlling the strength of a chain being the pitch and width of the chain.

Google Borg Warner Morse Hy-Vo chain designs.

 

[Alky V6]

Mike, what are the latest and greatest technology features of these new chains you're presenting? The chain on the Buick block doesn't look a whole bunch different from the normal, run of the mill timing set.

 

[Mike E]

No idea. It's a stock type timing chain, so I'm sure noise is kept to a minimum. Noise = Vibration = Harmonics

The chain has a lot more links and the pins are better supported, so I'm sure it's much stronger than a double roller.

 

[Alky V6]

It really worries me when you see "the newest timing chain gearset" being advertised. Why are we continually coming out with "the newest" timing chain gearset? Does that mean that the gearset before this one wasn't holding up? What about this newest gearset? What are the design features of this new gearset that set it apart and promise better performance than the previous offered gearset?
Ultimately, are we still searching for the 'bestest in the westest' timing chain gearset?

 

[Alky V6]

It's surprising that a timing gearset that came out in the 70s, 80s, went through a few design level changes, would still be considered a very reliable alternative to drive the camshaft on a Buick V6. While today, around 30 years later, we're still discussing the newest and bestest timing chain gearset to come out for the Buick V6. That's sad.
That's 30 years that has been burned trying to come up with a timing chain gearset that can be as reliable as a system that has already proven and made a name for itself decades ago.
I don't know why Smokey might have changed his opinion on chains vs. gearsets, but I know he wasn't considering the Buick V6 racing engine when he did.

 

[dr_frankenstein]

What would one suggest for someone who is driving a mechnical fuel pump from the cam?

as in a Hilborn pump for a mechanical injection?

Would one still have the confidence in the chain? or at this point would the gear drive be the only option?

 

[Alky V6]

With people still holding their breath to see if they've come up with a timing chain that will hold up in a Buick V6 racing engine, why on earth would you consider adding more load to the chain? Doesn't make sense to me.

 

[Mike E]

What would one suggest for someone who is driving a mechnical fuel pump from the cam?

as in a Hilborn pump for a mechanical injection?

Would one still have the confidence in the chain? or at this point would the gear drive be the only option?

How do you actually plan to drive the pump? Do you plan to use a customized timing cover or are you somehow driving it off the back of the cam? The physical connection to the cam may dictate what you do more so than the type of drive. FWIW I've seen both belt drives and gear drives turn mechanical fuel pumps, but usually the gear drive is prefered when one is available for the application. Although the Moroso Gear drive that was offered for the buick v6 is not quite as stout as the RCD gear drives most people use today.

 

[geno]

You cant teach the teacher .. I think the fastest Buick V6 to ever run down the 1/4 mile had a chain? I dont even look or post in the Stage area much anymore because of it.

 

[Nick Micale]

It really worries me when you see "the newest timing chain gearset" being advertised. Why are we continually coming out with "the newest" timing chain gearset? Does that mean that the gearset before this one wasn't holding up? What about this newest gearset? What are the design features of this new gearset that set it apart and promise better performance than the previous offered gearset?
Ultimately, are we still searching for the 'bestest in the westest' timing chain gearset?

You should not be concerned Don, the "newest" chain set is the best ever for a V-6 Buick which was not in the picture over 2 years ago when this thread was started, and yes the old sets are not holding up!

The double roller sets have some issues that have proven un-reliable and un-suited to our turbo application which has more than tripled the HP levels since Ruggles and Smokey were dealing with Buick engines over 30 years ago. Our turbo application in drag racing is also different than running at constant high RPM for hundreds of miles in circle track racing.

Only 2 double roller sets are now supplied with billet gears. The cast cam gear in all the cheaper sets will NOT hold up to the HP and RPM loads of a turbo application.

The cast gear in a street application will wear quickly even in a street application, like 5K miles, and you then have a very loose chain which degrades performance even if it does not fail.

Since all the roller sets cannot use a chain tensioner, this allows LOTS of chain whip when RPM is quickly changed which is why and where most double roller chains break.

Now we have the TA link timing set with billet gears and it can use a tensioner, or even 2 tensioners which we have done in some high HP applications.

The link chain is MUCH stronger as it has a minimum of 5 links vs. 3 in a double roller.

This chain also used a smaller link pin so the link is stronger there than a double roller link, which is exactly where the link will fail.

We have not personally conducted a pull test on the link chain, but the manufacturer has rated it much stronger than a double roller chain and from common sense we can easily tell this is true.

With all the good stuff stated about the new link set, it is 1/3 the price of a billet gear double roller.

Having tried every double roller set available, and all have failed [some more than once], I feel very confident that the new link chain will last beyond the time for an engine freshen. So far the link set is beyond the number of runs where the double rollers have failed.