I have the 3.4L Crate Egnine with the 390 Holley on it Edelbrock Preforma intake, cams are what came with the engine, Mallory distrubotor, improved exhaust not true header. My question what the care was on the dyno it was found that the
The car is running rich (11.4:1 and it's got white plugs!). I thought white looking plugs was a lean sign yet the ratio is 11.4:1 What does every think about this??

Paul

 

Did you shut down and pull the plugs immediatly after the dyno pull?

 

I was not there when it was dynoed. Please explain why you ask.
If I remember well before I had the car dynoed I had checked at least one plug #1 at one time and was suprised to see the plug on the white side.

I would imagine the plug(s) were pulled at some point after the pull but don't know if right after the pull I will find out.

Paul

 

white plugs don't always mean rich. It sounds like you're only looking at the insulator.
BTW, many stock systems run at 11.5:1 at WOT, so it's not a disaster or anything.
pull a plug and rub your finger across the outer ring. You should get some black soot indicating a slight rich condition. A ton of soot is very rich, and so on.

 

The 11.4:1 the way I was told was rich and the plugs being white was a sign that it is lean?????? ratio rich but white showes lean?? a bit of a contradiction, like jumbo shrimp LOL

Paul

 

Yeah you've already said that once, and I answered. The person telling you didn't explain it well enough to you for whatever reason and is the one who confused you.

 

They sure did. It is a new engine and I don't want to wreck it

 

I dont think that ratio is rich.

Are the plugs clean and white are burned and white?

Are the plugs the right heat range?

Can you smell gas in the tail pipe?

I dont think you have a problem.

 

i would imagine the plugs are white from day to day driving which is typically normal. under WOT in a dyno session perhaps the engine is running on the rich side, but not to terribly so. Under part throttle day to day driving sounds like it is close to being right on. try upping the main jets 2 sizes and check the plugs again if you're worried about it.

 

305sbc when I said they sure did, I ment the the people as you said did not explain themselvs clearly.. Rereading my post I felt I was not clear.

 

the only way to really tell how the car is running from the plugs is shut the car off right after doing a run.

so lets say your doing day to day driving. the carb is prolly tuned to be a tad lean. helps on gas. when you pull the plugs you are only going to see what has happend the last little bit of driving that is all.

to see how the plugs read during the dyno run you would make the pull and then right at the end of the pull at the end of your rpm range shut the car off. (this isn't let the car coast back down then shut it off it's at your highest rpm reading you are going to pull to shut the car off at that point.
then you should see your plugs, doubt they should be white at that point

 

I have a quick ? I pulled my plugs the other day because the car was sluggish and backfiring. The motor has 2800 miles on the rebuild and I am running a holley DP. The plugs on the drivers side had ALOT of carbon build up but the plugs on the passenger looked fine, maybe a little white but nothing to make me worry. I have been doing alot of reading and I have come to the conclusion I need to rejet it because I am at 7000 miles above sea level. Does this plug problem sound right to anyone and is there anything I can do to adjust the carb manually to fix the problem or do I have to re-jet it. I can smell alot of gas in the exhaust and it is sucking gas like mad.
Thanks

 

I would try to determine the problem for sure first before rejetting.
What type of intake manifold are you running?

 

I have an edelbrock manifold. This engine is new to me and I am used to the Iron Duke so I am just learning about 350? The person I bought the car from didn't tell me anything I needed to know about the rebuild and I think he is a dumb *** It also has an accel dizzy, a mild cam, and I wish I knew more about the motor than I do. Is there any way for a lay person to look at what he has and make a determination on what he is running? The car runs great and all but runs very rich, the person I bought it from was able to tell me that the motor was built to run low 12's, and I guess I believe him because it burns tires even if I don't mean it to

 

That's a brand name. What type? single plane? dual plane? tunnel ram?

 

There you go again? It has a holley double pumper on it so I assume a dual plane? I am trying to learn so I can work on it. Thank you for helping me

 

What type the intake is has nothing to do with the type of carburetor.

Here's a dual plane intake manifold.
http://static.summitracing.com/globa...e/edl-2101.jpg



and here's a single plane manifold.
http://static.summitracing.com/globa...e/edl-5001.jpg

 

Is there any way to tell the difference without pulling the carb?

 

Which is better the single or double, if that is the correct way to ask, and in what way and why? and if you were to pick between the two which would be the better pick, or are each one for a specific puropose??

 

each one is more or less for a specific reason.

the single plane manifolds with the large plenum generally have a weak signal to the carb and low intake velocity so the lower end power isn't quite so great. the dual planes help eliminate that issue by using a divider down the middle that makes the plenum a little smaller and in turn helps with the lower end torque as well as mid range a little bit but then when the rpms start getting up it doesn'tquite have the oomph that a single plane would

 

Thanks for that lession. It seems Edelbrock uses the dual plane intake manifold for the 60* V6 for the 4 Brl.