The recent thread on what carb jetting to use on the 4.6 engine reminded
me that I should report some carb findings to this list. This may be of
particular interest to those of you that have stuffed the BOPR engine
into the MG car, however I'm sure the info will carry over to all
carbureted versions of the BOPR.
I am running a Buick 215 with the stock Buick 4bbl intake and a Carter
400 carb. It was running "sweet" all winter, never skipped a beat.
However, lately I've been having all sorts of issues with idling,
stalling, hard starts, you name it I've had it. Of course just like all
of you I start tweaking what I can. All of my tweaking was to no avail.
It still ran like crap. Then the revelation.
I went to put fuel in the car and I noticed a BIG whoosh, vapors were
coming out of the filler neck. In fact I began to notice that I could
tell when it would "whoosh" because the filler neck would actually start
to push out of the body of the car. When you opened the fuel cap not
only would you get the whoosh but the filler neck would snap back into
place.
You may remember I wrote this list about vented gas caps. Of course I
knew and this list confirmed I needed the vented type. Well checked and
mine is vented. But it turns out the vent is a one way check valve. It
lets air in but not out. Presumably so as fuel is consumed air is
allowed to enter the tank to fill the void the fuel has left. The
reason it doesn't let vapor out is for pollution issues. But what about
on those hot days in Denver at 5280 feet? The fuel goes into the tank
at 65 degrees F and get heated in an enclosed container. I'm here to
tell you there is tremendous pressure built up in the tank. So I
drilled a small 1/16" hole on the inside of the cap. It appears to be
just large enough to vent freely but not large enough to let anything in
or out (except vapor). I did this over a week ago and decided to see if
I notice any changes before I wrote the list. I did notice changes. No
"whoosh" when I open the gas cap; and yes the car is running 100 percent
better, and hot starts are not a problem any more.
So if you are experiencing some of the issues I have been I'd suggest
the old style vented cap with the hole(s) or drill a small hole in your
present one.
Thanks.
Larry Hoy
"It's not how fast you go, it's how fast you go fast"
http://pages.prodigy.net/larryhoy/
///
/// mgb-v8@autox.team.net mailing list
/// Send admin requests to majordomo@autox.team.net
/// Send list postings to mgb-v8@autox.team.net
/// Edit your replies! If they include this trailer, they will NOT be sent.
///
|