New intake now carb is running lean?

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RobbAdams

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I installed a RPM Airgap, and K&N AirCleaner with the xtreme flow top, as well as Cutting a hole in my hood to make room. The Engine seems to be missing at the 3500 to 4500 rpm rangem almost like when you hit the rev limiter on a newer car? Does this sound like some sort of lean condition?

It does not seem like pumpshot, as it is fine when I first step on it hard, the condition only arises after sustained throttle mashing?

I'm going to remove the carb spacer this afternoon, and see if that helps.
 
To be absolutely sure rob ya need to put in a new set of plugs and take her on a high speed run for a couple of minutes then pull the plugs and check the color or if ya know of a shop thats got a exhaust gas analyser and chassis dyno they can tell ya if your lean but that's an expensive service. You sure could be running lean cuss that RPM is moving more air.
 
RobbAdams said:
OK I will go get some new plugs at Lunch, Any reccomendations?
Click to expand...

Ya your looking for lite brown or tan, diffeniately not white. White is bad meaning way lean. You'll probably need to run it down the highway for 10 - 15 minutes. Don't be speeding ya just got to get the RPM's up. You also want to pull a couple plugs as soon as ya shut it off, no idling.

Terry
 
HMMMMMMmmmmm a 10 or 15 minute trip on the highway would probably bring me close to the "Demons Lair" ?!?!?!

I live in Millrise
 
if nothing else has changed check for an intake gasket leak too. spray some carb. cleaner around the intake gasket and the carb. and spacer gasket. one cylinder could be sucking in air and causing a lean miss.
 
Just a couple quick ? Rob, fuel pressure is ?, fuel filter..., Total timing advance ?, is your vacuum advance connected with the 6AL box (it shouldn't be).
Don't intend to undermind you, but most times the obvious things are over-looked.

Best of luck,
Giles
 
I am not sure on the fuel pressure, I am running a standard Fuel Pump (Mechanical) the Fuel filter is only been on for about 300 miles I am running an Edelbrock inline AN type fuel filter. I set the Timing at 10 degrees at Idle, I am not that tuning Savy, (Just bought the 4 seconds flat e-book) I am unsure how to check total advance, as I can no longer see the Line, much past say 15 Degrees as it Gets burried.

Why should the vac. Advance be disconnected with my MSD? (I'm not doubting you, I'd just like to know why ), and I am running a 6A not an AL not sure if this makes a difference.
 
I'd have to look at the specs for the 6A, but in general, after market electronic ignition have approx. 14 deg. advance built into them. Therefore with the vacumm and your initial engine timing at about 14 deg. advance, and the box already with 14 deg, you end up with to much total advance.

Does your car seem to accelerate if you let off the gas slightly ?
 
Sounds like fuel flow if it will pull hard and then nose over a few seconds after you floor it. Float level would be my first suspect, fuel pump next.

As for running vacuum advance, do it. An MSD 6 box, is an amplifier not a crystal ball. It can't magically fire a plug 14 degrees before the switching signal. They do not contain any sort of internal advance. (if they did, you would end up retarding your static timing by the same amount, net change zero).
 
I installed a new sending unit last week, I assume it came with a new filter (I had it done at my mechanic.)

Perhaps I should just replace the fuel pump since Im unsure of its age. They are pretty cheap, and it can't hurt to have a spare around.
 
Hey Robb I assumed from your original post that the only change you made is the new intake and before the change everything was running fine. Is that the case?

Terry
 
(I got sdome work done on the front end (Idler arm) Replaced the Tank sending unit (Spout was leaking), New intake manifold, 1 inch 4 hole spacer, Replaced gasket set (Again) for Right Angle oil filter.

After some more driving, it may have been a product of the very cool weather that morning, as I have not been able to really repeat it in the last couple days (Warmer Weather).

I am still planning to replace the plugs, and go for a quick jaunt, sometime this week, to see what they Look Like.


Demon,

I am planning to get out to race city this coming Friday, if the weather holds out. are they still doing the rental helmet thing? I dont have one, and it looks like buying one will be a dumb move since they are shutting things down after this season!?!?!?
 
Hey Robb, if I go I'll probably be just to watch. I was there last friday and the stinking track was so cold I couldn't get any traction, even with the sticky tires at 16 lbs I was leaving 10 feet of rubber. Anyway let me know if you're going and I can meet ya and you can use my helmet, it's regulation.
PM me and I'll reply with my phone number.

Terry
 
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