Ok guys, give me some ideas here....

I replaced my spark plugs when I started experiancing an errant miss at cruise.
I pulled them and all my plugs were black and sooty.
I found a definate fouled one with my pyrometer.
I put same kind of plugs in except I reduced the gap from .04 to .035.

I still have that inconsistant miss during idle and light cruise.
If i try to rev it up and keep it at a certain rpm, the miss.. more of a flutter is very noticeable, the rpms bounce around pretty bad as cylinders missfire. the vaccum guage say 14hg at idle and it twitches within 1hg along with the miss.

I had my distributor off and the rotor and everything seems ok.

perhaps I got too little of a gap?
I pulled my plugs and they show awesome coloration.. if a bit lean. my a/f guage was saying normal to extreme lean.

I couldn't find any vaccum leaks anywhere, but it feels like thats what it is.

the flutter completely goes away with anything past 1/4 throttle, but detonates occasionally.

Any ideas?

 

It's lean. Some where.

 

I still hear ya...

After I got side tracked there with the cam, I had a chance to take it out today.
It bogged so bad it would almost stall. My A/F would follow it down lean as it got worse up until I would break through it, and the A/F would jump back up, and all as well. I jetted it back up to a .104/.100, and still did it.
I was surprised that my plugs looked good with a .104 jet, I guess I was wrong, and sort of right. I guess that little lift cam I had would load up on anything over a .101, but now she wants more fuel.
I dropped on .107/.101 tonight, and well see tomorrow. I don’t know about you, but man I’m a ****ing pro at changing jets on these Edelbrocks. I know I could do it with the lights out.

Another thought was the vacuum advance? Not sure it you have one or not, but could be dropping to much advance off the line.
I'm going to try mine disconnected tomorrow. Again, I’m running about 38 total /17 initial and thats with the pro-billet 8361.

There is also the accelerator pump to deal with?

I guess the final solution would be – meeting me at Jegs to get a couple of those Keith Dorton/Holley 830CFM 4150's.

BTW: That cam is unreal. I couldn't get no traction, it would just burn out for a 100 feet. Got back home and had a look-see at the memory on the tach - 6200rpm without trying. I've got a 6700rpm pill in my 6AL

Ron

 

Try going back to the stock jetting and work leaner.
Your motor will tend to want less total timing wounce
you establish the right jetting.

Sounds like the accelerator pump needs work.

I think when you're done you'll end up with a screamer.

 

Hault. Stop. Back up.

You have 14" vacuum with a 1" flutter? Run a compression check on the cylinder with the fouled plug vs. a known-good cylinder. I suspect there's something mechanical going on here. Like a burnt valve or a cam lobe going flat.

Not enought vacuum (should be around 19") and it shouldn't flutter unless you have a hyper-sensitive gague.

 

I'm at high elevation, my vaccum guage has always read low.

Is it possible a .04 gap was too much before? I have MSD coil, wires, 6al...
I got new plugs with a shorter electrode and decided to reduce the gap from .04 to .035. (.035 was their gap outa the box) now the plugs burn freakin awesome.
I richened the carb a bit and the flutter goes away on warm days, but comes back at night, cold days. Still too lean maybe.

I'm going to try stock jets/rods and start from scratch.
the car seems to pull harder on warm days.
the tires turn easier than ever before

If i still get that flutter, I'm pulling valve covers and see if i can find anything with the valve train.
I'm not sure, but the valve train seems to tick pretty loud. If I rev it up in idle the lifters chat quite a bit.. not sure if thats normal or if I have something out of adjustment.

thanks guys.

 

Sounds like the classic cold = dense, and your leaning out at night when it's cooler & the air is denser.

I had a .050 gap with a Blaster 2, and went down to .045 a few weeks ago and didn't find any change in my fouling problem at the time. So hell no .04 is to much! I think a stock HEI is gapped at .045 - I would run at the very minimum a .045 gap with a beefed up coil. I'll be playing with .050 through .060 - You might have to mess around with the heat range though.


