vapor lock question(update4/10/8 fixed prob.)

[tick68charger]

when its above 75 degree's my 440 after 30 min would loose idle when
cruising below 30 mph. and if i opened her up it's like i ran out of fuel.
she would also heat up to about 210 to 220.

I thought it was because she was running hot. so i got a aluminum becool
radiator, mildon high flow water pump and high flow thermosat, a new temp
gauge. I got the manual trans radiator and the B@M super stack trans cooler.
now she runs at 180 all day but i still have problems with idle and when i open her
up after 30 min of running.

here is my engine specs.

1968 charger with the 440hp 727 trans
1967 closed chambered 915 heads mild port bowl blend with harden seats and port matched
i have the valley pan that blocks off the heat port
holley street dominator intake
850 holley mechanical dbl pumper (jets 80 in front and i pulled the 80 in back and put 84 in no change in performance)
1/4 " paper gasket under carb
hooker super comp headers 1 7/8 to a 3 " collector
3" hedmen x-pipe
40 series flow masters
3 1/2" turn downs dumping out just before the rear end
mopar purple cam 484 lift
3000 stall
b@M 0 balanced flex plate
carter high flow mechanical fuel pump
stainless steel 5/16 fuel line
stainless steel 1/4 return line
7 blade mechanical fan
electric fan pushing air for back up
converted to an 80 amp alternator
mp electronic conversion kit
accel super coil
becool radiator for a manual trans
11"x11"x1 3/4" B@M super stack trans cooler
mildon high flow water pump
mildon 180 high flow thermostat
i insulated the fuel line(no help)
i bypassed the return line(no help seem to run worse)
timing i have the advance plugged off and i run it between 32 to 38 total timing
3.91 gears
b@m larger 4qrt trans pan with fins

i did not want to leave anything out just in case you see something wrong with this combo
im tierd of spend all this $$$ and still having this problem

[dodge freak]

I am guessing now--I have hear that sometimes the gas tank vent gets clog up, and if you take the gas cap off the gas will flow again. Not sure if thats it, cause the heat seems to be the problem. Are you sure its the gas  and not something else ? You should take the fuel level hole screw off on the carb. fuel bowl and see if there is gas in it,the next time it acts up, if so its something else, if theres no gas in the fuel bowl, the gas is boiling away or not flowing. Check it out tomorrow, and let us know. You get this taken care of, even if you have to get a electric fuel pump and maybe re-rout the fuel lines, but it might be something in the ignition.

[tick68charger]

i did forget to mention that it usually starts right back up unless its really hot out
then it takes a few cranks but once she is started i have to use the foot feet to
keep her running, but that is a good idea i will look through the site plug and
see if she has gas. i will try this tomarrow after work and get back to you with the
results. thanks

[grouseman]

I know that the AFB/AVS carbs sometimes had a Hot Idle Compensator built into them, depending on application.  Basically a temperature-controlled vacuum leak.  A small part that fit just above and behind the secondary clusters.  It would allow more air in, which bumped up the idle speed. 

Run a vacuum line into the psngr compartment, and open it when you experience the condition; see if it helps.  Real band-aid, though. 

[tick68charger]

it was raining here yesterday, but today its going to be 86 and sunny. time for a test
i'll report my findings.

[dodge freak]

I hate the rain, wish it would only rain when I don't have time to drive ha ha. Guess out west like in Nevada it would be nice, expect it gets so hot and the girls there would get all my gas money 

[tick68charger]

well its about 85 degrees or better. drove the car for about 45 min when i got to
the big city with all the traffic and lights it wasn't 5 minutes and she wanted to die
so i hit the back streets and waited. sure enough she died i wiped into a parking lot
took out the sight plugs, bumber i still had fuel in the bowls. i did notice that my
accel super coil was very hot to the touch could hang on to it for about 3 seconds
before i had to let go. it took several cranks to get it started, once started i took off
down the road about 1/8 throttle and its like i was running out of gas so i pumped the
foot feet to bout 1/4 to 1/2 throttle and she fired back up and i could keep her running
barley but if i let off the foot feet she would die if i got her up to  30 mph and above
she came out of it? any ideas ill be checking in off and on tonight for replies.

[dodge freak]

Well it sounds like its in the ignition. Maybe bad coil or the pick up coil inside the dist. Something when hot is giving out, and when you turn it off its starts to cool off. I doubt if its vapor lock. No , you have gas-you must have a weak spark. Sorry but its maybe swap time until you hit it. New coil and then the pick up coil in the dist, not sure if the spark box goes bad like that- I have MSD, just a Moper dist , then its all MSD. Thats all it can be. Once you fix it, it be fine, forgot about trying to lower the temp. something is going bad on you. You could have a shop look at it for you but you could change everything for the same $.

