My 86 SR-5 4x4 pickup had a rebuilt engine when I bought it.The previous owner put in high compression pistons and rings and after market cam new 4 barrel intake manifold with a holley 4 barrel carb and a non vacuum advance Mallorey distributor.All this required me to use Aviation fuel at 100 octane to run it,or suffer serious knocking and pinging.After 3 years of this I put a new engine in it over the weekend useing the 4 barrel intake and carb set up and the mallorey distributor.Started it up yesterday it runs great,no knocking and pinging with regular gas but the distributor has no advance which throws off the timing.I have two other distributors,an EFI and stock vacuum advance with two hoses that I have no clue what to do with.I love my Yota and need distributor advice bad.

 

The dual vacuum ports on the distributor are advance side and retard side. The advance side will go to a vacuum port on the carburetor. I would not worry much with the retard side, likely an emission feature. You will have to use your timing light to figure out which one advances the timing and plug that one into the carburetor base vacuum port. I presume about 6 degrees advance, with vacuum advance blocked, should get you started. Once set, pug in the vacuum line to the carburetor and off yo go.

 

Both diaphragms advance the timing. The inner diaphragm advances a few more degrees than the inner. You'll want manifold vacuum at the inner diaphragm and ported vacuum for the outer.

You can't use the EFI distributor since there the computer adjusts the timing and you no longer have one.

 

Thanx to all.Ive kept the Mallory distributor in for now.The problem Im now having is fine tuning the distributor.Going by the manual I put the rotor at the twelve oclock position so that when the distributor is fully inserted it rotates to the number one piston at top dead center.I then have to turn the distributor counter clockwise completely until it stops at the end of the mounting bolt to start and run the engine,which leaves me no room for more adjustment.Also there is a wire that comes off the coil that attaches to the distributor housing at the same screw as the condensor on the distributor,if I were to use the stock vacuum advance distributor where would I attach that wire?

 

If you have to turn it the way 1 way to get it to run, you were 1 notch off when you droped the dis. Atleast on all the chevys ive done, that would be the case

 

You will most likely need to get a factory coil and igniter. The vacuum advance has two ports and both of them go to ports on the carburetor. The inner is only pulled at idle and is mainly for emmissions. The outer port is the main port and is pulled just above the idle position. You will most likely need a factory carb to use both of them. If you want to keep the 4 barrel carb, try putting a vacuum line from the outer port to the intake manifold and nothing on the inner port.