I pulled this pic off another thread....... Anybody have any idea of the source of tach drive on this crank? I've havn't seen this setup before but it is super trick! I know somebody has seen these before.
The tach drive is the mechanical device off the crank pulley. In other words it's a 1/1 direct drive from the crank. Yankee Dave thinks early SW?
So what were they from? Was this an aftermarket hot rod piece or maybe heavy equiptment? Any idea if they are still available or where should I start looking?
Its aftermarket and was also used on stationary equipment like water pump motors etc etc, they are hard to come by and highly sought after, there are also 2 different designs. I thought someone repoped the brackets, but not the drive, im thinking a guy could take a 90 speedp end and figure out a way to adapt it this type of use. JEFF
Fryguy has one locally so I'm going to try to get a look at it and see what I can do to fake one if necesary. Of course, now that I know what I'm looking for I can add it at any time. So there's no rush. That setup is just too neat!
I like the thought, i dont need a tack drive for any current project but that's sure as hell gunna remain in the back of my mind, especially since i have a '48 dated SW 8k rpm tach....
The pic of Myke's coupe at the top shows the drive version with no bracket. A through-bolt into the crank holds it on the engine, and the cable out the end keeps it from spinning around. The version in Titus's pic shows the drive that is connected to the crank via a short flex shaft. A bracket holds the body of the drive in position in front of the engine. These brackets were either one-sided or a straddle-mount style. Both types of these vintage SW tach drives are hard to find for a flathead. If you can find a straddle-mount drive for a Chrysler hemi (maybe a little easier to find?) the holes in the mount can be filed just a hair and it will bolt onto your flathead.
Here's a couple views of the one on my roadster, uses the 90 degree bracket. If you click the pop up picture a second time it will open in a separate window which can then be enlarged again (in most systems anyway). In addition to the stationary stuff Titus referenced they are sometimes found on larger trucks with flathead power. There was an NOS drive unit on ebay a month or so ago, was listed a couple times at I think $165 before it finally sold. No connector or brackets, just the head.
Great pics Uncle Bob. There sems to be two types, one that uses a short section of flex and the other kind that bolts directly into the crank snout and uses the cable as the anchor point. If I can get a look at Fryguys direct drive unit I'll probably secure the SW right angle 2/1 drive and just machine up an appropriate direct drive stud. This will give me the shortest unit as well, not that it matters with this car but it will just look nicer. The pics you guys are posting help imenesly. By the way, Way sweet roadster!
Check out this recent thread with lots of pictures of different set ups. There are pictures of my home made set up in there as well. http://www.jalopyjournal.com/forum/showthread.php?t=705820
Probably alread in that link above, but click around here: https://www.pegasusautoracing.com/group.asp?GroupID=JONESTACHDRIVE All you need is one of their drive stubs and a hole in the center of crank bolt to spin the drive. The pictures on here will geive you ideas for the several fairly simple bracketing methods used in the SW ones for different flathead fronts. (drive dog as they call it and various other bits are in the same site, keep clicking.)
You need one that is a speed reducer. Every mech tach I have seen are designed to run off the distributer so 1/2 speed. Run your tach up with a drill and see if it reads 3600 or 7200
Bruce, that is the perfect part! I'm going to make up a crank drive with the same thread as my current crank bolt and an extended shaft with a flat for tightening. If possible I'll make it a floater like Mikeys. Great site for some cool racing parts! Thanks, That's what I was looking for! Andy, You are absolutly correct as most tachs are calibrated to run off either the distributor or the cam, both of which operate at half the speed of the crank so you need the 2/1 reducer to make them read correctly. It gets tricky when you have one driven off the generator like Homemadehardtops Hemi setup as you get into all kinds of calibrations due to pulley size and belt slippage etc. This one is actually pretty simple.
Koz, just got back from Vacation and I wasn't able to return your call until this week. Hit me up this week and we can get together
Here's another. View attachment yanmar_mda flathead tach adapter.pdf I hope this comes out. This is the mechanical adapter I have, and a spare 90 degree, also is the S & W nut a person will need. That nut goes to the crank. . View attachment yanmar_mda flathead tach adapter.pdf The mechanical tach and the other mechanical gauges kind of make the set. Guess I can't remove that Yanmar PDF file that I inserted twice. HellRaiser
My plan was always to run a Chevy tach-drive distributor machined to fit the flathead...a little simpler and easier to source the parts! I know...lazy.
Damn Hellraiser! That's one neat setup. The underdash panel is the nuts. I still like the right angle drive that works directly off the crank bolt like Mikeys. I'm going to do some relativly easy machine work to do the floater which I think just looks a little nicer. I know what your talking about Flat Ernie. I'm actually considering the GM distributor myself using one of the MSD maroon caps that kind of looks like the old Cadillac caps of the fifties. When I get that far I'm going to see what Bubba thinks and follow his advice. The Chevy vacuum advance would be super nice if I can get it to run with my cam and carb setup.
Koz, My bracket and 90 degree angle drive is the same as Uncle Bob has on his. What cam and carbs are you using? I know, there's going to a bunch chime in and say you can't run a Mag on a street car...Wrong. Most of the mags are set up to come full in above 2000 RPM, That's the same as a stock dizzy with the vacuum advance. They mostly come full in by 23 or 2400. That's about where most of the early flatty's would be run at. I had Tom Cirello at Cirello Magnetos cos. go thru my Vertex, and had it set up for 23 degree. That's for a street engine...Well not exactly a stock engine...but...if a person wanted a mechanical tach and a magneto to boot... . You could drive all week with your GM dizzy, and go racing on Saturday's with a Vertex!!!!! HellRaiser
My 8ba is going together with a 3 5/16 bore, Ross pistons, 3 3/4 crank, (I need the rpms more than the torque the 4" would make). A pair of Merc headss cut about .010 depending on where the chamber comes in at. I'm doing a really nice port and polish as per my Dads old method, some decent headers and an Eddie Meyers Hollywood high rise with two Holley 94's. I'm going to have Bubba put the distributor together for it and balance everything to the nines. Cam is up in the air yet. Maybe a Potvin 3/4? It's running in front of a '36 box with stock '48 gears and a 3.78 banjo. 7.50-16s' on the rear. Mags are cool. Right now I'm scratching cash just to get it together. These sombitches are expensive! Toys will have to wait but I admit they are cool! Ultimately I'd love to have a Scott on it. Maybe next year! My build thread. Read through, it started out a lot different than it's ending! http://www.jalopyjournal.com/forum/showthread.php?p=7814107#post7814107
By the way Hellraiser, I love the panel your gauges are in! Stewart aWarner I assume. Anybody know if they are still available?
Back to the top and looking for further info on one I just acquired. P/N clearly visible but no SW or ratio but it is 2:1. It’s either been cleaned up or possibly NOS. Not 100% sure but from what I have read, it doesn’t need any bracketing and is held from turning by the cable. Also read that because of the position of the motor in a 32, clearance is minimal so this will alleviate clearance issues. It’s going to be used in my 32 pickup with a C69A and now looking for a suitable tach. Sent from my iPad using The H.A.M.B. mobile app
The Jalopy Journal
