Bad news: my PRV has no connection from breather to cold start tube. Is Renault rendition, laid out just like pic page C:02:01. See pics in #5939's photo album DMCNEWS Group. Breather attached to two plain old 1/4" (or some metric equivalent) nipples in the U pipes. No orifices or reductions, just a glorified Y pipe. Only thing in my cold start tube was an idle speed motor, and we all know what happened to it. Valve covers in my Fords (400 and 460) connected through intake manifolds. Air sucked in one side, other side connected to carburetor. Has always bothered me that PRV has no obvious way to vent passenger side of engine. Guess it's supposed to pass through timing chain cover. My physics buddy going out with cancer, so unfortunately can't run all these pressure differentials and vaporizations by him. Simple fact remains: many PRV gaskets and O rings, if not tight, allow test solvents inside combustion chambers. You'll see and smell it in exhaust, so obviously getting in there. Not all of them are usual suspects. Passenger valve cover, where it overlaps timing chain cover, was such a location for me. One of the cam access covers in back of the engine was another. Can't say for sure if timing cover crank seal is too, but will try tomorrow. Have spent most of my ownership in quest for perfect idle. Has driven me fair to crazy. Absolutely nothing on the engine was tight when I bought it (inspires confidence in French quality control). Have made tremendous progress, but still not quite there yet. Bill Robertson #5939 >--- In DMCForum@xxxxxxxxxxxxxxx, "checksix3" <jetjock11@xxxx> wrote: > Ok, I don't wanna keep you from quality Ford time.... > > You're either not reading my posts or you don't follow them. There > *is* a path from the valve cover into the induction system through > the cold start pipe engine via the oil filler breather. > > Do you know the meaning of vapor pressure? There is a huge difference > between pulling in a little air and shooting something with a vapor > pressure of carb cleaner into the induction system, not to mention > it's hydrocarbon based. It's a very volatle substance and flashes > very quickly into a vapor. > > In other words, if the vacuum leak altered the engine's operation > enough you wouldn't need the carb cleaner to find it. Of course > you're gonna see a change, especially when you aim it up towards the > breather in the valve cover. A direct measurement of the pressure in > the valve cover is the only way to be accurate, you can't cheat by > using an substance that will drastically effect the engine's mixture. > After all, *thats* why you use it to find....vacuum leaks! (I hate > that term, there is no "vacuum" leaking into the induction system.) > > So your carb cleaner is getting into the induction system via the > cold start pipe and makes a much greater difference than a little air > would. This will happen anywhere you spray it around the valve/timing > covers where there is a path to the inside. In effect it *is* a good > way to find leaks, but you're finding leaks that make no little or > difference in manifold pressure. Try disconnecting and plugging the > vacuum line to the cold start pipe and then see if the solvent has > any effect, thats a direct path into the manifold. Yahoo! Groups Sponsor ADVERTISEMENT <http://rd.yahoo.com/M=259538.3793308.5048975.1261774/D=egroupweb/S=170512 6215:HM/A=1712983/R=0/SIG=11u38u3s2/*http://hits.411web.com/cgi-bin/hit?pa ge=1374-105951838331032> click here <http://us.adserver.yahoo.com/l?M=259538.3793308.5048975.1261774/D=egroupm ail/S=:HM/A=1712983/rand=341978340> To unsubscribe from this group, send an email to: DMCForum-unsubscribe@xxxxxxxxxxxxxxx Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service <http://docs.yahoo.com/info/terms/> .
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