Right now there set at .045, and I might mess with a greater gap as soon as I get this sucker tuned. BTW: I bought a set of those Jacobs spark gapping pliers a couple of months ago. It makes a nice flat level gap - real nice but kind of pricey @ 40 bucks. I would say there worth closer to 10 bucks.

I know mine flutters a little, maybe 1 or 2" at idle.
I did notice that the power stage pistons where fluttering up & down when I checked, so I went to a yellow spring, and that holds the piston down at idle.
You might want to double check that your power stage piston isn't boppen up & down. Mess with the idle mixture screws, and check your idle is around 850 or so out of gear. My flutter seems to smoothen out as I rise the RPM. I'm not sure of the over lap on these XE cams, but I'm sure that would cause a little flutter?

Ron

 

The .107/.101 68x47 helped a lot today, but it still leans a little while starting out. Plugs looked good !!!!!!!!!!!!!!!
So I going to try 65x47 rods tomarrow.

I mounted the accelerator pump to the bottom hole, & that didn't help.

The only mishap today is that I blew the damn water pump belt off hitting 6 grand on the tach. I was on a dirt road, about a mile from home(I live sort of rural), and I get a warning light about my water temp. Looked down and it's at 250, so I shut it down and coast a little. I'm almost there, oil temp at 220, so I fired it back up and get it into the garage.

I'll have to get side tracked again, and get a serpentine pulley setup. I would love to stay with the V-Belts, but I can't get them from flying off at 6 grand.

Ron

 

LOL I've done that a few times too, damn vbelts

The one time I didn't notice until I saw smoke hauling out the back. talk about a panic attack. the cap on my overfill blew off and coolant start pouring out onto my headers. I look at my guage and it's wrapped past 260.


Whats the disadvantage with running a smaller gap?
I'm going to try .04 again and see how that works out, it mighta been because my other plugs had a different electrode, maybe they just didn't agree with the 6AL's triple fire thing.

As far as I remember, my guage has always fluttered with the lope of the cam.. so maybe its an overlap thing on these XE cams like you say...


I'm running the same jets/rods as you, but i'm gonna fool around with the plug gaps first.

later,
jeremy

 

People sometimes like a .045 to .050 gap because they feel it lights a better flame in the chamber, due to its extra width, and is supposedly worth a few hp. You need a strong coil to jump that gap. I personally run .035 on my Bosch Platinums and I have had no problems, even though I have a 50000 volt coil. I just prefer to be sure that my plugs are actually firing. I don't care about a few theoretical hp, I want performance and clean plugs.

 

Hmm, maybe I'll try tuning my carb first. I can't see anything wrong with running a smaller gap. especially if it seems to be workin

I'm such a newb with tuning

 

It's really a more complete burn resulting in better economy resulting in more horse power when dealing with a wider gap.

Why do you suppose my 'stock' plugs are pre gapped to .060 for my Impala. It does have as much coil power if not a little more then my blaster 2.
My Vette comes pre gapped at .050, with a conventional HO coil.
Don’t get me wrong, there are limitations to how much gap you can go. But **** if you have a MSD 6, Blaster 2, and 8.5mm wires your not going to run a smaller gap than a stock HEI? Well maybe if your running Nitrous Oxide, super high compression, or a Super Charger...

----------------------
Hey Jeremy,

Sorry I haven’t got around to jetting since the last time out, but like I said I've been side tracked with these pulleys. I'm expecting a set of serpentine pulleys from Summit tomorrow. I spent this afternoon pulling the old ones off. I'm sick of V-Belts flying off right at 6 grand!!! I risking bending the shaft of a 150 dollar water pump, and warping boo-coo buck heads from over heating.
The conversions pulleys are from March Performance, and consisted of a alt/water/crank & I bought there press fit power steering pulley.
They set me back a clean 265.00, which isn't to bad, but what I spent over the last couple of week with the cam and ****, my old lady has put me in the dog house
I'll make it up to her some how

I keep you posted, and if the 107's with smaller rods don't cut it this weekend, I just might have to go with 110's - do the plug check - the works...

Ron

 

Well, I'll try widening the gap when I put my reworked heads on in a couple of weeks.