[tick68charger]

I thought about picking up a new coil today when I felt how hot it was.  I think I'll pick one up tomorrow and mount it in a cooler spot. 
I wonder if I should relocate the orange box for the mopar performance electronic ignition conversion kit?  It's right on the fire wall above the header.  I wonder if that can go bad?  I'll try changing the coil first, and see what happens.  After it dies I can hit the throttle and the accelerator pump pushes gas into the carb, so I am getting gas.  I think you are right, it's probably electrical.  I'll give an update in a couple of days.  I'm going to order a phenolic 1 inch carburetor base gasket, and a new coil.

[dodge freak]

Swapping parts stinks, its always the last thing you change. Coils , boxes , etc. CAN get hot, just that sometimes when they get old they start breaking up, then it cools off and is ok again. That pick up coil in the dist can be a pain to change but MIGHT be it, its only $20 or so but you have to pry the reluter off and take a few screws on the side of the dist off and un hook the vacuum advance. I think the box too can go but it might not be as old as that dist. pick up, nobody ever change those until it goes bad. If you got the bucks, you could just get a brand new dist.- about a $100 or so. You know, I had a bad plug wire one time , when it was cold it was fine , then when it was hot it "leak" the spark to the header- turns out the boot was spilt-Guess what ? It was the LAST thing that I changed.

[firefighter3931]

  I'm going to order a phenolic 1 inch carburetor base gasket, and a new coil.

That's a good place to start. Make sure your fuel lines and filter aren't leaning up against any heat sources ( rad/heater hoses or the block/heads).


Ron

[dodge freak]

Would it still be vapor lock if there was gas in the carb. ? Seems to me even if the gas was very hot so long as it did not boil away it would be ok.

[NYCMille]

DUDE!

Had the same EXACT symptoms as you - my engine combo is simliar as well with the exception of that I have 906 heads punch .030 over and I went exact same steps you did. A big one was going back to the original 18/.5 7 blade clutch fan set-up. I drop 25 degrees and now I idle 180 all day long.

The problem was the 850DP I had on the car - I swapped it out for my buddies 750 Barry Grant and the car ran fine... no problems whatsoever. I just ordered a Holley 750 3310 with Vacuum secondaries as my motor is a pretty mild build. I should have it tomorrow.

Try swapping out the carb with a buddy and run the carb... my bet is your 850DP is to much for the motor. Give it a shot...

Mike

[tick68charger]

friday i hit the road to heat up the car and try and figure out what was going on in 30 min she
died when slowing down. i put her in neutral and shut it off pulled over pulled the sight plugs of
the carb full of gas, next i put a spark plug on the #1 wire no spark then i started to get a
spark after about a minute but it was very week. I'm going to try the new coil and wires.

Saturday well its 90 out today and i got my new coil and spark plug wires in. i got the msd blaster 2  coil
and accel high temp 8mm plug wires. i mounted the coil on the outside of the radiator support
to keep it cool. took her out for a test same thing happend after 30 min it died when slowing down at
a stop sign on a highway  . well i tried to start her back up, nothing, all i was doing was flooding it.
so i sat there for about a minute or two and she fired back up and i headed for home. she did run a little rough until
i got going. when home i felt the coil and she is nice and cool. but the electronic conversion kit orange box was very
hot i think i will mount the box inside the car under the dash and see what happens. if that don't work.
i was thinking of getting the msd 6 box and the msd distributer. by the way after she died i pulled the
sight plugs on the carb again and she was full of gas.

any ideas? also what do you think about the msd set up would you get it.  if so what one would you recommend?

[firefighter3931]

Tick, before you go and scrap the whole ignition system...try swapping out that POS orange box. Those are notorious for going bad. If the MP conversion kit is less than 3 years old.....the box is junk. The older orange boxes were much higher quality....whoever is producing these for MP now (low bidder) isn't doing a very good job. Mine was leaking resin (melting) on the firewall 

I luv MSD stuff....the 6A or 6AL with the built in rev limiter would be all you need. If you decide to stick with the MP stuff....upgrade to the Chrome Box...those are much more reliable.

Ron

[dodge freak]

It still could be the pick up coil inside the dist. but it sounded like you may have gotten a new dist a few years ago when you swap over. If so its might be ok, good chance. Its either one of those now-the box or the pick up in the dist.

