I had a no start problem, that I compounded by trying to change several tihngs at once. I have it where I can start the car with just a click and it will run fine, unless I hook up the vac advance, then it bogs and runs like crap. I have had the dist in and out a hundred times and have it set where it should be, I will verify with a timing light but I have it at the right mark on the timing tab and pointing the way it should, I had a mark on the manifold where it was running before. I have the crane adjsutable advance and whether turned in or out, once it is hooked up the motor will want to run like garbage. Anyone hear of this before?
You may well have wear in the pivot the point plate moves on to advance and/or slop in shaft bushings...point springs take out the slop at rest, movement caused by vac can then bollixes up gaps.
I just set the timing and it is right on. Starts revs great and idles fine w/o vac advance. I've had the dist apart to ad a crane points eliminator. Could too ligt advance springs cause this? Where does the plate pivot? It feels snug when advancing the plate by hand. when advance is hooked it backfires through the exhaust.
The vac is hooked to the carb, and I had it that way for the past 2 years before this problem happened. Holley carb...
I think you may still have the dist one tooth off. turn the engine till the timing mark is about 20 degrees advanced which is about where it will be firing when its running, then pull off the dist cap and see if the rotor is pointing right at #1 or #6 or if its between posts. If its between posts then the vacuum advance may be causing the spark to jump to the previous post in the firing order which will result in backfiring.
With the vac line off/plugged and timing light flashing on mark, running smooth, first re-adjust idle mixture, then hook up the vac line to the distributor. Observe what happens to the timing mark. Then tell us what happens.
How does the engine run if you hook up the vacuum line to the carb, with the end that goes to the vacuum advance disconnected? If the same crappy way, then the diaphragm inside the vacuum advance is shot.
Does the car run crappy at idle when the vacuum advance is hooked up or when you get going? My Holley carb. only pulls vaccum at the advance port when the engine revs up past idle.
Lobucrod is onto something. Check rotor phasing with the cap and the Crane points eliminator/reluctor relationship. Using a vacuum pump, put vacuum on the diaphragm to determine where the point plate moves to. Now align the reluctor with the Crane points eliminator. Note where the rotor is positioned in relationship to distributor cap terminals. If the rotor is half way between two terminals, the voltage will follow the path of least resistance ie. the cylinder with less amount of pressure, the next one in the firing order. Easier to do this with the distributor out of the engine. Also if you have an old cap, cut the center of the cap out but leave the terninals so that you can clearly see rotor-to-terminal relationship during your testing. How to correct? Re-index the cap to the distributor body.
If it is one tooth off would you still be able to bring the timing without the vac advance to the normal 8 degrees before? This sounds like what is wrong with mine but I am not sure. If it is still off one tooth would you move it clockwise one? This is really starting to piss me off.
Mine ran bad at idle as soon as I hooked it to the carb, it would pop through the exhaust. At higher RPM it was worse. Now I had Phil 1BB41 listen on the phone to make sure he heard it too. Last month I drove it to a club meeting with the vac disconnceted and plugged, to see if I could have someone take a look. I asked some guys to look, went out and started it and hooked the adv up and...it ran fine. I drove it after this to work twice and no problem. What I think happened was the adj va adv was somehow stuck, and once warmed up it worked. I am confused about being a tooth off since the dist housing turns would this correct it? I did have to adjsut the idle once done as I had a lean off idle stumble. I also think my motor, which is timed at 36deg can take more maybe 38-40, but I can play with that.
i was also having alot of trouble with my vaccum advance. inconsistant idle, jumpy at stop lights, bogged down when i went to take off, crappy road manners........drove me nuts......every weekend adjusting something.......finally i met up with some H.A.M.B'ers at bad bobs village idiot get together. Explained my situation and was told my carb and intake might already create a high vaccum situation at idle, which isnt good for the distibutors advance, and to try it without the vac. advance connected......i went home that night and took it off and plugged the carb........it ran fockin great, ive probably got around 800 miles on this set up and no problems (except for the trans)......my distributor is an MSD.....no box, the carb is a 700cfm berry grant, and the intake is a rpm gap manifold.......on a bored out belly buttom motor you might want to try it without the vac advance
Yes I have had this, even had the thing some mornings refuse to start, pushed the vac pipe back on, gone a few miles ,and then had to stop and pull the pipe off again, because it's gone back to running rubbish with the vac advance working. I have long assumed that it's actually nothing to do with the dizzy, and more to do with some strange carb problem which leans it off to the point where the extra advance of the vac unit is too much advance and poor running results, but I have never solved it, just left the vac pipe off and run like that perfectly well. But I admit I am not sure that my theory is right !
Keep in mind that one of the reasons for vacuum advance is that the advanced timing gives a lean mixture time to burn. Are you plugging your vac 'pipe' (rubber line?) or leaving it open at the carb or manifold? If it's open you may be creating an overly lean condition.
