Big Block Gear Drive On A Slant?

[RustyRatRod]

Does the crank gear have adequate chamfering on it when you flip it backwards to clear the radius where the snout meets the front main journal?

Help me understand why this is important. I know one side has a good size chamfer and the other does not. I'll put a chamfer on it if I need to. But they both spin together. I'm not arguing....but help me unnerstand here. I'm not gonna let a small thing like a chamfered gear stop me. I can do that in 15 minutes. I just want to know why you think I need it. It's no doubt chamfered on what is normally the back side.

I'll have some pictures coming soon.

 

[CNC-Dude]

Rusty, it's just a clearance/alignment issue. On a gear drive it may not be critical, but on a chain setup, if the chamfer is too small on the gear compared to the chamfer on the snout. The smaller chamfer on the gear will hit the chamfer on the snout and prevent the gear from seating flat against the flat surfaces on the cam and gear. This can create a misalignment of the crank gear and cam gear binding the timing chain. Again, it may not be an issue on a gear drive. But it can prevent the gear from seating flatly on the two intended mating surfaces.

 

[RustyRatRod]

Rusty, it's just a clearance/alignment issue. On a gear drive it may not be critical, but on a chain setup, if the chamfer is too small on the gear compared to the chamfer on the snout. The smaller chamfer on the gear will hit the chamfer on the snout and prevent the gear from seating flat against the flat surfaces on the cam and gear. This can create a misalignment of the crank gear and cam gear binding the timing chain. Again, it may not be an issue on a gear drive. But it can prevent the gear from seating flatly on the two intended mating surfaces.

Ok, I understand now. Thanks for splainin it so well.

 

[Ottmundr]

Hey rusty, I have been waiting a year and four months for an update… have you poked around on slantsix.org?

Timing Gear for Slant 6 - Slant Six Forum

I am not sure but it looks like some guys in kangarooistan made one a while back.

http://www.slantsix.org/galleries/lasvegas/geardrive.jpg

edit:
fixed the stupid ipad autocorrect. wishbone to dogbone. SMDH, I dislike apple products.

You may want to take a look at the milodon small block gear drive, maybe apply that type of design and order the crank and cam gears, and a single idler gear with the dogbone. Would you really need both idler gears?

Milodon 13000 Gear Drive Assembly
Milodon Gear Drive Components

 

[RustyRatRod]

Hey rusty, I have been waiting a year and four months for an update… have you poked around on slantsix.org?

Timing Gear for Slant 6 - Slant Six Forum

I am not sure but it looks like some guys in kangarooistan made one a while back.

http://www.slantsix.org/galleries/lasvegas/geardrive.jpg

View attachment 1715887551


You may want to take a look at the milodon small block gear drive, maybe apply that type of design and order the crank and cam gears, and a single idler gear with the wishbone. Would you really need both idler gears?

View attachment 1715887554

Milodon 13000 Gear Drive Assembly
Milodon Gear Drive Components

Mine will be somewhat similar to the Milodon. I am leaving one of the dual idler gears off and am going to use the remaining one as a fixed idler gear. So no, I am not using both idler gears. I've also found a way to keep the camshaft from walking. I just need to figure out "where" in the block is best for proper lifter and oil pump gear interface and adjust it accordingly.

 

[Ottmundr]

Mine will be somewhat similar to the Milodon. I am leaving one of the dual idler gears off and am going to use the remaining one as a fixed idler gear. So no, I am not using both idler gears. I've also found a way to keep the camshaft from walking. I just need to figure out "where" in the block is best for proper lifter and oil pump gear interface and adjust it accordingly.

Found their website. Diecrest, in Victoria.
Diecrest Engineering - Custom Gears, Gear Cutting

 

[CNC-Dude]

Ok, I understand now. Thanks for splainin it so well.

You are welcome anytime!

