Does anybody have a pic of a SW flathead tach drive? From an old catalog maybe? The Mallory distributor on my 8ba looks like it has a place for some kind of drive to be machined in, but what did they use for pre-'49 flatties?
I'll have to dig it out, somewhere I've got some pix of an "early" flattie tach drive set-up. It was bracket affair that ran the drive directly off the crank snout. May or may not have been army surplus. I read where the flattie was used to power a WWII "Bren gun carrier" (A lightweight tracked vehicle for a heavy machine gun.) Had a tach drive on the flattie. Basically, the drive unit looks like a heavy bronze angle drive. Likely has a 2:1 ratio reduction, but I don't know that. -Keith
Someone is reproducing the engine mount for the flathead. It shows up on Ebay from time to time. pricey The angle adapter clamps into this mount. I have never seen a tach drive distributor for a flatty BUT I have seen a Chevy old Mallory tack drive distributor turned down to fit the flatty. Same process as adapting an HEI. It went for big bucks a year or so ago on Ebay. He bolted on a 1/4" aluminum piece to work as the dist. hold down on the flatty head.
Keith's got the answer. I haven't set up a tach yet on my 21 stud engine. I actually have two tachs for it, one's a modern Westech that I had them make for a 6-volt system, the other's a 12-volt positive ground Smiths. They're both modern electric, and don't require a tach drive. (I think I'm going to use the Smiths, but I need to convert it to positive ground). My engine has the diver's helmet distributor, and I'm going to pick up the signal from the point where the condenser goes down to the distributor on the passenger side. (I think...) It's not period-original, but it's a lot cheaper than a proper setup, and I don't think that too many people are going to know the difference. Bruce Lancaster might fill in some additional details on they way mechnical tachs were set up. --Matt
The guy on Ebay selling the repros of the original SW bracket is Doug Clem in Nevada, goes by "whygoby". They are pricey, and you still need to find the angle drive too, though it may be available new from SW. On my flatty I am using a drive bracket from an old Chrysler hemi. It's an old chrome aftermarket bracket that bolts to the flatty perfectly on those unused bolt bosses next to the water pumps. I'd have thought it was made for the flatty if I didn't see the hemi it came off of. Keep your eyes open for old hemi brackets and you might find a deal.
And on the Chevy Mallory with tach drive, be aware that two different codes were used on Chevy Mallory's--the tach drive version had a different number and was listed under Corvette, since early Vettes generally had tachs stock. I can dig up the numbers if anyone cares. Chevy made Corvette point distributors with tach drive are fairly easy to get but pricey.
I built a tack drive for a flatty by tapping a late cover and screwing a Triumph motorcycle right angle drive into it. I had to drill and file a square hole into the end of the cam and ran a reducer box behind the dash.
Neat--if you try this, look for a Canadian aluminum cover. They have a big flat area in front of the cam center that I believe would make mounting something there much easier.
Modernbeat - I built a tack drive for a flatty by tapping a late cover and screwing a Triumph motorcycle right angle drive into it. I had to drill and file a square hole into the end of the cam and ran a reducer box behind the dash. __________________ Ex nemo non fesces. That sounds like a great way to do it. Did you have a problem with LH threads?? I had a 70(?) Triumph Tiger with a tach drive block off plug in the case. Just out of curiousity, I unscrewed it. Alum plug, Alum case. Seemed kind of tight and hard to turn...til it sheared out. I think I learned later that the damned thing was left hand thread. Stripped real good! -Keith
Found an auction on eBay right now for the mounting and drive. Interesting pics. Looks like it could be done up fairly easily. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=4542025477&category=10076
Nope, but if I was going to do another one, I'd cut out a section of the Triumph case, turn it down, drill a bigger hole in an aluminum Flathead timing cover and weld the Triumph case section into the Ford cover.
Thanks for all the replies. Lots of good info. I like the idea of the drive in the front cover. Since the later (8ba) engines take the cam thrust on the cover, do you have to use the early timing gears to reverse thrust to the block? Guess I'll have to go look at some engine to find out if that's a dumb question.
Another (dumb?) question--If you run the drive off the cam that's turning at 1/2 crank speed, what do you need a reducer box for? Do old SW tachs run at different reduction speeds? I don't see anyhing on tachs I've looked at that indicates 1:1, 2:1, etc. or did I miss that??? Sorry if I'm being dense here, wouldn't be the first time.
Most tachs expects 1:1. It's been awhile, but I seem to remember that the Triumph angle drive puts out a 1:2. When you combine that with the cam turning 1:2 you end up with a 1:4. The tach I first used was a Jones, which used the 1:1 so I ran a reduction box, or I guess more accurately it was a ratio box, to jump the speed back up to 1:1.
OK, That makes sense. I think I'm going to make a thing like that crank-drive unit on Ebay, and avoid messing with the cam thrust surface on the front cover. Now I'd like to find a cool old chronometic tach...
Here is some pics of a Stewart Warner Tachdrive. From a Scrips landingcraft boat. It bolts to the crank, by removing the crankbolt, and screwing it in then you can remount the crankbolt to the drive, so you still can handcrank it. and it has a 1:2 reduction.
Thanks Lars, those were the pix I had hoped to post at the outset. There's some interesting mechanical tach stuff at Pegasus Racing. Haven't dealt with them, but they've got good catalog stuff. Here's two (pdf) links to (2) pages in their catalog. http://s2.pegasusautoracing.com/038.pdf re angle drives and brackets and http://s2.pegasusautoracing.com/039.pdf re tach cables. they've got your chrono tach here http://www.gagg-and-sons.freeserve.co.uk/main.html, but not cheap. I'm going (hopefully) a cheaper route, with 50's Jag (Smiths) tach & speedo, like these:
I'll resurrect the dead here. Anyone know where to find a nut like this? It attaches the Flathead angle tack drive to the crankshaft. Searching here on the old threads, Nothing... Searching the internet, Nothing. This nut and drive wire looks like it is brand new, so someone has to be making them. Thanks, HellRaiser .
I beleive I seen this on E-Gay (the whole unit including the bolt) My guess is that the guy bought the bolt new, then machined it himself. probably made the drive wire also. If nothing else i'll give this thread a bump, maybe someone else has info.
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