I have a 67 riv and a 68 wildcat. The wildcat is the one I need to jet now. The carb is a stock 1968 q-jet. it has been rebuilt and runs, but I know it needs to be jetted for the alky mix we buy at the pump. The gas in 68 is nothing like we burn today. I also need a supplier for jets and rods. thanks. ps its a 430 +030 lower comp. feels as if it has a lean miss.(swapped out plugs ,wires.) no difference . thanks
My 67 Riviera has stock 73 mains with 41 rods, but the stock rods actually measure in at about 0.039" with the digital calipers. Smaller rods give you a slightly richer mixture at idle. If you get replacement rods from Edelbrock, get the 39 set instead of the 41. I had the Edelbrock 41 rods in a different Q-Jet with 73 jets, and it had a lean stumble. I put in the original RPD 41 rods, and the stumble went away. RPD rods have the numbers stamped in them horizontally, while the Edelbrock rods have the numbers stamped in them vertically. Go to Summitt Racing (www.summitracing.com) for the rods & jets for the Edelbrock Performer carbs. Remember to get the single taper rods, not the dual-taper rods for 75 & newer carbs.
www.quadrajetparts.com Its Greg Gessler's site. TONS of Qjet parts, jets/rods etc. Great service and fast shipping.
Right to start with, this new fuel isn't that bad. We have been able to use it effectively at 11 to 1 compression in my current engine without any metering changes. No loss of power at any level, and drives perfect on the street. It has a few negative traits. Evaporates quickly, and absorbs moisture. NOTHING made of rubber will hold up in contact with it for very long. We have upgraded our carburetor parts accordingly, so no issues there. I passed some specific information on the other thread running about jetting, etc. For the early Buick units, it is not possible to determine the A/F ratio change precisely when swapping jets and rods around in them. They used an early APT system, and specific primary metering rods. The height of the power piston was carefully controlled to delivery the correct A/F ratio at part throttle (normal driving). Keep in mind that aftermarket replacment primary metering rods are not exactly the same as the factory "B" series rods. In order to effectively fine tune the primary side of the carburetor, one may have to modify the APT system to make it externally adjustable, or get rid of it all together and take the top on and off to make metering rod changes. Here's a pic of a modified baseplate I set up yesterday. If you set up your carburetor in this fashion, and use a primary metering rod that tapers on the upper section, and between steps, it will allow the tuner to have full control of the part throttle A/F from rich to lean, just like the 1976 and later units. I also put a pic of our latest accl pump compared to a replacment old style pump, that last about as long as it took me to type this!.....Cliff
Thanks for the photos Cliff..... So that screw / spring toward the front of the baseplate is the mod you made to control the PT setting? Tommy
Yes, we remove the factory screw, and cut a longer replacment in the lathe, heat treat the end of it, and add the spring shown to provide an easily accessed external adjustment. With the right jet/rod combo, the top of the carb never has to come off for fine tuning the carb exactly for the application......Cliff
Just be aware that the factory APT screw can be very difficult to remove. I have a combination of steps that we use here to get them out, and still not 100 percent successful. I do NOT recomend that most folks attempt this, and why it is not covered in our book.....Cliff
Yep, I pulled out the book last night wondering how I missed that one. AHHHHHHHHHHHHH, it's not in there....:grin: Tommy
BEFORE attempting ANY metering changes, it is necessary to be sure that you have an engine. That means being sure that ALL of the cylinders are firing. Determine the cause of the miss... It is easy to determine the cylinder misfiring. Once you know which one is the culprit, determine the cause. It is possible, for example, for the Qjet to cause a miss on four cylinders at idle, either 1,4,6,7, or 2,3,5, 8, if one of the idle tubes is blocked. Why is the compression lower? Let's start with the basics first... BTW, Cliff, good post on the carb. Ray
Which is yours? Our pump is on the left. It comes with a much better Viton seal, garter spring under the seal to keep it against the pump bore, custom wound duration and return springs, crimped on retainer to keep it from pulling apart, and a new spring retainer.....Cliff
