Leakdown and Italian Tune ups. very dirty

Super easy to get the carbon out with plenum off. I just did this last week. If I ever see this again this top end cleaning will just be part of my major service. All heads have some of the brown goop from the vapor recovery system. This is my head with 20k miles. It is very clean yet the intake valves are carboned up more than I would like to see. Stone cold Leak down was 4-5% so valves and guides rock solid. I had Fuel injector spray patterns rated fair with 4 of 12 dripping! That can account for lots of carboning up plus possible short hop driving. I have always promoted the idea of having injectors serviced at every major service by a quality service like RC engineering. The PO did good hour plus drives but we don't know about the PO PO for this car. After talking to my friend the last PO I suspect the fuel injectors.
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I would assume that the stuff is pretty volatile, and that the effective additives would all be gone if you put it in a full tank but did not drive enough to empty the tank for a month. (That's actually a question for some of you who are much more knowledgeable than I.)

Have any of you ever heard of "Throttle Muscle" FI cleaner? I received a couple of bottles in the goodie bags for a rally we were on.

 

Thanks, Tim. So the plan is to put 20 gallons worth of the mouse milk in 10 gallons, then go run off 6 gallons or so. (I start to get nervous when the fuel light comes on, even though it is designed to come on at about 5 gal.)

 

Tim,

How are you doing with this project?

 

ACES IV Gasoline Formula « BND Automotive

This is the best fuel additive I have found.

I have been using it in everything for over five years.

 

That was nothing.

Seen much worse and often. A common sight in 355 motors. We have seen the back side of the valve that looked like half a black fluffy golf ball and nearly occluded the port.


Guides and seals combined with conservative driving.

 

Black tar heroin smuggled in the heads of a 355!!

 

This is an excellent thread. I'm a novice so how long should I idle car after hard hot drive? I'd it horrible to just turn it off and pop the hatch to cool? Any input is greatly appreciated. Many thanks in advance.

 

I suggest to my customers that every car should be started, then adjust you a$$ in the seat, put seatbelt on, check mirrors, etc., etc., then drive off and let the motor/box warm up as you drive. I believe those two minutes or so are crucial.
Similarly, upon arriving at a destination, allow the car to idle while you collect your stuff/thoughts etc., release your belt, as you open the door, turn off the engine and remove key. Again those two minutes allowing temps to normalise can make a difference IMO

 

As far as carbon buildup, meth/water injection etc...
Ever notice how your car seems a bit 'snappier' on a rainy day?
Most of these cars are driven on sunny days.
Water/moisture in the air on a good rainy day goes through your air intake and to where? Water is a great way of removing carbon deposits in the heads, it's proven years ago, so water injection was used on many performance engines as a standard practice.
We've used it on our high horsepower turbocharged snowmobiles, winter grade windshield washer fluid, as it won't freeze like water (methanol in it) to prevent detonation etc.
Basically, a conservative driven engine will start collecting all this buildup, along with poor fuel quality, easily.
Pumping 400 HP out of a 4 cylinder sled engine at 18 lbs boost, burning straight 100LL aviation gas can be a pricey repair, yet when I pulled my heads off, clean as a whistle!
Techron is a super, proven product, maybe others out there similar, but if you're going to baby it, I'd expect a gummed up set of heads/valves.
It would be interesting to see a list/graph of all the badly gummed up heads, with driving habits, fuel brand and location, just for curiosity. My 2 cents worth

 

Can someone explain why conservative driving leaves this tar stuff around the intake valves?
And why it is that a long spirited drive getting the motor up to 8000 rpm, etc. is best?
Interested in what mechanically is happening in there.

Something to do with oil temperature is it?

 

I think it's just a richer fuel/air mixture, not getting a good dose of a constant steady burn rate, along with higher flows in the chamber.
Think of it this way, your engine as an air compressor trying to run a high air demand device on an empty air tank. The fuel is going in at a basic/minimal programmed rate, evap system adding extra oil/gas vapors, yet not getting the most air it could use. Your loading your engine head chambers with more fuel/gases then it would be happy with and wants to breathe, so the by-products build up. As I mentioned previously, a rainy day drive will clean this up, as water in the air will actually clean off deposits, proven fact!
I have personally trickled a garden hose down a carburetor on my rodded up '56 chevy just to clean the crap out of the valves/chambers.

 

I need to get a smog check on the 355 next week. I ran a couple bottles of Techron in with about 12 gallons of gas a few months back.

Good or bad idea to have Techron in the tank when taking a smog check? I'm down to about 1/3 tank of gas and thinking about adding another bottle but some will be left in the tank for smog check time.