Hi John,
I have not even bothered to take a look. The car is starting up OK, however if I try to start it after a hard run with only a couple of minutes of down time, it can take a couple of cranks.
I suspect it is just flashing off some fuel when hot out through the vents. Like I said, when I drive back to SF and park it I do not notice it. It cools down quick.
I will try a spacer and see what I get. Not much work to do it and it cannot hurt anything to try.
James
From: John Grady <jkg@xxxxxxxxxxxxxxxxx>
Sent: Thursday, June 15, 2023 6:48 AM
To: dplotkin <dplotkin@xxxxxxxxxxxxxxxxxxx>
Cc: James Douglas <jdd@xxxxxxxxxx>; Chrysler 300 List Server (chrysler-300-club-international@xxxxxxxxxxxxxxxx) <chrysler-300-club-international@xxxxxxxxxxxxxxxx>
Subject: Re: {Chrysler 300} Shutdown fuel perk
this is interesting , but many theories make no sense . I have a 60 buick 401 that has always done this . Hard start especially after sitting , carb was on and off several times . I thought a crack or internal leak , as even after a week
it would take a very long crank , distressing to you if far from home . Carb was apparently empty . But you are not sure flooded or empty ? pulling air cleaner is often inconclusive as some gas has come up from first crank . Been there, add in ? closed
choke etc
First , even if fuel “ boiled in the bowls” which may happen just after shutdown , ( called “ hot soak” ) especially if you have typical rusted shut exhaust heat valve , — the boiling can’t be so aggressive as to raise bowl gas level enough
to run into engine . Remember all paths to venturi involve air vents in their path ( those open brass tubes) and vacuum to lift the fuel up . That vacuum is not there sitting . Gas is below any path to venturi .
I think modern gas has such a high vapor pressure it just rapidly evaporates, a matter of a day (?) leaving a dry carb . But within an hour choked a rich start would happen . If fuel pump is perhaps lower in flow than optimal takes time
to refill maybe all this is normal , with 2023 fuel —what I think now ( if exhaust heat is ok) — just shut that heat off permanently unless you live in alaska .
It goes back to 20’s and 30’s when fuel could be like kerosene .
I am rebuilding a packard with stock 37 hot spot intake design like a slant six . I separated the manifolds and machined 1/4” off the exhaust and closed top hole with a bolted steel plate , threw away huge heat riser valve . I expect more
hp and no problems with a cooler intake . See also Edelbrock air gap manifolds . They simply outperform heated ones . Right idea . Cool intake flow .
Related , “ vapor lock” as a term is so misunderstood it is unreal . First , the line from pump to carb is under 3 psi pressure , if inlet float valve in carb opens any gas vapor air anything in that line is going to run right through
pushed by pump and out that open end . When one sees THIS line insulated etc , it shows a lack of understanding .
But , if suction line near fuel
pump or pump itself gets warm , the suction impact will significantly lower boing point a lot and then you have vapor which the pump cannot move very well , flow stops . This is why electric pumps help real vapor lock by pressurizing what
was the warm suction line . But don’t run it through the mechanical pump as a diaphragm rupture means a big fire
🔥 .
This subject could go on , but i have fought random fuel flow stopping in a 50 stude with a 354 hemi for a long time . Finally got into it this week — electric Carter pump , changed it , large 100 micron SS alcohol dragster type stainless
mesh filter stead of pump clean as can be no restriction still erratic flow . All lines good no mechanical pump .
After gas tank in and out 2 nd time , we found the line inside the tank (!) was partially full of that same tan/ white residue one finds sometimes in our carbs . It can form a kind of mud deposit . I think ethanol is the culprit when sitting
. Some chemical thing goes on with steel or galvanized steel yielding that powder ; also why AFB accell pump check valve sticks .
I am going to try suggestion of marvel oil , i admit to cynicism but why not ? Nothing to
So insulate suction line near fuel pump , packard had a large thin steel wing between fuel pump mount and block sort of a hot air shield maybe 6 “ projection and heat fin . Jesse Vincent ( Packard Engine designer ) was a genius , we
might copy that .
Also stude V8 has fuel pump on top of engine with resulting long suction pipe in hot place . Guess what brand vapor locks all the time ?
James, the Corvette folks I deal with
use those spacers with good results.
Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------
Date: 6/15/23 8:34 AM (GMT-05:00)
Subject: RE: {Chrysler 300} Shutdown fuel perk
Hi Danny,
The problem does not happen in my garage in San Francisco. Of course, the temp there is between 60F and 65F 99% of the year. In Winters when it gets over about 85F I notice it.
James
My understanding of percolation is boiling fuel bubbling out into the throttle bores after hot shutdown, flooding the engine and causing a hard hot restart. Is that your experience?
Any pre-emission V8 parked hot in a sealed garage will smell of fuel for several days or as long as it takes for the bowls to dry out.
Danny Plotkin
-----Original Message-----
From: "'James Douglas' via Chrysler 300 Club International" <chrysler-300-club-international@xxxxxxxxxxxxxxxx>
Sent: Wednesday, June 14, 2023 7:50pm
To: "Chrysler 300 List Server (chrysler-300-club-international@xxxxxxxxxxxxxxxx)" <chrysler-300-club-international@xxxxxxxxxxxxxxxx>
Subject: {Chrysler 300} Shutdown fuel perk
In San Francisco it has never been an issue with fuel perk on shutdown. Too cool 99% of the time. However, at our Winters
house, in the Sacramento valley, when I park the car in the garage and close it up, I can smell the gas for a couple of hours.
Has anyone had any luck using a something like this:
PS, I do plan on sleeving all the steel fuel lines from the frame rail up to the fuel pump and carb at some point.
But that will do little for the perk.
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