 

[Dave999]

cam end float. this is how chrysler Australia directed dealers to fix it
i just use a nylon button but many ways to skin a cat
for hemi 6 but works on any with pressed steel cover and a cam with a hole in the end

DR.HEMI Hemi 6 Camshaft End Float Restrait

 

[Hyper_pak]

If you want to hear a slant 6 with a Pete Jackson big block MoPar gear drive go to youtube and put in "Green Grenade Mo-Kan Dragway". I think the sound might be louder than an iron block with a gear drive as this sound is with an aluminum engine block.

That is a Bad Bad Rail. I enjoyed the sound, but couldn't really hear the slant till about the 60 foot mark. I am sure it would sound different from the track side.

 

[RustyRatRod]

Bringing this back to the top. I "BELIEVE" I have this figured out so it will actually work. I clamped the idler gear TIGHT against the crank and cam gears with a ratchet strap and printer paper between the cam and idler gear and between the crank and idler gear to set clearance. I got a 5/16 ID, 3/8 OD reducer sleeve and pressed into the 3/8 bore I had drilled through the center of the idler gear pinion and drilled a 5/16 hole right through the front of the block. Then I took the ratchet strap and idler gear off and tapped the hole to 3/8. Now the idler is bolted rigidly in place and it has I would "guess" about .006" of play back and forth for the idler. Should be just right. The bolt even goes through the block far enough to put a nut on the back side and secure it even more. I figure on final assembly (a ways off yet) I'll put blue locktite on the bolt threads into the block and on the nut on the back side as well. A good, grade 8 bolt should hold it fine I think. I feel confident enough that this may work. Now all I need is to have the camshaft drilled for the three bolt big block pattern and I'm done.

 

[RustyRatRod]

@Rat Bastid what are your thoughts here? You think anything about cam walk? I always thought the cam lobe taper would keep that from happening. I can always devise a camshaft button of sorts.

 

[Badvert65]

Are you making any mods to get additional oil to the gears?

 

[Ottmundr]

@Rat Bastid what are your thoughts here? You think anything about cam walk? I always thought the cam lobe taper would keep that from happening. I can always devise a camshaft button of sorts.

Rusty, have you considered getting helical gears? I bet someone makes the sizes you'd want. If worse comes to worse, you could probably get some made. (Probably cost a lot though) If you cut them the right direction, I bet you could get away from even needing a cam button. The forces acting on the gears could be set so it's a complete non-issue.

Helical Gears vs. Spur Gears - How are they different? - Gear Motions

Helical Gears vs. Spur Gears - Learn about the differences between the two most common types of gears from the Gear Experts at Gear Motions.

gearmotions.com

 

[RustyRatRod]

Are you making any mods to get additional oil to the gears?

Yup. I plan on about a .040" hole in the main oil gallery plug right behind the cam gear. I believe that'll do it.

 

[Charrlie_S]

Yup. I plan on about a .040" hole in the main oil gallery plug right behind the cam gear. I believe that'll do it.

Do you have the champher on the #1 main bearing? Aftermarket bearing does not have the chamfer. I always chamfer the bearing with a file.
From the factory service manual.

"CRANKSHAFT MAIN BEARINGS The NOS. 1, 2 and 4 lower main bearings are interchangeable (Fig. 41). The NOS. 2 and 4 upper main bearings are interchangeable. The NO. 1 upper main bearing is not interchangeable and is chamfered on the tab side for timing chain oiling and can be identified by a red marking on the edge of the bearing. "

 

[RustyRatRod]

Do you have the champher on the #1 main bearing? Aftermarket bearing does not have the chamfer. I always chamfer the bearing with a file.
From the factory service manual.

"CRANKSHAFT MAIN BEARINGS The NOS. 1, 2 and 4 lower main bearings are interchangeable (Fig. 41). The NOS. 2 and 4 upper main bearings are interchangeable. The NO. 1 upper main bearing is not interchangeable and is chamfered on the tab side for timing chain oiling and can be identified by a red marking on the edge of the bearing. "

I've read that. I don't have it yet, but I plan to. Thanks, Charlie. Would you happen to have a picture of how it's supposed to look?

