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  #1  
Old 01-19-2000, 07:31 PM
Tim_K Tim_K is offline
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Question

First, read the HEADS OR TAILS topic for the latest updates.
Then - here are some questions I've just thought of.
When I pulled off the old head to put on my ported one, I noticed the combustion chambers and intake valves were black, lots of carbon, but the spark plugs and exhaust valves were WHITE! The #1 and #6 plugs and valves were more of a grey-white than white, so I think it is a fuel distribution thing there. No surprise on a /6 intake. But the white valves and plugs - running lean? I don't think so, the BBD has its original 318 jets still in it. Any carburetor tuning experts want to take a guess at this one?
The spark plugs (80,000+ mile Splitfires) had a lot of hard white stuff built up on them, and when I took the wire wheel to the first one, it immediately lost half of its insulator, so I junked the set. Dug around and found an old set of Champion RN12YC's. Set them at 0.035" and wire wheeled them and put them in.
After start up with the new head, and a 10 minute test drive, I saw that 4 of the 6 spark plugs tubes were leaking, no, make that POURING out oil. Auto parts stores were closed already, so I pulled the plugs and cleaned and RTV'd the plug tubes back in, fixing the leaks. But the plugs looked weird. The middle 4 were a little wet (fuel, I guess), but #1 and #6 were totally covered with carbon! In less than 10 minutes! Blackness! I had oiled the valve stems heavily for installation, but I don't think that was the problem. I think some intake manifold modifications might be needed, but I'll wait and see what you have to say about that. If it matters, the end of the tailpipe is black. Carbon to spare.
Now for performance. Anyone have an idea of a safe upper rpm for /6 engines? I've always thought 4000-4500 was maximum with a stock motor. I've seen race /6 engines going past 5500-6000. I think the long (4.125") stroke is a limiting factor, but how much rpm is too much? Even with a race oiling system and bearings and valvetrain and so on?
Well, I'm looking forward to seeing what all of you have to say about all of this.

[This message has been edited by Tim_K (edited January 19, 2000).]
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  #2  
Old 01-20-2000, 01:21 AM
hemi-1 hemi-1 is offline
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I won't try addressing anything but the RPM question. A few years back, my daily driver was a 65 Valiant 2-door sedan. Originally had a 170 and three on the tree. I swapped in a 225 and a 4-speed with a 3.09 low gear. Bottom end and oiling system were totally stock. Dropped in a Comp Cams 264 degree, .440 lift cam and a set of used 340 valve springs, milled the head .090, Offy four-barrel intake, Holley 390 carb, electronic ignition, and stock exhaust manifold with 2 1/4 inch exhaust and a stock 340 muffler. Stock valves and standard valve job. Nothing fancy, very low-buck, but this motor would rev to 6,000 in every gear except top, where it was horsepower limited to 5700. With 3.23 gears and 24 inch tires, that works out to 125 mph. That motor saw six grand hundreds of times; it wouldn't quite run with 5.0 Mustangs, but it would outrun Nissan 300 ZX's, Chevy Z-24's, V-6 Grand Ams, 350 V-8 Chevy pickups and so forth. I sold it to a friend of mine almost ten years ago. He still has it and it still hasn't blown up. Even with the long stroke, those motors are tough.
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Old 01-20-2000, 06:57 PM
71Demon 71Demon is offline
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I heard of a way to even out the mixture from cylinder to cylinder in a /6. the center two ports of the intake run richer than the outer ones, because of the length and angle of the path. /6 racers weld in a blocking plate in the 3&4 port of the intake to allow more flow to the outer ones. I think the plate is 1/4" tall. See http://flag.blackened.net/mopar/
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Old 01-21-2000, 10:19 AM
PRO PRO is offline
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What do exh valves and spark plugs have in common? heat!! the hotter the item the less chance of carbon build up.If you have 318 jets you are way too rich about 35% too rich.Thats why all the black carbon,did you know running an engine too rich will dilute the oil film off the cyl wall and cause you to destroy your ring seal? and it dilutes your oil.One minor help would be to remove the cover plate on your 2bbl and loosen the screw that holds the metering rods in position and drop the rods as far down in the jet as the slotted hole will let you,this will lean out your jetting some.the white build up is very common,its due to fuel additives most gas suppliers put in their gas,now if it were white with no build up then it would be too lean.If you can find an old DC engine manual there is a picture of where to add a dam to the intake to improve fuel distribution.Max rpm is determined by piston speed,in feet traveled per minute,because cast iron can only take so much heat and if you get the piston moving too fast it will create too much heat and you will ruin your rings and their sealing capability,in your case its around 6200 rpms,although momentary overspeeding isnt as detrimental as continuous....PRO..
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Old 01-21-2000, 08:28 PM
Tim_K Tim_K is offline
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Lightbulb

