Hello, I have the following: 462 camel hump heads 355 C.I. small block chevy flat top pistons, 10:1 compresion ratio camshaft: 106 degree LSA, 250 degree duration at .050" 165-180 cranking PSI in all cylinders. Quadrajet, stock intake, exhaust and heads, no porting (it is on a circle track street stock and those are the rules). What spark plug do you suggest? The spark plugs I have in there right now are fowling out.
Something a little hotter than stock... Try a set of NGK's that are made for those heads... P.S. Better do an intro first before the dogs on here start barkin' at ya!!
What are you running for ignition...? Guessing cam is around 3600-7000ish rpm wise? No porting.....look into brezenski (sp)...
What do mean by fowling out, picture of plug would be a great help. Could be a number of problems, not just type of plug
How much total advance are you running? What plugs do you have in there now? I'm a Chevy guy but pretty much have always run Autolites (don't use Bosch!) and go from there. Is it fouling at full throttle, part or idle? Sounds like it's waaaay too fat! Lean is mean!
I've almost got to agree with the above AC R44 as a starting point. These work in a "somewhat" similarly equipped Corvette engine. Forty years ago with a "somewhat similar", fairly warm SBC Chevy, I had to run Champion J8s or even J6s to keep from fouling, as compared to the "stock J12s. Today, I wouldn't buy a CHAMP for my lawnmower. Only stating what worked for me in the distant past. I'd start with the R44 plug. DD
I was thinking the same thing.... NGK does make a pretty hot plug as well . I think they are actually who makes Accel header plugs
I would try AC R44S. The extended tip burns a little cleaner. But there is no reason a circle track engine should foul plugs, just because of the plug. You've probably got other problems. Larry T
I put a carburetor on it rebuilt by Sean Murphy Induction, and ever since then it's been fouling the plugs. The car runs good, no real hesitation or bogging, as long as I change the spark plugs every 3 races, as they get completely carbon fouled. I wanted to get some plugs that should work in this application, and let him know what happens to the plugs then. I have been using some cold plugs so that may be part of the problem. In the past I have used 5/8 Autolite AR 25 with no problems, and some NGK but I cannot recall the part number. As soon as I went with Autolite 353 which are 13/16 head and this carburetor, I've been having this problem. But I do not want to do anything to the carb myself. Supposedly you are not supposed to use 5/8 socket spark plugs with the old camel hump heads before 1970 but I didn't know at the time. They seemed to work just fine.
I ran Autolite AF42 to stop fuel fouling problems,, would not change then all season, over 100 p***es, -- the 5/8 socket plugs have a tapered seat sealing,, and the 462 head requires the 13/16 socket sealing gasket plug. Unless you cut the head for the taper seal,,I wouldn't use them,, my .02
I believe that I'd talk to Sean Murphy Induction if the car started fouling plugs when you put his carb on. Hotter plugs are not the answer. I helped a guy with an engine that turned between 7000 and 7500 twice every lap and we didn't have fouling problems with AC 43s. That's GM's recommendation for "track" racing. Drag Racing can even use 42 heat range. BTW We ran a Fuel Curve Engineering (don't know if they are still in business, it's been a few years) 750 double pumper with the power valve plugged and 80's all the way around (most of the time). It did have an extra intermediate fuel circuit, so you might have to jet a little richer, but I wouldn't go much bigger unless the carb has had some major work done to it. Larry T
Try here as well, what this place is to hot rods, the dirt forum is to dirt circle track racing.....***uming you are racing on dirt. http://www.thedirtforum.com/
AC 44s the 43s maybe a bit too cold for your street stock. The extended tip on the 's' plug will help self cleaning of the plug tip.
Borrow another known good carb and try it out. Sounds like a small internal leak in the carb, the power valve gasket slightly off center maybe. What is it a 500cfm 2bbl?
I always run AC R44 in the Camel hump heads. Even with flat top pistons you have to watch the extended tip plugs. If the block has been decked and the motor has .040 or less quench the extended tip plugs might hit the pistons.
i been having the same problem for 4 yr always fouling plugs , i run autolite 85's tried 86's and the samething ,so last month i was talking to my buddy and he ask what ignition i was runnig i told him a mollory unilite and he ask what the plug gap was i told him 35 he said to try 45 gap , guess what haven't fouled any plugs yet
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