60 over, offy heads and a 3/4 cam. Two 94's with one blocked off on a slinshot intake. Timing is right on and carb was adjusted and jetted. Runs like a champ with the exception that the plugs faul in about 200 miles. The ignition is stock, stock generator, but running 12v battery and regulator. Does electronic ignition really help? Or do I have a mixture problem? Plugs are gapped .025. It doesn't load up, cough, nothing. But after about 200 miles the plugs are black.
oil or carbon. Check your float level on the carb. lower your jet size, check the exhaust gas color from the engine, check for leaking accelerator pump. traderjack
OK, lets start, are all the plugs dry soot black or damp oily black? If you start the car , check the exhaust by having someone accelerate the car in neutral. Is there a black smoke or a blue smoke? Most newer gases burn pretty white on the plugs so the question becomes is this a fuel problem or an ignition problem. Does the car run 200 miles at a pop or after 200 miles of idling at the car show your problem shows up? Does this thing start and run good cold or does it deteriorate as it gets warmer?
All plugs are dry soot black. I can drive the car around town or on the highway for about 200 miles say. Then it starts to run like crap. After a quick cleaning of the plugs I'm on my way agian. I don;t see any black smoke anymore it suns really good and idles without loading up. It runs pretty good cold and after it warms up it really runs good.
Well, that appears to be an excessive fuel issue like you are running with the choke on. Who rebuilt the carbs or have they been setting with gas stored in them for a period of 6 months or more. Next question, you say you have two carbs with one blocked off. Is it blocked off at the top or is it blocked off at the the base of the carb and do you have any fuel running to this blocked off carb or just the back one? If you have fuel running to the unused carb and have the top blocked off it will still run on the idle circuit, creating a rich mixture.
Pull the carb apart between throttle body and main body and unscrew the power valve. Many recently made rebuild kits have a valve from a 4150 type holley which cannot seat like the original: On the bottom of carb main body, there will be a flat ring around the hole for the valve. Proper 94 valve has a matching flat and a fasket the size of the two rings. 4150 power valve has its seating ring too far out to seat on the carb body, and a tapered area near the hole. Someone recently posted a method to seal this without rewaorking anything. Without trickery, the taper kinda sets and the gasket kinda gets pinched into place, and it might or might not seal. If it doesn't seal, any gas that gets past can run right down the vac passage into the engine. In fact, you can probably do an adequate test without taking carb apart: Run engine so carb is known to be full, remove carb, set it down and see if any gas trickles out. Another thing on 94's...my details apply 1937--1951, locations change on later versions: There are two small air bleed holes on each nozzle bar near front. One of each pair bleeds a bit of air into idle circuit, the other the main circuit. At top, holes are fairly big, but the actual bleed hole at the bottom is TINY and sometimes remains blocked by dirt after much soakinfg in rebuild. Make sure they are clear. 94's generally like low float level...set to lowest spec (biggest number) or even a touch lower.
Is it running up to temp? A cold engine may foul plugs more. That manifold may cool the incoming charge too. It would be great during the summer, but was it a cool day when this happened? Try a different coil, yours may not have enough zap to fire the charge under pressure.
Also, you just say "flathead" and "stock ignition". They made flatheads for several years... Stock ignition if that is '49-53 often has inadequate advance on single carb stockers, and of course will have zero advance if diaphragm has failed, utterly fubar advance if hooked to wrong vac source...retarded ignition can somewhat mimic over richness.
while we're talking about set ups on flatty's, what is the correct timing? I have a 24 stud french flatty with edelbrock heads, offy intake with two 94's (soon to be 97's as I can't stop them running rich) and a mallory duel pointer. There's no vacuum advance only centrifugal and the way it's set up doesn't seem to advance much. There is some adjustment which is set about middle and doesn't fully advance and it looks to me like the springs are too strong, but unless I know what to time it at at idle and when rev'd I can't change anything. thanks .............Pete
Sorry for delay, Bruce gave you a good run down on how to check the carbs, the next step is to check the ignition, c9 suggests having the coil hooked up wrong but if you have not changed these parts, the next place to look is the condenser. With the ignition turned off rotate the engine to close the points and turn the ignition switch to the ON position and manually open the points up. You should see a very small dull spark jump, if you get a large bright spark, the coil is good but the condenser is questionable. This diminished spark is not giving full energy to the plugs and promotes fouling. So this would be the next area to check. You can also check the ignition with the engine running and pulling a plug wire, You should have a strong white spark about 3/8" -1/2" away from the plug or ground. If you have a weak blue colored spark that jumps the distance at 1/4"-3/8" gap then it is necessary to check both the coil and condenser.
What plugs are you running? Flathead should be Champion H-10. I also run H-12 with my Edelbrock heads on an 8BA. More here: Champion NGK Always the same ol' things right? Spark, air/fuel mixture, timing, compression. Anyone know if running resistor core or non-resistor core could cause this issue? Mike
Are you running a 6V coil with a voltage reducer, or did you switch to a 12V? I had a similar problem before I upgraded my coil to 12V (I also have a 12V charging system).
Stumptown I just changed the coil to 12v. That is my start with the ignition. It runs so well I hate to change anything on the ignition. Everyone has really good points here. I went from champian to AC plugs gapped stock at .025. I might have afuel problem, but with a fuel problem I think I would see something wrong with the idle, something. This engine starts hot or cold with a burp of the starter. Runs out good, with not problems. Letme add something. The old rearend was a 8 inch 278 gear with the old top loader trans. I'm running a 5spd
I like Autolite 216, but many folks have good luck with Champions. You can also try NGK B6L. Some engines seem to prefer certain plugs...defies logic. Condensor as suggested previously...
So.."Stock ignition"...what IS that?? Is it a '49 type or a real distributor?? Advance must be addressed if carbs check out.
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