Thanks, Pro (and everyone else). I just got home from work for the weekend, and I'll be looking up as much information as I can on this. After a week, the new cylinder head (see HEADS OR TAILS for more info.) is doing well, and cold starting is better, as is power in general. I think I'll try to find a Super Six BBD in the junkyard and swap the jets and metering rods. This should be all that is necessary to change the fuel/air mix, right? I'll pull the spark plugs this weekend and see how they're doing, too. Maybe it's time for me to install the manual choke cable I've had sitting around brand new for over 5 years now, instead of relying on the vaccum pull-off to hold the choke open in all driving conditions.
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Old 01-22-2000, 06:47 AM
Speedy#1 Speedy#1 is offline
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TIM-K look for the BBD-8198S OR BBD8199S models if you can find one .I was told buy the chrysler lab guy's years ago that the 318 bbd wouldn't work .I don't remember why.But i can tell you how the IDLE SYSTEM WORKS.Fuel used during curb RPM and LOW SPEED operation flows through the main metering jet into the MAIN WELL, fuel continues into an IDLE FUEL PICK UP TUBE where the fuel is mixed with air which enters through IDLE BY PASS AIR BLEEDS located in the venturi cluster screws.THE FUEL PICK-UP mite be larger?well any way's at curb RPM THE fuel and air mixture flows down the IDLE CHANNEL and is further mixed or broken up by air entering the IDLE CHANNEL through the transfer slot which is above the throttle valve OR (butter-fly) at curb RPM.THE IDLE SYSTEM IS EQUIPED WITH A RESTRICTOR IN THE IDLE CHANEL , LOCATED BETWEEN THE TRANSFER SLOT AND THE IDLE PORT WHICH LIMITS THE MAXIMUM ATTAINABLE IDLE MIXTURE.During low speed operation the throttle valve moves exposing the transfer slot and fuel begins to flow through the transfer slot as well as the idle port.As the the throttle valves open further and engine speed increases the air flow through the carb also increases . This increased air flow creates a vacum or depression in the venturi and the main mettering system BEGINS to discharge fuel.Bottom line is i don't think you can make it work write .Check HEADS OR TAILS for more .


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Old 01-25-2000, 02:46 AM
Tim_K Tim_K is offline
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New updates on HEADS OR TAILS. Check it out.
The engine seems to be running a little better now. I pulled out the spark plugs to check them after a week, and the 4 center ones look ok, kind of a dark tan color, some carbon. The #1 and #6 plugs are more heavily covered with carbon, but not as bad as before. It seems like the outer 2 cylinders are running the richest, but I thought that was supposed to be the center 2. Any more ideas?
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Old 01-26-2000, 03:25 AM
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Christopher Christopher is offline
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If you are thinking of changing the carb,try looking for a Holley "Economaster" 2bbl replacement carb.I put one of these on my 79 Volare with a super six and it worked great.I ordered it for a 69 318,and it bolted right on.Gas mileage went way up as did the performance.
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Old 01-27-2000, 02:48 AM
DodgeMan DodgeMan is offline
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Hey Tim
About 12 years ago I had a 75 Valiant. It was a 6 cylinder car. I loved that 6. Anyway I aquired a 2 barrel intake off a super 6, and a carb off a 318. Like Pro said it was way too rich. I did find out that the Carter carb shared jets with the old AVS. I picked up a strip kit and had plenty of jets to play with. Only the primary jets interchanged. I got it tuned in with no problem. I also found that the 318 accelerator pump adjustment was too rich also, and backed it off. Unfortunatly when I sold the car I had left the AVS strip kit under the drivers seat. Of course the new owner couldn't find it at a latter date. Maybe some one out there can hook you up with one.
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