Fuel fouling plugs easily on my stroker

[68charger440]

Here is my basic setup:
1968 Charger
440 bored 40 over with a balanced 500 inch stroker kit installed
Stock fresh 906 heads. 
10.52 static compression. 190 compression across the board when adjusted for my altitude.
edelbrock performer rpm intake
Edelbrock performer cam
Holley 870 street avenger
Stock converter
3.91 sure grip
18 initial timing 34 total
5280 foot altitude here in Denver

last year you guys helped me get rid of a pinging problem because I am right on the edge of getting it to run without pinging on 91 pump gas.  My problem that I still have is that I can fuel foul out my plugs real easily if I don't get it to start up right away.  I also have to let it completely warm up for 5 or 10 minutes before driving it or will also start to miss a bit and foul the plugs.  I'm OK with the warm up period, but not the fouling if it doesn't start right away.  Once it is warmed up it runs great, the plugs look good,  and the air/fuel ratio is good as well. I am not at all happy with the 870 street avenger and have battled it to get it as good as I can get it, but this fouling is so bad that once it doesn't start it won't start without cleaning or replacing the plugs.

My question is... does 91 pump gas make it hard to start a high compression motor or will it only affect performance?
Thanks for any input.

[cdr]

what kind of choke is it? if it is electric , it might be set to tight.

[Charger4404spd]

First thing I would do (and I have done it) is trash that Street Avenger and get a good quality carb.

[68charger440]

I have played with the choke and I would like to trash the street avenger, but back to my question, should it start fine with a motor that really should be running higher octane? Or will it struggle starting?

[cdr]

no to the octane

[cdr]

back the choke all the way off & try it.

[Back N Black]

What is your start up prodecure? Do you pump it once, twice etc...... I know my car was a little hard to start until i figured out what prodcure to start when cold. Now i know pump it four times and it fires right up. 

[68charger440]

What is your start up procedure? Do you pump it once, twice etc...... I know my car was a little hard to start until i figured out what prodcure to start when cold. Now i know pump it four times and it fires right up. 

I have yet to find a starting procedure that works consistently.  I have also opened up the choke and cranked it , but no go.  Right now I think I'm back to where I need to replace all of the plugs again because it is not even getting close to firing no matter what I do, so I think the plugs are all fouled again.  Is there a good cleaning procedure for the plugs or should I keep replacing them? This is getting old and expensive to replace the plugs every week..  I have heard some say replace them and others say I can bake them In an oven or some other method of cleaning?

[firefighter3931]

What plugs are you running in the stroker ?

I've had excellent results with NGK plugs & have recommended them to hundreds of the members here....allways with positive feedback. 

A weak spark will also contribute to fouling. You should have a nice blue/white spark....a dull orange/yellow spark indicates excessive resistance in the ignition system. 


Ron

[68charger440]

What plugs are you running in the stroker ?

I've had excellent results with NGK plugs & have recommended them to hundreds of the members here....allways with positive feedback. 

A weak spark will also contribute to fouling. You should have a nice blue/white spark....a dull orange/yellow spark indicates excessive resistance in the ignition system. 


Ron
[/quote
I have an msd all in one dizzy, Blaster II coil, Accell 8.8 spiral core 300 wires, NGK xr5 plugs. I have tried a few different plugs, and swapped out the dizzy and coil.  I hooked up an in line spark plug light that flashes when cranking but have not checked the exact voltage.  I have had more people than I can count tell me to get rid of the street avenger, and I think I am ready to do just that.  Any suggestions on a carb?   Keep in mind that I may or may not swap out the stock 906 heads and performer cam.  I'm still open to other suggestions to fix this problem as I consider new carbs.

[68charger440]

I don't think my last post posted so I'll repost it.
I have an msd all in one dizzy, Blaster II coil, Accell 8.8 spiral core 300 wires, NGK xr5 plugs. I have tried a few different plugs, and swapped out the dizzy and coil.  I hooked up an in line spark plug light that flashes when cranking but have not checked the exact voltage.  I have had more people than I can count tell me to get rid of the street avenger, and I think I am ready to do just that.  Any suggestions on a carb?   Keep in mind that I may or may not swap out the stock 906 heads and performer cam.  I'm still open to other suggestions to fix this problem as I consider new carbs.

[firefighter3931]

I really like the ProForm & Quickfuel carbs. Something in the 850cfm range is fine for a 500in street engine.

I'm still wondering why it's fouling plugs if they still look clean as you say. Questioning the spark "quality" 

The ready to run distributors are designed for a constant 12V power supply which creates a hotter spark for better combustion. 

Is the distributor wired directly to a 12V power supply ? There should be no stepdown voltage (ballist resistor) with a RTR style ignition. If the ignition is weak it can cause plug fouling issues.



Ron

[Charger4404spd]

X2 on the QuickFuel carbs. Im tellin ya man, change that carb, they are junk, then go from there. That may be your only problem.

[68charger440]

Here is a pic of one of the fouled ones.  When I test it it is clearly arcing from the insulator to the inside of the threaded part of the body.  The blast register is bypassed. 

[68charger440]

They look like the pic above only when I struggle with it fouling, but if I get it to start and take it out for a 20 minute ride it will look good.  At this point they are all so fouled that I will have to take them all out and clean/replace them

[firefighter3931]

Yep....that's Pig rich.       The exhaust must stink like hell ! 

