I just reread your post. You said you bought it off of eBay already rebuilt. Commercially remanufactured? Is there a white sticker on it somewhere?
I'll have to check, it might be on the back of the carb. I know it had one when I got it. I looked and looked through my gmail account for the winning ebay email to see if I could find who made it but no luck. I know it was a known commercial reman company as I looked up the name on the sticker when I 1st got it 2 yrs ago.
The quad I have on it right now is a 17057204. Here's the spec from another post off this site:
17057204 CHEV 77 CHVL, VETTE 350 AUTO A/C 77 52 7029529 CH
The old quad I took off (was missing some pieces) is a 17058213, specs are:
17058213 CHEV 78 GMC HD Truck & '79 Canada HD 63 40 7036019 CP
77/52 vs 63/40 is a big difference. I wonder why the rod and jet sizes are so different even though both carbs came off 350 engines. Maybe the cam profile is way different in the vette vs the hd truck.
Here's what the cylinder head code comes out to be on the truck:
UTT 1978 305 van & bus hp 145 2 barrels C-10 & 1500
So, some one added a 4 barr intake to it. Maybe the cam profile needs the 64/40 or slightly larger, say a 72/40 or 71/40 from a 305 setup, and moving the accelerator pump shot linkage back to the original position?
The only thing I haven't verified is that someone hasn't put 305 heads on a 350 block. Sigh......this poor truck(64 c10) has had the most backwoods, jacked repairs/patch jobs I've ever seen so anything is possible.....lol. Such as wrapping the end of a stripped wire around a washer, then sliding the washer down the starter solenoid post and putting the nut on.....:;
Just wanted to give you as much info as I can, thanks for your help so far...