Big Block Gear Drive On A Slant?

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yellow rose said:
If they pinch in the timing cove they don't work. How would one pinch in a small block Chrysler or a Pontiac or Ford with a thick, cast cover?
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Everything I've read so far says the idler gears are not supposed to be pinched, but there's supposed to be space so that they float. It won't be difficult to make that happen if the cover comes down tight on the idlers, but I am pretty sure it will not.
 
That is the beauty of the Slant block, you've got a factory machined flat surface to take a mod like this to the next level and make it fixed instead of floating. You don't have that luxury with many V8's.
 
yellow rose said:
Read my post and do a fixed idler. You'll be much happier in the end.
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Ok then, so lets just say for the sake of argument, I decide to convert to a fixed idler. How much clearance do you think will be good between the cam gear and idler and the crank gear and idler? In other words, WHERE would you mount the idler?
 
RustyRatRod said:
Everything I've read so far says the idler gears are not supposed to be pinched, but there's supposed to be space so that they float. It won't be difficult to make that happen if the cover comes down tight on the idlers, but I am pretty sure it will not.
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Yes, they have to float to work. I wish you could see one on an engine that's already assembled. All you have to do is watch the degree wheel and see how far the crank will move in either direction without moving the cam. I'd bet everything jpar has (and some stuff he probably doesn't) that it will be a minimum of 7 degrees. If it does that on the stand, it will damn sure do it in operation. And it does.

Also, some of them are noisy. A good gear drive, like the Milodon I have makes ZERO noise. Most people don't know I even have it.
 
RustyRatRod said:
Ok then, so lets just say for the sake of argument, I decide to convert to a fixed idler. How much clearance do you think will be good between the cam gear and idler and the crank gear and idler? In other words, WHERE would you mount the idler?
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You can mount the idler gear on either side of the crank and cam gears. It won't matter. The idler always has to turn in the opposite direction of the crank and cam gears so you don't have to turn the cam in reverse direction like you would with a 2 gear drive.

I'd mount it where you have the most room to make it fit. I set the lash with a dial indicator. I keep the lash between .002-.004 and let it run. You can also set the clearance with some magazine stock. Set the idler so it just tears the paper as it moves through the gears. Either way you'll be golden.
 
You'd have to make stops on the back of the cast timing covers. You're not trying to totally eliminate the front to back movement, just minimize it where it's not a quarter inch. It still needs to float side to side, but even that can get excessive as you've mentioned. I've seen billet timing covers with the idlers mounted in them as well. I guess it's time for a Slant cover like that now. LOL
yellow rose said:
If they pinch in the timing cove they don't work. How would one pinch in a small block Chrysler or a Pontiac or Ford with a thick, cast cover?
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CNC-Dude said:
You'd have to make stops on the back of the cast timing covers. You're not trying to totally eliminate the front to back movement, just minimize it where it's not a quarter inch. It still needs to float side to side, but even that can get excessive as you've mentioned. I've seen billet timing covers with the idlers mounted in them as well. I guess it's time for a Slant cover like that now. LOL
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If you've got the machine...help RRR and dial him up and new cover. LOL.
 
Also back to the spacer, I'm sure it's already been thought of, but a longer dowel for the cam will be needed to compensate for the spacer thicknes.
 
Well, like I said, I've set up a few of the dual idler sets and watched the degree wheel. I've not seen the variation you describe. Not arguing, just saying I have not seen it and I haven't. It would be very easy to just center drill the arbor for one of the idler gears and bolt it directly to the front of the block. I would rather mount it on a plate and make it adjustable. That way I could really zero in on the gear lash.
 
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CNC-Dude said:
Also back to the spacer, I'm sure it's already been thought of, but a longer dowel for the cam will be needed to compensate for the spacer thicknes.
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Yes sir. Thanks for that. I already have it covered. I have some longer 5/16 dowels already. And sure, I'd be up for all the help I can get.
 
RustyRatRod said:
Well, like I said, I've set up a fer of the dual idler sets and watched the degree wheel. I've not seen the variation you describe. Not arguing, just saying I have not seen it and I haven't. It would be very easy to just center drill the arbor for one of the idler gears and bolt it directly to the front of the block. I would rather mount it on a plate and make it adjustable. That way I could really zero in on the gear lash.
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I don't see why that won't work. If you arent going to spin the engine to 7500 and run the P/V at .045/.065 you'll be fine.

I've just broken so much stuff that I get very leery about using stuff that I've seen cause issues. And I hate to tell anyone to do something that could cost them time or money or both.
 
RustyRatRod said:
Yes sir. Thanks for that. I already have it covered. I have some longer 5/16 dowels already. And sure, I'd be up for all the help I can get.
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I know part of the fun is doing a lot of things yourself, but if you get tangled up in any of it and need some input or assistance, just let me know. I've got a brand new lathe and two mills in my shop at home, so I pretty much have it covered.
 
yellow rose said:
I don't see why that won't work. If you arent going to spin the engine to 7500 and run the P/V at .045/.065 you'll be fine.