The idle air bleeds may be clogged up....you can try spraying carb cleaner in the idle & high speed bleeds to see if that clears things up. The carb is definitely a problem. Anything can be tuned but some take a lot more work than others. 

A wideband with an O2 sensor works great. 

I shoot for :

13.5-14.5 A/F at idle
13.5 at cruise (light throttle)
12.5-13.0 at Wide Open Throttle




Ron

[firefighter3931]

One other thing ; if the idle screw is cranked down too much the transfer slot will be overexposed and the engine will be idleing on the main circuit instead of the idle circuit. If the power valve is blown it will also idle very rich.

The fact that it cleans up after a long drive shows that it's an idle circuit tuning issue or possibly a blown power valve.   


Ron

[68charger440]

I've had it with trying to tune this avenger.  You guys like the quickfuel carbs.  I am not to familiar with them.  Is there a particular model you guys would suggest, or should i just look for an 850 with electric choke.  Also, will the 850 still be good if I put on some average aluminum heads no porting, and a higher performance street cam?  Nothing radical.  I just want to go to the track once in a while.
thx

[firefighter3931]

Here's the one I would use on that engine combo :

http://www.summitracing.com/int/parts/pro-67214/overview/


Ron

[c00nhunterjoe]

Send me that junk holley before you chuck it! 

[68charger440]

Thanks for the input guys...
Coonhunterjoe...  I'll give you this fine piece of precision engineering for $295; that's an easy 30% off for a beautiful carb that just needs to be tuned properly.

[BSB67]

My question is... does 91 pump gas make it hard to start a high compression motor or will it only affect performance?
Thanks for any input.

No.

Also, your description of what happens really does not make sense.  Flooding an engine will keep it from starting.  Fouling a plug only happens when the engine is running.  So something is not correct in how you linked your car not starting to the fouled plugs.

Finally, you realize the statement you are making about yourself if you sell that carb for 295 and state that it just needs a proper tune.

Anyways, I not a fan of the 870 Avenger either.

[68charger440]

My question is... does 91 pump gas make it hard to start a high compression motor or will it only affect performance?
Thanks for any input.

No.

Also, your description of what happens really does not make sense.  Flooding an engine will keep it from starting.  Fouling a plug only happens when the engine is running.  So something is not correct in how you linked your car not starting to the fouled plugs.

Finally, you realize the statement you are making about yourself if you sell that carb for 295 and state that it just needs a proper tune.

Anyways, I not a fan of the 870 Avenger either.

Maybe my understanding of fouled is incorrect.  I was taught that if a plug got so soaked in gas and soot that it would not fire then it was fuel fouled.  As for the statement about myself, my conscience is clear.  I made it clear that I think there is something wrong with the carb while others seem to think it just needs to be properly tuned.  So I am saying if your sure that it just needs to be tuned properly; then this is in fact a good deal.  That being said, my statement was meant to be half serious and half sarcastic.

[BSB67]

If you put a good plug in, and you cannot get it to start right away, it will not come out looking like that.  

The plug does look to probably be fuel fouled, and it could be due to a rich carb condition.  Could be from a lean miss.  Could be ignition.   But not starting right away does not cause it to look like that.

Either you have two different problems, or the previous operation caused the plug to get so fouled that it won't start.

Curious, what was your actual cranking cylinder pressure.  What your motor and fuel actually sees is what matters irrespective of your elevation.

[68charger440]

To be fair, that plug has been cleaned and reused and has been in for a few weeks before the car acted up to the point of fouling them out so badly that the car wouldn't start again. Typically what happens is If I put in new plugs it will start easier for a short while, but unless I take it out for a ride every time I start it to really heat it and burn them clean it will act up and start to foul them much quicker than any car I have had in 40 some odd years of driving.  The idle circuit is loading it up and I can't get it to lean out.  It runs great once you take it out and blow the cobs out, but the idle is just way to finicky for me.  I want to be able to play around with it idling in the garage without having to take it out for a full cruise to burn it clean every time.

[BSB67]

To be fair, that plug has been cleaned and reused and has been in for a few weeks before the car acted up to the point of fouling them out so badly that the car wouldn't start again. Typically what happens is If I put in new plugs it will start easier for a short while, but unless I take it out for a ride every time I start it to really heat it and burn them clean it will act up and start to foul them much quicker than any car I have had in 40 some odd years of driving.  The idle circuit is loading it up and I can't get it to lean out.  It runs great once you take it out and blow the cobs out, but the idle is just way to finicky for me.  I want to be able to play around with it idling in the garage without having to take it out for a full cruise to burn it clean every time.

Okay.  This is way different than what you stated in your original message.....and makes more sense.  So, it is possible that the carb is too lean on the idle circuit.  This is why it takes so long to warm up and idle, as a rich idle will idle nicely when cold, why it stinks, why the plugs get black, and if you have an 02 meter, why shows lean at idle.  It could also cause part throttle detonation.  Could be the carb (likely) or could be a vacuum leak.

Just maybe.

[69wannabe]

I tried one of the 670 street avenger carb's on my 383 several years back and it took me awhile of tuning and jetting to get it to run "OK". Not a fan of the street avenger carbs either....

[68charger440]

Yea, I've heard that more times than I can count now.  Too bad I didn't hear it before I bought it.