Big Block Gear Drive On A Slant?

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RustyRatRod said:
No, I'm listening just fine. Now I am asking you politely to drop it. I don't give a damn who started what. You have the opportunity to drop it here and now. So do it please.
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AGEED! When I first started reading the thread I'm thinking "oh brother" a timing gear for a slant six? that's so lame! But then I read on and you're putting custom pistons and lowering the deck height and doing some cool stuff! like that cam that looks bigger than the one that I have in my V8 and I got extremely interested. But I got to say a little bewildered how I keep getting called out yet they're like you said is a place for that and no answer? Anyways again I'm back to enjoying the thread and what you're doing with the/6...
You got to know I was totally laughing when you debunked the timing moving all over the place....
 
Well, I am not saying the timing cannot move. I simply cannot see how. Especially on this. When the block is cleaned up, I'll post better pictures, but the idler gears are trapped by the block casting, plus it's just a very tight fit between the idlers and cam and crank gears. You have to ge them "just perfect" before they will even think about dropping in.

Even still, it would take very little movement to make up for a few degrees of timing. It's still early in the game. I may still attach one of the idlers to the front of the block and make it a fix idler system. Either way, it will have gear drive.
 
RustyRatRod said:
Well, I am not saying the timing cannot move. I simply cannot see how. Especially on this. When the block is cleaned up, I'll post better pictures, but the idler gears are trapped by the block casting, plus it's just a very tight fit between the idlers and cam and crank gears. You have to ge them "just perfect" before they will even think about dropping in.

Even still, it would take very little movement to make up for a few degrees of timing. It's still early in the game. I may still attach one of the idlers to the front of the block and make it a fix idler system. Either way, it will have gear drive.
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I know what you're talkin about about that just right tight fit. I have a friend who has a few Pontiac Motors on stands and one of them has the floating gears and I can tell you if you pop that thing out you'd better have a couple minutes to get that thing back in there cuz it has to go in just right...
 
RustyRatRod said:
Well, I am not saying the timing cannot move. I simply cannot see how. Especially on this. When the block is cleaned up, I'll post better pictures, but the idler gears are trapped by the block casting, plus it's just a very tight fit between the idlers and cam and crank gears. You have to ge them "just perfect" before they will even think about dropping in.

Even still, it would take very little movement to make up for a few degrees of timing. It's still early in the game. I may still attach one of the idlers to the front of the block and make it a fix idler system. Either way, it will have gear drive.
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Make sure you check the movement with a full load of valve springs on it. Also, blocks that have had the **** line honed out of them can get some of the movement out of them. When that happens, the gear tooth is shoved too far into the root of the groove.

IIRC they make undersized floaters for that situation. I've seen more than one have much more movement than a chain with slop in it.
 
I was just over at my friend's house today and I remember grabbing this gear out and regretting it when I was putting it back in, it took a few minutes...
IMG_20190418_085633.jpg
 
RustyRatRod said:
Cool Pontiac.
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The worst part is he's 81 years old and that motor will never be ran by him. One hell of a chance it could end up in a scrap yard! I went with them today to two more big huge double garage is full of seats and parts in a really nice car. He's got a driveway and out in front of his house at least four GTO's he's got about seven out in a field with a friend who has about a hundred out in a field it's crazy. He also has about six of them in storage parking lot.
IMG_20190409_110656.jpg
that's just one picture in One Direction. It goes on and on and on forever...
Anyways back to the Slant six Gear Drive I've been accused of derailing...
 
After looking at the two camshaft gears, the timing MARK is not in the same place. The holes for the locating dowel are the same. I haven't checked the crank gear to be 100% sure, but I'll remark them both as needed.
 
Yeah, I thought I recalled that when I compared the slant six cam gear to the BB cam gear from the gear drive.
 
Badvert65 said:
Yeah, I thought I recalled that when I compared the slant six cam gear to the BB cam gear from the gear drive.
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In the back of my mind, I knew there was a red flag there, but I was going by the dowel location. lol. No big deal. Probably take less than 15 minutes to do using a degree wheel.
 
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?
 
yellow rose said:
Make sure you check the movement with a full load of valve springs on it. Also, blocks that have had the **** line honed out of them can get some of the movement out of them. When that happens, the gear tooth is shoved too far into the root of the groove.

IIRC they make undersized floaters for that situation. I've seen more than one have much more movement than a chain with slop in it.
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Just bringing thread back up as @Hyper_pak asked some questions. I have changed my mind about the dual idler gears. yellow rose is right. There's too much slop to use them, so I am converting it to a single, fixed idler system. I'll post up more as I go along. I am going to modify the camshaft to be a three bolt, like the big block so I can run the cam button. Also to convert to a fixed single idler, I am going to drill the big idler gear pinion dead center with a 3/8 hole. Install all three gears on the engine. and jack them together with a .003" feeler gauge between them. Next, using the drilled pinion as a guide, drill a 5/16 hole through the front of the block and tap it 3/8 24. Then finally bolt the pinion and large idler gear to the front of the block. Since there's minimal lateral force on the idler gear, it should work fine. I'll be adding pictures as I go.
 
