John Scott Posted October 21, 2000 Share Posted October 21, 2000 Started as a really noticible surging between 6-7000. Now seems more like a rev limiter. I've run it w/o the supercharger so I think I can rule out fuel starvation. Valve springs suddenly lost tension?? Never had it happen. Throw some ideas at me. I'm bummed! JS Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted October 22, 2000 Share Posted October 22, 2000 Hrm, supercharged motor losing power... I'd check compression real quick just to be sure you've not got anything real bad going on. Oil and water look okay? Plugs? Quote Link to comment Share on other sites More sharing options...
John Scott Posted October 22, 2000 Author Share Posted October 22, 2000 No wierd misses in the low or mid range. Power is still strong below 6000. Just past 6 it feels like someone stuffed a rag in the carb. Hmmm I did take that out before I reconnected the supercharger last time. Would a coil lose power in just the upper end as it starts to fail? I'm pretty sure its going to be ignition related, but am open to any suggestions. Thanks JS Quote Link to comment Share on other sites More sharing options...
John Scott Posted October 22, 2000 Author Share Posted October 22, 2000 Maybe I should amend topic to ...and my mid range, low end and soon to be everything!! What ever it is is having a slow death. New plugs and wires. Max rpm went from 6 to 5500, to 4500. Hah! pretty soon it'll just be the starter. Tach bounced once, twice and then engine died. Started again and had one good rev to 7500!! That's the ol' engine! Then thppppp! (sound of low reving 6 cyl) Man, it sounds like it hits a rpm wall! All wiring to tach, distributor, and coil seem well. I have an extra module for the distributor, but my experience with Unilites is when they go, its dead. Still worth a try. Dang, where's that old Super coil I had for years? Maybe when this "thing" falls out, burns up, or disintegrates, I can say "There it is!!" JS Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted October 23, 2000 Share Posted October 23, 2000 My advice is to not do anymore "testing" until you can determine you have the correct fuel pressure in the upper RPM range. If that is the problem, be glad you gave not already blown a head gasket or worse. ------------------ Scottie 71 240GN-Z http://www.mindspring.com/~vscott911/gnz.html Quote Link to comment Share on other sites More sharing options...
MYRON Posted October 23, 2000 Share Posted October 23, 2000 John, Your motor is fuel injected right? . What about the air flow meter> Dont those regulate fuel pressure/and how much fuel the injector lets through? I think they also regulate spark curve dont they. Maybe your main computer is dying? Myron Quote Link to comment Share on other sites More sharing options...
John Scott Posted October 24, 2000 Author Share Posted October 24, 2000 I wish it were injected!! Nope, its just a holley dp. As of last night, dead. No spark from the coil. Found an old MSD blaster. I'll try it out. BTW what's a near new MSD6AL worth? A local drag racer put 2 runs on his this summer and blew his motor. Bought a 7 series to go on the new 509(?!). Maybe this electical SNAFU was an omen to upgrade? JS Quote Link to comment Share on other sites More sharing options...
Guest RON JONES Posted October 24, 2000 Share Posted October 24, 2000 Summit sells 6al's for $172.95.Used? I would think $100 to $125 would be fair. Quote Link to comment Share on other sites More sharing options...
John Scott Posted October 24, 2000 Author Share Posted October 24, 2000 Ahhhh this is driving me nuts!! Mallory coil died. Put a blaster 2. Started, but same problem. Lots of fuel in the carb. Just winging in neutral shouldn't cause a fuel starvation problem!! Pressure is 4.5 at idle. Anything past 0 in. 14 psi. (vacuum/boost regulated) Where's a zz430 when you need one?? JS Quote Link to comment Share on other sites More sharing options...
clint78z Posted October 25, 2000 Share Posted October 25, 2000 I would suspect that Holley myself, I have always found that the needle valves stick quite a bit . Never let a Holley sit over the winter, the seals dry up and need rebuilding often . Quote Link to comment Share on other sites More sharing options...
