Help with 400

[73ChargerSE]

I just got around to working on my Charger again.  I put a new intake on it and I'm in the process of putting a cable kickdown on it.  The problem is that after it runs for a few minutes, I'll shut it off, and it wont start again until it cools down.  Also, after you shut it off, you can hear a tapping noise about 10 times at a steady pace, like something tapping on the aluminum intake or the valley pan. What could be causing this?

[RD]

sounds like vapor lock, but I am sure ron will chime in on this one.

[Todd Wilson]

sounds like vapor lock, but I am sure ron will chime in on this one.

BOAT ANCHOR!     


Todd

[firefighter3931]

Need more info to diagnose the problem. It could very well be vapour lock like RD said but it could be something else as well.

When you say it won't start after being run....does the engine turn over at all ?
How hot is the engine running....what temp ?
Is this a new problem since the manifold swap ?
What else was done to the engine....headers ?
What manifold gasket did you use when the aluminum intake was installed ?
Are any fuel lines resting against heater or radiator hoses ?

Ron

[Brightyellow69rtse]

ok ill chime in and throw my pennys worth on knowledge here but how about the timing. now i know if you get too happy advancing it it will start wicked hard or not at all if its hot. just a thought easy to try it........Mike

[73ChargerSE]

Need more info to diagnose the problem. It could very well be vapour lock like RD said but it could be something else as well.

When you say it won't start after being run....does the engine turn over at all ?
How hot is the engine running....what temp ?
Is this a new problem since the manifold swap ?
What else was done to the engine....headers ?
What manifold gasket did you use when the aluminum intake was installed ?
Are any fuel lines resting against heater or radiator hoses ?

Ron

Yes, the engine does turn over, it just seems like it's not getting enough gas.  It will start idling really low after a while and when it does that, it will shut off.  I do not know what temp the engine is running at.  I used a Fel-pro valley pan and gaskets, and the fuel line is away from everything. It was doing this last summer, but it was while I was driving it, but the tapping noise never occurred. I was thinking it was vapor lock.  What would help it if it was?

[firefighter3931]

two things will help ;

(1) felpro 1214 intake gasket with the heat crossover blocked off.

(2) thick carb insulating base gasket.

Try and verify the engine temp to see how hot it's running....


Ron

[RD]

have you made sure you blocked off all of your vacuum ports?

[73ChargerSE]

Could it be that because I don't have the heat crossover blocked that it's cooking fuel before it gets to the cylinders?  The old valley pan had the crossover open, so naturally I opened it on the one I bought.    DOH!

[Nacho-RT74]

jus a question... I knoW some people gets blocked the crossover for whatever reason ( get better performance or whatever ) but:

Why the hell the crossover becomes on a PROBLEM if is originally designed from an specific purpouse ( that works BTW ) for street cars ?

[dodge freak]

Well these new motor don't have them anymore, not with F.I. its not needed. I have mine open but its only 80 degrees for 2-3 months and only during the day. When its 40-50 degrees I am glad its open, but if I lived where Nacho-rt74 does and still had my MSD 7al spark box I would close it. When I had the MSD 6 al box the cross over seem to help burn the gas but its not needed with a strong spark but it does warm up faster, much faster when its 45 outside and at night time even this week it was that cold up here in Michigan. Why did the factory have it, well they had a crank handle to start the motors at one time, just cause they did something does not mean its always the best way. Yes sometimes it is but not always. When crossovers first came out gas had lots of lead in it now of days the gas is different so things change. Say Nacho can you still buy gas with lead in it at all the stations?

[Nacho-RT74]

Here leaded gas was removed from market last year, right now just 91 and 95 octanes unleaded. Before mids of last year we had 87 and 91 leaded and 95 unleaded.

I rmemeber when I was a kid ( mids 80s ) we had 6 gas kinds all leaded, 81-83-85-87-89-91... don't remember also if 93 But I don't think so...

and still can fill a gas tank with US$2.5 91 octanes, and $3 with 95 octanes LOL

Here the average temperature at day allong the year is ( In Caracas ) 25-30ºC... depends of year season some degrees less or more, but not too much ( +/- 2 degrees ).

Of course, there is HOTTER cities and also colder AROUND The Andes Mountains.

So unleaded gas makes hotter engines ?

Sorry, highjack this thread is not my intention, but since this came out...

[73ChargerSE]

The average temp around here right now is about 103, so something is definitely getting hot.

[dodge freak]

103?? you don't need that crossover, it will be better shut. I have just used a thin piece of sheet metal right up on the port before the gasket that will do it. No unleaded doesn't make it run hotter but the gas might not boil as fast or at as low of a temp. We can't get 95 -91-93 depend on where we live. That 95 still might have a tiny amount of lead in it, $3.00 to fill up that buys 1 gallon here or about 10-12 miles.

[GreenMachine]

Why isn't anybody answering the tapping question? I'm kinda curious about that too. My buddies 454 does that, seems like it might be lifter bleed down but wouldn't think it would be that loud.

[dodge freak]

The only thing I can think of is that the fuel is boiling, I know some cars with cats the exhaust bangs after is turn off, Fords mid 90's, but never hear a old car with no cats make any noises when off, but maybe it happens.  Lifters can make lots of noise but not when the motor is off,  That hard to start deal would get better if the crossover was sealed so we are staying on the subject.

[RD]

have you made sure you blocked off all of your vacuum ports?

never answered this, did ya do it?

[firefighter3931]

Get the felpro 1214 gasket and don't cut out the heat crossover. Order up a thick carb base gasket while you're at it and install it under the carb. Aluminum conducts heat very well and this can cause fuel temp issues.

The pinging/popping noise you're hearing is probably just the valley pan cooling off once the engine shuts down. Try and get a functioning temp guage on the engine to see how hot the engine is running.

Ron