help with vacuum lines

[70xlt]

I rebuilt engine, new intake and eldebrock 600, won't run smooth, how does the vacuum lines of distributor hook to carb. I put it back original but new carb just won't run, timing and all correct. any suggestions would be appreciated. this is a senior retirement project

[colnago]

I rebuilt engine, new intake and eldebrock 600, won't run smooth, how does the vacuum lines of distributor hook to carb. I put it back original but new carb just won't run, timing and all correct. any suggestions would be appreciated. this is a senior retirement project

First, every truck is different, so the following is what works FOR ME. Hopefully, it will help, but don't take it as a final solution (I'm still tweaking, and probably will be for the next 20 years).

I rebuilt a 352, with a Ford iron 4BBL intake, and Ford iron iron exhaust manifolds. I have an Edelbrock 1405 carb, which is leaned down one step (stock, it idled rough; lean, the idle smoothed out). I'm currently using the yellow springs, but might go back to orange. Idle screws are out 1-1/4 turn.

I recurved my Duraspark distributor to using the 10L slots, and moved my initial advance to 18 degrees (giving a total mechanical advance of 38 degrees). I replaced the springs to bring it all in by 3500RPM. Vacuum advance is currently on ported vacuum, but I'm still playing around with the timing curves. Because of this, I wouldn't suggest you go crazy with your timing. Initial at 12 degrees (max) will get you started. Depending on what you have, you may want less initial than this, but 12 degrees should give you a good starting point.

If you don't have one, buy a vacuum gauge. The general rule is to hook it up to manifold vacuum (driver side port on your Edelbrock), bring the idle screws out 1-1/2 turns, and adjust them (slowly) to give you max vacuum. I have found that an engine analyzer helps, to tell me the RPM (I've been using a digital meter for years, but just picked up an analog meter on ebay; it is so much easier to use!).

Also, check for vacuum leaks. Take a can of carb cleaner, and spray around the carb and all gaskets. If the RPM changes (up or down), you found a leak.

Finally, check your ignition. Is the spark firing on #1 during it's compression stroke? Are the plugs firing in the right order? Are you getting the proper voltage to the coil? I'm going by memory, but I think stock points want 9V running, but electronic wants 12V.

If it's not idling smooth, my first guess would be a vacuum leak. That's where the carb cleaner helps. Do you have power brakes? Are they hooked to the port at the back of your carb? If not, is this blocked off? If they are, maybe the brake booster diaphragm is torn. It might be good to disconnect them and plug this port, just to check. Are you using the PCV port in the front? Do you have an auto transmission? Is it hooked up to the manifold? When you are setting up the idle, are the ports on the front capped, or hooked to a vacuum gauge?

Hopefully, some of this blathering helps. Keep asking, and keep us posted.

Joseph