I missed why you added the crane vacuum controller, were you trying to fix a different problem or is this a continuation (but disguised) of the same problem? I think i saw this same problem come up elsewhere recently, best i go and read about this crane thing. Do you have a part # from crane?
http://store.summitracing.com/partdetail.asp?part=CRN-99601-1&autoview=sku I had installed that awhile back, it comes with new springs so you can fiddle with the advance rate. What happened is that I had a no start problem (I now think it was bad plugs) but while changing plugs I added the breakerless ignition conversion from crane as well. I had run the crane adj vac adv for a long time before with no issues, but when I changed over to the breakerless I started to have all of the problems posted in the first post.
Don't know if someone mentioned this or not, but is it possible you have a hole in the diaphragm of your distributor, and it runs crappy when you hook it up because you're adding a huge vacuum leak when you hook it up (which would lean out the mixture a lot at idle)? A vacuum leak makes an engine run really crappy. If you have a hot cam and a big vacuum leak, it'll make things worse because a hot cam doesn't give you as much vacuum at idle to begin with. If you have a "mighty vac" or similar hand powered vacuum pump you could test the diaphragm out -- pump on it and see if it holds vacuum. You might want to double check your firing order, check for cracks in the distributor cap, carbon tracks inside the cap, burned spark plug leads or leads shorting out to each other. Try running it in total darkness at night and see if you see any high voltage arcing anywhere.
You do not mention replacing plug wires. Use your ohmmeter to check each wire, all 8 plus the cap-to-coil wire. 20,000 ohms per wire is way too much, but that is what many auto-parts retailers are selling. Go with a good set of spiral cores - longest wires usually less than 2,ooo ohms. I chased a similar problem as yours on my son's Nova. When I built it, I put on a new set of TVRS black 7mm wires, new plugs, cap, rotor, Igniter points conversion, used Delco coil (tested good), rebuilt Carter AFB. Engine ran strong - couldn't be more pleased with the performance. Five to six thousand miles later the performance decline began. Eventually hot starts were next to impossible. Replaced the carb (new 650 Edelbrock) - no difference, new coil - no difference, new plugs, cap & rotor - no difference. Checked the plug wires - some read infinity ohms, some way over maximum allowable - new-to-garbage in less than 6,000 miles. Replaced the plug and coil wires and the strong running engine returned. I still have to learn: "never assume anything"! BTW, I used to live in the St. Catharines area. Niagara Raceway Park east of Niagara Falls was a favorite Sunday event in the '60s, especially the Dodge vs Chev vs Ford Funny Car wars. Jim Zakia and Jim Oddy, the Funny Farmer, the Bad Banana, the Karbelt C/A Fiat, etc. were favorites.
When you did the points conversion did you eliminate the resistor/resistor wire? This gizmo getting full spark? Could you generalize the problem also as being under a high-load condition? Needing more grunt? And that with the vacuum advance working the grunt factor would be that much greater? Try to take that train of thought and see if it goes anywhere. Lat us know, oj
My car is running fine, I think the vac diaphram was stuck and unstcuk itslef, that is the only thing I can think of. The same problems are happenning to hr31hr now.
Yes, I did the conversion when I was wiring the car and never put in the resistor. Same as Dooley mine runs fine with the vac advance plugged but when attached it back fires and wont take fuel well. When I bought the car as a project the motor was in it with a new HEI and the vac was capped on the HEI. It is a Ron Barret motor and I assume it was that way from them.
I've always thought that the vacuum line should be hooked up to ported vacuum, so advance is given at part throttle cruise and during non-WOT take off. If it backfires immediately and at idle when the vacuum line is attached, wouldn't this mean you're hooking it up to manifold vacuum? I know some factory vehicles were configured for manifold vacuum sources, but it seems to me if you're pulling all your vacuum advance in at idle it could give you some sass. I know this won't help you here, but I was having a similar problem with a mopar 318 engine that I replaced the dist with an electronic model in. Turns out, they have an adjustable vacuum advance mechanism built right into the dizzy (stick a 3/32 allen key into the vacuum port and turn in or out) and it was way off!
I have not tried switching it to the ported or timed outlet yet. It did get a little better when I truned the asdjustment you reference in all the way exept two turns. I did not want to turn it in all of the way thinking what's the point of having it if you shut it off to make it work.
The vacuum source for the distributor should be ported vacuum. Check the vacuum reading for the hose that is connected to the distributor. It should be zero at idle and increase as engine rpm increases. If it is a high reading at idle and drops off when you stab the throttle it's manifold vacuum. If manifold vacuum is applied to the distributor it will advance the timing at idle and retard when accelerating--just the opposite of what you want. It's a good idea to see if the vacuum diaphragm has a leak too but a leak in ported vacuum will not cause a rough idle like a manifold vacuum leak will. The ported vacuum connection on most Holley carbs are located on the passenger side of the front metering block.
you won't believe this but I have the same problem again. Car ran fine when parked, I changed nothing with the motor, put a new radiator in and started right up, let her warm up and same thing; runs crappy with the vac can hooked up. I take it off and it runs great. Checked the timing and it is right on and revs great, hook up the vac can and backfire out the exhaust and rough running past 1500 RPM. I did change to lighter springs back earlier in the thread when I changed to electronic conversion. I had the problem before and it cleared up on it's own but now it's back Help New rad works good tho...
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