Gun Jam

yes they have the baffle. They are the scott drake cast Al covers...I like em.

-Gun

rmodel65

install a catch can between the pcv and the intake see if it fixes the problem

MonsterBilly

It was what groho said. My new awsome ford racing cast valve covers did not have a baffle. I was getting oil sucked from the pcv into the intake and it gunked up everything. I switched out the valve covers to one's that had baffles and the problems were gone.

67mustang302

What temperature do you run the engine at?

Gun Jam

I think im running a 185 or 190 tstat

67mustang302

Well, with aluminum vs iron heads, it's not the same. We measure average coolant system temperature, usually near the thermostat housing. That's completely different that valve/head/chamber temp. Combustion spikes local in-chamber temps up into the 1,300-1,400 degree range, which then sheds into the head/valves and as the combustion stroke continues chamber temps drop precipitously. The chamber walls in the head, and valves then dump their heat into the cooling system (the valves have to dump heat into the head which sheds it into the coolant) and their temperature drops rapidly, and in the case of the intake valve it receives extra cooling when fuel flows over it with a new incoming charge. So the actual valve and chamber wall temps fluctuate wildly from a peak during combustion, to a low during the end of the intake stroke in the case of the intake valve. The temperature range can be 1,000* or more depending on the engine.

Iron has less conductivity than aluminum, so the rate that the heat is shed into the coolant is lower (everything else being equal). As a result, the chamber walls and valves tend to run at an average higher temperature with iron heads. With aluminum heads, because the heat is shed faster into the coolant because of higher conductivity, the chamber walls/valves tend to run cooler on average. Total energy transfer is roughly the same (measured in BTU's). Higher temp. difference means faster transfer...so the lower conductivity of iron is offset by the higher average temps; or the higher transfer rate of aluminum is offset by lower average temps.

What that means, is that while the coolant temp. still runs at the thermostat rating (provided adequate radiator capacity), the intake valve in an iron head will run at an average higher temperature (the peak temps might be a bit higher, but the minimum temps will be quite a bit higher, so the average temp. between the min and max is higher).

So then we have the fuel, which is rarely talked about and often forgotten. People frequently forget that the entire purpose of a piston engine is to burn fuel...and spend 90% or more of the time talking about the engine and largely ignoring the most important thing...fuel. Modern fuels are not "gasoline" or a gasoline-alcohol mix, even though we talk about them as such. They're actually a mix of many many different chemicals, mostly hydrocarbons. Some fuels are a mix of more than 100 different chemicals. Some have higher heat of vaporization points and some have lower points. Sometimes they're referred to as light ends and heavy ends, where the light ends vaporize very easily at low temps., and heavy ends vaporize well only at high temps.

So when you have an intake valve that runs at cooler average temps (which can occur for a variety of reasons), as the fuel flows over it in a new charge during the intake stroke, it cools further. If it gets to a low enough temp, there is still enough heat in the valve to vaporize the light ends, but not the heavies. When the valve closes there's always some fuel on the valve and port walls. If the valve temp is too low the light ends of any liquid fuel accumulation on the valve will vaporize, but the heavies will accumulate and start to cook off. The temp is too low to vaporize them, but high enough to cause them to burn and react with air and form solid compounds, tars and ashes. So then you get valve deposits.

The 2 main ways these are tackled are either from 1) changing the fuel composition to reduce heavy ends (which can make the fuel more detonation prone) or adding cleaners (Techron for instance) to try to break up deposits as they form; or 2) run everything hotter to keep the temps from getting low enough to form deposits. Modern engines deal with it from both ends, these days they're typically all aluminum with really good cooling designs that can transfer tons of heat...so they run the engines at high temperatures and with high compression, so chamber/valve temps remain inside an engineered range. The cooling passages are often specifically engineered to keep temperatures of certain parts within a specific range for longevity, reduced deposits, better vaporization etc. Fuels are also constantly being engineered to both reduce deposit formation in the first place, and constantly clean deposits should they form.

