I pulled my plugs today. From what I understand, black=rich, white=lean, and grey=good mixture. My #'s 1 & 6 are black. The rest are grey. Is this common to some kind of adjustment (i.e. timing or carb)? Maybe the intake needs a divider? I have a Edelbrock 500 with an Offy intake, Clifford "shorties" with 2" dual exhaust.
I have slow acceleration, but I think that's due to the original cam. I have the timing at about 8*.

Thanks for any input!

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"Nothing in all creation is hidden from God's sight. Everything is uncovered and laid bare before the eyes of Him to whom we must give account."

on a normal /6.... 1 & 6 run rich... 2 & 5 run about right.... 3 & 4 run lean... I believe the reason has to do with runner length.... which is why the Hyper-pak had those long runners gave more HP!

But I think the bigger problem is your carb being to large... 500 is to much for a 225 w/ stock cam, even worse if you dont have any head work to give better flow. You might try adjusting your mixture screws and metering rods.

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Mike C
http://cuda.iclownz.com
67 - Barracuda Coupe - 225 - Automatic

I was pretty sure the carb was too big. I'm getting a Comp 252s. Do you think this will help or do I need bigger valves too?

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"Nothing in all creation is hidden from God's sight. Everything is uncovered and laid bare before the eyes of Him to whom we must give account."

Not on any normal and properly tuned \6 I've encountered. This kind of mixture distribution problem can happen with nonstandard carburetion setups (4bbls, creatively-installed 2bbls, etc.) but generally doesn't happen with *most* of the factory 1bbl and factory 2bbl setups. There were some mid-'70s setups that did tend to run rich on 1 and 6; the TSB fix was a so-called "1 and 6 plate" to be installed between the carb base gasket and the manifold. I don't have a TSB or part number.
No. The longer runners weren't to improve mixture distribution. They were to create a resonance-supercharging effect.

I agree the guy's carb is WAY too big.

I think you need to stop buying bigger-bigger-bigger and start going back to smaller-smaller-smaller.

Unless you're building a race car, but it sounds like you're wondering why your car doesn't work well on the street.

Your slow acceleration isn't due to the stock camshaft. It's due to the vastly excessive carburetor size! Bigger valves will make it worse, not better.

Dan, true, but the hyperpack manifold does provide for better distribution characteristics because the runners are a lot closer in length then the stock 1/2 barren manifold. In the stock manifold, the #1 runner is probably double the #3 from head to plenum. In the hyperpack manifolds the ratios are a lot closer. May of not been mopars original intention, but it is a good side effect.

In the clifford (and offy as well I believe) the #3/#4 runners have a small bump on the plenum floor to help even out the distribution.

Think about it for a minute: The original complaint is that 1 and 6 are running rich. If your runner-length theory were correct, 1 and 6 would be running lean because 1 and 6 have the longest runners.

I'm aware of what the original complaint was (which does seem odd because slants usually have #1 and #6 running leaner... maybe there is a valve adjustment issue or oil creeping past the rings maybe?) but my point was that with the HP manifolds more even runner lengths, fuel distribution is improved.

I must be lucky or sumpin'...haven't seen slants running lean on 1 and 6 as a general rule as you seem to have.

Yes, the more even the intake pipe length in a wet-manifold system, the better will be the performance.

For tha problem of 1 & 6 running rich, I would lean down the carb a couple of steps and if these cylinders still run rich, try hotter plugs in those cylinders.

On the subject of fuel distribution, there are so many things that influance the way fuel mixture flows in a "wet' manifold but in general, runners that are connected to outer walls of the plenum will run a little richer just because wet fuel collects on the walls and runs down the walls into those runners / cylinders.
DD

OK Thanks for the feedback. If bigger valves will make it worse, what about the cam?
Is a street driven 4bbl slant possible?
If so, what combination is needed?

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"Nothing in all creation is hidden from God's sight. Everything is uncovered and laid bare before the eyes of Him to whom we must give account."

Sure, a street-driven \6 4bbl is quite possible. Lots of people have done it. But rather than focusing on building a car around this kind of carburetor or that kind of camshaft or a specific-size valves, which will usually just cost you money and leave you disappointed, why not figure out what your *goals* are in terms of driveability, utility, performance, reliability and economy, and then post here with those goals so you can get some input that will help set you on the right track to getting the car set up to work the way you want?

OK
1. The car is not used to commute or anything. It is my weekend car.
2. I don't want to pull out the engine if possible.
3. I don't want a high rev engine (above 5000 rpm).
4. It has a 4 speed. I don't know what you mean by driveability, but I think low end torque is good (No high rev's).
5. A stock slant gets 15-20 mpg, right? I would be happy with 10+ mpg (I get about 10 right now).
6. Reliability is kind of a non issue with a slant, no? I mean I live in a warm climate so other than cold start, I don't know what other issues I should consider.
7. I'd like to avoid high compression (and high priced high octane gas) if possible.
8. As for performance, is 16 sec 1/4 mile out of the question? I guess I want it as good as possible while keeping with 1-7.
9. I'm on a budget like most. But of course I will pay attention to any feedback.
Thanks for helping me along.

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"Nothing in all creation is hidden from God's sight. Everything is uncovered and laid bare before the eyes of Him to whom we must give account."

Actually that plate was sandwiched between two gaskets between the carburetor bowl and carb top. I have/had the service bulletin and there was one of those kits on Ebay a while back.

Some of the Holley 1945 carbs were redesigned to have that fix built into them as a modified casting. I have some of those carbs and they don't run rich on cyls 1 and 6.

Also note.... 1 and 6 tend to run rich from short trip driving because the choke is still partially on.

Have you recurved the distributor and do you know what rear end gear ratio is in the vehicle?

It sounds like you need to make sure you have a good combination of parts all working together.
10 mpg, black plugs and sluggish performance does sound like the carb is running rich but it could also be a distributor with little to no advance.
(or a stuck choke, if you are using a choke)
DD