ok i am to the point where i need to find out what size reamer to get and where to get it.......here's what i got, oversize shafts for holley 94. they measure .282". everyone says to run a 9/32 drill bit through it, but a 9/32 in decimal is .28125" so if you run a 9/32 bit or reamer through, the shaft is still not gonna fit its .00075 bigger than the hole......am i right or am i looking at this wrong? i think i read somewhere that i need .003 clearance for a nice shaft fit, so i believe i need a reamer of .285" or 57/200 in fractional. where in the world am i gonna find one of these? has somebody do this before? i searched but did not find any solid info...thanks
Three thousandths clearance is bang-on right. McMaster-Carr has all sizes of reamers for about 25 bucks. The rest of the story is that, that little .007" oversize shaft is going to reduce the CFM rating of your carb by around 10%. . .
Try MSC for the reamer Drills rarely cut on size they usually cut .0005 to .001 oversize. You will also need to indicate the throttle bore within at least .0005 square with your mill spindle before you run the reamer through. P.S I'm a machinist
i looked at msc and only found a 9/32. i noticed they sell blanks would i have to buy the next size bigger and turn it down to the size i need then turn it ito a reamer?
McMaster has the reamer indeed, but yeah Unkie, where do you get the 10% figure? if you're talking additional obstruction of the venturi by the shaft I don't see it...
Both McMAster-CArr and MSC have the reamer you need, but I don't think you want .003 over. .001 to .0015 would be plenty of clearance. Indicate the shaft straight, use a GOOD cutting oil, go slow, as suggested.
Take a good look at the shaft bores. I just rebuilt a couple and the holes were worn well beyond the 9/32", out of round to boot. Strangely, the shafts were almost free of wear, so I put bushings in the bases and used the stock throttle shafts. Flatman
This is also a good idea....I had one carb that was the same, but I turned a custom shaft for mine, this would be alot faster and work just as well.......Littleman
is it mandatory to use a mill or can i do it by hand with a hand reamer? also i am using the extended shafts. i thought this might be an easier task as i don't have a mill in my pocket, maybe i should wait and find a machine shop
Could a drill press work here as well? Just wondering as I have never done this, but will be looking to try it sometime in the future. If you were to use a drill press vise and made sure the base is square to the table and the reamer/bit?? Or does the reamer not work in the drill?
I used valve grinding compound on the old shafts and kept checking the bases until the new .003 over shafts fit. Didn't take long at all. Neal
I just sold a bunch of 94 cores to a guy who rebuilds them for a "living" (sort of). He said that almost all but the rustiest clean up to +.005". He bought a reamer made just for 94's, not sure where he got it.
I guess I don't understand, how can a brass shaft wear cast iron, there must have been sand or some kind of dirt to wear the base..I have found, at least with the 97s is to just replace the shaft. Mic a new one with a old, what a difference...??????????? Duane..
Yeah, you could use a drill press, but it will take much longer and you will probably pull out your hair. You do have a good indicator right?
You wouldn't think so, but I have stuck my reamer in the throttle bell crank side and it will not be snug. If I stick it in the other side, it is snug and requires turning.
Yes I have decent equipment, but if it will be that big of a pain in the a$% I might be further ahead to just get it done professionally. I just wondered about the press since this seems like a slow and steady kind of "race" to do it right.
ok, in case anyone wants to know what worked for me. here's what i did...i went to local Wholesale Tool bought a 9/32 reamer, put it in my drill press, chuck everything up, i don't like how everything looks so i decide not to use the reamer...instead i take an old throttle shaft that is nice and round still, stuck it in my hand drill on the lowest speed setting and smear fine valve lapping compound over it and gently ream out my bases out with that, alittle at a time i would clean the holes out and try the new shaft till it fit smooth. i did all three bases in about an hour piece-o-cake.....hope it works!
Ford was no help on this...their overhaul instructions cheerfully advise tossing the entire base when it's worn! No bushings like Strombergs had... Flow is a serious issue...I had always assumed carbs were restricted by their venturis enough that nothing else mattered much. Wrong. Vizard published a bunch of flow tests based on Q-Jet flogging, mostly the primaries, which are bigger than a Ford and have smaller shafts. He got The Q well beyond 1000 cfm. Two of his basic findings: Cutting down size of shaft produced large flow increases, AND anything you do to increase flow through carb WITHOUT enlarging venturis improves response and makes ventuis more efficient. Draggers routinely use this principle by using Holley 850 bases on cleaned up 750 bodies to build an 850 carb without all the driveability problems of the biggest sizes. Bushings and stock shafts, or bigger shafts slab cut to minimum would be good here. I would think an industrial supply catalog (http://www1.mscdirect.com/CGI/N2SRBR) would produce any reamer or bushing you could imagine.
You know, some guys won't give you the time of day when you need a hand or some info. Bruce, I've got to say you astound me. Not only are your posts always full of good info, you seem to have a good way to get it across and able to be understood. Thankyou for always sharing.Sincerly. Pistinbroke.
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