projectresto83

As I have posted previously I just got my car running. Its a 306, mild cam, performer intake and perofrmer 600 carb. I set my timing at aprox 12 deg with the vaccum advance line off and it seems to run pretty good. but when i do put on the vaccum line it starts backfiring out he exhaust. which means its firing when the exhaust is open. so am I a tooth off then? and when the vac adv line is off and i rev above 4000 it backfires once or twice when comming back done.

Joel5.0

Nope....looks like you have the vacuum advance line connected to the ported (not timed) vacuum port in the carb. You shouldn't have vacuum at the line when the engine is idling.

projectresto83

Ok, well I hooked it up to the left port as shown in the diagram that i have for the 1400 series setup. It says to use the port on the left hand side (if looking at the carb from front) if the distributor is vaccum timed (no vaccum at idle).Ihave a stock 83 302 distrubutor. what would this use then? carbvaccumor manifold vaccum (vaccum at idle)???????????????? I can try again tomorrow to double check but i would like some input first!!! I don't know what the original setup is because it was a v6 and I pulled that out about 4 years ago.

What if I dont have the electric choke hooked up yet, would that be part of the problem???????

projectresto83

anyone else wanna put in there 2 cents??????

1985stang

So which carburetor do you have? My vac. advance line goes to the port on the side of the carb next to the fuel bowl. I know it shouldn't have any vacuum at idle anyway, but why did you adjust it without everything hooked up?

creekrat

It doesn't matter what dist you have or what carb you have. The vac advance line needs to be attached to the port above the carb butterflys for timed advance. If it is below you will have manifold vac. You should double check your timing, bring up #1 and make sure the rotor is pointing at the #1 terminal in the cap. Sounsd like you may be a tooth off because the advance in the dist shouldn't pull the timing that far off to make it backfire. Also, double check your firing order and plug wire routing.

projectresto83

Ok,I have the edelbrock performer 600 with electric choke (1406). and i thought i may be a tooth off. plug wires are in the correct order and all that. I dont know if I will get to mess with it again before I leave again to go back to iraq but i will definitly be working on the fine tuning.

mjr46

You need to check base timing if that's okay then make sure the vaccum advance line goes to the left hand port on a edelbrock if facing the carb....it's the smaller ports. I have a 1406 and a 1405 edelbrock that I run.......if you have a nasty cam as mentioned in your signature I had a similar problem on my 66 mustang when I redid the engine and added heads cam and intake. when I hit about 4000 rpms the car would spit and spudder and break down bad.......to make a long story short I had installed a cam with .500/500 lift and the duration was quite agressive compared to stock it had 300 degrees duration anyway I tried to used the stock distributor without tunning the rate of advance......turns out my total advance was about 55-60 degrees and the rate at which it reached full advance was about 3000 rpms.. way to much.... so I ended up tuning the curve in the distributor via weights and springs and wham!!!! 6200 rpm's all day long with ease now. So what I'm saying is you need to check your total advance and the rate at which it reaches that.... yoiu can use an adjustable timing gun to do it. sears sells craftsman ones with the dial on it that's what I have and it works well as long as you don't use it formsd ignition.

hellas85stang

edelbrock= left timed port,right constant maifold vacume...go to edelbrock website,the have free videos2 watch on timing,tuning there carbs..

hellas85stang

most carb set ups need 8-10 degrees initial,and 32-36 totle timing on agun.. i have 512 lift/230@50 /110-106 lobe..my timing goes,9advanced,34 totle...screams// there are exceptions..