Ok I've been having the same issue with my vacuum advance. I did everything that everyone told me to do and still in the same spot. I checked for vacuum leaks all around the intake, egr, carb, didnt find any. I've plugged everything except the top breathing vent on the carb, intake etc. Gapped the sparks plugs to 045, double checked spark plug wires to make sure of firing order, re-adjusted the timing to 10 degrees, checked all connections to my msd distributor and ignition. Installed a vacuum check valve, adjusted the air fuel mixture screws, but they dont do anything or I cant really tell from having headers only, rebuilt the carb again and used a compressor to blow out all of the vacuum sources. Installed a fuel pressure gauge before the carb, it gets 7 psi at idle. Looked inside the MSD distributor and the springs are the heavy silve ones that advance around 3,500rpms. Talked with MSD Tech support and they are very unhelpful. Not sure what else to try, Im all ears and will try anything you recommend as soon as I have time. The issue is when I plug in the vacuum advance to the spark port or manifold vacuum the engine pretty much dies or runs like crap. From what i've been told the vacuum advance has to be plugged in to advance at higher rpms. My car will drive fine until I hit about 3,000-3,200rpms around 60mph then it dies. The only thing I have not done is lock out the vacumm advance inside the distributor or change the springs. I contacted MSD about what springs should be used and they were unhelpful.
I would remove the vacuum advance line and put a cap on the carb nipple. Then set the total (max when engine is reved) advance at 32-34* and see how that works. What size carburetor do you have on what engine?
Its a Motorcraft 2150 2v and the engine is a 79 302 5.0 pretty much all stock except its bored 030 over. Will it show that high on the harmonic balencer?
I went back and read your other thread so I wouldn't be asking redundant questions. Only other thing I can suggest is check to see if the steel vacuum line for the modulator is rusted out causing a vacuum leak. Better yet, just pull the hose off at the firewall and plug the line going to the carb and see if that has any effect. Oh yeah, one other thing might be ignition wiring. Do you have 12V to your MSD ignition? i.e., did you bypass the resistor wire? Maybe just run a jumper from the pos battery post to the + side of the coil and see if that helps. Recheck all the ignition wiring. Think you might need some on-site help.
Ive checked the modulator hose and blocked it off before. Same thing will happen. I get about 20hg with a vacuum tester at idle. Yes theres 12volt going to my ignition, I've went through the MSD ignition tests everything passes on the ignition module. One of the only things at this point I can think of is I actually need a MSD 6AL Ignition. The msd 8479 distributor says it must be used with a msd 6,7,8,9 ignition module and im running an msd 5520. I've called one of my friends and asked them to come out and take a look at it, but im sure he wont figure it out.
Heres the difference in the2 MSD-5520 Voltage Output to Coil 435, Spark Output (millijoules)95 Millijoules, Minimum Operating Voltage 10, VMaximum Operating Voltage 18 V MSD-6421 Voltage Output to Coil 535, Spark Output (millijoules)135 Millijoules, Minimum Operating Voltage 10, VMaximum Operating Voltage 18 V
Well back to the drawing boards. I called MSD and they said that the MSD 5520 street fire will work with my 8479 distributor and have no problems. Im guessing they put that on their website so you think you have to buy a new updated ignition module.
Ok Im trying to figure out this MSD distributor setup. I know that it came with 2 heavy silver springs and a blue advanced stop bushing which makes it advance at 5,500rpms and gives it 21 degrees. With everything being stock on the engine what should I set these to? Here is the exact link to the instructions, but I dont understand what all this means. If someone could point me in the right direction that would be awesome. http://www.jegs.com/InstallationInstructions/100/121/121-8479.pdf Advanced stop bushings and approximate crankshaft degrees. Red-Smallest = 28* Silver = 25* Blue = 21* Black-Largest = 18*
I know you said it had 7 PSI at idle! but what did it have when you hit the 3000 to 3200 RPMs before it died if it still had good press. THEN! you can eliminate fuel delivery as a problem.
I havent drove it with the fuel gauge on and the fuel gauge is under the hood. I will rev it when I get home and let you know what it says around 3000-3500rpms. The odd thing is it will rev high all day and go higher than 4,000rpms if its in park. its only when driving theres an issue.
I want to make sure I understand the timing thing. I want to line my balencer to the 0 mark, which would mean number one piston is at TDC. Install the distributor and make sure it point towards number one piston and the wire is plugged into the cap where it points to. Start the car and adjust it to my initial timing, turn it off then back on and rev the engine and hold it at 3,000 and find the spot where it moves the highest and keep it there. Then tighten it down? Normally a friend of mine does this for me and I want to learn how to do it myself. I tried it the other night and this is what I did except reving the engine and finding the highest degree.
Thats why you need to drive it with the gauge on it and you need to have it where you can see it, add a longer hose run it through the hood where it wont pinch the hose tie it to the wiper! (it requiers alot more fuel to run under a load)
I will have to wait until a friend of mine can come with his truck to drive it again. Once I take it on the road it never makes it home on its own.
When you get it home what happens to get it to start agine! do you have to let it cool off, crank a long time or what
