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Hi all,
I have a '72 302 that came with my truck. The orignal owner had recently rebuilt it. '66 289 heads, 9.5:1 comp., and a holley 4160. Thats all he told me went into it. Then he told me he converted to a manual trans and the engine started shaking. I am thinking it has something to do with the pressure plate. So I fire it up and the carb starts leaking from the secondary side, rebuild it, starts right up. I then gave it a tune up and tossed in a pertronix ignitor in the dizzy. When I was putting the wires back on I noticed that they were all one place ahead of where they should have been. I put the wires back to the factory positions and tried to start it. It started backfiring out of the exhaust. I advanced it alittle, got it running ,and used a timing light on it. I set it at 6 deg. like motors manual said and it ran rough. I ended up having to advancing the distributor all the way until it hit the upper radator hose. What could cause this? I was thinking the dummy didn't phase the cam correctly. If so is there any way to find out without pulling the front off the engine?
Any help is appreciated
I would say to just set it from scratch, you shouldn't need the timing light. Just bring up the #1 cylinder and rerun the wires starting with the #1 wire above the rotor button. 1-5-4-2-6-3-7-8. Works fur me everytime. Maybe you have already done that, but if not give it a try.
Broncoguy I did the whole TDC on the #1 cylinder and pulled the distributor and jumped some teeth on the cam. Got it as close as I could to the #1 plug. The only problem is that the distributor is advanced as much as it was before I moved it. Thats what has me scratching my head.
To begin with, since you have no solid history on the engine, there are two firing orders that are possible determined by the cam that is installed.
What you need to do is turn the engine to TDC on the compression stroke and stab the distributor so that you KNOW where number one is. THEN connect your wires in the order given by broncoguy. Once you get it started then you can see if it is the other order which you will have to look up. The order that broncoguy gave is the 302 order. The other order is for the 351W/5.0 HO cam and I think it is five and three that switch, but look it up.
Ok I started from scratch. I pulled the distributor and set it up at T.C. on the #1 cylinder, set the timing at 6* and it still ran pretty crappy. I advanced it all the way up to 20* and The engine smoothed out. I let the engine warm up to adjust the timing again but before i was able to do anything the engine started to run rough again. Went through all the steps again and still the same problem. When I get the engine to idle smoothly it shutters and shakes when I give it some gas. When I retard the timing it idles rough but when I give it gas it smooths out. One thing I did notice is that the distributor is very hard to get out and if I jump teeth it is pretty hard to get it back down. Could it be a bad distributor or possibly a streched timing chain? Or maybe its both?
Thanks for the help guys.
My gut tells me that the problem you are describing is not distributor or timing related.
Use a vacuum gauge and see if it changes when it starts running bad. I think there is some form of a vacuum leak. Without being there it is impossible to know too much, but try that.
Don't get hung up on the numbers. Make sure vacuum advance is disconnected and plugged at carb. TDC compression stroke and stab dizzy wherever it gives you room to adjust and place wires starting where rotor is pointing. Tune it by ear or to max vacuum. And yes, def. check for vacuum leaks. At 9.5-1 93 octane will probably be helpfull. Just because you rebuilt carb, doesn't mean it didn't clog up again. Took 3 times to get my son's 4160 right.
Well I went at it again and I figured out that the major problem was ME. The distributor was too loose and was moving around, and the carb was too lean. Live and learn. It runs good now. Thank you guys for all the help and sticking with me. Now I get to move on to the fun stuff, like jetting.
Thanks again