 

[RustyRatRod]

Do you have the champher on the #1 main bearing? Aftermarket bearing does not have the chamfer. I always chamfer the bearing with a file.
From the factory service manual.

"CRANKSHAFT MAIN BEARINGS The NOS. 1, 2 and 4 lower main bearings are interchangeable (Fig. 41). The NOS. 2 and 4 upper main bearings are interchangeable. The NO. 1 upper main bearing is not interchangeable and is chamfered on the tab side for timing chain oiling and can be identified by a red marking on the edge of the bearing. "

I found a good explanation of it on the .org site. Thanks, Charlie!

 

[Hyper_pak]

I am glad you are back working on this Rusty.
I have a friend who has run a gear drive, I will bounce it off him and see what he thinks.
I had been thinking about cam walk, were cam profiles supposed to keep the cam back?
I know Will with the 68 Turbo Barracuda had to run a thin roller bearing behind his top gear.
His cam was walking backward.

 

[RustyRatRod]

I am glad you are back working on this Rusty.
I have a friend who has run a gear drive, I will bounce it off him and see what he thinks.
I had been thinking about cam walk, were cam profiles supposed to keep the cam back?
I know Will with the 68 Turbo Barracuda had to run a thin roller bearing behind his top gear.
His cam was walking backward.

I have the thin torrington bearing. It came with the gear drive kit. I plan on utilizing it. I've just left it out as I mock things up. Thanks for that. I'd like his input as well.

 

[Hyper_pak]

I remember you talking about timing changes with the dual unit.
Do you think that would be less with fewer rpm up and down that you see in a street vs race car?

 

[RustyRatRod]

Rusty, have you considered getting helical gears? I bet someone makes the sizes you'd want. If worse comes to worse, you could probably get some made. (Probably cost a lot though) If you cut them the right direction, I bet you could get away from even needing a cam button. The forces acting on the gears could be set so it's a complete non-issue.

Helical Gears vs. Spur Gears - How are they different? - Gear Motions

Helical Gears vs. Spur Gears - Learn about the differences between the two most common types of gears from the Gear Experts at Gear Motions.

gearmotions.com

I thought about it. Mo money money. lol

 

[RustyRatRod]

I remember you talking about timing changes with the dual unit.
Do you think that would be less with fewer rpm up and down that you see in a street vs race car?

I would think a street car would see more timing changes with the dual idler, because of all the back and forth movement of the throttle. Race is more wide open. The dual idlers on this moved I "BET" a good 5 or more degrees. We caint have all that.

 

[volaredon]

I thought the whole reason FOR a gear drive was to limit/prevent timing changes. Be a whole hell of a lot more timing change with a chain especially once it wears/stretches

 

[RustyRatRod]

I thought the whole reason FOR a gear drive was to limit/prevent timing changes. Be a whole hell of a lot more timing change with a chain especially once it wears/stretches

It is. That's why I converted the dual idler system to a single idler. You might want to read from the beginning.

 

[Rat Bastid]

I would think a street car would see more timing changes with the dual idler, because of all the back and forth movement of the throttle. Race is more wide open. The dual idlers on this moved I "BET" a good 5 or more degrees. We caint have all that.

Exactly. And think about those of us with two *&$$@ that drag race clutch cars. Every time you uncouple the engine from the drivetrain you get the timing chain unloading the tension side to the slack side.

It‘s tough on parts and causes the need for more piston to valve clearance. I can run whatever my piston to head clearance is on the intake valve (Ive run as close as .050 on aluminum rods and .040 with steel rods) and .080 on the exhaust and not hit.

There are some (myself included) who think that you have a significant flow loss (and power loss) when piston to valve clearance gets excessive.

Think of the pressure loss under the valve when the valve is too far from the piston at overlap.