308 V12 conversion begins

It was just a cruise. My first and hopefully last.....I was borred out of my skull most of the time.

 

We really didn't have enough time in any place to give it a try

 

Nothing very interesting to report.

After about an hour digging around on the tilon web page I decided to just send them an email asking what the shoutest throw-out bearing is. I'm guessing it will be a couple days before I hear back. I'm thinking I'll just make a flywheel that accepts the 360 bolt-on ring gear.

I also called the cam guy again and he promised to send out a quote with some grind choices in "a day or two". I told him I couldn't ship the blanks out without some kind of quote without Lana having my head after the block bill. I need to drill oil holes and the sprocket pin holes anyway, I guess I'll get going on that so they are ready to go when I get the quote and I'm free when I get the bearing info from tilton.

 

I got a response from tilton already. 1.600" and it's uncommon so expect 2 weeks delivery. I'll have to see how that fits into the plan. The stock bearing is about 1.65" but I need to add an adapter to work with the clutch I have so 1.9 at least I think. It's a flange mount so I might also be able use it to secure the bearings into the bell housing and that would save at least another .200" if I can make that work....almost 1/2" and every little bit helps.

After not finding a replacement pulley for my compressor I also decide that I had given up on repairing the old one too soon....and I welded it becasue I'm way too cheap to buy a new compressor over a broken pulley. Good as new....well it works again anyway even if the pulley isn't all that round
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It just ocurred to me that the clutch shaft has double bearings in the bell housing. If I moved one of them into the drop gear cover I'd gain another 1/2"+ and have a stronger assembly but I need to do something custom with the shaft....or set it up to work custom hub in the upper gear.

 

I was supposed to work on the cams tonight but it's just so much more fun to saw stuff....so I sawed the bell housing apart a little

I cut off the lower corner that is supposed to line up with the trans shafts and didn't look too happy about the angle it was sitting at due to my changing the engine location. It will still need more cut away to clear the flywheel, but it fits on for now.

After I get the flywheel and clutch figured out I'll know the final length for the bell housing and I'll mill the whole original mounting flange away then weld on a new one in the correct location. After that I can add whatever fill pieces I need to reconnect it to the chuck I sawed off tonight and it will be good as new....I hope.
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I spent a little time thinking about drop gears and laying out what I think can be done. I want the engine gear on the transmission and the transmission gear up on the engine to give me a more appropriate final drive ratio. I also need to correct for the change in length of the assembly.

It looks like there is just metal on the trans gear to allow me to simply re-machine it to fit the up on the clutch shaft. It will be a little thinner than I’d prefer, but I think it will be ok.

For the transmission end I think I can cut out the center of the old engine gear leaving a large spline pattern and put a small counterbore on the front and back faces. Then I can make a new hub that matches what I cut on the gear and bolts onto the transmission input shaft to extend it enough to put the gear back in the right place and also let me add an outboard bearing in the cover so I don’t lose any strength with the increased length. Then I make a cute little ring nut to hole the gear on the new hub and special wrench to tighten it.

That’s the current thought anyway…..subject to change withot notice of course
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I did a quick rough out on what the flywheel might look like. I'll measure everything up this weekend and put real dimensions to it so I can order material after the holiday. This is set up to use a bolt on 360 ring gear although I guess I could cut the gear directly on the too.....but that's a little work.
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I spent a little time measuring and thinking about the flywheel today. The first step was to drop the crank in…and it did in fact go in so that made me happy.

Next I dropped the stock 400i flywheel on to see where the ring gear sits and it always gave me a good reference point when eyeballing the 360 ring gear position. Now remember the reason I was thinking about the smaller 360 ring gear is because I’m pretty sure the 400 flywheel will hit the frame the way I lowered and positioned the engine after looking at the mess I’ll have to deal with to get a starter to work I think I’m going to drop the engine back in the car now that I can actually install the flywheel and just make sure there is a real problem. The stock flywheel does cover the oil return tube, but I’m sure I could sort that out pretty easily.

The 360 gear is about 1 ¼” smaller diameter than the 400 gear so the starter has to move about 5/8” closer to the crank to engage it and that is just not going to happen. I thought that maybe if I made a custom nose for the starter I could do it, but no go. The drive assembly is small enough to move over, but the body of starter motor hits the block before the drive gets where it needs to go.

That leaves me 2 options I think. I could flip the starter over and mount it to the bellhousing but then I’d have to either reverse the rotation direction of the starter I have or get a different starter that was a reverse rotation. I kind of wanted to run the one set of the front headers out over the bellhousing which would put them right over the starter, but I guess I could make that work

The second option is to get a gear reduction starter. They are much smaller and I should be able to make it fit. I hate to buy one that’s all set-up for a 308 and take it all apart to make new mounts and reconfigure the housing but I’m not sure if I could get the stock 308 starter gear installed on a cheap generic chevy/ford starter. I may see what ebay has to offer cheap before I order the $300+ 308 version.
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interesting...so they have what looks like a gear reduction built into the cases.

It occurred to me after my last post that I have a 3rd option. I'm making the flywheel so I can cut any gear tooth profile I please on it....like a tooth to match the available anywhere and very cheap chevy starters

I just ordered a 3hp gear reduction chevy starter to have a look at, $88 with shipping brand new. It's a pretty small diameter motor and if you look at the picture you can see the drive gear is offset all the way to the side of the motor case eliminating any chance of the starter motor hitting the engine block before the drive hits the flywheel. It's got way more output torque than a the stock ferrari unit so it should work just fine with whatever diameter ring gear I use. There are lighter ones with less torque, but this one only weighs 11 lbs and saving 3ich lbs by going with a smaller one didn’t seem worth the risk that it wouldn’t have the torque to work with my reduced diameter flywheel.
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and I ended up with a project that is completely out of control and miles beyond the original scope becasuse I'm an idiot who never seems to learn from my mistakes....at this point and with the rate I'm progressing I'm just hope hope I live long enough to see it run again

 

I think the 308 truck looks like about 3 cases.....but it would be really really warm by the time I got there

 

I discovered I’d had a bit of good fortune that I was not mentally prepared for. I borrowed a chevy flex plate to measure the ring gear tooth profile in preparation for having to cut it on my new flywheel. What I discovered is that it is exactly the same as the teeth on the 360 ring gear (which is also the same as a 308 gear). That means the chevy starter I ordered the other day because it was cheap just so happens to come with the correct drive gear and all I need to do to use it is make a new mounting plate so it bolts on properly. The starter is coming from CA so it will be about a week in transit before I get it in my hands to see how big a job the new mounting plate will be.
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Yes! I don't know why I didn't think of that