I like -make that love-MSD but if you have no smog checks where you live you may want to get a 7 al unit at Jegs or Summitt before they are all gone-MSD has a 7 al plus now for $575 , thats too much. I know everybody says the 6 unit is fine and all you need, but I have a 9-1 compression motor and did notice a nice improvement over my 6a box that I had in there, it had no rev limiter so thats why I change. I think the price difference is like $145 or so WELL worth it. You don't have to swap coils. I had a Mopar chrome box and thought the 6 unit MSD was way better. Marroly , Crane make boxes too but don't know how they are. You could just go to Auto zone and get a $15 well's box to check if thats it, if it is great ,take it back to Auto Zone for a refund, they may give you one. If its not , its in the dist. I have the Mopar dist. with light springs in it and a Accel cap and rotor, works great.

[tick68charger]

i think i will get the msd 7 box and the distributer since i have such high compression. i thought i had 11.5 to 1
but in a recent mopar mag it said my combo was 13 to 1.
does the msd box automaticly adjust your timming for the best performance?
i live in iowa so ther are no smog laws here

[firefighter3931]

i think i will get the msd 7 box and the distributer since i have such high compression. i thought i had 11.5 to 1
but in a recent mopar mag it said my combo was 13 to 1.
does the msd box automaticly adjust your timming for the best performance?
i live in iowa so ther are no smog laws here

The MSD box just supplies the spark....timing is controlled by the distributor. If this motor is an actual 13:1 compression build, you would have to be running 110 octane race fuel in the tank....are you ?

Ron


Ps. The 6AL is all you need. The digital series boxes are for Race type applications with a lot of features that a street car would never use. 

[tick68charger]

thanks for the info time to save up some more $$$ for an msd box.  i want to get both
distributer and box so i have the complete msd set up. i think i might put the msd box
under the dash so i wont have to worry about engine bay temps and maybe it will
last longer.
i don't know how long it will take to get.  but when i do i will post my findings.
first i will put in the distributor and test, then the box to pin point the problem.
thanks for the help all

[dodge freak]

The box CAN get hot and work fine might last longer in the trunk or pass. area but I ran a MSD 6 for 8 years no problems. On the digital boxes Firefighter is right its race only no street only the 6 digital can be use on the street. The 7al box is NOT digital and with most coils can be used everyday on the street, the 6 might be all you need but it does not hurt anything by having a stronger spark then needed. Your plugs might wear out a Little sooner but I had my in for a year-5000 miles- and when I changed them last week they were all clean, very clean, when I was running the 6 box a few were brown-to black with a little oil , now all I did was to get the MSD 7 al box and the 7251 coil and all the spark plugs were clean. The gaps opened up from .038 to .045 so I am glad I changed them. I think FF might be right about that mopar box being bad but its not the heat-well it is but it should not be. That MSD stuff is a lot of money but it is good and the way I see it if you are going to spend $230 for a 6 al you might as well go for the 7 al at $380, you get $20 summitt bucks off your next oder too. Like I said everybody told me I was throwing away $150 but I did notice a difference-when the motor is cold after a few days of not running it still will not stall in gear, with the 6 al box it would until it ran for a min. And now my plugs stay super clean. Its your money maybe its not needed but so is a lot of stuff we have on our cars, right?

[firefighter3931]

when I was running the 6 box a few were brown-to black with a little oil , now all I did was to get the MSD 7 al box and the 7251 coil and all the spark plugs were clean.

From what you're describing, a new coil was installed at the same time as the 7 series box....is this correct ? The reason i bring this up is because the coil likely helped more than the switch in boxes. The 6al works well, even better with a high voltage coil.  I have a buddy who ran 10's for years with an old 6A box and no rev limiter....he tried a digital box and went back to the old 6a because of electrical gremlins. The digital boxes are very sensitive to electrical interference from other wiring. The distributor feed wires need to be shielded & isolated from all other wiring or the box can act wierd. 


Ron

[dodge freak]

Thats true I never said get a digital box! The 7 comes both ways-the 7al is not digital-the digital one should never be use on the street only the 6 can be. I seen the horror story's too on those digital boxes-might be why it comes both ways. The coil I just change this spring the box I changed last summer, before I was using a Morroso plasm coil , cost $80 , maybe it was cause my MSD 6a was 8 years old. Maybe I am not be fair comparing a brand new 7al to a 8 year old 6a box, but like I said for $150 I would just get the stronger box even if is over kill.

[dodge freak]

The MSD 7220 is the one thats not digital --The 7530t,-75301,-7535,-, 7531 7520 are all digital and will burn up on a street motor-and be a pain to work with. Why do MSD even make them IDK but I would never get one. MSD has the 8 units and the 10 unit boxes if you need more spark and those are not digital also. But that would be a waste and you might start getting in to crossfire problems with that strong of a spark.

[tick68charger]

I like over kill! I'll look at all the boxes and coils, but I think I will do the over kill. I'll report my findings. Thanks All!

[grouseman]

Next time it happens, pour water on your mechanical fuel pump and report back.