Not surprisingly, my fancy oversized, undercut, swirl polished valves are completely covered in carbon and varnish deposits, rendering the benifits of having them pretty much useless.

I still have yet to find an additive or fuel that does not crud up the backs of the intake valves. Nor have I found any cleaner that will clean them without removing the heads and actually soaking the valves. Ive tried the injector cleaners, as well as sea-foam, which is total fail.

Has anyone found anything that actually works? Obviously its due to the heat from combustion that causes the fuel and any oil in the intake stream to break down into sludge and varnish, but it would be nice to prevent the build up.

 

Im no help, but I thought this was quite funny.



Screen shot from when I clicked on the thread. According to site sponsors, you should try BG 44k

 

Lol I saw that too.

How bad is it? Some is inevitable, just part of a running engine. If its real bad, there could be a problem. If too much oil is on the valve stems you'll get a lot of buildup. Excessively rich will do it. Leaking seats causes a lot of buildup. If its something wrong, then nothing will fix it short of fixing the problem. As for what normally happens, running fuel additives on a regular basis can help but is it worth doing that?

 

It's oil. Good valve stem seals and low blow-by (gets into the intake tract via the PCV) are the best ways to control it.

(The BG ad popped up when I clicked on the thread as well. Those guys are getting pretty clever.)

 

It's google ad's picking up on keywords. ^^

 

Gotta have nice tight valve guides and good seals. My old Dart heads would always get carbon on the backs of the valves after a few thousand miles. My AFRs apparently have better guides/seals as there is almost no buildup last time I changed the intake.

I ran PCV on both of them so that wasn't what made the difference. I do run baffled vavle covers with the PCV valve, however. With unbaffled covers you can pull quite a bit of oil through the PCV system.

Mostly it's the oil that runs down the guide after you shut off the motor that "bakes" onto the back of it before the engine cools off. That's what makes that hard black carbon coating.

 

Yeah, I saw that too after I posted. Good ol' google adsense...

Anyway...

Yes, I do have positive valvestem seals and a baffled PCV inlet which seems to keep most of the oil mist out of the intake.

The build-up isnt bad, and for a street car I would consider it not to be an issue. But, on this engine, the heads manage to get near 100% volumetric efficiency at redline, which Id like to maintain over the long run. The deposites are mainly on the back of the valve and the undercut stem where its the hottest. The rest of the stem is fairly clean. It seems like more of a slimy varnish as opposed to carbon. Part of the problem is the injector placement. The victor-e intake has them pointing straight down at the floor of the intake port, which causes fuel puddling and wetting when the intake is cold. Theres a lot of varnish on the intake ports as well.

I suppose its probably the type of fuel. Most of the stations by me are no-name types with cheap gas. Its great for driving, but maybe not necessarily for keeping the engine clean. Who knows how their additive packages are.

I thought of maybe trying the shell or some other actual name brand stuff over the long run, but its so damn expensive compared to the generic. It would be nice if there was something that you could just dump in that would keep it all clean inside. Although my experience is that the only way to really clean them is to physically remove them and dissolve the gunk with solvents.

 

The higher quality gas will prevent some of that but i'm assuming you are also running a healthy cam as well.. valve overlap will cause some carbon buildup in the intake ports and on the backs of the valves, even worse depending on how rich it's running at idle.

 

I haven't seen it for a while, but Slick 50's Fuel System Cleaner really did work.
I agree with better intake seals. I like these: http://www.competitionproducts.com/P...uctinfo/S5325/

 

What did you try the slick 50 on?

The seals I currently have are positive type seals like those pictured, so theyre not leaking any oil down the guids.

 

The engine did have a good sized cam in it with a decent ammount of overlap and low vacuum at idle. It was inherently a bit rich due to the air scavanged by the exhaust being picked up my the MAF.

The guy I know that used to just slap an inspection sticker on my car no matter what is retiring, so now Im converting over to a smaller roller to actually pass emmissions.

 

FWIW, I just pulled the heads off my LG4-controlled ZZ4 w/World 305 heads. The radiator fan failed right after I replaced the valve stem seals about 2 years ago, so it was using a quart of oil every 1200 miles or so (wasn't getting past the rings, just the stem seals).

The intake ports and valves are squeaky clean. I have used AMSOIL PI with every fill-up http://www.amsoil.com/storefront/api.aspx (they're recommending less frequent use than they used to). Being a wet intake, the inside of the manifold looked like it just came from the factory (should have snapped a picture of it, but it's already boxed up to ship to the member who is buying it - sorry).

FWIW. . .

 

The OEs all have TSBs posted on the use of top tier fuel(Shell, Chevron, 76, etc) for the prevention of performance issues which may be caused by deposits on valves, upper cylinders and fuel injection components.

You say you dont like to spend the money on good fuel, what about all the money you spent building your motor. Are you just going to throw that away to save a few bucks on cheap gas? Just a thought.

 

The last motor I built also was run on cheap gas for around 100k. While it doesnt seem to be destructive to the engine pre-se, it does take its toll on the intake valves and seats over the long run, which are hot enough to decompose the fuel, but not hot enough to drive the deposits off.

 

i know that particular ad popping up is funny, but 44K does work quite well.
i've used it in the past and have seen it do things that i didn't think were possible.
one example is a TBI chevy pickup that at cold start would die once or twice
every mourning. another shop had already done a complete tuneup and replaced the fuel pump and injectors with no change.
with a bore scope i checked a couple intake valves & found some pretty heavy deposits. i told him he really needed a valve job. but he said there was no way he could do without the truck at that time.
we had just started selling some of the BG products and i told the guy to give it a try, that if it didn't help he didn't have to pay for it.
the next saturday he came back in. i expected him to say there wasn't any change. he said he came in to pay. he said the truck had not died at cold startup for 3 days in a row and he wanted another can for his wifes' car.
when it was stolen a few months later the truck was still starting fine.

BG also makes some killer throttle body cleaner too.

 

not going to lie. I used muriatric acid. I was having the same issues. I used CRC valve cleaner and it didn’t do anything. I also used wd40. And I just used the acid to break it down. It took a while. But it worked for me. I wouldn’t recommend it. But it’s an option. lol.