I just did the 2 barrel swap to a 4 barrel swap on my Jeep. 1970 350 42k original/actual miles GS intake completely stock I purchased a holley rebuild Rochester 64-7778 Off the shelf idle/and general operation is perfect. The problem I notice is that a mid/part throttle it will surge until i stepp a lil harder for the secondaries to hit in. Any advice?
Too much ignition advance will also cause a surge. Typically, this may happen when you install lighter springs in the distributor to bring the mechanical advance in sooner. When you do this, you have to reduce the amount of vacuum advance. If you don't, it will surge. If you step on it hard, vacuum drops, and the vacuum advance drops out. Try pulling the vacuum advance off and plugging it. See if that makes the surge disappear.
I hope you don't think that whatever you set the initial timing to is what it stays at. There is absolutely no way I can answer your question. What counts here is the total timing. As soon as you go above idle, the mechanical (centrifugal) advance and vacuum advance adds timing. You need to be able to measure the total timing. If it exceeds 50*, it can surge and/or ping.
Holley is actually one of the WORST commercial sources to obtain a "remanufactured" Quadrajet from. It will be full of poor quality components, generic calibration, miss-matched components, bent/broken parts, poorly adjusted, not set to spec's, and overall just not a good carb. I hate to see them coming, as they are always labor intensive to get set up correctly. I'm certain that Holley does NOT do these "in house". Most likely they are farmed out down South of the border someplace, and probably assembled on Monday mornings after a weekend trying to get to the worm at the bottom of the bottle!......Cliff
