E85Forum.com

68LAR · Joined: 22 Feb 2008 Posts: 34 Location: South Park, Pa.

After running my engine for about 20 miles of so, I had taken the carb off to do some tweeking. Below the throttle blades of the carb I notices a dark, almost black coating. It looked like it was coming from the transfer slots. I also notices the same residue inside of the intake manifold. It's not heavy, just a coating and there isn't much of it. I never saw this with gasoline. Does anyone have any idea what this might be? It doesn't seem to affect performance. I did clean it off with brake kleen and reassembled everything. The engine started and ran normal, so I guess I'm just curious as to what this stuff is?
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'68 Roadrunner 440 4 speed
3900#street cruiser.
Best et 11.60 @ 120mph with 1.62 60' time

Drag Chevette · Joined: 18 Sep 2007 Posts: 458

68LAR · Joined: 22 Feb 2008 Posts: 34 Location: South Park, Pa.

Yep, It is shaped like a fan, clean at the transfer slot then darker as it gets further away. The whole underside of the throttle blades have some coating, but more the the transfer slot side of the throttle shaft.
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'68 Roadrunner 440 4 speed
3900#street cruiser.
Best et 11.60 @ 120mph with 1.62 60' time

hotrod · Joined: 19 Apr 2005 Posts: 872 Location: Colorado

How long has the car been run on gasoline?

I would suspect it is varnish build up from the fuel system that is getting dissolved from the fuel lines and such and left behind when the ethanol evaporates on the surfaces in the carburetor.

Larry

68LAR · Joined: 22 Feb 2008 Posts: 34 Location: South Park, Pa.

I bought the car new in 1968. It was on gas up until December of '07 when I made the conversion to E85. You may be right. Come to think about it, it does look and resemble varnish. Everything from the gastank to the intake is new. The only "OLD" piece of the project was the OE gas tank. I did have it out a few years ago and cleaned up. Could be I didn't get it clean enough. Embarassed

_________________
'68 Roadrunner 440 4 speed
3900#street cruiser.
Best et 11.60 @ 120mph with 1.62 60' time

68LAR · Joined: 22 Feb 2008 Posts: 34 Location: South Park, Pa.

It's been 4 months and I still have that black tar like reside under the carb and at the top of the intake. Are you guys sure that this is normal? It seems that there will come a time when this will start clogging something. One thing I have noticed is that I have a cracking or poping sound from the exhaust at 2000 rpm and going away at 2500 rpm. From my experience this is due to an over rich mixture. I don't have access to an LM 1 at this time to see what is happening. Question

_________________
'68 Roadrunner 440 4 speed
3900#street cruiser.
Best et 11.60 @ 120mph with 1.62 60' time

hotrod · Joined: 19 Apr 2005 Posts: 872 Location: Colorado

Frankly yes, back in the late 60's and early 70's I spent a lot of time rebuilding carburetors of that period and they all had dark deposits on the throttle valves, and air horn etc. You should be able to get most of it off with simply a spray of carb cleaner and a wipe down with a cloth.

It could also be a sign you are getting just a bit of reversion into the intake manifolds, or a hint of leakage past the intake valves, or the PCV vapors are doing it.

If you want to be safe, do a compression or leak down test if it comes back good, and the PCV checks out, I would just clean up the carburetor and see if it comes back.

Larry

68LAR · Joined: 22 Feb 2008 Posts: 34 Location: South Park, Pa.

I doubt it is a valve problem. My heads are new Eddy' RPM's. My PCV is hooked up, but I have a .060" Holley jet installed in the line. I am running a crank case evac system. The thing is, that the residue looks like it is coming from the idle discharge port of the carb. The round hole just below the T slot. If this is normal, then fine, I'll live with it. I just wanted to be sure that there wasn't something else going on that I hadn't experienced before.
Thanks for the reply,
Larry
_________________
'68 Roadrunner 440 4 speed
3900#street cruiser.
Best et 11.60 @ 120mph with 1.62 60' time

eldabo · Joined: 24 Nov 2008 Posts: 4 Location: Alabama

I have the same thing going on with mine . My fuel system is new. I have rubber lines all the way on mine .My thought on it was that the rubber was eroading .Any on e like to chime in on this ?

David
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David

cripple_rooster · Joined: 06 Sep 2009 Posts: 5

newalky · Joined: 30 Sep 2008 Posts: 84

I had my carb off and I can see a fan shaped stain from the idle ports.
In the intake on the floor near the divider between ports, there was a sticky black, tar like substance.
Enough that it covered the tip of my index finger.
I don't see any inside the bowls or jets. So this is accumulating there because the fuel/air mixture slows down or puddles there??!!
I am going to inspect the inside of my regulator to see if there is anything there? This regulator has only had E85 run thropugh it, but the fuel lines in front of it have had 110 Torco in them for 4 years. newalky

Alcohol · Joined: 17 Apr 2007 Posts: 634 Location: Central Wisconsin

Newalky- I'm just thinking out loud here Confused

*Are you all metal braided fuel lines or is there some "rubber" fuel lines involved?
*In a clear glass jar held up to sunlight - exactly what is the color of your E85 from the retail pump-- water clear or a slight yellow tint?
*What is the color of the E85 as drained from the carb bowls?
*How many run hours did this take to accumulate? (or-how many times has the fuel tank been MT'ed and refilled since conversion?
*Do you add anything to the E85?
*What is your air filtration system consist of?
*As Hotrod pointed out- blowby/EGR could contribute to this in many systems. I wonder if the lube oils/vapor are soluble in gasoline and not fully soluble in E85-thus leaving a deposit in high evap/slower flow areas whereas with gasoline it fully enters the combustion chamber?

I do not think you will find anything anywhere but where evaporation is occuring at a high rate (not including the jets where the air is screaming by ripping off the fuel and leakage does not exist on shutdown). If you have some "rubber" lines upstream from the fuel filter consider letting it dry out and cutting it open to look for black particles/deposits (maybe consider this even if there are no non-metalic lines involved to see if this is debris/varnish from the tank.

Speedy8311 · Joined: 30 Jun 2009 Posts: 22 Location: Long Island,NY

I actually have had the same thing happen to me,I did a E85 conversion and had taken the carb off after about 5 weeks.Same thing except a little bit more than just a coating.The intake has a light coating right under the plates but the plates had a bit more.I cleaned what I could then ran the car on my gas carb for a few days while I made the nessasary adjustments to the E85 carb.When I put the E85 carb back on 2-3 days later the residue was gone from the intake and the leftover from the plates was also gone.I though it was from an Excessivly rich idle condition(which I still do have)but DC makes sense the E85 is probly flushing the system out and this is probly all the crap thats left over from running gasoline for years.It'll probly happen again untill all of it is gone.