John Scott Posted October 25, 2000 Author Share Posted October 25, 2000 Holley is becoming suspect again. I have a Mallory unilite. Replaced with my spare module, tried wiring direct from battery to ballast, and disconnecting tach. I beginning to think its an internal blockage in the carb. clint78z, this afternoon I'll put some faith in your suggestion. Thanks to everyone so far. If I don't find the problem soon I'm having a demolition free for all followed by a weenie roast Update 10/29: Still chasing my tail! What the @#$% is wrong with this thing!! Took the carb apart everything looked really clean. Floats are free and needle/seat are fine. Blew out all holes with carb cleaner. No difference. Why did my Mallory coil die? Coincidence? A new MSD coil changes nothing. Two different modules have no effect. Never tried before, but if I leave my foot to the floor long enough it can stumble past the dead spot and rev to the sky. I need to find another carb and see if it makes a difference. I've never had a problem elude me for so long!! Emailed a carb tech line, Parker carburetion. Got a response within the hour. Invited me to a phone consult. Big circle track race tuner. Had lots of good tips and advice, but he too, is baffled by the symptoms. Glad to know its not just me. Got my 6AL today Hope I can get this nailed down. JS [This message has been edited by John Scott (edited October 29, 2000).] Quote Link to comment Share on other sites More sharing options...
Guest Frank280z Posted October 26, 2000 Share Posted October 26, 2000 John, What type of distributor are you running? I replaced my 4 pin GM module with MSDs. Because I had the same problem at 4500. Now it shoots up to 6500 no prob. Or maybe the timing is not adv. enough. Quote Link to comment Share on other sites More sharing options...
Rob Posted October 30, 2000 Share Posted October 30, 2000 John, if you want to try my carb, let me know. Since you are working in Niwot, you are very close to the south end of Longmont, where I work. I could drop it by if you give me directions to your work site. I think the 390 will be just fine for you to try on the v6 without the blower, and I can get the thing off the Bronco in a hurry. Give me a call at home or email at work if you want to do this. Quote Link to comment Share on other sites More sharing options...
John Scott Posted October 30, 2000 Author Share Posted October 30, 2000 A Ford 390?? That'll take care of my problems! Just kidding! Yes, I'll take you up on the carb offer. Niwot is completed and off North to Windsor. If I could pick it up some evening, that would be great! Thanks!! JS Quote Link to comment Share on other sites More sharing options...
Ray Posted October 30, 2000 Share Posted October 30, 2000 Do you have another distributor??? If the pickup in the unilite is going bad it can cause this, but usually they just die altogether. You can always go to the wrecking yard and pickup a HEI, and use it to isolate the problem. I also agree with a few of the other people on the site check the motor out, aka comression or leakdown test to make sure you didn't hurt anything else when this started to occur. Good luck, and don't get discouraged it usually takes time to figure electrical parts out. Quote Link to comment Share on other sites More sharing options...
clint78z Posted October 30, 2000 Share Posted October 30, 2000 Hmm seems like you are going through the possibilties in a systematic order good . Before replacing anything do everything besides . Get a multimeter check for a proper 12v at the coil wiggle connectors and wire checking for shorts . Check for a proper ground . Pull cap off dizzy and inspect to see nothing has come loose inside or looks suspect . Look for burn marks in the cap and rotor from spark scatter . Check module with multimeter it should give an off and on signal . I fthis is ok go to the fuel system, put in a new fuel filter . Then get a fuel pressure guage and check for sufficent pump pressure . Next I would turn to that Holley . Start easy and work to hard !! Quote Link to comment Share on other sites More sharing options...
Rob Posted October 31, 2000 Share Posted October 31, 2000 Its a Holley 390 vacuum secondary. Not a Ford symbol on it! With the blower the 650 would be better, but I think you said you had to mill the choke horn and install plastic floats to do that. According to Holley your 4.3 is best suited to a 413 CFM carb rating at this altitude and 85% volumetric, at 7000 RPMs normally aspirated, not far from 390. I think you can also sense that I don't want to tear down my 650 after my 3 months or so of getting it set up, shipping it back and forth to the factory because they forgot to drill the bleeds, a wheezing gasket, carb fire, broken stud and a whole lot of cussing. Those double pumpers are touchy little buggers and the odds of bolting mine on your 4.3 and it working without problems seem quite remote. So if its OK with you I will unbolt the non-brand loyal Holley 390 for you. Quote Link to comment Share on other sites More sharing options...
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