My engine is bogging under hard acceleration, it seems like when the secondaries open up it bogs. Quick summary of the engine:
10.7:1 compression, .510 lift cam, msd ignition (29 degrees total timing), 600 cfm edelbrock with 100% factory jets/metering rods. The car ran good prior with only minimal bogging. The only changes to the engine since is a 1" carb spacer, and a K&N stubstack filter housing. Is it possible that it is running lean, and I need to richen it up on the top end? The plugs always burnt light brown before, but I would get alot of soot out the tailpipes. I am just wondering if It needs more or less fuel on the top end. I guess this is where an A/F meter would be nice. I would appreciate the racers thoughts. I am not concerned with fuel mileage, I am only thinking about next weeks race. Thanks for the help.

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Ryan Covalt
62 Plymouth Valiant Race Car 2170# 11.008 @ 117.65 MPH 1/4 Mile Best
72' Dart Swinger Street Car, 4 spd, 3330# 14.061 @96.58 1/4 mile Best

Bogging is usually rich, surging or a backfire is usually lean. Does is "bog" and then pick up? If so that would probably be rich.Get an o2 meter.

,Cliff

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'72 4 dr Dart
'63 4 dr Dart

Hard to tell, in my experience, but might likely be fuel puddling on the floor after to step on it. Accel pump shot does not make it to the cylinders, in other words.

Why not just take the 1" spacer and stub stack off?

Lou

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Home of Slant6-powered fun machines since 1988

Lou has a good idea, go back to where you had it with a slight bog. That way the car will be more consistent.

From what you describe, it could be a couple of things, and you will only cure it by trial and error. If it is getting fuel puddling from the accel pump shot, then try a smaller pump shot and see what effect it has. The other option is to play with jetting.

Brian

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Flyin' Brian

74 Duster, 225, rear-mounted blow through turbo at 12psi boost, street/strip car
"Sixy Beast"

as far as the spacer/stubstack goes, I will try it without them again and see if it goes back to the way it was.

I would like to play with the carb jets and metering rods to see it I can eliminate it completely that way, because it did always have a slight bog before, now it is just worse. It does seem to pull much better from the bottom end now but is bogging at wot. To clarify, the "bog" never really goes away thru the entire upper rpm range. If I let off of the throttle slightly it picks up, but even when I go from 3/4 throttle to WOT at high rpm's it still will bog.

Basically it runs best at 3/4 throttle now instead of WOT. I wish you guys could drive it, I feel like my wife trying to explain a car problem to me. With my updated description are you all still suspecting too much fuel? If so I will try some leaner jets/rods first and see if it helps. Like I said, the carb is box stock, so I am sure it needs some tuning. Thanks for your help

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Ryan Covalt
62 Plymouth Valiant Race Car 2170# 11.008 @ 117.65 MPH 1/4 Mile Best
72' Dart Swinger Street Car, 4 spd, 3330# 14.061 @96.58 1/4 mile Best

OK, that is more helpful. Usually if you let off and it picks up, it is rich. What main jets are in your carb secondaries and mains/rods in primaries?

Lou

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Home of Slant6-powered fun machines since 1988

Lou, Here is what the factory jets and rods are listed as. I didn't pull them to verify, but this is what edelbrock says. Primary .100, Secondary .095; Metering Rods - .070 x .047; Step-Up Spring - orange. Edelbrock says the manual choke carb that I have is factory jetted for "performance" not economy, where as the electric choke is jetted for economy. So if it is jetted for a performance v8 that would go along with what you said about it being too rich. Do you have any suggestions for rods/jets? I have some rods/jets at home, so I will check to see what I have. Thanks.

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Ryan Covalt
62 Plymouth Valiant Race Car 2170# 11.008 @ 117.65 MPH 1/4 Mile Best
72' Dart Swinger Street Car, 4 spd, 3330# 14.061 @96.58 1/4 mile Best

Couple things to think about - have you pulled the crush washers off the spark plugs? Maybe more timing? Fuel pressure to high? I remember one 600 Edelbrock a guy wanted me to look at because of a rich condition. I took it apart and found that the factory had jammed both rods in and bent them. Carb had never been apart. I would check all jets and rods for consistent #'s. Something may be mismatched. Goodluck and Later.
Ryan

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10.74 @ 127.47 mph 1320 ft
6.65 @ 107.80 mph 660 ft

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Ryan's at a banquet so I stole his car and pulled the carb apart. I adjusted the floats to the proper height and pulled all the jets to verify what they were. They were the correct stock settings. With the kits I have the combination of jets and rods I ended up with was 1 step richer at cruise but one step leaner at power. I also install the heaviest step up spring in the kit (plain silver) and moved the accelerator pump to have less of a shot. I drove it and I think it ran great. I think the bog is gone. But Ryan will need to test it out tomorrow.

Rick

Rick,

Those settings are how my aftermarket carbs have usually set up (leaner on power, richer on cruise).

Lou

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Home of Slant6-powered fun machines since 1988

Ok Lou, That is good to know.

Rick

Dont you just love when dad steals your stuff and sets it straight?

Too bad The oil change places dont have that kind of service

Greg

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http://www.youtube.com/hyperpack

Your right Greg, it doesn't get much better than that. I come home, check slantsix.org, read what jets/metering rods my car has in it now, and it runs great. The bog is gone, and it pulls strong all the way through now. I can't wait until we all get to race saturday. Thanks again Dad, and thanks for the advice guys.

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Ryan Covalt
62 Plymouth Valiant Race Car 2170# 11.008 @ 117.65 MPH 1/4 Mile Best
72' Dart Swinger Street Car, 4 spd, 3330# 14.061 @96.58 1/4 mile Best

Just wait until the bill arrives in the mail. You won't be so happy then!

Rick (DAD)

Great work, Covalt Males. Next stop, history...

Lou

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Home of Slant6-powered fun machines since 1988