Hot start issue, help needed

[vick79]

Hi Guys, Trying to sort out some hot starting issues I'm having. Starts up well when cold. Starter is strong when it turns over, carb and fuel lines cool to touch.. it just doesnt fire up.  So far I've done the following to try to fix it. I've got hedman headers btw.

-New starter (old one had broken journal )heat wrapped before install
-Holley carb was rebuilt professionally
-1/2" carb spacer added
-new ignition coil
-new spark plugs
-changed oil

I'm changing the distributor tomorrow when it arrives, my vac advance was broken.

I feel its getting fuel, maybe weak spark? Bad coil? How do i find out? Any ideas what to check next?

[johnnyseville]

Electronic ignition or points?  If electronic is it Mopar magnets?  If so, maybe dist pickup is bad, they are a problem when engine is up to operation temperature then work fine when engine cools down,  othewise consider vapor lock, maybe a fuel line is passing too close to the headers.  Does it have stock fuel pump with return vapor line, you can check that too.

[vick79]

I have electronic ignition, Mopar magnets. Actually I have been having issues with the dist lately, diaphragm was siezed, I get my replacement tomorrow.

I will check the lines passing near the headers.

Electronic ignition or points?  If electronic is it Mopar magnets?  If so, maybe dist pickup is bad, they are a problem when engine is up to operation temperature then work fine when engine cools down,  othewise consider vapor lock, maybe a fuel line is passing too close to the headers.  Does it have stock fuel pump with return vapor line, you can check that too.

[b5blue]

Is the heat passage to the intake blocked? (It should be if intake is aluminum.)

[Cooter]

Mopar Electronic Ignition? If so, try another Control Box. Usually, these are the "hot Start" problem.

[John_Kunkel]

Will it hot start if you hold the throttle wide open?

[vick79]

Will it hot start if you hold the throttle wide open?

Never tried doing that, ill give that a try tonight

Ordered the felpro 1215 gasket to block the heat crossover.

[b5blue]

  Pay attention to the gaskets for above and below the valley plate. Depending on your exact build you may need thinner or thicker ones to match the compressed height of your intake to heads. You'll know when you mock it up, the bolts may pinch the fit if too thick.
  I drilled a 1/8th hole in both L and R sides of the block off to allow "just a little heat" on my aluminum six pack manifold. That solved my heat soak and still gave heat to the choke well so it pulls the choke off sooner. 

[vick79]

  Pay attention to the gaskets for above and below the valley plate. Depending on your exact build you may need thinner or thicker ones to match the compressed height of your intake to heads. You'll know when you mock it up, the bolts may pinch the fit if too thick.
  I drilled a 1/8th hole in both L and R sides of the block off to allow "just a little heat" on my aluminum six pack manifold. That solved my heat soak and still gave heat to the choke well so it pulls the choke off sooner. 

I have an electric choke on my Holley, so I could probably skip drilling holes?

[vick79]

Will it hot start if you hold the throttle wide open?

I tried this tonight when I had trouble starting and it worked, fired right up. What does that mean?

I really appreciate all the help from everyone. This is my first carburated car!

[b5blue]

  Pay attention to the gaskets for above and below the valley plate. Depending on your exact build you may need thinner or thicker ones to match the compressed height of your intake to heads. You'll know when you mock it up, the bolts may pinch the fit if too thick.
  I drilled a 1/8th hole in both L and R sides of the block off to allow "just a little heat" on my aluminum six pack manifold. That solved my heat soak and still gave heat to the choke well so it pulls the choke off sooner. 

I have an electric choke on my Holley, so I could probably skip drilling holes?

Yea no need to. Matting the peddle when hot bypasses the throttle plates as they are wide open, you get a big shot of air that helps overcome the hot air/fuel in the intake. (I got by that way for a long time.) 

[vick79]

Took my intake off, holy sh** threw my back out that thing is heavy. I'm used to plastic/aluminum intakes 

Pan looked in poor shape, did not find any gaskets in between pan,block,manifold, thought that was odd?

The felpro kit comes with them.

Hoping the heat block, and a good idle mixture tune will fix it.

[cowboy4x4n]

does this also work with small blocks.  when my motor gets up to operating temp and u shut off for a min or two its hard starting.  ive done everything from phenolic spacers to re-routing the fuel line to cool the fuel.

[b5blue]

does this also work with small blocks.  when my motor gets up to operating temp and u shut off for a min or two its hard starting.  ive done everything from phenolic spacers to re-routing the fuel line to cool the fuel.

It should, heat block off is "mostly for aluminum intakes" as the heat up much faster and seem to stay hotter.

The oil on top of the valley pan is from the lack of gaskets, also put sealant on intake to head bolts as oil can "creep up" sometimes. Many debate gaskets/no gaskets, I go by the "Mopar Performance B/RB Book" and Larry Shepard's "Performance Tuning Six Pack Engines" book.  Pay close attention to the intakes mating surfaces as it effects port alignment!   

[Brightyellow69rtse]

if your timing is too far advanced it will do that too. back it off a hair and see if it fixes it. i would use the cross over blockoff anyway even if i wasnt having a problem.

[vick79]

I cleaned both cylinder head and intake mating surfaces with WD-40 and a sharp razor blade to remove all the buildup till it was nice and smooth. Installed valley pan with hi-temp silicone over the 4 corners of the valley and across. Didnt install the paper gaskets.

Waiting for it to dry.

[vick79]

that valley pan made a big difference, no where near as hard to get started! 

[b5blue]

Keep checking for oil on the back of the valley pan.