Hi guys, I'm new on this forum and I was wondering if anyone out there can help me find a set of .100 main jets for the Zenith SV5D carburetor on the 1927 Stutz I'm working on. I'm just looking for an extra set. Does anybody know if Zenith made larger jets for these carburetors? A few thousandths bigger would be OK, too. The car is a rumble seat coupe and it belongs to a close friend. It was restored almost 30 years ago and it is still driven every week.
Anyway, I just don't know where to look first so I thought I would ask around. Thanks!
Eddie

I'll get my son to scan the information I have in a Radco tune-up book for you in the next days. I do not know whether there is common fitting between these early AA carbs and those of 105D and 105DC carbs used with the better inlet manifold from then on. I made probably a dozen bronze 105DC replicas when people desperately needed them, after I had set up to make those I needed for my own cars. (I haven't done my own yet.) The reason I have not bothered to make for others since is that I have not yet made tooling to my satisfaction to make floats. These were the only secondhand parts that I used, and my supply is down to one sample.
It is not all that difficult to make new jets out of brass stock. You should find that there is a size marking on your jets. I would have to dig out my workshop book on the carb work to give you the code. You will probably find that the threads are UNC or UNF gauge sizes. I found that there was variation in the Orifice length of some of the original old jets I worked from. I made mine of consistent length in case there was small difference in running from that. I always drilled the orifice last, with the jet screwed into a mounting piece in the lathe chuck. Best way is to hold the tiny number drill in a jewellers' pin vyce, with the drill dipped into cutting oil, and the lathe on the fastest spindle speed. With this you can feel what the drill is doing. It is best to drill straight to size, because if you try to enlarge a drill hole without grinding the cutting angle the drill may grab and break.
If your engine is standard it should be fine with the original setup. One owner here had higher compression ratio on his BB with better cam timing with valve overlap, and when they tuned the car on the chassis dynomometer, they had to discard the large main venturis to get enough airflow.
There is a lot of "knife and fork" work to make everything for a complete carb, and I did multiples of all the small items while I was set up. The only thing I had to modify was the accelerator pump plunger, which is an interesting item to make. My fit was too good, and the upper disc would lift raw fuel out the top when you closed the throttle. The simple remedy was to drill a ring of six 1/8" holes round the top disc.
I'll get the information together so you can work out what you want to do. Then if you find that the jets you want are similar to 105D or DC, I'll see what I can do to help.
Ivan Saxton

Thanks Ivan! The number on each jet is 100. This car was restored in Canada in the late 70's. We purchased it about 10 years ago. I believe the engine is unmodified and the cam is the stock spec unit. I did have to advance the cam 2 teeth when we got it because it was mistakenly assembled in the retarded position. I don't know how the car was driven for so many years with such a sluggish engine. The other issue is that it has always seemed to run lean and has favored the choke to be in the 1/3 to 1/2 position. I have gone through the engine and searched for EVERY possible (and common) reason for this lean condition to occur, but everything seems to be in proper order. I finally took the jets out of the carburetor and drilled only one just slightly oversize. The problem has nearly disappeared now and the car will run almost perfectly with the choke pushed all the way in.
Anyway, because I modified one, I would really like to have a nice pair (or two) of proper sized jets or a pair of slightly larger ones.
Let me know what you find in your comparisons between the two models.
Thanks again!
Eddie Call