Rob. I think .003 feeler gauge is gonna be impossible to fit, just use a piece of .0032 newsprint per the milodon installation page. Use a strip between all 3 gears, push the idler in tight and tighten ( they use a small tapped bolt floating in a larger bolt hole in the plate) to 35 ft/lbs as the center idler is retained on a plate. If you could mount that idler on said movable mount plate then you could move it and tighten. If space does not permit that, maybe an eccentric type bolt with an offset bushing so you could turn those and get what your shooting for backlash wise. Per Milodon:
".....You can now proceed with the backlash adjustment. Use a single strip of newsprint (not gloss magazine
paper) 1/2" wide x 6" long, and wrap the newsprint around the idler gear, between the cam gear, idler gear and
crank gear. Press the mounting plate and idler gear assembly firmly by hand toward the cam and crank gears (this moves idler plate in) , being
sure the newsprint is in place. This centers the idler gear between the other two gears as well as sets the lash
between two pairs of gears all in one procedure. A dial indicator while appearing more high tech, can not
accomplish all these procedures. .006-.008 on each set of gears....? Not sure how you check between gears but I got my LA set up so there was .007 cam play against a stationary crank. Am I supposed to have 6 to 8 thou X2 at the cam gear? It's adjustable with 3 bolts (1 moves, 2 just tighten) so im not stuck with a bad drilled and tapped hole.
 
I think he should tie that slant 6 to the end of a rope to keep his boat from going adrift and put that big block in his car...
 
pishta said:
Rob. I think .003 feeler gauge is gonna be impossible to fit, just use a piece of .0032 newsprint per the milodon installation page. Use a strip between all 3 gears, push the idler in tight and tighten ( they use a small tapped bolt floating in a larger bolt hole in the plate) to 35 ft/lbs as the center idler is retained on a plate. If you could mount that idler on said movable mount plate then you could move it and tighten. If space does not permit that, maybe an eccentric type bolt with an offset bushing so you could turn those and get what your shooting for backlash wise. Per Milodon:
".....You can now proceed with the backlash adjustment. Use a single strip of newsprint (not gloss magazine
paper) 1/2" wide x 6" long, and wrap the newsprint around the idler gear, between the cam gear, idler gear and
crank gear. Press the mounting plate and idler gear assembly firmly by hand toward the cam and crank gears (this moves idler plate in) , being
sure the newsprint is in place. This centers the idler gear between the other two gears as well as sets the lash
between two pairs of gears all in one procedure. A dial indicator while appearing more high tech, can not
accomplish all these procedures. .006-.008 on each set of gears....? Not sure how you check between gears but I got my LA set up so there was .007 cam play against a stationary crank. Am I supposed to have 6 to 8 thou X2 at the cam gear? It's adjustable with 3 bolts (1 moves, 2 just tighten) so im not stuck with a bad drilled and tapped hole.
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I have a set of 12" long feeler gauges. I think it'll fit. I'll find out anyway.
 
I'm thinking the gear mesh clearance set with the paper, not the standoff from the block. Your long ones will work for that for sure.
 
pishta said:
I'm thinking the gear mesh clearance set with the paper, not the standoff from the block. Your long ones will work for that for sure.
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What my plan is, is to use a couple of long hose clamps and clamp the idler gear in between the cam and crank gears with the .003" feeler gauge between them all. Then, use the idler gear pinion as a guide to drill a hole through the front of the block foe a 3/8-24 bolt to bolt the idler gear in place. I believe that will work. It's goin to dammit. lol
 
j par said:
I think he should tie that slant 6 to the end of a rope to keep his boat from going adrift and put that big block in his car...
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Hay man, you're forgettin one thing. This ain't your car.
 
RustyRatRod said:
Hay man, you're forgettin one thing. This ain't your car.
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very true but friends don't let friends put slant 6's in cars that are meant for Big blocks.... Now stop letting me bust your nut so easily and get on with your gear Drive it sounds damn interesting....
 
j par said:
very true but friends don't let friends put slant 6's in cars that are meant for Big blocks.... Now stop letting me bust your nut so easily and get on with your gear Drive it sounds damn interesting....
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It is damned interesting, because it's going to work.
 
The paper will center the gear and give you the .0032 mesh clearance on both sides. Give it a try, its free. Are the idler shafts going to sit square on the block? Just trying to utilize those existing Dogbones for some sort of square up support. ie remove small gear, swing them up 90 just outboard of the cam gear and use them with a hollow axle for a second mount point. May be overkill if the bearing base sits flush on the block and a grade 8 bolt will keep if from walking away from the gear? Just thinking about rigidity... or even deleting the small gear as it sits and use same hollow spacer axle as 2nd mount point, maybe a little cleaner.

gear2.jpg
 
pishta said:
The paper will center the gear and give you the .0032 mesh clearance on both sides. Give it a try, its free. Are the idler shafts going to sit square on the block? Just trying to utilize those existing Dogbones for some sort of square up support. ie remove small gear, swing them up 90 just outboard of the cam gear and use them with a hollow axle for a second mount point. May be overkill if the bearing base sits flush on the block and a grade 8 bolt will keep if from walking away from the gear? Just thinking about rigidity... or even deleting the small gear as it sits and use same hollow spacer axle as 2nd mount point, maybe a little cleaner.

View attachment 1715604820
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I thought about utilizing the dogbones for that. There's plenty of room. The block is flat where the gear pinion sits.......now. It had a small raised section, but I dressed it flat with with the grinder, so now it sits flat. I honestly believe a grade 8 bolt will hold it in place fine.
 
I thought I would bring this thread back to the top and revisit it. I've gotten a little more done on this. I am going to try it. All I need to do now is figure out a way to keep the camshaft from walking.....and I don't have the room for a cam button. Has anyone ever made a camshaft thrust plate for a slant 6?
 
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