I've just broken so much stuff that I get very leery about using stuff that I've seen cause issues. And I hate to tell anyone to do something that could cost them time or money or both.
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The plan is to run the 198 rods I have and the 2.2 Chrysler 4 cyl non turbo pistons I have. With the pistons and rods, if I mill the block .018" from the standard deck height, I will have a zero deck slant. The valve reliefs are plentiful and even in the correct location. The camshaft I have is this one:

Hughes Engines

I don't think I'll have difficulties with piston to valve clearance. I should be able to run the Comp 901 spring. I also have a nice Rollmaster chain set for a slant, so if something goes wrong with the gear drive conversion, I have that to fall back on. I think I can make it work though. It's not far off at all like it is.
 
CNC-Dude said:
I know part of the fun is doing a lot of things yourself, but if you get tangled up in any of it and need some input or assistance, just let me know. I've got a brand new lathe and two mills in my shop at home, so I pretty much have it covered.
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I may just do that. I have to figure out how and where to mount the single idler on a plate and affix the whole thing so it will have the correct arc of travel to engage the cam and crank gears equally. I can figure out the how and where, but I am sure I will need some help getting it made.
 
RustyRatRod said:
I may just do that. I have to figure out how and where to mount the single idler on a plate and affix the whole thing so it will have the correct arc of travel to engage the cam and crank gears equally. I can figure out the how and where, but I am sure I will need some help getting it made.
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I have several Slant blocks myself that I already have earmarked to put billet main caps on one and making a main girdle for the other and some other way overkill goodies like a torque plate and other stuff. I have designed and made patterns and am casting 3 different intakes for a couple of other inline engines, and already have one 3D modeled for the Slant. So I may blow the cobwebs off of that project and bring it to the table as well.
 
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CNC-Dude said:
I have several Slant blocks myself that I already have earmarked to put billet main caps on one and making a main girdle for the other and some other way overkill goodies like a torque plate and other stuff. I have designed and made patterns and am casting 3 different intakes for a couple of other inline engines, and already have one 3D modeled for the Slant. So I may blow the cobwebs off of that project and bring it to the table as well.
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I wonder......do you happen to know how thick the slant is under the timing cover area?
 
Not without just studying the block, but it's pretty thick. Shouldn't be a problem mounting the idlers directly to the block.
 
Ok, I have made the dual idler big block gear drive fit properly, with no spacer and just a little grinding on the block in the timing cover area. These dual idler gears fit tight, so I might just try it like it is. Plus, it all fits under the stock timing cover. I don't believe anyone's tried this, as I have not seen it, but all I did was flip the crank gear over upside down and pressed it on. That made the difference up and the gears align fine. Being straight cut gears, they'll never know which direction they're installed. All I'll have to do is remark the crank gear with a mark for TDC. Other than that and the minimal grinding, this is a 100% bolt on swap. So, if you want a gear drive on your slant, this is all you have to do. Now, I will still probably get the camshaft drilled for the three bolt pattern on the cam gear so that I can use the cam button that came with the kit, even though I found one that will work with the center bolt.

SLANT GEAR DRIVE2.jpg

SLANT GEAR DRIVE1.jpg

SLANT GEAR DRIVE.jpg
 
RustyRatRod said:
Ok then, so lets just say for the sake of argument, I decide to convert to a fixed idler. How much clearance do you think will be good between the cam gear and idler and the crank gear and idler? In other words, WHERE would you mount the idler?
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I wouldn't try and ruin your thread but you know yellow rose just called me out twice in this thread just now and I would really like him to answer to his thread (quote) "it will happen!?" there's plenty of conversation there and everybody is wondering where he's at and why he's out giving all this technical advice without owning up to his shortcomings....
Honestly I'm quite enjoying the conversation here about the Gear Drive. I talk to my own machine shop about that when I first had my motor done and was discouraged and told I could spend my money in better places. Anyways I'm enjoying just reading the conversation...
 
Is the camshaft gear's timing mark in the same place on both engines? I think the crank gear mark is different between the two. I have never looked to be certain.
 
Badvert65 said:
Is the camshaft gear's timing mark in the same place on both engines? I think the crank gear mark is different between the two. I have never looked to be certain.
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Yes. The timing mark is in the same place on both engines, plus, it's in the same place on both style big block camshaft gears, the center bolt and three bolt. The crankshaft gear and timing chain are the same. The camshaft gear between the slant and big block is where the difference is. The slant six camshaft gear has more offset to the front. This is the reason for turning the crankshaft gear around. The big block camshaft gear sits closer to the block than the slant six gear would. Chrysler could have saved some money here, had they simply machined the camshaft gear for both engines the same. They could have used the same timing set.

Edit: ....and even if the crankshaft gear mark is different, it's a moot point, because I am going to remark it anyway, since I flipped it over.
 
RustyRatRod said:
Good, then don't. Yall can create your own thread and blow each other there. Thank you.
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You miss my point you big dummy! I've tried that but he comes on your thread twice and mentions my name and here again I get the retribution... And again I'm talking in English and you're listening and dingbat...
 
j par said:
You miss my point you big dummy! I've tried that but he comes on your thread twice and mentions my name and here again I get the retribution... And again I'm talking in English and you're listening and dingbat...
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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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