So, if you switched from iron to aluminum heads and are getting deposits, you have a few choices. 1) Just deal with it, accept the fact that you have deposits. 2) Same as 1, but run periodic cleaners through the engine, Seafoam etc. 3) Run better fuel, bargain brand fuels are bargain for a reason, better fuels are more expensive for a reason...usually the additive packages that prevent wear and deposits. 4) Run the engine hotter. Remember that if it ran at X temp on iron heads, because aluminum transfers heat better you can run at a higher temp and still have the same average chamber temps (though peaks might be a bit higher with a warmer engine, it mainly brings the minimum temps up). 5) Some combination of the above.

barnett468

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although i like 67mustang302's post, its STILL not likely that the deposits are from fuel . . first of all, you are running gas that has techron . . secondly, the deposits built up WAY too quickly to suggest gas as the primary cause imo. . theories are formed on available facts and deductive reasoning and even though you say you do not butn oil, it takes very little leakage to get these types of deposits.

if this is from the temp of aluminum heads, then why doesn't anybody else runniung aluminum heads on an iron block have this proble? hmmm

also, why doesn't every new car gave this problem since they are also aluminum? hmmm

in addition to running gas witrh techron, chevron is a tier 1 gas which has the most cleaners in it.

the most likely culprit based on the info supplied is still excessive valve guide clearance and/or vaLve seals imo.
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67mustang302

Aluminum heads are 1 variable in a multi variable equation. There are literally dozens and dozens of other variables that all effect what the valve temperatures are going to be. New cars are all aluminum and don't have this issue (normally). New cars also run typical coolant temps of over 200* and frequently are over 10 or even 11:1 compression (more compression = more heat). They also have highly engineered cooling system passages in the head to specifically control component temperature. The engineers also spec specific alloys, and call for certain thicknesses of materials, and engineer based on certain fuels, and certain valve timing events and so on.

Could he be burning oil? Sure. But keep in mind, that just because you pump gas from a gas station, doesn't mean it's all gas either. It's not unheard of for some drivers to not clean their tanker trailers out after hauling crude for instance, then running a load of fuel. So then you end up with oil contaminated fuel. Maybe the stations in your area hired ****ty truck drivers? If the heads were rebuilt and had new seals, it's unlikely that all the seals failed within 2k miles.

Also keep in mind that some of the heavy end hydrocarbon chains in the fuel aren't that far away from some of the lighter HC chains found in lubricating oils. Fuel is a form of oil, just a light oil (it's all HC chains). Heavier fuels used in marine engines are typically referred to as fuel-oils, similar to diesel.

Also keep in mind, fuel deposits are a common enough problem that fuels contain chemicals to try to reduce deposits.

Aluminum heads with low compression (under 10:1) and low engine temperature are asking for deposit formation.

Also, what do the plugs look like? If you're burning enough oil to get deposits on the valves after 2k miles, then the plugs should show signs of burning oil as well.

barnett468

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he is the only person i know running aluminum heads that has this problem and the other cars are not running techron, techron, techron...

to suggest that tecxhron wpuld do thgis because every tanker has contaminated fuel seems a bit unrreakistic to me . . he would have be using contaminated gas ever since he chsnged hos heads to caouse this especially since the gas he iuses ha techron, techrin, texhron.

your commrents suggesy that virtually every single old school engine that had aluminum heads added has this oporoblem . . this seems a bit unrealistic to me.

when you can come up with a plausible explanation as to why out of all the cars i know of running aluminum heads, he is the only one with this problem then yours would sound more plausible.

67mustang302

What?

Techron is a deposit reducer, it doesn't form deposits.

Also, I said aluminum heads are 1 variable. That means that not all engines with aluminum heads will have this problem. The problem is likely the result of valve temperatures dropping low enough to form deposits from the heavier HC chains in the fuel. Aluminum heads can contribute to that, but are not the sole cause.

Where someone lives is a factor too, since it results in environmental variables.