I'm running a 1974 sbc 350 with a three deuce intake. The engine would have come stock with an hei distributor, but I replaced that with an early points style distributor to help clear the carbs and intake. The problem is I foul my plugs almost instantaniously after putting them in. I've been all through the distributor, new coil, new wires and new plugs obviously. The fouled plugs lead to a bad miss. I am running stock AC Delco plugs that would have run in the 1974. My question is whether those plugs are too cold or too hot to be running with the points distributor? Thanks guys
running three holley 94's, but only idling on the middle carb. Also missing on one and seven cylinders, although when I pull the plug and check there is a spark, just very weak. I'm almost positive my problem is in the ignition system with the misses, but I'm not sure how to fix it. New plugs, new wires, reman distributor, new stock coil, but still have the miss. Seems like I'm losing some of the punch from the coil on the way to the plugs. 8mm Accel wires so its not through the wires, thought maybe the plugs were too restrictive for a points style distributor.
Try a new cap or rotor. I've seen that before great spark going in and weak coming out. Check and see if you have good spark at the coil and not at the plugs. Should not need to change plug heat range for carb change.
suggest adding an hei of some sort to start. or add a pertronix system. more spark will help with fuel burn. then plug checking after that, assuming carbs are working correctly.
Ok Shiner, here is my 2 cents worth. First, chevy did not use hei (big cap) as standard equipment until 1975. You need a small unit for clearance anyway. Second, as Rd says above the pertronix, with the proper coil will make a huge improvement in spark output. I have used pertronix for many years with good sucess. My personal favorite would be an MSD billet dizzy with the small cap.. Pertronix is good...MSD the best.. IMO. Third, we run autolite plugs. They will recover from a foul when champion and ac will not. (learned this from 39 seasons of racing ) Now for the real problem. Is the engine new / fresh ? Have you adjusted the valves recently? Has this intake / carb combo run sucessfully on another engine ? Cyl #1 and #7..Hmmm.. End cyls on left bank..Not the usual problem of physically next to each other or in firing order. If the valves check out ok and all 8 have good compression and the cap etc. check out I would focus on a carb issue.( stuck float or debris ) Let us know if we can help you solve your problem.. And keep us posted when you do, so we share the info. The HAMB rocks ! Dave
Also hotter plugs do not generate more spark than a colder plug,the term has something to do with the length of the insulator and the plugs ability to store actual temperature within the plug.dont let someone tell you hotter plugs give you more spark!
Does your coil get hot?you could possibly be putting too much voltage to your coil,you may need a ballast resistor.a cooked coil will loose power and eventually quit.
ive got a sbc with a tri carb running 3 94s. i use accel shorty 0576S plugs, never had any problem with them... what jets and power valve are you using in the centre carb?
Meddler1, where does the ballast resister go? My coil does get very hot, but up until now nobody has had a good reason why. I did put an ignition resistor in there before inline between the ignition switch and the coil, but I couldn't get the truck to run. Not sure what kind of resitor it was, I asked for an ingnition resistor at the auto parts store and they gave me one. Not real knowledgeable on the wiring stuff, but I do know that the coil gets very hot. Also, today when I pulled the plugs it looked like it was misfiring on every other plug in the firing order. 1, 7, 2, and 4. I'm not sure if that tells you guys anything. Thanks for all of the posts guys.
1) the ballast resistor goes between the ignition switch and the coil. It cuts the voltage to the coil down to about 9V. I have been using Mallory resistors for about 15 years as I had two or three 'bad' stock replacements from the local part store. 2) Are ou sure you have the correct firing order? I only ask because you said you have every other plug fouled in firing order 1 7 2 4. Chevy V8s have 1-8-4-3-6-5-7-2 for a firing order, clockwise on the distributer, cyl #1 is left front/drivers side. 3) If firing order is correct, check dist cap and rotor as mentioned. if cap/rotor are good, check wires. Just because they are a name brand wire doesnt mean they can't be bad. If you have taken them off at some time, you could have pulled the terminal ends free of the wire it self inside the boots. Once all of your ignition is verified as correct and good (not assumed) I would check the carbs for flooding/leaking, especially if running an electric or high pressure mechanical pump. You only need about 1 1/2-2psi for those carbs.
you could run a 12 volt coil , it is stamped 12 volt no resistor AC Delco P/N U515 Universal 12 volt coil Does NOT require external ballast resistor also run 2 or 3 capacitors hang on the coil look funny and people ask why ?? saves on point burn, they just seem to last longer in tune, cheap enough to do that napa has them has always worked for me, nice spark, just dont run cheap points,and take the time to get the faces hitting together nice and square
If you aren't allready,run a copper core non restor plug wire and non resistor plugs,NGK has a wide range of them.The difference in spark energy is noticable over resistor plus and any kind of resistor wire when using points.Don't doubt me ,try it.Of course you won't be listening to static free radio tunes..........
shiner1 this would have been my answer as well sorry for not replyinng sooner my pc crashed im using the one at work now this sucks i can fix cars but cant do squat with computers!
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