12/21/02 It’s winter here in Minnesota, but so far there really has not been any snow to speak of. This is unusual given the considerable snow elsewhere in the U.S. Anyway, it is rather cold here. The TurboStude is stored about 65 miles away, and I visit it on week-ends. Right now, I’m devoting a fair amount of time to our Bonneville project ( 53’ Stude with a 185″ flathead 6 which will have a blower ala TurboStude) .
I have been diddling with the TurboStude though. Hard to stop thinking about what I might want to do next. Two weekends ago, I installed the new floats, added the big float needle jets/seats and did a little mod to the high speed air bleeds. The floats needed a little scraping away of epoxy where the needles touch them, or the adjustment will be off. I didn’t bother trying any floatation experiments or careful measurement of float weights yet. I just made the top of the floats sit parallel to the inverted carb’s top surface. The drop should be similar to the stock measurement, but doesn’t seem too important.
I used the larger needles/seats which I believe were 0.110″. When I removed the old seats, I found two tiny screens. Given the fact that I already had a strainer and a large replaceable fuel filter on the circuit, I can only see these as one more restriction to fuel flow. I didn’t replace them.
On the Blow-Thru e-mail list, the subject of richening up the high speed, high boost was discussed, and mention was made of restricting the high speed air bleeds. According to my Avanti shop manual (these also used an AFB) this is a small brass tube (two) sticking up from the primary cluster . For lack of anything else, I denuded a twisty-tie (used on sandwich bags….) and wound it around the tube. The suggestion was to occlude about 50% of the area of the bleed. In a not very scientific way, I slid two bits of wire into the orifice on each air bleed. When the top of the carb is screwed down, it will keep the wires from moving.
So, the roads were dry, the wind was low, and the air was cold. I took off for a series of hill climbs and a little highway running. No speedo working, but despite the 3.40:1 gears, this thing accelerates up hills and more than keeps up with traffic. It really is running like a v-8 now, and with a little sand, or a bit of turn on the start, it will squeal the rear tires! Still haven’t monkeyed much with the timing. The boost is set to open the waste-gate at about 10# right now, and I can’t see what happens to fuel pressure on sustained 10# since the fuel pressure gauge is 15#, but it doesn’t sound like it’s running out of gas yet. Now that I’m using those restrictors in the high speed air bleeds, I believe I can start backwards on the jetting/springing etc. since there is plenty of blue smoke around. The A/F meter at idle is up at 0.8-0.9 volts, which means that my mixture is too rich at low boost. On the other hand, the ratio is now sitting up at about 0.9 volts at wide open throttle. One way or another, it really seems dialed in between 2100 and 3200 rpm under some load. The car on the highway goes fast enough to be scary, since the front end may be a little loose, combined with the body shape. Ted Harbit doesn’t seem to have much trouble going fast with his 51’. He doesn’t have to turn though…..
I’ll pull the speedo when I get a chance, and back off on the primary jets etc. Maybe I’ll play with the timing too, but it just started snowing and traction may be a problem over the next month or two. With two 185″ motors at the machinist for the Bonneville project, I will keep busy!
To follow along on the Bonneville project, double click here. It is not as detailed a site, but will be following our quest for speed in a stone-age vehicle.