Tech - 454 plugs fouling out bad

Subject: 454 plugs fouling out bad

Original Message

Name: Rick Bucci
Date: February 15, 1998 at 21:52:20
Subject: 454 plugs fouling out bad

Comment:

I just put a 454 in my car after having it built by an engine builder. I just took it out on the road and the plugs are fouling out so bad they are junk after 3 times around the block. I talked with him and he said it must be a timing problem. Unfortunatley he's about 1 hour away from me and I'd be afraid of driving it to him in this shape. The distributor is an Accell HEI unit with adjustable vacuum advance. He said put new plugs in and advance the vacuum advance until it runs right. the plugs started fouling out immediatley and it didnt run right (misses) at about 2500 rpm and up. these plugs are about as black as can be in no time at all. Anybody ever have a problem like this. The engine has been broken in before installation on an engine jig. the cam is pretty lumpy and the carb is a Holley 750 vacuun secondarys.

Response Number 1

Name: Christian Webb
Date: February 15, 1998 at 22:04:32
Subject: 454 plugs fouling out bad

Reply:

I don't have a whole lot of experience with engine building but I seriously doubt its the ignition timing. How competent is the engine builder? Is he absent minded enough to forget the valve seals?

Response Number 2

Name: Gene McGill
Date: February 15, 1998 at 22:45:08
Subject: 454 plugs fouling out bad

Reply:

I would check your ignition system. (Not being familier with the Accel unit...) Is it possible that your HEI needs a full 12 volts, and is not getting because you're running through the stock resitive wiring? This could result in a weak spark and eventual fouling of the plugs. With them being black, that shows that your running rich, which could happen with inefficient combustion due to weak spark. Oil fouling (like if the seals were forgotten) would probably not happen so fast, and would be putting alot of blue smoke out of the tail pipe before they finally foul. The plugs would also have alot of carbon buildup on them.

Response Number 3

Name: Ron
Date: February 15, 1998 at 23:21:38
Subject: 454 plugs fouling out bad

Reply:

Hi Rick;
Yes I agree your Accel system runs on 12volts. I have run these systems some what successfully along with their Bei unit.
I would suggest that you remove the Chevy resistor wire to the unit and replace it with solid copper inorder to deliver the full 12 volts to it and a 12 volt coil. You can Install a Dodge ballast resistor ( HEAVEN-FORBID) on the firewall that will function as an optional terminal for the stock Chevy components if ever the Accel unit should fail.
z15cam

Response Number 4

Name: Rick Bucci
Date: February 16, 1998 at 06:16:47
Subject: 454 plugs fouling out bad

Reply:

The previous engine was a 350 with the exact same setup Accell HEI distributor with an Accell super coil in place of the stock coil, so I'm definatley getting a full 12 volts.

Response Number 5

Name: Bob Tiley
Date: February 16, 1998 at 06:31:52
Subject: 454 plugs fouling out bad

Reply:

Sounds like your carb could be flooding the engine. Is the float stuck? Is gas pouring down into the engine when you carefully look into the carb. ( This can be dangerous with the air cleaner off and engine running is gas pouring out of the boosters in the carb throat?)

Response Number 6

Name: Jeff
Date: February 16, 1998 at 12:57:32
Subject: 454 plugs fouling out bad

Reply:

Rick,
I am running a 454 with the same carb as you
with a stock HEI and wiring and platinum plugs. The only times I have had problems in the past has been when the car set for an extended amount of time and the carb went dry. When I started running it again the floats were sticky and out of adjustment allowing way to much fuel. If there is a problem with the valve stem seals your plugs would be very wet when you pulled them. I believe your problem is purely in the carb. P.S. I can generally run around 30,000 miles on a set of plugs.

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